Performance, meat quality, and pectoral myopathies of broilers fed either corn or sorghum based diets supplemented with guanidinoacetic acid

Performance, meat quality, and pectoral myopathies of broilers fed either corn or sorghum based... ABSTRACT One experiment was conducted to evaluate the effects of guanidinoacetic acid (GAA) supplementation in broilers fed corn or sorghum-based diets on live performance, carcass and cut up yields, meat quality, and pectoral myopathies. The treatments consisted of corn or sorghum-based diets with or without the addition of GAA (600 g/ton). A total of 800 one-d-old male Ross 708 broiler chicks were randomly placed in 40 floor pens with 10 replicates (20 birds per pen) per each of the four treatments. At hatch, 14, 35, and 50 d, BW and feed intake were recorded. BW gain and FCR were calculated at the end of each phase. Four broilers per pen were selected and slaughtered at 51d and 55d of age to determine carcass and cut up yields, meat quality and myopathies (spaghetti muscle, white striping, and wooden breast) severity in the Pectoralis major. Data were analyzed as a randomized complete block design in a 2 × 2 factorial arrangement with grain type and GAA supplementation as main effects. At 50 d, diets containing GAA improved (P < 0.01) FCR (1.682 vs. 1.724 g: g) independently of grain type. At 55 d, broilers fed corn diets with GAA had higher breast meat yield (P < 0.05) compared to corn without GAA. Drip and cook loss, and shear force (Warner-Bratzler) were not affected (P > 0.05) by GAA supplementation at any slaughter ages. However, GAA decreased (P < 0.05) the ultimate pH at 51 and 55 d in breast meat samples compared to unsupplemented diets. At 51 d, broilers supplemented with GAA had double (P < 0.05) breast meat fillets without wooden breast (score 1) compared with broilers fed non-supplemented diets, therefore reducing the severity of this myopathy. In conclusion, GAA supplementation improved broiler live performance in broilers raised up to 50 d independently of grain source, increased breast meat yield in corn-based diets and reduced the severity of wooden breast myopathy. INTRODUCTION Dietary guanidinoacetic acid (GAA) has been proven to act as precursor of creatine (Ringel et al., 2007; Michiels et al., 2012, DeGroot, 2014) as does endogenous GAA. Creatine and its phosphorylated form phospho-creatine are naturally occurring metabolites and play a major role in muscle cellular energy metabolism (Wyss and Kaddurah-Daouk, 2000). The creatine/phospho-creatine system functions as a backup to the adenosine tri-phosphate (ATP)/adenosine di-phosphate system to store and mobilize energy when required on short notice, particularly in muscle cells (Lemme et al., 2007a). Creatine can be produced naturally in the body from GAA, which in turn is synthesized from the amino acids arginine and glycine (Wyss and Kaddurah-Daouk, 2000). GAA is a compound synthesized in the avian kidney and liver (Wyss and Kaddurah-Daouk, 2000). It has been reported (Ringel et al., 2007) that dietary GAA was efficiently transformed to creatine in the liver which subsequently was transported to the muscles. Consequently, affecting muscle development (Lemme et al., 2007b; Michiels et al., 2012; Heger et al., 2014; Esser et al., 2017). Previous studies showed that GAA supplementation improved FCR in male broilers fed diets containing corn and wheat-based diets at 41 d of age (Lemme, et al., 2007b) or corn-soybean meal diets (Ringel et al.,2007). Other researchers found that GAA supplementation had a sparing effect on arginine, therefore replacing dietary arginine efficiently in young chicks (Dilger et al., 2013; DeGroot, 2014). It has been discussed (Ringel et al., 2007) that as long as animal by-products formed a certain part of poultry diets, no signs of creatine deficiency may be detected. However, there is an increasing trend in the poultry industry to use the denominated “all vegetable” diets based only in plant ingredients (Vieira and Lima, 2005). As a result, dietary creatine supply will be marginally low in vegetable protein sources since it has been reported (Khan and Cowen, 1977; Gabor et al., 1984) that these feedstuffs contain limited (< 0.01 mg/g) or no creatine. Generally, poultry diets are comprised of corn because of its higher dietary energy content compared to other cereal grains (Mohamed et al., 2015). Although it is produced throughout the world, there is a stiff competition for corn among human consumption, ethanol production and the feed industry. Additionally, the poultry industry has faced high variability on feed costs (Etuk et al., 2012). Consequently, the use of alternative feed ingredients such as sorghum has been considered (Torres et al., 2013; Tandiang et al., 2014). Some low-tannin sorghum varieties had been assessed to have the potential to replace corn as an alternative poultry feed ingredient. Its nutritional value is only slightly lower than corn (Douglas et al., 1990). Low-tannin sorghum has been shown to substitute corn in poultry feeds without affecting live performance (Garcia et al., 2005; Campos, 2006; Bozutti, 2009). In contrast, some other authors had found that high-tannin sorghum negatively affected live performance (Pour-Reza and Edriss, 1997). Kumar et al. (2005) concluded that cut up yields, especially breast meat yield, were not affected by different tannin levels in red sorghum. Therefore, the use of sorghum with low tannin content could be an alternative for corn in poultry diets (Tandiang et al., 2014). Lemme et al. (2007a) observed that dietary inclusion of 20% sorghum and GAA supplementation improved FCR and breast meat yield, compared with broilers fed a negative control corn-sorghum diet without GAA, when broilers were raised up to 42 d of age. According to Li et al. (2011) sorghum showed similar total amino acid content in arginine and glycine (main sources for the synthesis of creatine) when compared to corn. However, Ebadi et al. (2005) suggested that availability of amino acids can be reduced by higher tannin content in the grain. Methionine, cysteine, lysine, arginine, and proline availability were decreased up to 23, 44, 32, 54, and 75%, respectively due to medium (0.19%) or high (0.37%) tannin content in the grain. Consequently, a better response on live performance could be expected in sorghum-based diets when GAA is supplemented. An increasing demand for white chicken meat has made the poultry industry focus on the selection of genotypes exhibiting faster growth rates with higher breast yields. Concurrently, pectoral myopathies, such as wooden breast (WB) and white striping (WS), are emerging as an increasing problem (Tasoniero et al., 2016). Based on mice trials, creatine may have a protective role in certain neuromuscular (Chung et al., 2007; Tarnopolsky, 2007) and neuro-degenerative diseases (Bender et al., 2006; Kolling and Wyse, 2010; Beal, 2011), and could potentially reverse muscular dystrophy (Nabuurs et al., 2013). Consequently, it could be hypothesized that GAA as precursor of creatine may play a role to prevent the inhibition of energy metabolism and lipid peroxidation related to muscle myopathies (Abasht et al., 2016). Even though most of the studies of GAA had evaluated live performance, there has been no previous data about the effects of supplementing GAA on pectoral myopathies in modern commercial broiler chickens. Therefore, the aim of the present trial was to evaluate the effects of GAA supplementation in corn or sorghum based-diets on live performance, carcass and cut up yields, meat quality and pectoral myopathies. MATERIALS AND METHODS Treatments and Birds Husbandry All procedures involving broiler chicken used in the present experiment were approved by the North Carolina State University Institutional Animal Care and Use Committee. Four treatments from a 2 × 2 factorial arrangement with 2 grain-based diets (corn or sorghum) and two levels of GAA (0 and 0.06%) supplementation (CreAMINO®, GAA content min. 96%) in all feeding phases as main factors. This study was conducted in a solid side wall house with negative pressure ventilation, tunnel capabilities, and evaporative cooling. A total of 800 Ross-708 d-old male chicks were placed in 40 floor pens (1.21 × 1.82 m) with 20 chicks per pen (9.18 broilers/m2 at placement) to form 10 replicate pens per treatment. Final stocking density was 37.5 kg/m2 at 50 d of age. Broilers were raised on used litter. Chickens were exposed to continuous light on a 23L:1D (30 lux of light intensity) program during the first 7 d of age. Day length was then gradually reduced to 17L:7D (10 lux) up to 28 d of age. From 28 d until the end of the experiment at 56 d, light program was maintained at 17L:7D with a light intensity of 5 lux. Brooding house temperature was set at 33.6°C at placement and gradually reduced until 20.6°C at 21 d of age kept until study end to guarantee chicken temperature comfort. Diets Basal diets were formulated (Table 1) to represent typical U.S. broiler industry practices (AgriStats, 2016), and digestible amino acid levels were based on AminoDat 5.0 (2015) recommendations (Table 2). Macro ingredients (corn, sorghum, soybean meal, and distilled dried grain with solubles) were analyzed for total amino acid and ME content prior to diet formulation. Digestible amino acid content was calculated from the total amino acid content obtained from lab analyses and using table values for digestibility coefficients (AminoDat 5.0, 2015). The ME values (kcal/kg) were obtained from an in vivo trial with roosters (Dr. Nick Dale, University of Georgia), since this technique is widely used (Bryden and Li, 2010) presenting some advantages as compared to other bioassays (Parsons, 1985; Garcia et al., 2007). Condensed tannins content (%) in sorghum were calculated from the absorbance at 500 nm of the anthocyanidin solutions (Makkar and Becker, 1993; Brenes et al., 2008). Diets were formulated to contain either corn or sorghum as the main grain source, soybean meal (SBM), and distilled dried grain with solubles (DDGs) as protein source. All dietary treatments were formulated to be isoenergetic, and isonitrogenous. Starter, grower, finisher and withdrawal diets were fed from 0–14, 15–35, 36–42, and 43–55 d of age, respectively. Starter was fed in crumbles and all other diets in pellets. For the pelleting process a temperature between 82 and 85°C in the conditioner was used for 30 seconds. The steam pressure was 32 psi, and the pellet die was 11/64” x 1” 3/8” (4.4 × 34.9 mm) for an L/D ratio of 8. The capacity of pelleting used was two to five ton/hour to improve pellet quality. After being crumbled or pelleted, representative samples of each manufactured diet were analyzed for crude protein, and total amino acids. Creatine and GAA (Table 3) in feed were determined by AlzChem AG (Trosberg, Germany) according to the ion chromatography method (CRL Feed Additives, 2007). Experimental diets were formulated either from corn or sorghum basal diets to ensure that diets had similar nutrient content independently of grain source. GAA was added “on top” of the basal diets (600 g/ton) in the corresponding treatments. For each one of the dietary phases 0.85, 2.90, and 2.48 kg of starter, grower and finisher, respectively, were offered for each bird alive during each phase. The withdrawal diet was offered ad libitum. Water was provided for ad libitum consumption. Feeders were shaken twice daily to stimulate uniform feed intake. Table 1. Ingredient composition of starter, grower, finisher and withdrawal basal diets for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Ingredient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum    ——————————————————– % ——————————————————–  Corn  52.509  -  56.573  -  60.911  -  64.344  -  Soybean meal, 46%  33.973  32.097  29.998  27.990  25.784  23.667  22.866  20.568  Sorghum  -  54.263  -  58.460  -  62.934  -  66.492  DDGs  5.000  5.000  5.000  5.000  5.000  5.000  5.000  5.000  Poultry fat  4.302  4.112  4.849  4.643  5.114  4.885  4.847  4.614  Limestone fine  1.366  1.414  1.166  1.218  1.095  1.151  1.109  1.168  Dicalcium phosphate, 18.5%  1.151  1.232  0.915  1.001  0.736  0.828  0.431  0.530  Salt (NaCl)  0.303  0.246  0.312  0.252  0.281  0.216  0.251  0.182  DL- Methionine, 99%  0.286  0.315  0.239  0.271  0.197  0.231  0.197  0.234  L-Lysine-HCl, 78.8%  0.218  0.304  0.160  0.252  0.123  0.220  0.171  0.276  Mineral premix2  0.200  0.200  0.200  0.200  0.200  0.200  0.200  0.200  Sodium bicarbonate  0.183  0.256  0.134  0.212  0.177  0.261  0.185  0.274  Choline chloride, 60%  0.180  0.180  0.180  0.180  0.180  0.180  0.180  0.180  Vitamin premix3  0.100  0.100  0.100  0.100  0.100  0.100  0.100  0.100  L-Threonine, 98%  0.081  0.103  0.055  0.078  0.035  0.059  0.052  0.079  Sand or GAA5  0.060  0.060  0.060  0.060  0.060  0.060  0.060  0.060  Coccidiostat1  0.050  0.050  0.050  0.050  -  -  -  -  L-Valine, 96.5%  0.031  0.060  0.001  0.025  0.001  0.001  -  0.035  Phytase4  0.008  0.008  0.008  0.008  0.008  0.008  0.008  0.008  Total  100.00  100.00  100.00  100.00  100.00  100.00  100.00  100.00    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Ingredient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum    ——————————————————– % ——————————————————–  Corn  52.509  -  56.573  -  60.911  -  64.344  -  Soybean meal, 46%  33.973  32.097  29.998  27.990  25.784  23.667  22.866  20.568  Sorghum  -  54.263  -  58.460  -  62.934  -  66.492  DDGs  5.000  5.000  5.000  5.000  5.000  5.000  5.000  5.000  Poultry fat  4.302  4.112  4.849  4.643  5.114  4.885  4.847  4.614  Limestone fine  1.366  1.414  1.166  1.218  1.095  1.151  1.109  1.168  Dicalcium phosphate, 18.5%  1.151  1.232  0.915  1.001  0.736  0.828  0.431  0.530  Salt (NaCl)  0.303  0.246  0.312  0.252  0.281  0.216  0.251  0.182  DL- Methionine, 99%  0.286  0.315  0.239  0.271  0.197  0.231  0.197  0.234  L-Lysine-HCl, 78.8%  0.218  0.304  0.160  0.252  0.123  0.220  0.171  0.276  Mineral premix2  0.200  0.200  0.200  0.200  0.200  0.200  0.200  0.200  Sodium bicarbonate  0.183  0.256  0.134  0.212  0.177  0.261  0.185  0.274  Choline chloride, 60%  0.180  0.180  0.180  0.180  0.180  0.180  0.180  0.180  Vitamin premix3  0.100  0.100  0.100  0.100  0.100  0.100  0.100  0.100  L-Threonine, 98%  0.081  0.103  0.055  0.078  0.035  0.059  0.052  0.079  Sand or GAA5  0.060  0.060  0.060  0.060  0.060  0.060  0.060  0.060  Coccidiostat1  0.050  0.050  0.050  0.050  -  -  -  -  L-Valine, 96.5%  0.031  0.060  0.001  0.025  0.001  0.001  -  0.035  Phytase4  0.008  0.008  0.008  0.008  0.008  0.008  0.008  0.008  Total  100.00  100.00  100.00  100.00  100.00  100.00  100.00  100.00  1Coban® 90 (Monensin), Elanco Animal Health, Greenfield, IN, at 500 g/ton in the starter and grower diets. 2Trace minerals provided per kg of premix: manganese (Mn SO4), 60 g; zinc (ZnSO4), 60 g; iron (FeSO4), 40 g; copper (CuSO4), 5 g; iodine (Ca(IO3)2),1.25 g. 3Vitamins provided per kg of premix: vitamin A, 13,227,513 IU; vitamin D3, 3968,253 IU; vitamin E, 66,137 IU; vitamin B12, 39.6 mg; riboflavin, 13,227 mg; niacin, 110,229 mg; d-pantothenic acid, 22,045 mg; menadione, 3968 mg; folic acid, 2204 mg; vitamin B6, 7936 mg; thiamine, 3968 mg; biotin, 253.5 mg. 4Quantum Blue 5G® at 0.176 lbs/ton (80 g/ton) to provide 500 FYT (AB Vista) delivering 0.13% of available P, 0.06% of calcium and 0.03% of sodium. 5CreAMINO: Guanidinoacetic acid (GAA) with 96% of concentration, Lot number 3/29/16. Evonik Industries, Evonik Degussa GmbH, Hanau-Wolfgang, Germany. View Large Table 1. Ingredient composition of starter, grower, finisher and withdrawal basal diets for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Ingredient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum    ——————————————————– % ——————————————————–  Corn  52.509  -  56.573  -  60.911  -  64.344  -  Soybean meal, 46%  33.973  32.097  29.998  27.990  25.784  23.667  22.866  20.568  Sorghum  -  54.263  -  58.460  -  62.934  -  66.492  DDGs  5.000  5.000  5.000  5.000  5.000  5.000  5.000  5.000  Poultry fat  4.302  4.112  4.849  4.643  5.114  4.885  4.847  4.614  Limestone fine  1.366  1.414  1.166  1.218  1.095  1.151  1.109  1.168  Dicalcium phosphate, 18.5%  1.151  1.232  0.915  1.001  0.736  0.828  0.431  0.530  Salt (NaCl)  0.303  0.246  0.312  0.252  0.281  0.216  0.251  0.182  DL- Methionine, 99%  0.286  0.315  0.239  0.271  0.197  0.231  0.197  0.234  L-Lysine-HCl, 78.8%  0.218  0.304  0.160  0.252  0.123  0.220  0.171  0.276  Mineral premix2  0.200  0.200  0.200  0.200  0.200  0.200  0.200  0.200  Sodium bicarbonate  0.183  0.256  0.134  0.212  0.177  0.261  0.185  0.274  Choline chloride, 60%  0.180  0.180  0.180  0.180  0.180  0.180  0.180  0.180  Vitamin premix3  0.100  0.100  0.100  0.100  0.100  0.100  0.100  0.100  L-Threonine, 98%  0.081  0.103  0.055  0.078  0.035  0.059  0.052  0.079  Sand or GAA5  0.060  0.060  0.060  0.060  0.060  0.060  0.060  0.060  Coccidiostat1  0.050  0.050  0.050  0.050  -  -  -  -  L-Valine, 96.5%  0.031  0.060  0.001  0.025  0.001  0.001  -  0.035  Phytase4  0.008  0.008  0.008  0.008  0.008  0.008  0.008  0.008  Total  100.00  100.00  100.00  100.00  100.00  100.00  100.00  100.00    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Ingredient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum    ——————————————————– % ——————————————————–  Corn  52.509  -  56.573  -  60.911  -  64.344  -  Soybean meal, 46%  33.973  32.097  29.998  27.990  25.784  23.667  22.866  20.568  Sorghum  -  54.263  -  58.460  -  62.934  -  66.492  DDGs  5.000  5.000  5.000  5.000  5.000  5.000  5.000  5.000  Poultry fat  4.302  4.112  4.849  4.643  5.114  4.885  4.847  4.614  Limestone fine  1.366  1.414  1.166  1.218  1.095  1.151  1.109  1.168  Dicalcium phosphate, 18.5%  1.151  1.232  0.915  1.001  0.736  0.828  0.431  0.530  Salt (NaCl)  0.303  0.246  0.312  0.252  0.281  0.216  0.251  0.182  DL- Methionine, 99%  0.286  0.315  0.239  0.271  0.197  0.231  0.197  0.234  L-Lysine-HCl, 78.8%  0.218  0.304  0.160  0.252  0.123  0.220  0.171  0.276  Mineral premix2  0.200  0.200  0.200  0.200  0.200  0.200  0.200  0.200  Sodium bicarbonate  0.183  0.256  0.134  0.212  0.177  0.261  0.185  0.274  Choline chloride, 60%  0.180  0.180  0.180  0.180  0.180  0.180  0.180  0.180  Vitamin premix3  0.100  0.100  0.100  0.100  0.100  0.100  0.100  0.100  L-Threonine, 98%  0.081  0.103  0.055  0.078  0.035  0.059  0.052  0.079  Sand or GAA5  0.060  0.060  0.060  0.060  0.060  0.060  0.060  0.060  Coccidiostat1  0.050  0.050  0.050  0.050  -  -  -  -  L-Valine, 96.5%  0.031  0.060  0.001  0.025  0.001  0.001  -  0.035  Phytase4  0.008  0.008  0.008  0.008  0.008  0.008  0.008  0.008  Total  100.00  100.00  100.00  100.00  100.00  100.00  100.00  100.00  1Coban® 90 (Monensin), Elanco Animal Health, Greenfield, IN, at 500 g/ton in the starter and grower diets. 2Trace minerals provided per kg of premix: manganese (Mn SO4), 60 g; zinc (ZnSO4), 60 g; iron (FeSO4), 40 g; copper (CuSO4), 5 g; iodine (Ca(IO3)2),1.25 g. 3Vitamins provided per kg of premix: vitamin A, 13,227,513 IU; vitamin D3, 3968,253 IU; vitamin E, 66,137 IU; vitamin B12, 39.6 mg; riboflavin, 13,227 mg; niacin, 110,229 mg; d-pantothenic acid, 22,045 mg; menadione, 3968 mg; folic acid, 2204 mg; vitamin B6, 7936 mg; thiamine, 3968 mg; biotin, 253.5 mg. 4Quantum Blue 5G® at 0.176 lbs/ton (80 g/ton) to provide 500 FYT (AB Vista) delivering 0.13% of available P, 0.06% of calcium and 0.03% of sodium. 5CreAMINO: Guanidinoacetic acid (GAA) with 96% of concentration, Lot number 3/29/16. Evonik Industries, Evonik Degussa GmbH, Hanau-Wolfgang, Germany. View Large Table 2. Calculated and analyzed nutrient content of basal starter, grower, finisher, and withdrawal diets for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Nutrient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Calculated nutritive value                  Metabolizable Energy, kcal/kg  3000  3000  3085  3085  3150  3150  3175  3175  Crude protein, %  22.11  22.11  20.41  20.41  18.68  18.68  17.60  17.60  Calcium, %  1.02  1.02  0.90  0.90  0.82  0.82  0.76  0.76  Total phosphorus, %  0.57  0.61  0.51  0.56  0.46  0.51  0.39  0.45  Nonphytate phosphorus, %  0.50  0.50  0.45  0.45  0.41  0.41  0.35  0.35  Total Glycine, %  0.91  0.87  0.84  0.80  0.77  0.72  0.73  0.67  Digestible lysine, %  1.22  1.22  1.08  1.08  0.95  0.95  0.92  0.92  Digestible methionine, %  0.59  0.60  0.53  0.54  0.47  0.48  0.46  0.48  Digestible total sulfur amino acids, %  0.89  0.89  0.81  0.81  0.73  0.73  0.71  0.71  Digestible threonine, %  0.78  0.78  0.70  0.70  0.63  0.63  0.61  0.61  Digestible tryptophan, %  0.23  0.24  0.21  0.22  0.19  0.20  0.18  0.18  Digestible valine, %  0.94  0.97  0.85  0.87  0.78  0.81  0.73  0.77  Digestible isoleucine, %  0.83  0.84  0.77  0.78  0.70  0.71  0.65  0.66  Digestible arginine, %  1.35  1.26  1.24  1.13  1.12  1.01  1.04  0.92  Sodium, %  0.20  0.20  0.19  0.19  0.19  0.19  0.18  0.18  Potassium, %  0.94  0.91  0.87  0.84  0.80  0.77  0.75  0.72  Chloride, %  0.28  0.28  0.28  0.28  0.24  0.24  0.25  0.25  Dietary electrolyte balance, mEq/100 g  264  262  241  239  232  230  216  213  Analyzed nutritive value1                  Crude protein, %  23.42  21.38  21.97  20.61  19.17  19.06  17.36  18.82  Total lysine, %  1.37  1.23  1.25  1.18  1.06  1.05  1.01  1.04  Total methionine, %  0.54  0.52  0.51  0.51  0.47  0.48  0.43  0.49  Total sulfur amino acids, %  0.90  0.84  0.85  0.82  0.78  0.79  0.72  0.78  Total threonine, %  0.93  0.86  0.85  0.82  0.76  0.76  0.68  0.73  Total glycine, %  0.95  0.83  0.88  0.79  0.79  0.74  0.72  0.72  Total valine, %  1.11  1.03  0.99  0.94  0.91  0.92  0.82  0.92  Total arginine, %  1.53  1.30  1.41  1.23  1.24  1.13  1.10  1.08    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Nutrient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Calculated nutritive value                  Metabolizable Energy, kcal/kg  3000  3000  3085  3085  3150  3150  3175  3175  Crude protein, %  22.11  22.11  20.41  20.41  18.68  18.68  17.60  17.60  Calcium, %  1.02  1.02  0.90  0.90  0.82  0.82  0.76  0.76  Total phosphorus, %  0.57  0.61  0.51  0.56  0.46  0.51  0.39  0.45  Nonphytate phosphorus, %  0.50  0.50  0.45  0.45  0.41  0.41  0.35  0.35  Total Glycine, %  0.91  0.87  0.84  0.80  0.77  0.72  0.73  0.67  Digestible lysine, %  1.22  1.22  1.08  1.08  0.95  0.95  0.92  0.92  Digestible methionine, %  0.59  0.60  0.53  0.54  0.47  0.48  0.46  0.48  Digestible total sulfur amino acids, %  0.89  0.89  0.81  0.81  0.73  0.73  0.71  0.71  Digestible threonine, %  0.78  0.78  0.70  0.70  0.63  0.63  0.61  0.61  Digestible tryptophan, %  0.23  0.24  0.21  0.22  0.19  0.20  0.18  0.18  Digestible valine, %  0.94  0.97  0.85  0.87  0.78  0.81  0.73  0.77  Digestible isoleucine, %  0.83  0.84  0.77  0.78  0.70  0.71  0.65  0.66  Digestible arginine, %  1.35  1.26  1.24  1.13  1.12  1.01  1.04  0.92  Sodium, %  0.20  0.20  0.19  0.19  0.19  0.19  0.18  0.18  Potassium, %  0.94  0.91  0.87  0.84  0.80  0.77  0.75  0.72  Chloride, %  0.28  0.28  0.28  0.28  0.24  0.24  0.25  0.25  Dietary electrolyte balance, mEq/100 g  264  262  241  239  232  230  216  213  Analyzed nutritive value1                  Crude protein, %  23.42  21.38  21.97  20.61  19.17  19.06  17.36  18.82  Total lysine, %  1.37  1.23  1.25  1.18  1.06  1.05  1.01  1.04  Total methionine, %  0.54  0.52  0.51  0.51  0.47  0.48  0.43  0.49  Total sulfur amino acids, %  0.90  0.84  0.85  0.82  0.78  0.79  0.72  0.78  Total threonine, %  0.93  0.86  0.85  0.82  0.76  0.76  0.68  0.73  Total glycine, %  0.95  0.83  0.88  0.79  0.79  0.74  0.72  0.72  Total valine, %  1.11  1.03  0.99  0.94  0.91  0.92  0.82  0.92  Total arginine, %  1.53  1.30  1.41  1.23  1.24  1.13  1.10  1.08  1Analyzed values are means of 2 samples. View Large Table 2. Calculated and analyzed nutrient content of basal starter, grower, finisher, and withdrawal diets for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Nutrient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Calculated nutritive value                  Metabolizable Energy, kcal/kg  3000  3000  3085  3085  3150  3150  3175  3175  Crude protein, %  22.11  22.11  20.41  20.41  18.68  18.68  17.60  17.60  Calcium, %  1.02  1.02  0.90  0.90  0.82  0.82  0.76  0.76  Total phosphorus, %  0.57  0.61  0.51  0.56  0.46  0.51  0.39  0.45  Nonphytate phosphorus, %  0.50  0.50  0.45  0.45  0.41  0.41  0.35  0.35  Total Glycine, %  0.91  0.87  0.84  0.80  0.77  0.72  0.73  0.67  Digestible lysine, %  1.22  1.22  1.08  1.08  0.95  0.95  0.92  0.92  Digestible methionine, %  0.59  0.60  0.53  0.54  0.47  0.48  0.46  0.48  Digestible total sulfur amino acids, %  0.89  0.89  0.81  0.81  0.73  0.73  0.71  0.71  Digestible threonine, %  0.78  0.78  0.70  0.70  0.63  0.63  0.61  0.61  Digestible tryptophan, %  0.23  0.24  0.21  0.22  0.19  0.20  0.18  0.18  Digestible valine, %  0.94  0.97  0.85  0.87  0.78  0.81  0.73  0.77  Digestible isoleucine, %  0.83  0.84  0.77  0.78  0.70  0.71  0.65  0.66  Digestible arginine, %  1.35  1.26  1.24  1.13  1.12  1.01  1.04  0.92  Sodium, %  0.20  0.20  0.19  0.19  0.19  0.19  0.18  0.18  Potassium, %  0.94  0.91  0.87  0.84  0.80  0.77  0.75  0.72  Chloride, %  0.28  0.28  0.28  0.28  0.24  0.24  0.25  0.25  Dietary electrolyte balance, mEq/100 g  264  262  241  239  232  230  216  213  Analyzed nutritive value1                  Crude protein, %  23.42  21.38  21.97  20.61  19.17  19.06  17.36  18.82  Total lysine, %  1.37  1.23  1.25  1.18  1.06  1.05  1.01  1.04  Total methionine, %  0.54  0.52  0.51  0.51  0.47  0.48  0.43  0.49  Total sulfur amino acids, %  0.90  0.84  0.85  0.82  0.78  0.79  0.72  0.78  Total threonine, %  0.93  0.86  0.85  0.82  0.76  0.76  0.68  0.73  Total glycine, %  0.95  0.83  0.88  0.79  0.79  0.74  0.72  0.72  Total valine, %  1.11  1.03  0.99  0.94  0.91  0.92  0.82  0.92  Total arginine, %  1.53  1.30  1.41  1.23  1.24  1.13  1.10  1.08    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Nutrient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Calculated nutritive value                  Metabolizable Energy, kcal/kg  3000  3000  3085  3085  3150  3150  3175  3175  Crude protein, %  22.11  22.11  20.41  20.41  18.68  18.68  17.60  17.60  Calcium, %  1.02  1.02  0.90  0.90  0.82  0.82  0.76  0.76  Total phosphorus, %  0.57  0.61  0.51  0.56  0.46  0.51  0.39  0.45  Nonphytate phosphorus, %  0.50  0.50  0.45  0.45  0.41  0.41  0.35  0.35  Total Glycine, %  0.91  0.87  0.84  0.80  0.77  0.72  0.73  0.67  Digestible lysine, %  1.22  1.22  1.08  1.08  0.95  0.95  0.92  0.92  Digestible methionine, %  0.59  0.60  0.53  0.54  0.47  0.48  0.46  0.48  Digestible total sulfur amino acids, %  0.89  0.89  0.81  0.81  0.73  0.73  0.71  0.71  Digestible threonine, %  0.78  0.78  0.70  0.70  0.63  0.63  0.61  0.61  Digestible tryptophan, %  0.23  0.24  0.21  0.22  0.19  0.20  0.18  0.18  Digestible valine, %  0.94  0.97  0.85  0.87  0.78  0.81  0.73  0.77  Digestible isoleucine, %  0.83  0.84  0.77  0.78  0.70  0.71  0.65  0.66  Digestible arginine, %  1.35  1.26  1.24  1.13  1.12  1.01  1.04  0.92  Sodium, %  0.20  0.20  0.19  0.19  0.19  0.19  0.18  0.18  Potassium, %  0.94  0.91  0.87  0.84  0.80  0.77  0.75  0.72  Chloride, %  0.28  0.28  0.28  0.28  0.24  0.24  0.25  0.25  Dietary electrolyte balance, mEq/100 g  264  262  241  239  232  230  216  213  Analyzed nutritive value1                  Crude protein, %  23.42  21.38  21.97  20.61  19.17  19.06  17.36  18.82  Total lysine, %  1.37  1.23  1.25  1.18  1.06  1.05  1.01  1.04  Total methionine, %  0.54  0.52  0.51  0.51  0.47  0.48  0.43  0.49  Total sulfur amino acids, %  0.90  0.84  0.85  0.82  0.78  0.79  0.72  0.78  Total threonine, %  0.93  0.86  0.85  0.82  0.76  0.76  0.68  0.73  Total glycine, %  0.95  0.83  0.88  0.79  0.79  0.74  0.72  0.72  Total valine, %  1.11  1.03  0.99  0.94  0.91  0.92  0.82  0.92  Total arginine, %  1.53  1.30  1.41  1.23  1.24  1.13  1.10  1.08  1Analyzed values are means of 2 samples. View Large Table 3. Analyzed nutrient content of the dietary treatments for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)    Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Nutrient  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  Calculated                                  GAA, mg/kg, as is  0  600  0  600  0  600  0  600  0  600  0  600  0  600  0  600  Analyzed1                                  Creatine, mg/kg, as is  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  GAA, mg/kg, as is  27  504  1  464  14  594  4  513  <20  528  <20  474  <20  526  <20  406  CreAMINO2, mg/kg, as is  28  525  1  483  15  619  4  534  <21  550  <21  494  <21  548  <21  423    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)    Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Nutrient  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  Calculated                                  GAA, mg/kg, as is  0  600  0  600  0  600  0  600  0  600  0  600  0  600  0  600  Analyzed1                                  Creatine, mg/kg, as is  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  GAA, mg/kg, as is  27  504  1  464  14  594  4  513  <20  528  <20  474  <20  526  <20  406  CreAMINO2, mg/kg, as is  28  525  1  483  15  619  4  534  <21  550  <21  494  <21  548  <21  423  1Values are means of 2 samples. Report issued by the Alzchem AG according to the IC method (CRL Feed Additives, 2007). 2Calculated values (CreAMINO®, GAA min. 96%), Evonik Industries, Evonik Degussa GmbH, Hanau-Wolfgang, Germany. View Large Table 3. Analyzed nutrient content of the dietary treatments for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)    Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Nutrient  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  Calculated                                  GAA, mg/kg, as is  0  600  0  600  0  600  0  600  0  600  0  600  0  600  0  600  Analyzed1                                  Creatine, mg/kg, as is  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  GAA, mg/kg, as is  27  504  1  464  14  594  4  513  <20  528  <20  474  <20  526  <20  406  CreAMINO2, mg/kg, as is  28  525  1  483  15  619  4  534  <21  550  <21  494  <21  548  <21  423    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)    Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Nutrient  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  Calculated                                  GAA, mg/kg, as is  0  600  0  600  0  600  0  600  0  600  0  600  0  600  0  600  Analyzed1                                  Creatine, mg/kg, as is  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  GAA, mg/kg, as is  27  504  1  464  14  594  4  513  <20  528  <20  474  <20  526  <20  406  CreAMINO2, mg/kg, as is  28  525  1  483  15  619  4  534  <21  550  <21  494  <21  548  <21  423  1Values are means of 2 samples. Report issued by the Alzchem AG according to the IC method (CRL Feed Additives, 2007). 2Calculated values (CreAMINO®, GAA min. 96%), Evonik Industries, Evonik Degussa GmbH, Hanau-Wolfgang, Germany. View Large Data Collection Live Performance At hatch, 14, 35 and 50 d, group BW and feed intake were obtained and BW gain and feed conversion ratio (FCR) calculated at the end of each phase. Mortality was monitored and recorded twice daily, and FCR was adjusted for mortality. At 50 d, individual BW were obtained to calculate flock uniformity using the CV%. Selection of Birds for Processing At 50 d, individual BW was obtained in addition to average BW as described above. Average for each pen was calculated. The power analysis based on previous statistics in our facilities indicated that to observe differences (P ≤ 0.05) on carcass characteristics, a minimum of 160 samples should be analyzed. Therefore, four broilers per pen were selected for each one of the two slaughter ages. Two days for processing (51 and 55d) were considered due to mechanical and personnel capabilities. Selected broilers had BW within two standard deviations above or under the corresponding average for each pen. Data for both processing days were analyzed separately and together. However, significant differences were found between the two processing times and consequently data is presented separately. Carcass and Cut Up Yields Chickens were subjected to 12-h of feed withdrawal in each processing day (51 and 55 d). Broilers were slaughtered at the NCSU pilot processing plant. Broilers were weighed, electrically stunned for 11 s, killed by exsanguination, and allowed to bleed for 90 s. Broilers were then scalded at 55°C for 90 s, picked for 30 s, and manually eviscerated. Furthermore, carcasses were manually dressed by removing liver, gizzard, heart, oil gland, crop, proventriculus, lungs, and viscera. Carcasses were then air-chilled for six h, and manually deboned on stationary cones. Parts of the leg quarters, breast fillets (Pectoralis major) without skin, breast tenders (Pectoralis minor), wings, and rack with skin were obtained and weighed. The carcass yield was calculated for the chilled carcass as a percentage of the fasted live weight. Cut up yields were expressed as a percentage of the chilled absolute carcass weight. The deboning technique was maintained similar among four trained cutters in order to minimize error and reduce variability in cut-up yields for both processing days. Meat Quality Evaluation To determine drip loss of the fillets samples after storage, the right Pectoralis major muscle was weighed six h postmortem and immediately placed in a plastic bag, hung from a hook, and stored between 4 and 6°C for 24 h. After hanging, the sample was gently wiped with paper and weighed again. The difference in weight corresponded to the drip loss and was expressed as the percentage of the initial muscle weight. Cook loss determination was performed on the left breast fillets (Pectoralis major). Samples were weighed, placed on grilled-aluminum trays, and cooked in a forced air oven (SilverStar Southbend, Model SLES/10sc, gas type, NC, USA). Fillets were cooked to an internal temperature of 75°C (approximately 35 min), as measured by a Therma Plus thermocouple with a 10-cm needle temperature probe (ThermoWorks Model 221–071, UT, USA). The cooked fillets were cooled to room temperature, gently wiped with paper and re-weighed to determine cook yield as a percentage of the cooked weight relative to the raw weight. Shear force (kg force) of cooked breast fillets samples was determined using a Warner-Bratzler shear device (Warner-Bratzler meat shear, Bodine Electric Company, Chicago, USA). Two samples per breast fillets (2 × 2 × 2 cm3) were sheared in a direction perpendicular to the muscle fibers. The maximum force measured when cutting the samples was expressed in kg force. Postmortem pH (t = 1, 6, and 24 h) was determined after skin was removed from Pectoralis major muscle samples using a portable pH meter (Oakton waterproof pH Tester 30). Color was measured on skinless Pectoralis major samples by the CIE L* (lightness), a* (redness), and b* (yellowness) system using a Minolta Chroma Meter CR-400 (Konica Minolta Sensing, Inc., Japan). A measuring area of 10 mm and illuminant D65 and 2° standard observer were used. The colorimeter was calibrated using a white tile (reference number 13,033,071; Y = 93.9, x = 0.3156, y = 0.3318). Pectoral Myopathies Sensorial analyses were performed on skinless breast fillets by experts in the field (College of Veterinary Medicine, North Carolina State University) to determine grade of severity for current pectoral myopathies. Spaghetti muscle (Baldi et al., 2018) was recorded as presence or absence of this abnormality, whereas WS and WB were scored based on severity. WB severity was evaluated based on a four-point scoring system. Score 1 represented a normal fillet with no WB signs, score 2 was considered a low severity, score 3 a medium and score 4 as severe (Tijare et al., 2016). WS was scored with a modified scale used by Kuttappan et al. (2016) which considered a four-point based scale of severity. Score 1 described a breast fillet with no white striations on the surface. Score 2 were the fillets with white striations less than 1 mm of thickness and easily observed in the surface, score 3 was represented by the white striation more than 1 mm of thickness and covering less than 50% of the breast's fillet area, and score 4 was considered the fillets with white striations with more than 1 mm of thickness and covering an area more than the 50% of the breast's fillet surface. Additionally, for WB and WS the distribution of the probability for each score were analyzed for both slaughter ages. Statistical Analysis Data were analyzed as completely randomized block design with a 2 × 2 factorial arrangement of treatments with grain (corn or sorghum) and supplementation or not of GAA as main effects to have a total of 4 treatments. Each treatment had 10 replicates distributed equally in two blocks (location of pens within the house) that were considered random effects. Data were analyzed in JMP 12 (SAS Inst. Inc., Cary, NC, 2016) using ANOVA in a mixed model. Differences between means were separated using Tukey's or t-student test at a level of significance of alpha = 0.05. Additionally, for carcass and cut up yields, meat quality and pectoral myopathies results, individual broiler's data from the same pen were nested within each corresponding treatment and considered as random effect. Cutter was also included in the model as random effect for carcass and cut up yields. Data of scores probability distribution for WB and WS were analyzed using GLIMMIX (SAS Institute, 2008). Results from each slaughter age were analyzed together and separately. RESULTS AND DISCUSSION Diets and Live Performance The analyzed GAA, and creatine concentration in the dietary treatments are shown in Table 3. The GAA concentration in diets supplemented with CreAMINO® showed slight differences compared to the intended dose (600 mg/kg). The CreAMINO® concentration was calculated using the standard concentration of GAA in the product (96%). As expected, low or absence of creatine was observed in all the diets. Crude protein and total amino acid, were similar to formulated values and these are presented in Table 2. Live performance results are shown in Table 4. No interactions effects (P > 0.05) of treatments were observed on BW or BW gain in any of the phases evaluated. An interaction effect (P < 0.05) on feed intake and FCR was observed only in the starter phase (0–14 d). In diets without GAA supplementation, chickens fed corn diets ate more (P < 0.05) than chickens fed sorghum diets resulting in higher BW and BWG, but no difference was observed when GAA was added. For the interaction results on FCR, no difference was observed when chickens were fed diets without GAA, but when GAA was added FCR of chickens fed corn diets was improved (1.242 vs. 1.333 g: g) as compared to broilers fed sorghum diets. At 35 d, feed intake was affected by grain source. Chickens fed corn diets had higher (P <0.01) feed intake than broilers fed sorghum diets. No differences (P > 0.05) due to GAA supplementation were detected at 50 d on feed intake. However, broilers fed corn diets ate more (P ≤ 0.05) than chickens fed sorghum diets, regardless of GAA supplementation. Table 4. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum based diets for Ross-708 male broilers on live performance up to 50 d of age.     BW  BW gain  Feed intake  FCR  Additive  Grain  Hatch  14d  35d  50d  CV1  0 - 14d  0 - 35d  0 - 50d  0 – 14d  0 –35d  0–50d  0 – 14d  0 –35d  0–50d      ——————– (g) ——————–  -(%)-  ——————————— (g) ——————————–  ———– (g:g) ————  GAA    39.9  468.5a  2,550a  4,167a  7.23  428.6a  2,509a  4111  551.2  3669  7030  1.288b  1.461b  1.682b  None    40.0  452.3b  2,498b  4,061b  8.44  412.3b  2,454b  4022  559.4  3693  7022  1.357a  1.499a  1.724a  SEM    0.1  3.2  12  51  0.35  3.1  11  57  6.7  25  43  0.016  0.007  0.009    Corn  40.0  470.4a  2,570a  4,172a  7.89  430.4a  2,528a  4,117a  561.5  3,741a  7,105a  1.306  1.478  1.700    Sorghum  39.9  450.4b  2,479b  4,056b  7.77  410.5b  2,435b  4,016b  549.0  3,621b  6,947b  1.339  1.482  1.706    SEM  0.13  3.1  12  51  0.35  3.1  11  5.72  6.7  25  43  0.016  0.007  0.009  GAA  Corn  39.9  479.1  2,590  4,237  6.92  439.2  2,550  4,168  545.4a,b  3,704  7,076  1.242b  1.453  1.675    Sorghum  39.9  457.9  2,510  4,096  7.54  418.0  2,467  4,054  556.9a,b  3,633  6,984  1.333a  1.469  1.689  None  Corn  40.2  461.8  2,549  4,106  8.86  421.6  2,506  4,065  577.9a  3,778  7,134  1.370a  1.504  1.725    Sorghum  39.9  442.9  2,447  4,016  8.01  403.0  2,403  3,978  541.0b  3,608  6,911  1.344a  1.495  1.723    SEM  0.2  4.3  16  60  0.57  4.3  16  66  9.5  38  70  0.023  0.011  0.014  CV%    1.39  3.01  1.96  3.45  24.70  3.32  1.99  3.62  5.46  3.55  3.44  5.71  2.77  2.71  Source of variation  ——————————————————————————— P—values ————————————————————————————  Additive  0.471  <0.001  0.002  0.027  0.071  <0.001  0.001  0.063  0.387  0.561  0.921  0.006  0.006  0.007  Grain  0.488  <0.001  <0.001  0.016  0.854  <0.001  <0.001  0.038  0.189  0.006  0.050  0.174  0.795  0.681  Additive*grain  0.505  0.793  0.496  0.569  0.252  0.773  0.498  0.774  0.015  0.244  0.405  0.017  0.339  0.604      BW  BW gain  Feed intake  FCR  Additive  Grain  Hatch  14d  35d  50d  CV1  0 - 14d  0 - 35d  0 - 50d  0 – 14d  0 –35d  0–50d  0 – 14d  0 –35d  0–50d      ——————– (g) ——————–  -(%)-  ——————————— (g) ——————————–  ———– (g:g) ————  GAA    39.9  468.5a  2,550a  4,167a  7.23  428.6a  2,509a  4111  551.2  3669  7030  1.288b  1.461b  1.682b  None    40.0  452.3b  2,498b  4,061b  8.44  412.3b  2,454b  4022  559.4  3693  7022  1.357a  1.499a  1.724a  SEM    0.1  3.2  12  51  0.35  3.1  11  57  6.7  25  43  0.016  0.007  0.009    Corn  40.0  470.4a  2,570a  4,172a  7.89  430.4a  2,528a  4,117a  561.5  3,741a  7,105a  1.306  1.478  1.700    Sorghum  39.9  450.4b  2,479b  4,056b  7.77  410.5b  2,435b  4,016b  549.0  3,621b  6,947b  1.339  1.482  1.706    SEM  0.13  3.1  12  51  0.35  3.1  11  5.72  6.7  25  43  0.016  0.007  0.009  GAA  Corn  39.9  479.1  2,590  4,237  6.92  439.2  2,550  4,168  545.4a,b  3,704  7,076  1.242b  1.453  1.675    Sorghum  39.9  457.9  2,510  4,096  7.54  418.0  2,467  4,054  556.9a,b  3,633  6,984  1.333a  1.469  1.689  None  Corn  40.2  461.8  2,549  4,106  8.86  421.6  2,506  4,065  577.9a  3,778  7,134  1.370a  1.504  1.725    Sorghum  39.9  442.9  2,447  4,016  8.01  403.0  2,403  3,978  541.0b  3,608  6,911  1.344a  1.495  1.723    SEM  0.2  4.3  16  60  0.57  4.3  16  66  9.5  38  70  0.023  0.011  0.014  CV%    1.39  3.01  1.96  3.45  24.70  3.32  1.99  3.62  5.46  3.55  3.44  5.71  2.77  2.71  Source of variation  ——————————————————————————— P—values ————————————————————————————  Additive  0.471  <0.001  0.002  0.027  0.071  <0.001  0.001  0.063  0.387  0.561  0.921  0.006  0.006  0.007  Grain  0.488  <0.001  <0.001  0.016  0.854  <0.001  <0.001  0.038  0.189  0.006  0.050  0.174  0.795  0.681  Additive*grain  0.505  0.793  0.496  0.569  0.252  0.773  0.498  0.774  0.015  0.244  0.405  0.017  0.339  0.604  Values are means of 10 pens per treatment combination with 20 male broiler chickens. a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Flock uniformity at 50 d of age. View Large Table 4. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum based diets for Ross-708 male broilers on live performance up to 50 d of age.     BW  BW gain  Feed intake  FCR  Additive  Grain  Hatch  14d  35d  50d  CV1  0 - 14d  0 - 35d  0 - 50d  0 – 14d  0 –35d  0–50d  0 – 14d  0 –35d  0–50d      ——————– (g) ——————–  -(%)-  ——————————— (g) ——————————–  ———– (g:g) ————  GAA    39.9  468.5a  2,550a  4,167a  7.23  428.6a  2,509a  4111  551.2  3669  7030  1.288b  1.461b  1.682b  None    40.0  452.3b  2,498b  4,061b  8.44  412.3b  2,454b  4022  559.4  3693  7022  1.357a  1.499a  1.724a  SEM    0.1  3.2  12  51  0.35  3.1  11  57  6.7  25  43  0.016  0.007  0.009    Corn  40.0  470.4a  2,570a  4,172a  7.89  430.4a  2,528a  4,117a  561.5  3,741a  7,105a  1.306  1.478  1.700    Sorghum  39.9  450.4b  2,479b  4,056b  7.77  410.5b  2,435b  4,016b  549.0  3,621b  6,947b  1.339  1.482  1.706    SEM  0.13  3.1  12  51  0.35  3.1  11  5.72  6.7  25  43  0.016  0.007  0.009  GAA  Corn  39.9  479.1  2,590  4,237  6.92  439.2  2,550  4,168  545.4a,b  3,704  7,076  1.242b  1.453  1.675    Sorghum  39.9  457.9  2,510  4,096  7.54  418.0  2,467  4,054  556.9a,b  3,633  6,984  1.333a  1.469  1.689  None  Corn  40.2  461.8  2,549  4,106  8.86  421.6  2,506  4,065  577.9a  3,778  7,134  1.370a  1.504  1.725    Sorghum  39.9  442.9  2,447  4,016  8.01  403.0  2,403  3,978  541.0b  3,608  6,911  1.344a  1.495  1.723    SEM  0.2  4.3  16  60  0.57  4.3  16  66  9.5  38  70  0.023  0.011  0.014  CV%    1.39  3.01  1.96  3.45  24.70  3.32  1.99  3.62  5.46  3.55  3.44  5.71  2.77  2.71  Source of variation  ——————————————————————————— P—values ————————————————————————————  Additive  0.471  <0.001  0.002  0.027  0.071  <0.001  0.001  0.063  0.387  0.561  0.921  0.006  0.006  0.007  Grain  0.488  <0.001  <0.001  0.016  0.854  <0.001  <0.001  0.038  0.189  0.006  0.050  0.174  0.795  0.681  Additive*grain  0.505  0.793  0.496  0.569  0.252  0.773  0.498  0.774  0.015  0.244  0.405  0.017  0.339  0.604      BW  BW gain  Feed intake  FCR  Additive  Grain  Hatch  14d  35d  50d  CV1  0 - 14d  0 - 35d  0 - 50d  0 – 14d  0 –35d  0–50d  0 – 14d  0 –35d  0–50d      ——————– (g) ——————–  -(%)-  ——————————— (g) ——————————–  ———– (g:g) ————  GAA    39.9  468.5a  2,550a  4,167a  7.23  428.6a  2,509a  4111  551.2  3669  7030  1.288b  1.461b  1.682b  None    40.0  452.3b  2,498b  4,061b  8.44  412.3b  2,454b  4022  559.4  3693  7022  1.357a  1.499a  1.724a  SEM    0.1  3.2  12  51  0.35  3.1  11  57  6.7  25  43  0.016  0.007  0.009    Corn  40.0  470.4a  2,570a  4,172a  7.89  430.4a  2,528a  4,117a  561.5  3,741a  7,105a  1.306  1.478  1.700    Sorghum  39.9  450.4b  2,479b  4,056b  7.77  410.5b  2,435b  4,016b  549.0  3,621b  6,947b  1.339  1.482  1.706    SEM  0.13  3.1  12  51  0.35  3.1  11  5.72  6.7  25  43  0.016  0.007  0.009  GAA  Corn  39.9  479.1  2,590  4,237  6.92  439.2  2,550  4,168  545.4a,b  3,704  7,076  1.242b  1.453  1.675    Sorghum  39.9  457.9  2,510  4,096  7.54  418.0  2,467  4,054  556.9a,b  3,633  6,984  1.333a  1.469  1.689  None  Corn  40.2  461.8  2,549  4,106  8.86  421.6  2,506  4,065  577.9a  3,778  7,134  1.370a  1.504  1.725    Sorghum  39.9  442.9  2,447  4,016  8.01  403.0  2,403  3,978  541.0b  3,608  6,911  1.344a  1.495  1.723    SEM  0.2  4.3  16  60  0.57  4.3  16  66  9.5  38  70  0.023  0.011  0.014  CV%    1.39  3.01  1.96  3.45  24.70  3.32  1.99  3.62  5.46  3.55  3.44  5.71  2.77  2.71  Source of variation  ——————————————————————————— P—values ————————————————————————————  Additive  0.471  <0.001  0.002  0.027  0.071  <0.001  0.001  0.063  0.387  0.561  0.921  0.006  0.006  0.007  Grain  0.488  <0.001  <0.001  0.016  0.854  <0.001  <0.001  0.038  0.189  0.006  0.050  0.174  0.795  0.681  Additive*grain  0.505  0.793  0.496  0.569  0.252  0.773  0.498  0.774  0.015  0.244  0.405  0.017  0.339  0.604  Values are means of 10 pens per treatment combination with 20 male broiler chickens. a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Flock uniformity at 50 d of age. View Large Consequent to higher feed consumption, broilers fed corn-based diets gain more BW (P < 0.05) throughout the whole experimental period than the ones fed sorghum diets. Therefore, chickens fed corn weighed more (P < 0.001) than broilers fed sorghum diets at 14 d, and remained heavier (P < 0.05) at 35 d (2570 vs. 2479 g), and 50 d (4172 vs. 4056 g) respectively. The GAA supplementation improved BW, and BW gain (P < 0.05) up to 35d, and FCR (P < 0.01) up to 50 d regardless of grain type. Improvements (P < 0.01) up to 4 points on FCR at 35 d (1.46 vs. 1.50 g: g), and 50 d (1.68 vs. 1.72 g: g) of age respectively, were attributed to GAA supplementation. No differences (P > 0.05) were detected on FCR at the end of each experimental phase due to grain source. Flock uniformity (CV%) at 50 d tended to be improved (P = 0.07) by GAA (7.33 vs. 8.44%) addition, while no interaction (P > 0.05) or effect of grain source was observed. Overall, total mortality was not affected (P > 0.05) either by grain source or GAA supplementation throughout the whole experimental period with no mortality in some replicates, but the average mortality rates per treatment were: 5, 3, 3 and 5% (corn-based diets with or without GAA; sorghum-based diets with or without GAA, respectively). Previous studies (Garcia et al., 2013; Torres et al., 2013; Tandiag et al., 2014) concluded that partial or total replacement of corn by sorghum did not depress (P > 0.05) FCR up to 42 d of age. Although FCR was not affected by grain source in the current study, there was a lower (P ≤ 0.05) feed intake in broilers fed sorghum-based diets that lowered BW gain and consequently BW. This could be attributed to the effects of the high tannin content in the sorghum (1.91% catechi equivalent) used for the experiment described herein. It has been reported that tannins lowered protein and starch digestion (Kumar et al., 2005; Del Puerto et al., 2016). Moreover, the fact that no significant differences were detected in FCR due to grain source in our study, suggests that the values used for digestible amino acids and available nutrients in the formulation were adequate. It has been reported a greater BW gain up to 70.2 g, when male Ross 308 broilers where fed corn-based supplemented diets with GAA and raised up to 39 d of age (Michiels et al., 2012). Several investigators have observed that GAA supplementation reduces FCR (P < 0.05), suggesting improvements up to five points on FCR due to GAA supplementation (Lemme et al., 2007a; Mousavi et al., 2013) in broilers fed corn-based or partially replaced with sorghum (20%) and raised up to 42 d. Ringel et al. (2007) observed improvements up to seven points in FCR with the same level of GAA (0.06%) inclusion, compared to a negative control diet that did not contain any animal by-product (“all vegetable diet”) without GAA supplementation. Findings in those studies concluded that GAA improved live performance in corn-based diets. In the present study, the improvement in BW gain was up to 55 g at 35 d, and FCR was improved by 7, 4, and 4 points at 14, 35 and 50 d, respectively, regardless of the type of grain source in the diet. Therefore, GAA could improve live performance in vegetable-based diets with either corn or sorghum as the base grain. The lack of interaction effects of GAA with grain source dismisses our hypothesis that GAA will have greater improvements on sorghum diets. Carcass and Cut up Parts Weights and Yields Results for the effect of grain source (corn or sorghum) on carcass and parts weights and yields for the selected broilers are shown in Table 5. These Ross-708 broilers were processed on two different days (51 and 55 d, 4 broilers/pen each time) to observe muscle development in two common stages in the US industry and meet experimental processing capabilities to evaluate all parameters at the same time. The four broilers used for processing were considered a subsample that represented each pen constituted of 20 chickens. Differences (P < 0.05) were observed between processing times and consequently data were analyzed separately. No differences (P > 0.05) on live BW of chickens selected for processing were detected due to either grain source or GAA supplementation for both slaughter ages. No interaction effects (P > 0.05) were observed at 51 d of age on carcass and cut up yields. However, at 55 d an interaction effect (P < 0.05) of grain source and GAA was detected on breast meat yield. Differences due to GAA supplementation at 55d were detected only in corn diets. In broilers fed corn diets, the addition of GAA improved breast meat yield (39.15 vs. 38.19%), compared to chickens fed corn non-supplemented diets, which attributed to an improvement of 96 g in breast meat per broiler at this age and weight (∼ 4521 g). Table 5. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum based diets for Ross-708 male broilers on carcass, breast meat, and cut up yields at 51 and 55 d of age.         Cut—up parts relative to carcass weight 51 d      Cut—up parts relative to carcass weight 55 d      Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Additive  Grain  weight  yield1  Wings  Quarters  major  minor  meat  Rack  weight  yield1  Wings  Quarters  major  minor  meat  Rack      –(g)–  ——————————————– % —————————————–  –(g)–  ——————————————– % —————————————–  GAA    4,148  78.28  9.50  30.63a  31.82  6.32  38.09  21.63  4,548  78.97  9.41  30.70  32.24  6.49  38.76  20.94  None    4,069  78.24  9.45  30.15b  31.93  6.30  38.15  21.91  4,464  78.72  9.39  30.94  32.02  6.45  38.43  21.94  SEM    50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.28  0.06  0.30  0.35    Corn  4,156  78.44a  9.43  30.23  32.11  6.37  38.42a  21.68  4,541  78.77  9.52a  30.77  32.21  6.45  38.67  20.95    Sorghum  4,060  78.08b  9.52  30.54  31.63  6.25  37.83b  21.86  4,470  78.92  9.28b  30.87  32.05  6.48  38.52  21.22    SEM  50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.27  0.06  0.30  0.35  GAA  Corn  4,217  78.33  9.49  30.42  31.93  6.36  38.21  21.61  4,597  79.02  9.48  30.47  32.59  6.51  39.15a  20.69    Sorghum  4,078  78.33  9.50  30.83  31.71  6.28  37.98  21.65  4,500  78.93  9.34  30.93  31.88  6.47  38.37a,b  21.18  None  Corn  4,095  78.54  9.37  30.05  32.30  6.37  38.63  21.75  4,486  78.52  9.56  31.06  31.82  6.40  38.19b  21.21    Sorghum  4,042  77.94  9.54  30.25  31.56  6.22  37.67  22.07  4,441  78.92  9.22  30.82  32.21  6.50  38.68a,b  21.27    SEM  62  0.16  0.11  0.23  0.27  0.08  0.28  0.28  63  0.21  0.13  0.24  0.34  0.08  0.37  0.37  CV%    5.32  1.30  6.15  4.98  5.89  6.34  5.06  5.84  4.81  1.18  5.53  4.45  5.63  7.39  5.34  5.35  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.136  0.781  0.325  0.043  0.710  0.756  0.839  0.236  0.158  0.123  0.865  0.236  0.435  0.570  0.274  0.085  Grain  0.072  0.025  0.635  0.170  0.091  0.112  0.044  0.435  0.235  0.352  0.035  0.594  0.573  0.662  0.627  0.123  Additive*grain  0.412  0.104  0.398  0.625  0.353  0.622  0.220  0.537  0.660  0.157  0.386  0.093  0.065  0.335  0.043  0.225          Cut—up parts relative to carcass weight 51 d      Cut—up parts relative to carcass weight 55 d      Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Additive  Grain  weight  yield1  Wings  Quarters  major  minor  meat  Rack  weight  yield1  Wings  Quarters  major  minor  meat  Rack      –(g)–  ——————————————– % —————————————–  –(g)–  ——————————————– % —————————————–  GAA    4,148  78.28  9.50  30.63a  31.82  6.32  38.09  21.63  4,548  78.97  9.41  30.70  32.24  6.49  38.76  20.94  None    4,069  78.24  9.45  30.15b  31.93  6.30  38.15  21.91  4,464  78.72  9.39  30.94  32.02  6.45  38.43  21.94  SEM    50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.28  0.06  0.30  0.35    Corn  4,156  78.44a  9.43  30.23  32.11  6.37  38.42a  21.68  4,541  78.77  9.52a  30.77  32.21  6.45  38.67  20.95    Sorghum  4,060  78.08b  9.52  30.54  31.63  6.25  37.83b  21.86  4,470  78.92  9.28b  30.87  32.05  6.48  38.52  21.22    SEM  50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.27  0.06  0.30  0.35  GAA  Corn  4,217  78.33  9.49  30.42  31.93  6.36  38.21  21.61  4,597  79.02  9.48  30.47  32.59  6.51  39.15a  20.69    Sorghum  4,078  78.33  9.50  30.83  31.71  6.28  37.98  21.65  4,500  78.93  9.34  30.93  31.88  6.47  38.37a,b  21.18  None  Corn  4,095  78.54  9.37  30.05  32.30  6.37  38.63  21.75  4,486  78.52  9.56  31.06  31.82  6.40  38.19b  21.21    Sorghum  4,042  77.94  9.54  30.25  31.56  6.22  37.67  22.07  4,441  78.92  9.22  30.82  32.21  6.50  38.68a,b  21.27    SEM  62  0.16  0.11  0.23  0.27  0.08  0.28  0.28  63  0.21  0.13  0.24  0.34  0.08  0.37  0.37  CV%    5.32  1.30  6.15  4.98  5.89  6.34  5.06  5.84  4.81  1.18  5.53  4.45  5.63  7.39  5.34  5.35  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.136  0.781  0.325  0.043  0.710  0.756  0.839  0.236  0.158  0.123  0.865  0.236  0.435  0.570  0.274  0.085  Grain  0.072  0.025  0.635  0.170  0.091  0.112  0.044  0.435  0.235  0.352  0.035  0.594  0.573  0.662  0.627  0.123  Additive*grain  0.412  0.104  0.398  0.625  0.353  0.622  0.220  0.537  0.660  0.157  0.386  0.093  0.065  0.335  0.043  0.225  Values are means of 10 pens per treatment combination with 4 male broiler chickens per pen selected for processing. Pen nested within each treatment and cutter (random effects). a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Relative to live weight of broilers selected for processing. View Large Table 5. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum based diets for Ross-708 male broilers on carcass, breast meat, and cut up yields at 51 and 55 d of age.         Cut—up parts relative to carcass weight 51 d      Cut—up parts relative to carcass weight 55 d      Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Additive  Grain  weight  yield1  Wings  Quarters  major  minor  meat  Rack  weight  yield1  Wings  Quarters  major  minor  meat  Rack      –(g)–  ——————————————– % —————————————–  –(g)–  ——————————————– % —————————————–  GAA    4,148  78.28  9.50  30.63a  31.82  6.32  38.09  21.63  4,548  78.97  9.41  30.70  32.24  6.49  38.76  20.94  None    4,069  78.24  9.45  30.15b  31.93  6.30  38.15  21.91  4,464  78.72  9.39  30.94  32.02  6.45  38.43  21.94  SEM    50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.28  0.06  0.30  0.35    Corn  4,156  78.44a  9.43  30.23  32.11  6.37  38.42a  21.68  4,541  78.77  9.52a  30.77  32.21  6.45  38.67  20.95    Sorghum  4,060  78.08b  9.52  30.54  31.63  6.25  37.83b  21.86  4,470  78.92  9.28b  30.87  32.05  6.48  38.52  21.22    SEM  50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.27  0.06  0.30  0.35  GAA  Corn  4,217  78.33  9.49  30.42  31.93  6.36  38.21  21.61  4,597  79.02  9.48  30.47  32.59  6.51  39.15a  20.69    Sorghum  4,078  78.33  9.50  30.83  31.71  6.28  37.98  21.65  4,500  78.93  9.34  30.93  31.88  6.47  38.37a,b  21.18  None  Corn  4,095  78.54  9.37  30.05  32.30  6.37  38.63  21.75  4,486  78.52  9.56  31.06  31.82  6.40  38.19b  21.21    Sorghum  4,042  77.94  9.54  30.25  31.56  6.22  37.67  22.07  4,441  78.92  9.22  30.82  32.21  6.50  38.68a,b  21.27    SEM  62  0.16  0.11  0.23  0.27  0.08  0.28  0.28  63  0.21  0.13  0.24  0.34  0.08  0.37  0.37  CV%    5.32  1.30  6.15  4.98  5.89  6.34  5.06  5.84  4.81  1.18  5.53  4.45  5.63  7.39  5.34  5.35  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.136  0.781  0.325  0.043  0.710  0.756  0.839  0.236  0.158  0.123  0.865  0.236  0.435  0.570  0.274  0.085  Grain  0.072  0.025  0.635  0.170  0.091  0.112  0.044  0.435  0.235  0.352  0.035  0.594  0.573  0.662  0.627  0.123  Additive*grain  0.412  0.104  0.398  0.625  0.353  0.622  0.220  0.537  0.660  0.157  0.386  0.093  0.065  0.335  0.043  0.225          Cut—up parts relative to carcass weight 51 d      Cut—up parts relative to carcass weight 55 d      Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Additive  Grain  weight  yield1  Wings  Quarters  major  minor  meat  Rack  weight  yield1  Wings  Quarters  major  minor  meat  Rack      –(g)–  ——————————————– % —————————————–  –(g)–  ——————————————– % —————————————–  GAA    4,148  78.28  9.50  30.63a  31.82  6.32  38.09  21.63  4,548  78.97  9.41  30.70  32.24  6.49  38.76  20.94  None    4,069  78.24  9.45  30.15b  31.93  6.30  38.15  21.91  4,464  78.72  9.39  30.94  32.02  6.45  38.43  21.94  SEM    50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.28  0.06  0.30  0.35    Corn  4,156  78.44a  9.43  30.23  32.11  6.37  38.42a  21.68  4,541  78.77  9.52a  30.77  32.21  6.45  38.67  20.95    Sorghum  4,060  78.08b  9.52  30.54  31.63  6.25  37.83b  21.86  4,470  78.92  9.28b  30.87  32.05  6.48  38.52  21.22    SEM  50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.27  0.06  0.30  0.35  GAA  Corn  4,217  78.33  9.49  30.42  31.93  6.36  38.21  21.61  4,597  79.02  9.48  30.47  32.59  6.51  39.15a  20.69    Sorghum  4,078  78.33  9.50  30.83  31.71  6.28  37.98  21.65  4,500  78.93  9.34  30.93  31.88  6.47  38.37a,b  21.18  None  Corn  4,095  78.54  9.37  30.05  32.30  6.37  38.63  21.75  4,486  78.52  9.56  31.06  31.82  6.40  38.19b  21.21    Sorghum  4,042  77.94  9.54  30.25  31.56  6.22  37.67  22.07  4,441  78.92  9.22  30.82  32.21  6.50  38.68a,b  21.27    SEM  62  0.16  0.11  0.23  0.27  0.08  0.28  0.28  63  0.21  0.13  0.24  0.34  0.08  0.37  0.37  CV%    5.32  1.30  6.15  4.98  5.89  6.34  5.06  5.84  4.81  1.18  5.53  4.45  5.63  7.39  5.34  5.35  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.136  0.781  0.325  0.043  0.710  0.756  0.839  0.236  0.158  0.123  0.865  0.236  0.435  0.570  0.274  0.085  Grain  0.072  0.025  0.635  0.170  0.091  0.112  0.044  0.435  0.235  0.352  0.035  0.594  0.573  0.662  0.627  0.123  Additive*grain  0.412  0.104  0.398  0.625  0.353  0.622  0.220  0.537  0.660  0.157  0.386  0.093  0.065  0.335  0.043  0.225  Values are means of 10 pens per treatment combination with 4 male broiler chickens per pen selected for processing. Pen nested within each treatment and cutter (random effects). a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Relative to live weight of broilers selected for processing. View Large At 55 d of age, carcass and other cut up yields were not affected either by GAA addition or grain source, except for wing yield. Broilers fed corn diets had greater wing (P < 0.05) yield than broilers fed sorghum diets (9.52 vs. 9.28%). At 51 d of age (∼4108 g live weight), the addition of GAA improved (P < 0.05) leg quarter yield but not breast meat yield regardless of grain type. No effects (P > 0.05) of GAA addition were observed on carcass or other cut up yields. At this age, corn-based diets improved carcass and breast meat yield (P < 0.05). Broilers fed sorghum diets had less carcass yield (78.44% vs. 78.08%) and breast meat yield (38.42 vs. 37.83%) than broilers fed corn diets. No other differences in cut up yields were detected at 51 d attributed to grain type. Previous studies (Kwari et al., 2012; Garcia et al., 2013; Torres et al., 2013; Tandiang et al., 2014) reported that partial or total replacement of corn by sorghum did not affect (P > 0.05) carcass and cut up yields at different slaughter ages and in different genetic lines. On the other hand, Rodrigues et al. (2007) reported in a trial up to 42 d, that even though the relationships were not significant, increasing tannin levels still tended to depress breast meat yields (r = −0.513; P < 0.07). Nasr and Kheiri (2012) concluded that lysine availability in the diet affected carcass and breast meat yield. In agreement, Ebadi et al. (2005) observed that sorghum containing medium levels of tannins could adversely affect lysine availability. Therefore, our results of carcass and breast meat yield at this age may be explained by the possible effect of high tannin content (1.91% catechin equivalent) on dietary lysine bioavailability. It has been concluded (Lemme et al., 2007a; Michiels et al., 2012) that the use of GAA improved breast meat yield in vegetable-based diets. This response was observed even when corn was partially replaced by sorghum up to 20% (Lemme et al., 2007a). However, no improvements on whole carcass, and other cut up (upper leg, lower leg, wings) yields were observed. Our interaction effect detected only in corn diets at 55d suggested that the improvements on breast meat yield could depend on the type of grain base in the diet, specific content and/or digestibility of some amino acids. Meat Quality Results from meat quality parameters are shown in Table 6. No interactions effects (P > 0.05) were observed on drip and cook loss at any of the processing days. Drip and cook loss, and shear force were not affected (P > 0.05) by GAA supplementation or grain type main effects at any of the slaughter ages. Table 6. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum diets for Ross-708 male broilers on meat quality at 51 and 55 d of age.           Post mortem pH  Color        Post mortem pH  Color  Additive  Grain  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*      –(g)–  (kg)            –(g)–  (kg)            GAA    1.24  28.67  4.60  5.91  6.01b  58.98  4.34  7.03b  1.31  31.01  4.58  5.88b  5.95b  59.49  3.90  7.23  None    1.28  28.57  4.35  5.94  6.08a  58.83  4.47  7.90a  1.19  30.52  4.67  5.92a  5.99a  58.57  3.81  7.55  SEM    0.06  0.46  0.18  0.01  0.02  0.33  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.34  0.17  0.22    Corn  1.28  28.30  4.50  5.92  6.05  58.61  4.17b  8.78a  1.26  30.97  4.59  5.88  5.95b  59.23  3.89  9.28a    Sorghum  1.24  28.94  4.45  5.93  6.04  59.21  4.64a  6.15b  1.24  30.57  4.66  5.91  5.99a  58.82  3.82  5.50b    SEM  0.06  0.46  0.18  0.01  0.02  0.34  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.35  0.17  0.22  GAA  Corn  1.28  28.14  4.57  5.90  6.03  58.50  3.78b  7.92b  1.31  30.98  4.54  5.87  5.95  59.85  4.02  9.34    Sorghum  1.20  29.19  4.62  5.91  5.99  59.46  4.91a  6.14c  1.31  31.04  4.62  5.88  5.96  59.13  3.78  5.13  None  Corn  1.29  28.47  4.43  5.94  6.07  58.71  4.56a,b  9.64a  1.21  30.96  4.64  5.90  5.96  58.62  3.76  9.23    Sorghum  1.27  28.68  4.27  5.95  6.09  58.95  4.38a,b  6.17c  1.17  30.09  4.70  5.95  6.03  58.52  3.85  5.87    SEM  0.09  0.65  0.22  0.02  0.03  0.48  0.23  0.33  0.07  0.72  0.17  0.02  0.02  0.50  0.24  0.31  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.674  0.887  0.182  0.100  0.015  0.753  0.592  0.009  0.078  0.499  0.637  0.008  0.009  0.068  0.691  0.310  Grain  0.630  0.333  0.692  0.626  0.719  0.211  0.049  <0.001  0.728  0.579  0.637  0.068  0.020  0.411  0.753  <0.001  Additive*grain  0.741  0.521  0.544  0.942  0.256  0.455  0.007  0.011  0.785  0.516  0.965  0.330  0.139  0.539  0.478  0.173            Post mortem pH  Color        Post mortem pH  Color  Additive  Grain  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*      –(g)–  (kg)            –(g)–  (kg)            GAA    1.24  28.67  4.60  5.91  6.01b  58.98  4.34  7.03b  1.31  31.01  4.58  5.88b  5.95b  59.49  3.90  7.23  None    1.28  28.57  4.35  5.94  6.08a  58.83  4.47  7.90a  1.19  30.52  4.67  5.92a  5.99a  58.57  3.81  7.55  SEM    0.06  0.46  0.18  0.01  0.02  0.33  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.34  0.17  0.22    Corn  1.28  28.30  4.50  5.92  6.05  58.61  4.17b  8.78a  1.26  30.97  4.59  5.88  5.95b  59.23  3.89  9.28a    Sorghum  1.24  28.94  4.45  5.93  6.04  59.21  4.64a  6.15b  1.24  30.57  4.66  5.91  5.99a  58.82  3.82  5.50b    SEM  0.06  0.46  0.18  0.01  0.02  0.34  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.35  0.17  0.22  GAA  Corn  1.28  28.14  4.57  5.90  6.03  58.50  3.78b  7.92b  1.31  30.98  4.54  5.87  5.95  59.85  4.02  9.34    Sorghum  1.20  29.19  4.62  5.91  5.99  59.46  4.91a  6.14c  1.31  31.04  4.62  5.88  5.96  59.13  3.78  5.13  None  Corn  1.29  28.47  4.43  5.94  6.07  58.71  4.56a,b  9.64a  1.21  30.96  4.64  5.90  5.96  58.62  3.76  9.23    Sorghum  1.27  28.68  4.27  5.95  6.09  58.95  4.38a,b  6.17c  1.17  30.09  4.70  5.95  6.03  58.52  3.85  5.87    SEM  0.09  0.65  0.22  0.02  0.03  0.48  0.23  0.33  0.07  0.72  0.17  0.02  0.02  0.50  0.24  0.31  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.674  0.887  0.182  0.100  0.015  0.753  0.592  0.009  0.078  0.499  0.637  0.008  0.009  0.068  0.691  0.310  Grain  0.630  0.333  0.692  0.626  0.719  0.211  0.049  <0.001  0.728  0.579  0.637  0.068  0.020  0.411  0.753  <0.001  Additive*grain  0.741  0.521  0.544  0.942  0.256  0.455  0.007  0.011  0.785  0.516  0.965  0.330  0.139  0.539  0.478  0.173  Values are means of 10 pens per treatment combination with 4 male broiler chickens per pen selected for processing. Pen nested within each treatment (random effects). a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Warner-Bratzler; Color: L* = lightness, a* = redness, b* = yellowness. View Large Table 6. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum diets for Ross-708 male broilers on meat quality at 51 and 55 d of age.           Post mortem pH  Color        Post mortem pH  Color  Additive  Grain  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*      –(g)–  (kg)            –(g)–  (kg)            GAA    1.24  28.67  4.60  5.91  6.01b  58.98  4.34  7.03b  1.31  31.01  4.58  5.88b  5.95b  59.49  3.90  7.23  None    1.28  28.57  4.35  5.94  6.08a  58.83  4.47  7.90a  1.19  30.52  4.67  5.92a  5.99a  58.57  3.81  7.55  SEM    0.06  0.46  0.18  0.01  0.02  0.33  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.34  0.17  0.22    Corn  1.28  28.30  4.50  5.92  6.05  58.61  4.17b  8.78a  1.26  30.97  4.59  5.88  5.95b  59.23  3.89  9.28a    Sorghum  1.24  28.94  4.45  5.93  6.04  59.21  4.64a  6.15b  1.24  30.57  4.66  5.91  5.99a  58.82  3.82  5.50b    SEM  0.06  0.46  0.18  0.01  0.02  0.34  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.35  0.17  0.22  GAA  Corn  1.28  28.14  4.57  5.90  6.03  58.50  3.78b  7.92b  1.31  30.98  4.54  5.87  5.95  59.85  4.02  9.34    Sorghum  1.20  29.19  4.62  5.91  5.99  59.46  4.91a  6.14c  1.31  31.04  4.62  5.88  5.96  59.13  3.78  5.13  None  Corn  1.29  28.47  4.43  5.94  6.07  58.71  4.56a,b  9.64a  1.21  30.96  4.64  5.90  5.96  58.62  3.76  9.23    Sorghum  1.27  28.68  4.27  5.95  6.09  58.95  4.38a,b  6.17c  1.17  30.09  4.70  5.95  6.03  58.52  3.85  5.87    SEM  0.09  0.65  0.22  0.02  0.03  0.48  0.23  0.33  0.07  0.72  0.17  0.02  0.02  0.50  0.24  0.31  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.674  0.887  0.182  0.100  0.015  0.753  0.592  0.009  0.078  0.499  0.637  0.008  0.009  0.068  0.691  0.310  Grain  0.630  0.333  0.692  0.626  0.719  0.211  0.049  <0.001  0.728  0.579  0.637  0.068  0.020  0.411  0.753  <0.001  Additive*grain  0.741  0.521  0.544  0.942  0.256  0.455  0.007  0.011  0.785  0.516  0.965  0.330  0.139  0.539  0.478  0.173            Post mortem pH  Color        Post mortem pH  Color  Additive  Grain  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*      –(g)–  (kg)            –(g)–  (kg)            GAA    1.24  28.67  4.60  5.91  6.01b  58.98  4.34  7.03b  1.31  31.01  4.58  5.88b  5.95b  59.49  3.90  7.23  None    1.28  28.57  4.35  5.94  6.08a  58.83  4.47  7.90a  1.19  30.52  4.67  5.92a  5.99a  58.57  3.81  7.55  SEM    0.06  0.46  0.18  0.01  0.02  0.33  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.34  0.17  0.22    Corn  1.28  28.30  4.50  5.92  6.05  58.61  4.17b  8.78a  1.26  30.97  4.59  5.88  5.95b  59.23  3.89  9.28a    Sorghum  1.24  28.94  4.45  5.93  6.04  59.21  4.64a  6.15b  1.24  30.57  4.66  5.91  5.99a  58.82  3.82  5.50b    SEM  0.06  0.46  0.18  0.01  0.02  0.34  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.35  0.17  0.22  GAA  Corn  1.28  28.14  4.57  5.90  6.03  58.50  3.78b  7.92b  1.31  30.98  4.54  5.87  5.95  59.85  4.02  9.34    Sorghum  1.20  29.19  4.62  5.91  5.99  59.46  4.91a  6.14c  1.31  31.04  4.62  5.88  5.96  59.13  3.78  5.13  None  Corn  1.29  28.47  4.43  5.94  6.07  58.71  4.56a,b  9.64a  1.21  30.96  4.64  5.90  5.96  58.62  3.76  9.23    Sorghum  1.27  28.68  4.27  5.95  6.09  58.95  4.38a,b  6.17c  1.17  30.09  4.70  5.95  6.03  58.52  3.85  5.87    SEM  0.09  0.65  0.22  0.02  0.03  0.48  0.23  0.33  0.07  0.72  0.17  0.02  0.02  0.50  0.24  0.31  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.674  0.887  0.182  0.100  0.015  0.753  0.592  0.009  0.078  0.499  0.637  0.008  0.009  0.068  0.691  0.310  Grain  0.630  0.333  0.692  0.626  0.719  0.211  0.049  <0.001  0.728  0.579  0.637  0.068  0.020  0.411  0.753  <0.001  Additive*grain  0.741  0.521  0.544  0.942  0.256  0.455  0.007  0.011  0.785  0.516  0.965  0.330  0.139  0.539  0.478  0.173  Values are means of 10 pens per treatment combination with 4 male broiler chickens per pen selected for processing. Pen nested within each treatment (random effects). a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Warner-Bratzler; Color: L* = lightness, a* = redness, b* = yellowness. View Large Postmortem pH values of breast muscle showed no interaction effects (P > 0.05) in both processing days. The pH of breast meat, 1 h post-processing, was not affected (P > 0.05) either by grain type or GAA supplementation for both slaughter ages (data not shown). In contrast, grain source affected (P < 0.05) the ultimate pH (24 h after slaughter) at 55 d only. Samples from chickens fed corn diets had lower pH than samples from broilers fed sorghum diets (5.95 vs. 5.99). On the other hand, GAA supplementation lowered (P < 0.05) pH of breast meat after 24 h of slaughter at 51 d (6.01 vs. 6.08) compared to samples from chickens fed non-supplemented diets. Similarly, GAA supplementation reduced (P < 0.01) pH after six (5.88 vs. 5.92) and 24 h (5.95 vs. 5.99) post-slaughter at 55 d of age. An interaction effect was observed on redness (a*) value at 51 d only. Differences were detected only in the supplemented diets with GAA, where chickens fed sorghum-supplemented diets had higher (P < 0.01) a* value than breast meat from chickens fed corn-supplemented diets (4.91 vs. 3.78). While samples of broilers fed corn or sorghum non-supplemented diets had intermediate results. At 51 d only, an interaction effect (P < 0.05) was found on yellowness (b*) value. Samples from broilers fed corn non-supplemented diets had the highest b* value. At 55 d of processing the b* value was affected (P < 0.001) by grain type. Breast fillets from broilers fed corn diets had greater b* values (9.28 vs. 5.50) than samples from broilers fed sorghum diets. Opposite response was observed for lightness (L*), where no differences (P > 0.05) between treatments were detected due to grain type or GAA supplementation at any processing days. It has been reported (Garcia et al., 2005; Del Puerto et al., 2016) that drip and cook loss were not affected (P > 0.05) by partial or total replacement of corn by sorghum. Likewise, GAA did not improve (P > 0.05) drip loss in a previous study (Michiels et al., 2012). On the other hand, Michiels et al. (2012) observed that cook loss was increased (P < 0.05) in diets containing GAA compared to a negative control (corn-soybean meal diets). Garcia et al. (2013) observed that breast meat pH was not affected (P > 0.05) by the substitution (50 and 100%) of corn with sorghum. In addition, Garcia et al. (2005) reported that the replacement of 100% of corn by sorghum lowered (P < 0.05) breast meat pH. Del Puerto et al. (2016) found no differences (P > 0.05) in ultimate pH when comparing samples of Pectoralis major from chickens fed corn or sorghum-based diets. However, they observed differences on pH after 45 and 90 min of slaughter, where samples from broilers fed corn diets had lower (P < 0.05) pH values than samples from broilers fed sorghum. These researchers suggested that the effect of sorghum to reduce the pH drop in the breast muscle as compared to corn, and this could be due to the difference in starch digestibility. Corn has higher digestibility than sorghum because anti-nutritional factors contained in sorghum grain such as tannins and kafirin proteins reduce the availability of amino acids and starch (Garcia et al., 2005). This effect associated with tannins in sorghum has been observed to differ among broilers, layers, and roosters (Huang et al., 2006; Moughan et al., 2014). A previous study conducted by Michiels et al. (2012) found that GAA supplementation lowered (P < 0.05) breast meat pH after 4 and 24 h post-slaughter of broilers fed supplemented diets in comparison with chickens fed non-supplemented diets. Our findings would suggest that GAA supplementation lowered the pH of breast meat to levels close to what is has been reported to be normal values (Fletcher et al., 2000), which could be beneficial for water holding capacity and therefore breast meat tenderness. However, no differences were detected on drip and cook loss, and shear force in both processing days. The water-holding capacity of marinated meat was not evaluated in the present study. Michiels et al. (2012) reported that when chickens were fed diets containing GAA, the ratios of phosphocreatine: ATP were higher than those fed a negative control without GAA supplementation, indicating the buffer capacity of ATP for hydrolysis by phosphocreatine which represent higher energy availability for muscle development. Moreover, intramuscular phosphocreatine can attract water into the muscle cell and increase the cell volume (Hultman et al., 1996). Haussinger (1996) found that a super-hydrated muscle may trigger protein synthesis, minimize protein breakdown, and increase glycogen synthesis, as partly demonstrated by Young et al. (2007). Abasht et al. (2016) observed that breast meat affected with wooden breast myopathy had lower (P < 0.001) glycogen content in muscle than samples from unaffected chickens. A significant higher ultimate pH (24 h after slaughter) observed in affected tissues may also be related to glycogen depletion and reduced glycolytic potential within affected muscle at the time of slaughtering (Sante et al., 2001; Del Puerto el al., 2016). A recent study (Majdeddin et al., 2017) concluded that higher phosphocreatine, creatine and glycogen concentrations in breast muscle of broilers were observed with increasing dietary GAA levels (0.06 and 0.12%). Shear force (Warner-Bratzler) was not affected either by grain source or GAA supplementation in the present experiment. Generally, results ranged between 41.87 to 46.09 N (4.27 to 4.70 kg respectively, Warner-Bratzler). According to different authors (Owens et al., 2000; Schilling et al., 2003; Corzo et al., 2009) these values have been considered as low tender, resulting in less acceptability by the consumer. However, Schilling et al. (2003) suggested that independently of the shear force value in samples considered as low tender, not many consumers would find these samples as unacceptable. The values obtained in the present experiment showed similar results as observed by Poole et al. (1999), who observed that broilers at 7 wk old had an average of 4.64 ± 0.18 kg shear force values (Warner-Bratzler). These authors concluded that shear force values of cooked breast meat changes, depending on age of the broilers. They suggested that shear force values of breast fillets in the scale from 3.46 to 6.41 kg (Warner-Bratzler) are considered “moderately tender”. According to Garcia et al. (2005), no differences (P > 0.05) in shear force were observed when corn was replaced by sorghum up to 100% in the diet. In agreement with our findings, Michiels et al. (2012) reported that shear force was not affected (P > 0.05) by up to 1.2% GAA dietary supplementation. Therefore, the shear force values obtained in our experiment were more likely due to age of the broilers than related to dietary grain source or GAA supplementation. Zotte et al. (2017) found no differences in shear force when comparing breast fillets affected by WB myopathy with non-affected breast fillets. According to Fletcher (2002), differences in tenderness can be due to the fact that older birds are more mature at the time of harvest and have more cross-linked collagen. Considering the age of broilers at processing in the experiment described herein, the incidence of WB is related to increased cross-linked collagen in the pectoral muscle. Results from the present study related to color in breast meat, are consistent with those detected by Garcia et al. (2013) and Harder et al. (2010), who evaluated the effects of sorghum replacing corn in the diet for broilers. These authors concluded that the L* value of broiler breast meat depends on the carotenoid content in the diet. In the same study, breast meat b* value decreased gradually as sorghum replaced corn in the diets. According to Etuk et al. (2012) and Garcia et al. (2013), grain sorghum is deficient in carotene and contains less yellow xanthophylls than corn. Therefore, the findings of b* value in the present study may be due to carotenoid content in the diets considering its grain-based origin; thus, breast meat from chickens fed corn diets had higher b* values at both processing days. Garcia et al. (2013) also concluded that breast meat redness (a*) decreased, and lightness (L*) increased when corn was replaced by sorghum at 50 and 100% level. However, results from our experiment showed no effect (P > 0.05) of grain source or GAA supplementation on L* value for both slaughter ages, and a* value was affected by grain type only at 51 d. Garcia et al. (2005) reported similar results as findings detected in the present study. Breast meat L* values were not affected when corn was replaced 100% by sorghum. Michiels et al. (2012) observed that L* and b* values were increased (P < 0.05) by GAA supplementation of corn-based diets. In contrast, we observed that dietary GAA supplementation reduced (P < 0.05) b* values. Zotte et al. (2017) found differences (P < 0.01) in color between breast meat of chickens affected with WB and non-affected samples. Breast meat with WB abnormality had higher (P < 0.01) L*, a*, and b* values, than those without the abnormality. According to several researchers, the impairment of the homeostasis of lipids and proteins leads to oxidation in muscle promoting changes in meat color due to modification of heme pigments state (Estevez, 2011; Xiao et al., 2011; Zhang et al., 2011). Poultry meat color depends mainly on myoglobin concentration and chemical state, while it is affected by numerous factors such as bird age, gender, genetic background, diet, intramuscular fat, meat moisture content, preslaughter conditions, and processing variables (Totosaus et al., 2007). In the project described herein, at 51 d of age only, an effect of GAA supplementation was observed on b* value (Table 6) and on WB average score (Table 7). At this age a positive correlation (P < 0.05; r = 0.238) between b* value and WB was detected and it is shown in Table 8. These findings support the results obtained by other researchers (Mudalal et al., 2015; and Wold et al., 2017) in which WB was associated with higher b* values. In addition, altered color with higher b* value has been related with breast meat abnormalities (Petracci et al., 2017), having an important potential to identify fillets with WB myopathy in an industrial scale (Wold et al., 2017). Differences as compared to the quoted references can be due to dose, age of chickens, diet and standardization of the applied technique. Table 7. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum diets for Ross-708 male broilers on pectoral myophaties sensorial average score severity at 51 and 55 d of age.     White striping  Wooden breast  Spaghetti muscle  Additive  Grain  51d  55d  51d  55d  51d  55d      — (1–4) —  — (1–4) —  — (1–2) —  GAA    2.24  2.30  2.33b  2.37  1.14  1.02  None    2.17  2.21  2.76a  2.41  1.09  1.04  SEM    0.09  0.08  0.10  0.08  0.03  0.02    Corn  2.16  2.29  2.51  2.58a  1.10  1.03    Sorghum  2.25  2.23  2.57  2.19b  1.14  1.03    SEM  0.08  0.08  0.10  0.08  0.03  0.02  GAA  Corn  2.20  2.30  2.18  2.58  1.13  1.02    Sorghum  2.27  2.31  2.48  2.15  1.16  1.03  None  Corn  2.13  2.27  2.85  2.59  1.08  1.05    Sorghum  2.22  2.15  2.67  2.23  1.11  1.04    SEM  0.11  0.11  0.14  0.11  0.04  0.03  Source of variation  ———————– P—values ———————–  Additive  0.573  0.417  0.003  0.723  0.279  0.411  Grain  0.447  0.610  0.667  0.001  0.436  0.973  Additive*grain  0.912  0.565  0.085  0.745  0.982  0.621      White striping  Wooden breast  Spaghetti muscle  Additive  Grain  51d  55d  51d  55d  51d  55d      — (1–4) —  — (1–4) —  — (1–2) —  GAA    2.24  2.30  2.33b  2.37  1.14  1.02  None    2.17  2.21  2.76a  2.41  1.09  1.04  SEM    0.09  0.08  0.10  0.08  0.03  0.02    Corn  2.16  2.29  2.51  2.58a  1.10  1.03    Sorghum  2.25  2.23  2.57  2.19b  1.14  1.03    SEM  0.08  0.08  0.10  0.08  0.03  0.02  GAA  Corn  2.20  2.30  2.18  2.58  1.13  1.02    Sorghum  2.27  2.31  2.48  2.15  1.16  1.03  None  Corn  2.13  2.27  2.85  2.59  1.08  1.05    Sorghum  2.22  2.15  2.67  2.23  1.11  1.04    SEM  0.11  0.11  0.14  0.11  0.04  0.03  Source of variation  ———————– P—values ———————–  Additive  0.573  0.417  0.003  0.723  0.279  0.411  Grain  0.447  0.610  0.667  0.001  0.436  0.973  Additive*grain  0.912  0.565  0.085  0.745  0.982  0.621  Values are means of 10 pens per treatment combination with 4 male broiler chickens selected for processing. a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. View Large Table 7. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum diets for Ross-708 male broilers on pectoral myophaties sensorial average score severity at 51 and 55 d of age.     White striping  Wooden breast  Spaghetti muscle  Additive  Grain  51d  55d  51d  55d  51d  55d      — (1–4) —  — (1–4) —  — (1–2) —  GAA    2.24  2.30  2.33b  2.37  1.14  1.02  None    2.17  2.21  2.76a  2.41  1.09  1.04  SEM    0.09  0.08  0.10  0.08  0.03  0.02    Corn  2.16  2.29  2.51  2.58a  1.10  1.03    Sorghum  2.25  2.23  2.57  2.19b  1.14  1.03    SEM  0.08  0.08  0.10  0.08  0.03  0.02  GAA  Corn  2.20  2.30  2.18  2.58  1.13  1.02    Sorghum  2.27  2.31  2.48  2.15  1.16  1.03  None  Corn  2.13  2.27  2.85  2.59  1.08  1.05    Sorghum  2.22  2.15  2.67  2.23  1.11  1.04    SEM  0.11  0.11  0.14  0.11  0.04  0.03  Source of variation  ———————– P—values ———————–  Additive  0.573  0.417  0.003  0.723  0.279  0.411  Grain  0.447  0.610  0.667  0.001  0.436  0.973  Additive*grain  0.912  0.565  0.085  0.745  0.982  0.621      White striping  Wooden breast  Spaghetti muscle  Additive  Grain  51d  55d  51d  55d  51d  55d      — (1–4) —  — (1–4) —  — (1–2) —  GAA    2.24  2.30  2.33b  2.37  1.14  1.02  None    2.17  2.21  2.76a  2.41  1.09  1.04  SEM    0.09  0.08  0.10  0.08  0.03  0.02    Corn  2.16  2.29  2.51  2.58a  1.10  1.03    Sorghum  2.25  2.23  2.57  2.19b  1.14  1.03    SEM  0.08  0.08  0.10  0.08  0.03  0.02  GAA  Corn  2.20  2.30  2.18  2.58  1.13  1.02    Sorghum  2.27  2.31  2.48  2.15  1.16  1.03  None  Corn  2.13  2.27  2.85  2.59  1.08  1.05    Sorghum  2.22  2.15  2.67  2.23  1.11  1.04    SEM  0.11  0.11  0.14  0.11  0.04  0.03  Source of variation  ———————– P—values ———————–  Additive  0.573  0.417  0.003  0.723  0.279  0.411  Grain  0.447  0.610  0.667  0.001  0.436  0.973  Additive*grain  0.912  0.565  0.085  0.745  0.982  0.621  Values are means of 10 pens per treatment combination with 4 male broiler chickens selected for processing. a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. View Large Table 8. Pearson correlation coefficients between breast meat quality parameters Ross-708 male broilers raised up to 51d.   Drip Loss  Cook Loss  Wooden Breast  pH (t = 6 h)  pH (t = 24 h)  Shear force1  L*  a*  Drip Loss  1                Cook Loss  0.313**  1              Wooden Breast  0.231*  0.355**  1            pH (t = 6 h)  0.209*  0.048  0.236*  1          pH (t = 24 h)  0.050  0.176*  0.195*  0.210*  1        Shear force1  -0.202*  0.070  0.144  -0.162*  -0.078  1      L*  0.302**  0.495**  0.341**  0.094  0.010  0.054  1    a*  0.144  0.124  0.156*  0.008  0.039  -0.057  -0.068  1  b*  0.151  0.132  0.238*  0.093  -0.002  -0.087  0.423**  0.136    Drip Loss  Cook Loss  Wooden Breast  pH (t = 6 h)  pH (t = 24 h)  Shear force1  L*  a*  Drip Loss  1                Cook Loss  0.313**  1              Wooden Breast  0.231*  0.355**  1            pH (t = 6 h)  0.209*  0.048  0.236*  1          pH (t = 24 h)  0.050  0.176*  0.195*  0.210*  1        Shear force1  -0.202*  0.070  0.144  -0.162*  -0.078  1      L*  0.302**  0.495**  0.341**  0.094  0.010  0.054  1    a*  0.144  0.124  0.156*  0.008  0.039  -0.057  -0.068  1  b*  0.151  0.132  0.238*  0.093  -0.002  -0.087  0.423**  0.136  **P < 0.001. *P < 0.05. 1 Warner-Bratzler; Color: L* = lightness, a* = redness, b* = yellowness View Large Table 8. Pearson correlation coefficients between breast meat quality parameters Ross-708 male broilers raised up to 51d.   Drip Loss  Cook Loss  Wooden Breast  pH (t = 6 h)  pH (t = 24 h)  Shear force1  L*  a*  Drip Loss  1                Cook Loss  0.313**  1              Wooden Breast  0.231*  0.355**  1            pH (t = 6 h)  0.209*  0.048  0.236*  1          pH (t = 24 h)  0.050  0.176*  0.195*  0.210*  1        Shear force1  -0.202*  0.070  0.144  -0.162*  -0.078  1      L*  0.302**  0.495**  0.341**  0.094  0.010  0.054  1    a*  0.144  0.124  0.156*  0.008  0.039  -0.057  -0.068  1  b*  0.151  0.132  0.238*  0.093  -0.002  -0.087  0.423**  0.136    Drip Loss  Cook Loss  Wooden Breast  pH (t = 6 h)  pH (t = 24 h)  Shear force1  L*  a*  Drip Loss  1                Cook Loss  0.313**  1              Wooden Breast  0.231*  0.355**  1            pH (t = 6 h)  0.209*  0.048  0.236*  1          pH (t = 24 h)  0.050  0.176*  0.195*  0.210*  1        Shear force1  -0.202*  0.070  0.144  -0.162*  -0.078  1      L*  0.302**  0.495**  0.341**  0.094  0.010  0.054  1    a*  0.144  0.124  0.156*  0.008  0.039  -0.057  -0.068  1  b*  0.151  0.132  0.238*  0.093  -0.002  -0.087  0.423**  0.136  **P < 0.001. *P < 0.05. 1 Warner-Bratzler; Color: L* = lightness, a* = redness, b* = yellowness View Large Pectoral Myopathies The average score of each myopathy is presented in Table 7, and the distribution of the probability for each WB score for both processing days are shown in Figures 1 and 2. No effects (P > 0.05) of grain type or GAA supplementation were detected on spaghetti muscle and WS for both slaughter ages. However, dietary supplementation of GAA decreased (P < 0.01) the severity of WB at 51 d of age, but not at 55 d. At this age (55 d), broilers fed sorghum based diets had lower (P < 0.01) WB average score severity compared to chickens fed corn-based diets, which may be related to a higher BW gain in broilers fed corn-based diets. Results of the probability distribution for each WB score at 51 d showed an interaction effect on WB score 2 (Figure 1). Dietary supplementation with GAA in corn-based diets, increased (P < 0.05) the probability of having breast meat samples with low severity of WB (score 2), mainly due to the reduction of probability for scores 3 and 4, whereas in sorghum diets the addition of the feed additive decreased the WB score 2 principally due to an increment of the probability for having breast meat with no WB myopathy (score 1). At 55 d, broilers fed sorghum had fewer (P < 0.05) breast meat samples with score 3 (medium severity) for WB myopathy compared to broilers fed corn-based diets (Figure 2). The differences in responses to GAA on myopathies between the two processing times could be due to a higher breast meat yield driven by GAA at 55d only in chickens fed corn-based diets (Table 5) that may promote the occurrence of myopathies compared to broilers non-supplemented with GAA that had even lower breast meat yield at 55 d compared to 51 d (38.19 vs. 38.63%) leading to a similar average score (2.58 vs. 2.59) of myopathies (Table 7). Figure 1. View largeDownload slide Interaction effect of grain source and GAA supplementation on probability distribution (0.00–1.00) for each wooden breast severity score in Ross-708 male broilers at 51 d of age. Means not sharing a common superscript (a-b) are significantly different (P < 0.05) by Tukey's test. Each value represents the probability (0 -1) of developing each severity score according to main factors or factorial arrangement of treatments, n = 40 broilers within 10 pens per treatment. Scores are based on a 4-point scale (4 = severe, 3 = medium, 2 = low, 1 = normal). Figure 1. View largeDownload slide Interaction effect of grain source and GAA supplementation on probability distribution (0.00–1.00) for each wooden breast severity score in Ross-708 male broilers at 51 d of age. Means not sharing a common superscript (a-b) are significantly different (P < 0.05) by Tukey's test. Each value represents the probability (0 -1) of developing each severity score according to main factors or factorial arrangement of treatments, n = 40 broilers within 10 pens per treatment. Scores are based on a 4-point scale (4 = severe, 3 = medium, 2 = low, 1 = normal). Figure 2. View largeDownload slide Effect of grain source on probability distribution (0.00–1.00) for each wooden breast severity score in Ross-708 male broilers at 55 d of age. Means not sharing a common superscript (a-b) are significantly different (P < 0.05) by t-student's test. Each value represents the probability (0–1) of developing each severity score according to main factors or factorial arrangement of treatments, n = 40 within 10 pens per treatment. Scores are based on a 4-point scale (4 = severe, 3 = medium, 2 = low, 1 = normal). Figure 2. View largeDownload slide Effect of grain source on probability distribution (0.00–1.00) for each wooden breast severity score in Ross-708 male broilers at 55 d of age. Means not sharing a common superscript (a-b) are significantly different (P < 0.05) by t-student's test. Each value represents the probability (0–1) of developing each severity score according to main factors or factorial arrangement of treatments, n = 40 within 10 pens per treatment. Scores are based on a 4-point scale (4 = severe, 3 = medium, 2 = low, 1 = normal). A previous trial (Mudalal et al., 2015; Mutryn et al., 2015) suggested that these abnormalities might be related to a reduced level of glycogen in the muscle. Additionally, Zotte et al. (2017) reported higher (P < 0.01) ultimate pH values of breast meat affected by WB than breast meat samples from non-affected broilers (6.30 vs. 5.92). Soglia et al. (2016) observed that ultimate pH of breast meat affected by WB was higher (P < 0.01) than fillets samples considered normal (pH: 5.87 vs. 5.82). Considering the results of the present study at slaughter age 51 d, dietary GAA supplementation reduced (P < 0.05) the ultimate pH and doubled the probability of having breast meat considered as normal or with no signs of WB (score 1). Evidently, dietary GAA supplementation helped to prevent myopathies in broilers fed vegetable-based diets or ameliorates the severity of WB. Apparently, the improvement on concentration of metabolites involved in muscle energy metabolism (creatine, phosphocreatine, and phosphocreatine: ATP) and the increase creatine and glycogen content by dietary GAA supplementation (Lemme et al., 2007a; Majdeddin et al., 2017; DeGroot et al., 2018) in muscle, may have a supportive effect on muscle energy metabolism (Balsom et al., 1994; Kolling et al., 2013; Nabuurs et al., 2013) as observed in previous trials conducted in rats with muscle dystrophies (Pearlman and Fielding, 2006; Chung et al., 2007; Tarnopolsky, 2007). Kolling et al. (2013) explained the effect of creatine and associated it with homocysteine-altered glucose oxidation that protects muscle from energy imbalances in rats. An impaired energy metabolism may trigger proapoptotic signaling (programmed cell death), oxidative damage to lipids, protein and DNA, and impair mitochondrial DNA repair. It has been demonstrated that alterations in energy metabolism seem to be implicated in the pathogenesis of several muscle and neurological complications, metabolic disorders, aging and neuromuscular diseases. Nabuurs et al. (2013) also observed similar effect reversing muscular dystrophy effects of creatine deficiency by providing creatine in diets to rats. Therefore, we could speculate that dietary supplementation with GAA as precursor of creatine may prevent or reduce the occurrence of WB myopathy by modulating intermediate metabolites related with muscle and energy metabolism. In addition, we could suggest that the response observed on b* value may be related to a protective effect of GAA supplementation on heme pigments reducing the fibrotic response that has been observed in muscle myopathies (Petracci et al., 2017). In conclusion, results of the current study indicated that dietary supplementation of GAA (600 g/ton) improved BW gain and FCR of broilers fed either corn or sorghum-based diets throughout their life to market age. An improvement in breast meat yield was observed at 55d when adding GAA to corn diets, but not when added to sorghum diets. GAA supplementation reduced the severity of WB at 51 d and reduced the breast meat ultimate pH. Findings associated with b* value of color and WB suggest that GAA as precursor of creatine may have a potential benefit in lowering the severity of this myopathy. Notes Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by North Carolina State University. REFERENCES Abasht B., Mutryn M. F., Michalek R. D., Lee W. R.. 2016. Oxidative stress and metabolic perturbations in wooden breast disorder in chickens. PLoS One  11: e0153750. Google Scholar CrossRef Search ADS PubMed  AminoDat 5.0. 2015. Evonik Industries , Evonik Degussa GmbH, Hanau-Wolfgang, Germany. PubMed PubMed  AgriStats. 2016. AgriStats Monthly Live Production, April . AgriStats, Inc. Fort Wayne, Indiana. Baldi G., Soglia F., Mazzoni M., Sirri F., Canonico L., Babini E., Laghi L., Cavani C., Petracci M.. 2018. Implications of white striping and spaghetti meat abnormalities on meat quality and histological features in broilers. Animal . 12: 164– 173. Google Scholar CrossRef Search ADS PubMed  Balsom P. D., Soderlund K., Ekblom B.. 1994. Creatine in humans with special reference to creatine supplementation. Sports Medicine . 18: 268– 280. Google Scholar CrossRef Search ADS PubMed  Beal F. M. 2011. Neuroprotective effects of creatine. Amino Acids . 40: 1305– 1313. Google Scholar CrossRef Search ADS PubMed  Bender A., Koch W., Elstner M.. 2006. Creatine supplementation in Parkinson disease: a placebo-controlled randomized pilot trial. Neurology . 67: 1262– 1264. Google Scholar CrossRef Search ADS PubMed  Bozutti S. R. A. 2009. Avaliacao de ingredients alternativos na alimentacao de frangos de corte com a adicao de enzimas . MSci. Diss. Faculdade de Zootecnia e Engenharia de Alimentos/Universidade de Sao Paulo, Pirassununga, Sao Paulo, Brazil. Brenes A., Viveros A., Goñi I., Centeno C., Sayago-Ayerdy S. G., Arija I., Saura-Calixto F.. 2008. Effect of grape pomace concentrate and vitamin E on digestibility of polyphenols and antioxidant activity in chickens. Poult. Sci.  87: 307– 316. Google Scholar CrossRef Search ADS PubMed  Bryden W. L., Li X.. 2010. Amino acid digestibility and poultry feed formulation: expression, limitations and application. R. Bras. Zootec.  39: 279– 287. Google Scholar CrossRef Search ADS   Campos D. M. B. 2006. Efeito do sorgo sobre o desempenho zootecnico, caracteristicas da caracca e o desenvolvimiento da mucosa intestinal de frangos . MSci Diss. Faculdade de Ciencias Agrarias e Veterinarias/Universidade Estadual Paulista, Jaboticabal, Sao Paulo, Brazil. Chung Y. L., Alexanderson H., Pipitone N.. 2007. Creatine supplements in patients with idiopathic inflammatory myopathies who are clinically weak after conventional pharmacologic treatment: Six-month, double-blind, randomized, placebo-controlled trial. Arthritis Rheum.  57: 694– 702. Google Scholar CrossRef Search ADS PubMed  Community Reference Laboratory Feed Additives (CRL Feed Additives). 2007. CRL Evaluation Report on Guanidinoacetic acid (CreAmino™ ). FAD-2007–0003. European Food Safety Authority (EFSA). The European Commission's science an knowledge service, EU SCIENCE HUB. EFSA-Q-2007-050. Corzo A., Schilling M. W., Loar R. E. II, Jackson V., Kin S., Radhakrishnan V.. 2009. The effects of feeding distillers dried grains with solubles on broiler meat quality. Poult. Sci.  88: 432– 439. Google Scholar CrossRef Search ADS PubMed  DeGroot A. A. 2014. Efficacy of dietary guanidinoacetic acid in broilers chicks . Master Diss. Univ. of Illinois at Urbana-Champaign, Illinois. DeGroot A. A., Braun U., Dilger R. N.. 2018. Efficacy of guanidinoacetic acid on growth and muscle energy metabolism in broiler chicks receiving arginine-deficient diets. Poult. Sci.  0: 1– 11. Del Puerto M., Terevinto A., Saadoun A., Olivero R., Cabrera M. C.. 2016. Effect of different sources of dietary starch on meat quality, oxidative status and glycogen and lactate kinetic in chicken Pectoralis muscle. J. Food Nutr. Res.  4: 185– 194. Dilger R. N., Bryant-Angeoni K., Payne R. L., Lemme A., Parsons C. M.. 2013. Dietary guanidino acetic acid is an efficacious replacement for arginine for young chicks. Poult. Sci.  92: 171– 177. Google Scholar CrossRef Search ADS PubMed  Douglas J. H., Sullivan T. W., Bond P. L., Struwe F. J.. 1990. Nutrient composition and metabolizable energy values of selected grain sorghum varieties and yellow corn. Poult. Sci.  69: 1147– 1155. Google Scholar CrossRef Search ADS   Ebadi M. R., Pourreza J., Jamalian J., Edriss M. A., Samie A. H., Mirhadi S. A.. 2005. Amino acid content and availability in low, medium and high tannin sorghum grain for poultry. International J. Poul. Sci.  4: 27– 31. Google Scholar CrossRef Search ADS   Esser A. F. G., Goncalves D. R. M., Rorig A., Cristo A. B., Perini R., Fernandes J. I. M.. 2017. Effects of guanidionoacetic acid and arginine supplementation to vegetable diets fed to broiler chickens subjected to heat stress before slaughter. Braz. J. Poult. Sc.  19: 429– 436. Estevez M. 2011. Protein carbonyls in meat systems: a review. Meat Sci.  89: 259– 279. Google Scholar CrossRef Search ADS PubMed  Etuk E. B., Ifeduba A. V., Okata U. E., Chiaka I., Ifeanyi C. O., Okeudo N. J., Esonu B. O., Udedibie A. B. I., Moreki J. C.. 2012. Nutrient composition and feeding value of sorghum for livestock and poultry: a review. J. Anim. Sci. Adv.  2: 510– 524. Fletcher D. L. 2002. Poultry meat quality. Worlds Poult. Sci. J.  58: 131– 145. Google Scholar CrossRef Search ADS   Fletcher D. L., Giao M., Smith D. P.. 2000. The relationship of raw broiler breast meat color and pH to cooked meat color and pH. Poult. Sci.  79: 784– 788. Google Scholar CrossRef Search ADS PubMed  Gabor E., Gaspar O., Vamos E.. 1984. Quantitative determination of muscle protein in meat products by measuring creatine content. Acta alimentaria.  13: 13– 22. Garcia R. G., Mendes A. A., Costa C., Paz I. C. L. A., Takahashi S. E.. 2005. Desempenho e qualidade da carne de frangos de corte alimentados com diferentes níveis de sorgo em substituição ao milho. Arq. Bras. Med. Vet. Zootec.  57: 634– 643. Google Scholar CrossRef Search ADS   Garcia A. R., Batal A. B., Dale N. M.. 2007. A comparison of methods to determine amino acid digestibility of feed ingredients for chickens. Poult. Sci.  86: 94– 101. Google Scholar CrossRef Search ADS PubMed  Garcia R., Mendes A., Almeida P., Komiyama C., Caldara F., Naas I., Mariano W.. 2013. Implications of the use of sorghum in broiler production. Braz. J. Poult. Sci.  15: 169– 286. Harder M. N. C., Spada F. P., Savino V. J. M., Coelho A. A. D., Correr E., Martins E.. 2010. Coloração de cortes cozidos de frangos alimentados com urucum. Ciênc. Tecnol. Aliment.  30: 507– 509. Google Scholar CrossRef Search ADS   Haussinger D. 1996. The role of cellular hydration in the regulation of cell function. Biochem. J.  313: 697– 710. Google Scholar CrossRef Search ADS PubMed  Heger J., Zelenka J., Machander V., de la Cruz C., Lestak M., Hample D.. 2014. Effects of guanidinoacetic acid supplementation to broiler diets with varying energy content. Acta Univ. Agric. Silvic. Mendelianae Brun.  62: 477– 485. Google Scholar CrossRef Search ADS   Huang K. H., Li X., Ravindran V., Bryden W. L.. 2006. Comparison of apparent ileal amino acid digestibility of feed ingredients measured with broilers, layers, and roosters. Poult. Sci.  85: 625– 634. Google Scholar CrossRef Search ADS PubMed  Hultman E., Soderlund K., Timmons J. A., Cederblad G., Greenhaff P. L.. 1996. Muscle creatine loading in men. J. Appl. Physiol.  81: 232– 237. Google Scholar CrossRef Search ADS PubMed  Khan A. W., Cowen D. C.. 1977. Rapid estimation of muscle proteins in beef-vegetable protein mixtures. J. Agric. Food Chem.  25: 236– 238. Google Scholar CrossRef Search ADS PubMed  Kolling J., Wyse A. T. S.. 2010. Creatine prevents the inhibition of energy metabolism and lipid peroxidation in rats subjected to GAA administration. Metab. Brain Dis.  25: 331– 338. Google Scholar CrossRef Search ADS PubMed  Kolling J., Scherer E. B. S., Siebert C., Hansen F., Torres F. V., Scaini G., Ferreira G., De Andrade R. B., Goncalves C. A. S., Streck E. L., Wannmacher C. M. D., Wyse A. T. S.. 2013. Homocysteine induces energy imbalance in rat skeletal muscle: is creatine a protector?. Cell Biochem. Funct.  31: 575– 584. Google Scholar PubMed  Kumar V., Elangovan A. V., Mandal A. B.. 2005. Utilization of reconstituted high-tannin sorghum in the diets of broiler chickens. Asian-Australas. J. Anim. Sci.  18: 538– 544. Google Scholar CrossRef Search ADS   Kuttappan V. A., Hargis B. M., Owens C. M.. 2016. White striping and woody breast myopathies in the modern poultry industry: a review. Poult. Sci.  95: 2724– 2733. Google Scholar CrossRef Search ADS PubMed  Kwari I. D., Diarra S. S., Igwebuike J. U., Nkama I., Issa S., Hamaker B. R., Hancock J. D., Jauro M., Seriki O. A., Murphy I.. 2012. Replacement value of low tannin sorghum (Sorghum bicolor) for maize in broiler chickens' diets in the semi-arid zone of nigeria. International J. Poult. Sci.  11: 333– 337. Google Scholar CrossRef Search ADS   Lemme A., Ringel J., Sterk A., Young J.. 2007a. Supplemental guanidino acetic acid affects energy metabolism of broilers. Proc. 16th Eur. Symp. Poult. Nut., Strasbourg, France . World's Poult. Sci. Assoc., Beekbergen, the Netherlands. Lemme A., Ringel J., Rostagno H. S., Redshaw M. S.. 2007b. Supplemental guanidine acetic acid improved feed conversion, weight gain, and breast meat yield in male and female broilers. Proc. 16th Eur. Symp. Poult. Nut., Strasbourg, France . World's Poult. Sci. Assoc., Beekbergen, the Netherlands. Li X., Rezaeri R., Li P., Wu G.. 2011. Composition of amino acids in feed ingredients for animal diets. Amino Acids . 40: 1159– 1168. Google Scholar CrossRef Search ADS PubMed  Majdeddin M., Braun U., Lemme A., Golian A., Kermanshahi H., De Smet S., Michielis J.. 2017. Guanidinoacetic acid supplementation improves feed conversion in broilers subjected to chronic cyclic heat stress in the finishing phase associated with improved energy and arginine metabolism. Proc. 21st Eur. Symp. Poult. Nut., Salout/Vila-seca, Spain . World's Poult. Sci. Assoc. Wageningen Academic Publishers, Wageningen, the Netherlands. Makkar H. P., Becker K.. 1993. Vanillin-HCl method for condensed tannins: Effect of organic solvents used for extraction of tannins. J. Chem. Ecol.  19: 613– 621. Google Scholar CrossRef Search ADS PubMed  Michiels J., Maertens L., Buyse J., Lemme A., Rademacher M., Dierick N., De Smet S.. 2012. Supplementation of guanidinoacetic acid to broiler diets: Effects on performance, carcass characteristics, meat quality, and energy metabolism. Poult. Sci.  91: 402– 412. Google Scholar CrossRef Search ADS PubMed  Mohamed A., Urge M., Gebeyew K.. 2015. Effects of replacing maize with sorghum on growth and feed efficiency of commercial broiler chicken. J. Vet. Sci. Technol.  6: 224. Moughan P. J., Ravindran V., Sorbara J. O. B.. 2014. Dietary protein and amino acids—Consideration of the undigestible fraction. Poult. Sci.  93: 2400– 2410. Google Scholar CrossRef Search ADS PubMed  Mousavi S., Afsar A., Lotfollahian H.. 2013. Effects of guanidinoacetic acid supplementation to broiler diets with varying energy contents. J. Appl. Poul. Res.  22: 47– 54. Google Scholar CrossRef Search ADS   Mudalal S., Lorenzi M., Soglia F., Cavani C., Petracci M.. 2015. Implications of white striping and wooden breast abnormalities on quality traits of raw and marinated chicken meat. Animal . 9: 728– 734. Google Scholar CrossRef Search ADS PubMed  Mutryn M. F., Brannick E. M., Fu W., Lee W. L., Abasht B.. 2015. Characterization of a novel chiken muscle disorder through differential gene expression and pathway analysis using RNA-sequencing. Genomics . 16: 399. Google Scholar PubMed  Nabuurs C. I., Choe C. U., Veltien A., Kan H. E., VanLoon L. J. C., Rodenburg R. J. T., Matschke J., Wieringa B., Kemp G. J., Isbrandt D., Heerschap A.. 2013. Disturbed energy metabolism and muscular dystrophy caused by pure creatine deficiency are reversible by creatine intake. J. Physiol.  591: 571– 592. Google Scholar CrossRef Search ADS PubMed  Nasr J., Kheiri F.. 2012. Effects of lysine levels of diets formulated based on total or digestible amino acids on broiler carcass composition. Braz. J. Poult. Sci.  14: 233– 304. Owens C. M., Hirschler E. M., McKee S. R., Martinez-Dawson R., Sams A. R.. 2000. The characterization and incidence of pale, soft, exudative turkey meat in a commercial plant. Poult. Sci.  79: 553– 558. Google Scholar CrossRef Search ADS PubMed  Parsons C. M. 1985. Influence of caecectomy on digestibility of amino acids by roosters fed distillers' dried grains with solubles. J. Agric. Sci.  104: 469– 472. Google Scholar CrossRef Search ADS   Pearlman J. P., Fielding R. A.. 2006. Creatine monohydrate as a therapeutic aid in muscular dystrophy. Nutr. Rev.  64: 80– 88. Google Scholar CrossRef Search ADS PubMed  Petracci M., Soglia F., Berri C.. 2017. Muscle metabolism and meat quality abnormalities. Pages 51– 75 in Poultry Quality Evaluation, quality attributes and consumer values , Petracci M., Berri C., ed. Woodhead Publishing Series in Food Science, Technology and Nutrition. Woodhead Publishing Limited, Cambridge, UK. Google Scholar CrossRef Search ADS   Poole G. H., Lyon C. E., Buhr R. J., Young L. L.. 1999. Evaluation of age, gender, strain, and diet on the cooked yield and shear values of broiler breast fillets. J. Appl. Poult. Res.  8: 170– 176. Google Scholar CrossRef Search ADS   Pour-Reza J., Edriss M. A.. 1997. Effects of dietary sorghum of different tannin concentrations and tallow supplementation on the performance of broiler chicks. Br. Poult. Sci.  38: 512– 517. Google Scholar CrossRef Search ADS PubMed  Rodrigues H. D., Perez-Maldonado R. A., Trappett P., Barram K. M., Kemsley M.. 2007. Broiler performance in Australian sorghum-based starter and finisher diets (2005 harvest). Proc. 19th Aust. Poult. Sci. Symp., Sidney, Australia . World's Poult. Sci. Assoc., Australia. Ringel J., Lemme A., Knox A., Mc Nab J., Redshaw M. S.. 2007. Effects of graded levels of creatine and guanidinoacetic acid in vegetable-based diets on performance and biochemical parameters in muscle tissue. Proc. 16th Eur. Symp. Poult. Nut., Strasbourg, France . World's Poult. Sci. Assoc., Beekbergen, the Netherlands. Sante V., Fernandez X., Monin G., Renou J. P.. 2001. Nouvelles méthodes de mesure de la qualité de la viande de volaille. INRA Productions Animales  14: 247– 254. SAS Institute. 2016. A User's Guide to SAS . Sparks Press, Inc., Cary, NC. SAS Institute. 2008. SAS/STAT Users Guide . Version 9.2. SAS Inst. Inc., Cary, NC. Schilling M. W., Schilling J. K., Claus J. R., Marriott N. G., Duncan S. E., Wang H.. 2003. Instrumental texture assessment and consumer acceptability of cooked broiler breast evaluated using a geometrically uniform-shaped sample. J Muscle Foods . 14: 11– 23. Google Scholar CrossRef Search ADS   Soglia F., Mudalal S., Babini E., Di Nunzio M., Mazzoni M., Sirri F., Cavani C., Petracci M.. 2016. Histology, composition, and quality traits of chicken Pectoralis major muscle affected by wooden breast abnormality. Poult. Sci.  95: 651– 659. Google Scholar CrossRef Search ADS PubMed  Tandiang D., Diop M., Dieng A., Louis G., Cisse N., Nassim M.. 2014. Effect of corn substitution by sorghum grain with low tannin content on broiler production: animal performance, nutrient digestibility and carcass characteristics. International J. Poult. Sci.  13: 568– 574. Google Scholar CrossRef Search ADS   Tarnopolsky M. A. 2007. Clinical use of creatine in neuromuscular and neurometabolic disorders. Subcell. Biochem.  46: 183– 204. Google Scholar CrossRef Search ADS PubMed  Tasoniero G., Cullere M., Cecchinato M., Puolanne E., Dalle Zotte A.. 2016. Technological quality, mineral profile, and sensory attributes of broiler chicken breasts affected by white striping and wooden breast myopathies. Poult. Sci.  95: 2707– 2714. Google Scholar CrossRef Search ADS PubMed  Tijare V. V., Yang F. L., Kuttappan V. A., Alvarado C. Z., Coon C. N., Owens C. M.. 2016. Meat quality of broiler breast fillets with white striping and woody breast muscle myopathies. Poult. Sci.  95: 2167– 2173. Google Scholar CrossRef Search ADS PubMed  Torres K., Pizauro J., Soares C., Silva T., Nogueira W., Campos D., Furlan R., Macari M.. 2013. Effects of corn replacement by sorghum in broiler diets on performance and intestinal mucosa integrity. Poult. Sci.  92: 1564– 1571. Google Scholar CrossRef Search ADS PubMed  Totosaus A., Perez-Chabela M. L., Guerrero I., 2007. Color of fresh and frozen poultry. Pages 455– 466 in Handbook of Meat, Poultry and Seafood Quality , Nollet L. M. L. ed. Blackwell Publishing Ltd, Ames, IA. Google Scholar CrossRef Search ADS   Vieira S. L., Lima I. L.. 2005. Live performance, water intake and excreta characteristics of broilers fed all vegetable diets based on corn and soybean meal. International J. Poult. Sci.  4: 365– 368. Google Scholar CrossRef Search ADS   Wold J. P., Veiseth-Kent E., Host V., Lovland A.. 2017. Rapid on-line detection and grading of wooden breast myopathy in chicken fillets by near-infrared spectroscopy. PLoS One . 12: 1– 16. Google Scholar CrossRef Search ADS   Young J. F., Bertram H. C., Theil P. K., Petersen A. G. D., Poulsen K. A., Rasmussen M., Malmendal A., Nielsen N. C., Vestergaard M., Oksbjerg N.. 2007. In vitro and in vivo studies of creatine monohydrate supplementation to Duroc and Landrace pigs. Meat Sci.  76: 342– 351. Google Scholar CrossRef Search ADS PubMed  Wyss M., Kaddurah-Daouk R.. 2000. Creatine and creatinine metabolism. Physiol. Rev.  80: 1107– 1213. Google Scholar CrossRef Search ADS PubMed  Xiao S., Zhang W. G., Lee E. J., Ma C. W., Ahn D. U.. 2011. Effects of diet, packaging, and irradiation on protein oxidation, lipid oxidation, and color of raw broiler thigh meat during refrigerated storage. Poult. Sci.  90: 1348– 1357. Google Scholar CrossRef Search ADS PubMed  Zhang W., Xiao S., Lee E. J., Ahn D. U.. 2011. Consumption of oxidized oil increases oxidative stress in broilers and affects the quality of breast meat. J. Agric. Food Chem.  59: 969– 974. Google Scholar CrossRef Search ADS PubMed  Zotte A. D., Tasoniero G., Poulanne E., Remignon H., Cecchinato M., Catelli E., Cullere M.. 2017. Effect of Wooden Breast appearance on poultry meat quality, histological traits, and lesions characterization. Czech J. Anim. Sci.  62: 51– 57. Google Scholar CrossRef Search ADS   © 2018 Poultry Science Association Inc. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Poultry Science Oxford University Press

Performance, meat quality, and pectoral myopathies of broilers fed either corn or sorghum based diets supplemented with guanidinoacetic acid

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Oxford University Press
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© 2018 Poultry Science Association Inc.
ISSN
0032-5791
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1525-3171
D.O.I.
10.3382/ps/pey096
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Abstract

ABSTRACT One experiment was conducted to evaluate the effects of guanidinoacetic acid (GAA) supplementation in broilers fed corn or sorghum-based diets on live performance, carcass and cut up yields, meat quality, and pectoral myopathies. The treatments consisted of corn or sorghum-based diets with or without the addition of GAA (600 g/ton). A total of 800 one-d-old male Ross 708 broiler chicks were randomly placed in 40 floor pens with 10 replicates (20 birds per pen) per each of the four treatments. At hatch, 14, 35, and 50 d, BW and feed intake were recorded. BW gain and FCR were calculated at the end of each phase. Four broilers per pen were selected and slaughtered at 51d and 55d of age to determine carcass and cut up yields, meat quality and myopathies (spaghetti muscle, white striping, and wooden breast) severity in the Pectoralis major. Data were analyzed as a randomized complete block design in a 2 × 2 factorial arrangement with grain type and GAA supplementation as main effects. At 50 d, diets containing GAA improved (P < 0.01) FCR (1.682 vs. 1.724 g: g) independently of grain type. At 55 d, broilers fed corn diets with GAA had higher breast meat yield (P < 0.05) compared to corn without GAA. Drip and cook loss, and shear force (Warner-Bratzler) were not affected (P > 0.05) by GAA supplementation at any slaughter ages. However, GAA decreased (P < 0.05) the ultimate pH at 51 and 55 d in breast meat samples compared to unsupplemented diets. At 51 d, broilers supplemented with GAA had double (P < 0.05) breast meat fillets without wooden breast (score 1) compared with broilers fed non-supplemented diets, therefore reducing the severity of this myopathy. In conclusion, GAA supplementation improved broiler live performance in broilers raised up to 50 d independently of grain source, increased breast meat yield in corn-based diets and reduced the severity of wooden breast myopathy. INTRODUCTION Dietary guanidinoacetic acid (GAA) has been proven to act as precursor of creatine (Ringel et al., 2007; Michiels et al., 2012, DeGroot, 2014) as does endogenous GAA. Creatine and its phosphorylated form phospho-creatine are naturally occurring metabolites and play a major role in muscle cellular energy metabolism (Wyss and Kaddurah-Daouk, 2000). The creatine/phospho-creatine system functions as a backup to the adenosine tri-phosphate (ATP)/adenosine di-phosphate system to store and mobilize energy when required on short notice, particularly in muscle cells (Lemme et al., 2007a). Creatine can be produced naturally in the body from GAA, which in turn is synthesized from the amino acids arginine and glycine (Wyss and Kaddurah-Daouk, 2000). GAA is a compound synthesized in the avian kidney and liver (Wyss and Kaddurah-Daouk, 2000). It has been reported (Ringel et al., 2007) that dietary GAA was efficiently transformed to creatine in the liver which subsequently was transported to the muscles. Consequently, affecting muscle development (Lemme et al., 2007b; Michiels et al., 2012; Heger et al., 2014; Esser et al., 2017). Previous studies showed that GAA supplementation improved FCR in male broilers fed diets containing corn and wheat-based diets at 41 d of age (Lemme, et al., 2007b) or corn-soybean meal diets (Ringel et al.,2007). Other researchers found that GAA supplementation had a sparing effect on arginine, therefore replacing dietary arginine efficiently in young chicks (Dilger et al., 2013; DeGroot, 2014). It has been discussed (Ringel et al., 2007) that as long as animal by-products formed a certain part of poultry diets, no signs of creatine deficiency may be detected. However, there is an increasing trend in the poultry industry to use the denominated “all vegetable” diets based only in plant ingredients (Vieira and Lima, 2005). As a result, dietary creatine supply will be marginally low in vegetable protein sources since it has been reported (Khan and Cowen, 1977; Gabor et al., 1984) that these feedstuffs contain limited (< 0.01 mg/g) or no creatine. Generally, poultry diets are comprised of corn because of its higher dietary energy content compared to other cereal grains (Mohamed et al., 2015). Although it is produced throughout the world, there is a stiff competition for corn among human consumption, ethanol production and the feed industry. Additionally, the poultry industry has faced high variability on feed costs (Etuk et al., 2012). Consequently, the use of alternative feed ingredients such as sorghum has been considered (Torres et al., 2013; Tandiang et al., 2014). Some low-tannin sorghum varieties had been assessed to have the potential to replace corn as an alternative poultry feed ingredient. Its nutritional value is only slightly lower than corn (Douglas et al., 1990). Low-tannin sorghum has been shown to substitute corn in poultry feeds without affecting live performance (Garcia et al., 2005; Campos, 2006; Bozutti, 2009). In contrast, some other authors had found that high-tannin sorghum negatively affected live performance (Pour-Reza and Edriss, 1997). Kumar et al. (2005) concluded that cut up yields, especially breast meat yield, were not affected by different tannin levels in red sorghum. Therefore, the use of sorghum with low tannin content could be an alternative for corn in poultry diets (Tandiang et al., 2014). Lemme et al. (2007a) observed that dietary inclusion of 20% sorghum and GAA supplementation improved FCR and breast meat yield, compared with broilers fed a negative control corn-sorghum diet without GAA, when broilers were raised up to 42 d of age. According to Li et al. (2011) sorghum showed similar total amino acid content in arginine and glycine (main sources for the synthesis of creatine) when compared to corn. However, Ebadi et al. (2005) suggested that availability of amino acids can be reduced by higher tannin content in the grain. Methionine, cysteine, lysine, arginine, and proline availability were decreased up to 23, 44, 32, 54, and 75%, respectively due to medium (0.19%) or high (0.37%) tannin content in the grain. Consequently, a better response on live performance could be expected in sorghum-based diets when GAA is supplemented. An increasing demand for white chicken meat has made the poultry industry focus on the selection of genotypes exhibiting faster growth rates with higher breast yields. Concurrently, pectoral myopathies, such as wooden breast (WB) and white striping (WS), are emerging as an increasing problem (Tasoniero et al., 2016). Based on mice trials, creatine may have a protective role in certain neuromuscular (Chung et al., 2007; Tarnopolsky, 2007) and neuro-degenerative diseases (Bender et al., 2006; Kolling and Wyse, 2010; Beal, 2011), and could potentially reverse muscular dystrophy (Nabuurs et al., 2013). Consequently, it could be hypothesized that GAA as precursor of creatine may play a role to prevent the inhibition of energy metabolism and lipid peroxidation related to muscle myopathies (Abasht et al., 2016). Even though most of the studies of GAA had evaluated live performance, there has been no previous data about the effects of supplementing GAA on pectoral myopathies in modern commercial broiler chickens. Therefore, the aim of the present trial was to evaluate the effects of GAA supplementation in corn or sorghum based-diets on live performance, carcass and cut up yields, meat quality and pectoral myopathies. MATERIALS AND METHODS Treatments and Birds Husbandry All procedures involving broiler chicken used in the present experiment were approved by the North Carolina State University Institutional Animal Care and Use Committee. Four treatments from a 2 × 2 factorial arrangement with 2 grain-based diets (corn or sorghum) and two levels of GAA (0 and 0.06%) supplementation (CreAMINO®, GAA content min. 96%) in all feeding phases as main factors. This study was conducted in a solid side wall house with negative pressure ventilation, tunnel capabilities, and evaporative cooling. A total of 800 Ross-708 d-old male chicks were placed in 40 floor pens (1.21 × 1.82 m) with 20 chicks per pen (9.18 broilers/m2 at placement) to form 10 replicate pens per treatment. Final stocking density was 37.5 kg/m2 at 50 d of age. Broilers were raised on used litter. Chickens were exposed to continuous light on a 23L:1D (30 lux of light intensity) program during the first 7 d of age. Day length was then gradually reduced to 17L:7D (10 lux) up to 28 d of age. From 28 d until the end of the experiment at 56 d, light program was maintained at 17L:7D with a light intensity of 5 lux. Brooding house temperature was set at 33.6°C at placement and gradually reduced until 20.6°C at 21 d of age kept until study end to guarantee chicken temperature comfort. Diets Basal diets were formulated (Table 1) to represent typical U.S. broiler industry practices (AgriStats, 2016), and digestible amino acid levels were based on AminoDat 5.0 (2015) recommendations (Table 2). Macro ingredients (corn, sorghum, soybean meal, and distilled dried grain with solubles) were analyzed for total amino acid and ME content prior to diet formulation. Digestible amino acid content was calculated from the total amino acid content obtained from lab analyses and using table values for digestibility coefficients (AminoDat 5.0, 2015). The ME values (kcal/kg) were obtained from an in vivo trial with roosters (Dr. Nick Dale, University of Georgia), since this technique is widely used (Bryden and Li, 2010) presenting some advantages as compared to other bioassays (Parsons, 1985; Garcia et al., 2007). Condensed tannins content (%) in sorghum were calculated from the absorbance at 500 nm of the anthocyanidin solutions (Makkar and Becker, 1993; Brenes et al., 2008). Diets were formulated to contain either corn or sorghum as the main grain source, soybean meal (SBM), and distilled dried grain with solubles (DDGs) as protein source. All dietary treatments were formulated to be isoenergetic, and isonitrogenous. Starter, grower, finisher and withdrawal diets were fed from 0–14, 15–35, 36–42, and 43–55 d of age, respectively. Starter was fed in crumbles and all other diets in pellets. For the pelleting process a temperature between 82 and 85°C in the conditioner was used for 30 seconds. The steam pressure was 32 psi, and the pellet die was 11/64” x 1” 3/8” (4.4 × 34.9 mm) for an L/D ratio of 8. The capacity of pelleting used was two to five ton/hour to improve pellet quality. After being crumbled or pelleted, representative samples of each manufactured diet were analyzed for crude protein, and total amino acids. Creatine and GAA (Table 3) in feed were determined by AlzChem AG (Trosberg, Germany) according to the ion chromatography method (CRL Feed Additives, 2007). Experimental diets were formulated either from corn or sorghum basal diets to ensure that diets had similar nutrient content independently of grain source. GAA was added “on top” of the basal diets (600 g/ton) in the corresponding treatments. For each one of the dietary phases 0.85, 2.90, and 2.48 kg of starter, grower and finisher, respectively, were offered for each bird alive during each phase. The withdrawal diet was offered ad libitum. Water was provided for ad libitum consumption. Feeders were shaken twice daily to stimulate uniform feed intake. Table 1. Ingredient composition of starter, grower, finisher and withdrawal basal diets for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Ingredient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum    ——————————————————– % ——————————————————–  Corn  52.509  -  56.573  -  60.911  -  64.344  -  Soybean meal, 46%  33.973  32.097  29.998  27.990  25.784  23.667  22.866  20.568  Sorghum  -  54.263  -  58.460  -  62.934  -  66.492  DDGs  5.000  5.000  5.000  5.000  5.000  5.000  5.000  5.000  Poultry fat  4.302  4.112  4.849  4.643  5.114  4.885  4.847  4.614  Limestone fine  1.366  1.414  1.166  1.218  1.095  1.151  1.109  1.168  Dicalcium phosphate, 18.5%  1.151  1.232  0.915  1.001  0.736  0.828  0.431  0.530  Salt (NaCl)  0.303  0.246  0.312  0.252  0.281  0.216  0.251  0.182  DL- Methionine, 99%  0.286  0.315  0.239  0.271  0.197  0.231  0.197  0.234  L-Lysine-HCl, 78.8%  0.218  0.304  0.160  0.252  0.123  0.220  0.171  0.276  Mineral premix2  0.200  0.200  0.200  0.200  0.200  0.200  0.200  0.200  Sodium bicarbonate  0.183  0.256  0.134  0.212  0.177  0.261  0.185  0.274  Choline chloride, 60%  0.180  0.180  0.180  0.180  0.180  0.180  0.180  0.180  Vitamin premix3  0.100  0.100  0.100  0.100  0.100  0.100  0.100  0.100  L-Threonine, 98%  0.081  0.103  0.055  0.078  0.035  0.059  0.052  0.079  Sand or GAA5  0.060  0.060  0.060  0.060  0.060  0.060  0.060  0.060  Coccidiostat1  0.050  0.050  0.050  0.050  -  -  -  -  L-Valine, 96.5%  0.031  0.060  0.001  0.025  0.001  0.001  -  0.035  Phytase4  0.008  0.008  0.008  0.008  0.008  0.008  0.008  0.008  Total  100.00  100.00  100.00  100.00  100.00  100.00  100.00  100.00    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Ingredient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum    ——————————————————– % ——————————————————–  Corn  52.509  -  56.573  -  60.911  -  64.344  -  Soybean meal, 46%  33.973  32.097  29.998  27.990  25.784  23.667  22.866  20.568  Sorghum  -  54.263  -  58.460  -  62.934  -  66.492  DDGs  5.000  5.000  5.000  5.000  5.000  5.000  5.000  5.000  Poultry fat  4.302  4.112  4.849  4.643  5.114  4.885  4.847  4.614  Limestone fine  1.366  1.414  1.166  1.218  1.095  1.151  1.109  1.168  Dicalcium phosphate, 18.5%  1.151  1.232  0.915  1.001  0.736  0.828  0.431  0.530  Salt (NaCl)  0.303  0.246  0.312  0.252  0.281  0.216  0.251  0.182  DL- Methionine, 99%  0.286  0.315  0.239  0.271  0.197  0.231  0.197  0.234  L-Lysine-HCl, 78.8%  0.218  0.304  0.160  0.252  0.123  0.220  0.171  0.276  Mineral premix2  0.200  0.200  0.200  0.200  0.200  0.200  0.200  0.200  Sodium bicarbonate  0.183  0.256  0.134  0.212  0.177  0.261  0.185  0.274  Choline chloride, 60%  0.180  0.180  0.180  0.180  0.180  0.180  0.180  0.180  Vitamin premix3  0.100  0.100  0.100  0.100  0.100  0.100  0.100  0.100  L-Threonine, 98%  0.081  0.103  0.055  0.078  0.035  0.059  0.052  0.079  Sand or GAA5  0.060  0.060  0.060  0.060  0.060  0.060  0.060  0.060  Coccidiostat1  0.050  0.050  0.050  0.050  -  -  -  -  L-Valine, 96.5%  0.031  0.060  0.001  0.025  0.001  0.001  -  0.035  Phytase4  0.008  0.008  0.008  0.008  0.008  0.008  0.008  0.008  Total  100.00  100.00  100.00  100.00  100.00  100.00  100.00  100.00  1Coban® 90 (Monensin), Elanco Animal Health, Greenfield, IN, at 500 g/ton in the starter and grower diets. 2Trace minerals provided per kg of premix: manganese (Mn SO4), 60 g; zinc (ZnSO4), 60 g; iron (FeSO4), 40 g; copper (CuSO4), 5 g; iodine (Ca(IO3)2),1.25 g. 3Vitamins provided per kg of premix: vitamin A, 13,227,513 IU; vitamin D3, 3968,253 IU; vitamin E, 66,137 IU; vitamin B12, 39.6 mg; riboflavin, 13,227 mg; niacin, 110,229 mg; d-pantothenic acid, 22,045 mg; menadione, 3968 mg; folic acid, 2204 mg; vitamin B6, 7936 mg; thiamine, 3968 mg; biotin, 253.5 mg. 4Quantum Blue 5G® at 0.176 lbs/ton (80 g/ton) to provide 500 FYT (AB Vista) delivering 0.13% of available P, 0.06% of calcium and 0.03% of sodium. 5CreAMINO: Guanidinoacetic acid (GAA) with 96% of concentration, Lot number 3/29/16. Evonik Industries, Evonik Degussa GmbH, Hanau-Wolfgang, Germany. View Large Table 1. Ingredient composition of starter, grower, finisher and withdrawal basal diets for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Ingredient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum    ——————————————————– % ——————————————————–  Corn  52.509  -  56.573  -  60.911  -  64.344  -  Soybean meal, 46%  33.973  32.097  29.998  27.990  25.784  23.667  22.866  20.568  Sorghum  -  54.263  -  58.460  -  62.934  -  66.492  DDGs  5.000  5.000  5.000  5.000  5.000  5.000  5.000  5.000  Poultry fat  4.302  4.112  4.849  4.643  5.114  4.885  4.847  4.614  Limestone fine  1.366  1.414  1.166  1.218  1.095  1.151  1.109  1.168  Dicalcium phosphate, 18.5%  1.151  1.232  0.915  1.001  0.736  0.828  0.431  0.530  Salt (NaCl)  0.303  0.246  0.312  0.252  0.281  0.216  0.251  0.182  DL- Methionine, 99%  0.286  0.315  0.239  0.271  0.197  0.231  0.197  0.234  L-Lysine-HCl, 78.8%  0.218  0.304  0.160  0.252  0.123  0.220  0.171  0.276  Mineral premix2  0.200  0.200  0.200  0.200  0.200  0.200  0.200  0.200  Sodium bicarbonate  0.183  0.256  0.134  0.212  0.177  0.261  0.185  0.274  Choline chloride, 60%  0.180  0.180  0.180  0.180  0.180  0.180  0.180  0.180  Vitamin premix3  0.100  0.100  0.100  0.100  0.100  0.100  0.100  0.100  L-Threonine, 98%  0.081  0.103  0.055  0.078  0.035  0.059  0.052  0.079  Sand or GAA5  0.060  0.060  0.060  0.060  0.060  0.060  0.060  0.060  Coccidiostat1  0.050  0.050  0.050  0.050  -  -  -  -  L-Valine, 96.5%  0.031  0.060  0.001  0.025  0.001  0.001  -  0.035  Phytase4  0.008  0.008  0.008  0.008  0.008  0.008  0.008  0.008  Total  100.00  100.00  100.00  100.00  100.00  100.00  100.00  100.00    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Ingredient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum    ——————————————————– % ——————————————————–  Corn  52.509  -  56.573  -  60.911  -  64.344  -  Soybean meal, 46%  33.973  32.097  29.998  27.990  25.784  23.667  22.866  20.568  Sorghum  -  54.263  -  58.460  -  62.934  -  66.492  DDGs  5.000  5.000  5.000  5.000  5.000  5.000  5.000  5.000  Poultry fat  4.302  4.112  4.849  4.643  5.114  4.885  4.847  4.614  Limestone fine  1.366  1.414  1.166  1.218  1.095  1.151  1.109  1.168  Dicalcium phosphate, 18.5%  1.151  1.232  0.915  1.001  0.736  0.828  0.431  0.530  Salt (NaCl)  0.303  0.246  0.312  0.252  0.281  0.216  0.251  0.182  DL- Methionine, 99%  0.286  0.315  0.239  0.271  0.197  0.231  0.197  0.234  L-Lysine-HCl, 78.8%  0.218  0.304  0.160  0.252  0.123  0.220  0.171  0.276  Mineral premix2  0.200  0.200  0.200  0.200  0.200  0.200  0.200  0.200  Sodium bicarbonate  0.183  0.256  0.134  0.212  0.177  0.261  0.185  0.274  Choline chloride, 60%  0.180  0.180  0.180  0.180  0.180  0.180  0.180  0.180  Vitamin premix3  0.100  0.100  0.100  0.100  0.100  0.100  0.100  0.100  L-Threonine, 98%  0.081  0.103  0.055  0.078  0.035  0.059  0.052  0.079  Sand or GAA5  0.060  0.060  0.060  0.060  0.060  0.060  0.060  0.060  Coccidiostat1  0.050  0.050  0.050  0.050  -  -  -  -  L-Valine, 96.5%  0.031  0.060  0.001  0.025  0.001  0.001  -  0.035  Phytase4  0.008  0.008  0.008  0.008  0.008  0.008  0.008  0.008  Total  100.00  100.00  100.00  100.00  100.00  100.00  100.00  100.00  1Coban® 90 (Monensin), Elanco Animal Health, Greenfield, IN, at 500 g/ton in the starter and grower diets. 2Trace minerals provided per kg of premix: manganese (Mn SO4), 60 g; zinc (ZnSO4), 60 g; iron (FeSO4), 40 g; copper (CuSO4), 5 g; iodine (Ca(IO3)2),1.25 g. 3Vitamins provided per kg of premix: vitamin A, 13,227,513 IU; vitamin D3, 3968,253 IU; vitamin E, 66,137 IU; vitamin B12, 39.6 mg; riboflavin, 13,227 mg; niacin, 110,229 mg; d-pantothenic acid, 22,045 mg; menadione, 3968 mg; folic acid, 2204 mg; vitamin B6, 7936 mg; thiamine, 3968 mg; biotin, 253.5 mg. 4Quantum Blue 5G® at 0.176 lbs/ton (80 g/ton) to provide 500 FYT (AB Vista) delivering 0.13% of available P, 0.06% of calcium and 0.03% of sodium. 5CreAMINO: Guanidinoacetic acid (GAA) with 96% of concentration, Lot number 3/29/16. Evonik Industries, Evonik Degussa GmbH, Hanau-Wolfgang, Germany. View Large Table 2. Calculated and analyzed nutrient content of basal starter, grower, finisher, and withdrawal diets for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Nutrient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Calculated nutritive value                  Metabolizable Energy, kcal/kg  3000  3000  3085  3085  3150  3150  3175  3175  Crude protein, %  22.11  22.11  20.41  20.41  18.68  18.68  17.60  17.60  Calcium, %  1.02  1.02  0.90  0.90  0.82  0.82  0.76  0.76  Total phosphorus, %  0.57  0.61  0.51  0.56  0.46  0.51  0.39  0.45  Nonphytate phosphorus, %  0.50  0.50  0.45  0.45  0.41  0.41  0.35  0.35  Total Glycine, %  0.91  0.87  0.84  0.80  0.77  0.72  0.73  0.67  Digestible lysine, %  1.22  1.22  1.08  1.08  0.95  0.95  0.92  0.92  Digestible methionine, %  0.59  0.60  0.53  0.54  0.47  0.48  0.46  0.48  Digestible total sulfur amino acids, %  0.89  0.89  0.81  0.81  0.73  0.73  0.71  0.71  Digestible threonine, %  0.78  0.78  0.70  0.70  0.63  0.63  0.61  0.61  Digestible tryptophan, %  0.23  0.24  0.21  0.22  0.19  0.20  0.18  0.18  Digestible valine, %  0.94  0.97  0.85  0.87  0.78  0.81  0.73  0.77  Digestible isoleucine, %  0.83  0.84  0.77  0.78  0.70  0.71  0.65  0.66  Digestible arginine, %  1.35  1.26  1.24  1.13  1.12  1.01  1.04  0.92  Sodium, %  0.20  0.20  0.19  0.19  0.19  0.19  0.18  0.18  Potassium, %  0.94  0.91  0.87  0.84  0.80  0.77  0.75  0.72  Chloride, %  0.28  0.28  0.28  0.28  0.24  0.24  0.25  0.25  Dietary electrolyte balance, mEq/100 g  264  262  241  239  232  230  216  213  Analyzed nutritive value1                  Crude protein, %  23.42  21.38  21.97  20.61  19.17  19.06  17.36  18.82  Total lysine, %  1.37  1.23  1.25  1.18  1.06  1.05  1.01  1.04  Total methionine, %  0.54  0.52  0.51  0.51  0.47  0.48  0.43  0.49  Total sulfur amino acids, %  0.90  0.84  0.85  0.82  0.78  0.79  0.72  0.78  Total threonine, %  0.93  0.86  0.85  0.82  0.76  0.76  0.68  0.73  Total glycine, %  0.95  0.83  0.88  0.79  0.79  0.74  0.72  0.72  Total valine, %  1.11  1.03  0.99  0.94  0.91  0.92  0.82  0.92  Total arginine, %  1.53  1.30  1.41  1.23  1.24  1.13  1.10  1.08    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Nutrient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Calculated nutritive value                  Metabolizable Energy, kcal/kg  3000  3000  3085  3085  3150  3150  3175  3175  Crude protein, %  22.11  22.11  20.41  20.41  18.68  18.68  17.60  17.60  Calcium, %  1.02  1.02  0.90  0.90  0.82  0.82  0.76  0.76  Total phosphorus, %  0.57  0.61  0.51  0.56  0.46  0.51  0.39  0.45  Nonphytate phosphorus, %  0.50  0.50  0.45  0.45  0.41  0.41  0.35  0.35  Total Glycine, %  0.91  0.87  0.84  0.80  0.77  0.72  0.73  0.67  Digestible lysine, %  1.22  1.22  1.08  1.08  0.95  0.95  0.92  0.92  Digestible methionine, %  0.59  0.60  0.53  0.54  0.47  0.48  0.46  0.48  Digestible total sulfur amino acids, %  0.89  0.89  0.81  0.81  0.73  0.73  0.71  0.71  Digestible threonine, %  0.78  0.78  0.70  0.70  0.63  0.63  0.61  0.61  Digestible tryptophan, %  0.23  0.24  0.21  0.22  0.19  0.20  0.18  0.18  Digestible valine, %  0.94  0.97  0.85  0.87  0.78  0.81  0.73  0.77  Digestible isoleucine, %  0.83  0.84  0.77  0.78  0.70  0.71  0.65  0.66  Digestible arginine, %  1.35  1.26  1.24  1.13  1.12  1.01  1.04  0.92  Sodium, %  0.20  0.20  0.19  0.19  0.19  0.19  0.18  0.18  Potassium, %  0.94  0.91  0.87  0.84  0.80  0.77  0.75  0.72  Chloride, %  0.28  0.28  0.28  0.28  0.24  0.24  0.25  0.25  Dietary electrolyte balance, mEq/100 g  264  262  241  239  232  230  216  213  Analyzed nutritive value1                  Crude protein, %  23.42  21.38  21.97  20.61  19.17  19.06  17.36  18.82  Total lysine, %  1.37  1.23  1.25  1.18  1.06  1.05  1.01  1.04  Total methionine, %  0.54  0.52  0.51  0.51  0.47  0.48  0.43  0.49  Total sulfur amino acids, %  0.90  0.84  0.85  0.82  0.78  0.79  0.72  0.78  Total threonine, %  0.93  0.86  0.85  0.82  0.76  0.76  0.68  0.73  Total glycine, %  0.95  0.83  0.88  0.79  0.79  0.74  0.72  0.72  Total valine, %  1.11  1.03  0.99  0.94  0.91  0.92  0.82  0.92  Total arginine, %  1.53  1.30  1.41  1.23  1.24  1.13  1.10  1.08  1Analyzed values are means of 2 samples. View Large Table 2. Calculated and analyzed nutrient content of basal starter, grower, finisher, and withdrawal diets for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Nutrient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Calculated nutritive value                  Metabolizable Energy, kcal/kg  3000  3000  3085  3085  3150  3150  3175  3175  Crude protein, %  22.11  22.11  20.41  20.41  18.68  18.68  17.60  17.60  Calcium, %  1.02  1.02  0.90  0.90  0.82  0.82  0.76  0.76  Total phosphorus, %  0.57  0.61  0.51  0.56  0.46  0.51  0.39  0.45  Nonphytate phosphorus, %  0.50  0.50  0.45  0.45  0.41  0.41  0.35  0.35  Total Glycine, %  0.91  0.87  0.84  0.80  0.77  0.72  0.73  0.67  Digestible lysine, %  1.22  1.22  1.08  1.08  0.95  0.95  0.92  0.92  Digestible methionine, %  0.59  0.60  0.53  0.54  0.47  0.48  0.46  0.48  Digestible total sulfur amino acids, %  0.89  0.89  0.81  0.81  0.73  0.73  0.71  0.71  Digestible threonine, %  0.78  0.78  0.70  0.70  0.63  0.63  0.61  0.61  Digestible tryptophan, %  0.23  0.24  0.21  0.22  0.19  0.20  0.18  0.18  Digestible valine, %  0.94  0.97  0.85  0.87  0.78  0.81  0.73  0.77  Digestible isoleucine, %  0.83  0.84  0.77  0.78  0.70  0.71  0.65  0.66  Digestible arginine, %  1.35  1.26  1.24  1.13  1.12  1.01  1.04  0.92  Sodium, %  0.20  0.20  0.19  0.19  0.19  0.19  0.18  0.18  Potassium, %  0.94  0.91  0.87  0.84  0.80  0.77  0.75  0.72  Chloride, %  0.28  0.28  0.28  0.28  0.24  0.24  0.25  0.25  Dietary electrolyte balance, mEq/100 g  264  262  241  239  232  230  216  213  Analyzed nutritive value1                  Crude protein, %  23.42  21.38  21.97  20.61  19.17  19.06  17.36  18.82  Total lysine, %  1.37  1.23  1.25  1.18  1.06  1.05  1.01  1.04  Total methionine, %  0.54  0.52  0.51  0.51  0.47  0.48  0.43  0.49  Total sulfur amino acids, %  0.90  0.84  0.85  0.82  0.78  0.79  0.72  0.78  Total threonine, %  0.93  0.86  0.85  0.82  0.76  0.76  0.68  0.73  Total glycine, %  0.95  0.83  0.88  0.79  0.79  0.74  0.72  0.72  Total valine, %  1.11  1.03  0.99  0.94  0.91  0.92  0.82  0.92  Total arginine, %  1.53  1.30  1.41  1.23  1.24  1.13  1.10  1.08    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)  Nutrient  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Calculated nutritive value                  Metabolizable Energy, kcal/kg  3000  3000  3085  3085  3150  3150  3175  3175  Crude protein, %  22.11  22.11  20.41  20.41  18.68  18.68  17.60  17.60  Calcium, %  1.02  1.02  0.90  0.90  0.82  0.82  0.76  0.76  Total phosphorus, %  0.57  0.61  0.51  0.56  0.46  0.51  0.39  0.45  Nonphytate phosphorus, %  0.50  0.50  0.45  0.45  0.41  0.41  0.35  0.35  Total Glycine, %  0.91  0.87  0.84  0.80  0.77  0.72  0.73  0.67  Digestible lysine, %  1.22  1.22  1.08  1.08  0.95  0.95  0.92  0.92  Digestible methionine, %  0.59  0.60  0.53  0.54  0.47  0.48  0.46  0.48  Digestible total sulfur amino acids, %  0.89  0.89  0.81  0.81  0.73  0.73  0.71  0.71  Digestible threonine, %  0.78  0.78  0.70  0.70  0.63  0.63  0.61  0.61  Digestible tryptophan, %  0.23  0.24  0.21  0.22  0.19  0.20  0.18  0.18  Digestible valine, %  0.94  0.97  0.85  0.87  0.78  0.81  0.73  0.77  Digestible isoleucine, %  0.83  0.84  0.77  0.78  0.70  0.71  0.65  0.66  Digestible arginine, %  1.35  1.26  1.24  1.13  1.12  1.01  1.04  0.92  Sodium, %  0.20  0.20  0.19  0.19  0.19  0.19  0.18  0.18  Potassium, %  0.94  0.91  0.87  0.84  0.80  0.77  0.75  0.72  Chloride, %  0.28  0.28  0.28  0.28  0.24  0.24  0.25  0.25  Dietary electrolyte balance, mEq/100 g  264  262  241  239  232  230  216  213  Analyzed nutritive value1                  Crude protein, %  23.42  21.38  21.97  20.61  19.17  19.06  17.36  18.82  Total lysine, %  1.37  1.23  1.25  1.18  1.06  1.05  1.01  1.04  Total methionine, %  0.54  0.52  0.51  0.51  0.47  0.48  0.43  0.49  Total sulfur amino acids, %  0.90  0.84  0.85  0.82  0.78  0.79  0.72  0.78  Total threonine, %  0.93  0.86  0.85  0.82  0.76  0.76  0.68  0.73  Total glycine, %  0.95  0.83  0.88  0.79  0.79  0.74  0.72  0.72  Total valine, %  1.11  1.03  0.99  0.94  0.91  0.92  0.82  0.92  Total arginine, %  1.53  1.30  1.41  1.23  1.24  1.13  1.10  1.08  1Analyzed values are means of 2 samples. View Large Table 3. Analyzed nutrient content of the dietary treatments for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)    Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Nutrient  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  Calculated                                  GAA, mg/kg, as is  0  600  0  600  0  600  0  600  0  600  0  600  0  600  0  600  Analyzed1                                  Creatine, mg/kg, as is  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  GAA, mg/kg, as is  27  504  1  464  14  594  4  513  <20  528  <20  474  <20  526  <20  406  CreAMINO2, mg/kg, as is  28  525  1  483  15  619  4  534  <21  550  <21  494  <21  548  <21  423    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)    Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Nutrient  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  Calculated                                  GAA, mg/kg, as is  0  600  0  600  0  600  0  600  0  600  0  600  0  600  0  600  Analyzed1                                  Creatine, mg/kg, as is  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  GAA, mg/kg, as is  27  504  1  464  14  594  4  513  <20  528  <20  474  <20  526  <20  406  CreAMINO2, mg/kg, as is  28  525  1  483  15  619  4  534  <21  550  <21  494  <21  548  <21  423  1Values are means of 2 samples. Report issued by the Alzchem AG according to the IC method (CRL Feed Additives, 2007). 2Calculated values (CreAMINO®, GAA min. 96%), Evonik Industries, Evonik Degussa GmbH, Hanau-Wolfgang, Germany. View Large Table 3. Analyzed nutrient content of the dietary treatments for Ross-708 male broilers.   Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)    Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Nutrient  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  Calculated                                  GAA, mg/kg, as is  0  600  0  600  0  600  0  600  0  600  0  600  0  600  0  600  Analyzed1                                  Creatine, mg/kg, as is  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  GAA, mg/kg, as is  27  504  1  464  14  594  4  513  <20  528  <20  474  <20  526  <20  406  CreAMINO2, mg/kg, as is  28  525  1  483  15  619  4  534  <21  550  <21  494  <21  548  <21  423    Starter (0–14d)  Grower (15–35d)  Finisher (36–42d)  Withdrawal (43–55d)    Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Corn  Sorghum  Nutrient  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  None  GAA  Calculated                                  GAA, mg/kg, as is  0  600  0  600  0  600  0  600  0  600  0  600  0  600  0  600  Analyzed1                                  Creatine, mg/kg, as is  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  <20  GAA, mg/kg, as is  27  504  1  464  14  594  4  513  <20  528  <20  474  <20  526  <20  406  CreAMINO2, mg/kg, as is  28  525  1  483  15  619  4  534  <21  550  <21  494  <21  548  <21  423  1Values are means of 2 samples. Report issued by the Alzchem AG according to the IC method (CRL Feed Additives, 2007). 2Calculated values (CreAMINO®, GAA min. 96%), Evonik Industries, Evonik Degussa GmbH, Hanau-Wolfgang, Germany. View Large Data Collection Live Performance At hatch, 14, 35 and 50 d, group BW and feed intake were obtained and BW gain and feed conversion ratio (FCR) calculated at the end of each phase. Mortality was monitored and recorded twice daily, and FCR was adjusted for mortality. At 50 d, individual BW were obtained to calculate flock uniformity using the CV%. Selection of Birds for Processing At 50 d, individual BW was obtained in addition to average BW as described above. Average for each pen was calculated. The power analysis based on previous statistics in our facilities indicated that to observe differences (P ≤ 0.05) on carcass characteristics, a minimum of 160 samples should be analyzed. Therefore, four broilers per pen were selected for each one of the two slaughter ages. Two days for processing (51 and 55d) were considered due to mechanical and personnel capabilities. Selected broilers had BW within two standard deviations above or under the corresponding average for each pen. Data for both processing days were analyzed separately and together. However, significant differences were found between the two processing times and consequently data is presented separately. Carcass and Cut Up Yields Chickens were subjected to 12-h of feed withdrawal in each processing day (51 and 55 d). Broilers were slaughtered at the NCSU pilot processing plant. Broilers were weighed, electrically stunned for 11 s, killed by exsanguination, and allowed to bleed for 90 s. Broilers were then scalded at 55°C for 90 s, picked for 30 s, and manually eviscerated. Furthermore, carcasses were manually dressed by removing liver, gizzard, heart, oil gland, crop, proventriculus, lungs, and viscera. Carcasses were then air-chilled for six h, and manually deboned on stationary cones. Parts of the leg quarters, breast fillets (Pectoralis major) without skin, breast tenders (Pectoralis minor), wings, and rack with skin were obtained and weighed. The carcass yield was calculated for the chilled carcass as a percentage of the fasted live weight. Cut up yields were expressed as a percentage of the chilled absolute carcass weight. The deboning technique was maintained similar among four trained cutters in order to minimize error and reduce variability in cut-up yields for both processing days. Meat Quality Evaluation To determine drip loss of the fillets samples after storage, the right Pectoralis major muscle was weighed six h postmortem and immediately placed in a plastic bag, hung from a hook, and stored between 4 and 6°C for 24 h. After hanging, the sample was gently wiped with paper and weighed again. The difference in weight corresponded to the drip loss and was expressed as the percentage of the initial muscle weight. Cook loss determination was performed on the left breast fillets (Pectoralis major). Samples were weighed, placed on grilled-aluminum trays, and cooked in a forced air oven (SilverStar Southbend, Model SLES/10sc, gas type, NC, USA). Fillets were cooked to an internal temperature of 75°C (approximately 35 min), as measured by a Therma Plus thermocouple with a 10-cm needle temperature probe (ThermoWorks Model 221–071, UT, USA). The cooked fillets were cooled to room temperature, gently wiped with paper and re-weighed to determine cook yield as a percentage of the cooked weight relative to the raw weight. Shear force (kg force) of cooked breast fillets samples was determined using a Warner-Bratzler shear device (Warner-Bratzler meat shear, Bodine Electric Company, Chicago, USA). Two samples per breast fillets (2 × 2 × 2 cm3) were sheared in a direction perpendicular to the muscle fibers. The maximum force measured when cutting the samples was expressed in kg force. Postmortem pH (t = 1, 6, and 24 h) was determined after skin was removed from Pectoralis major muscle samples using a portable pH meter (Oakton waterproof pH Tester 30). Color was measured on skinless Pectoralis major samples by the CIE L* (lightness), a* (redness), and b* (yellowness) system using a Minolta Chroma Meter CR-400 (Konica Minolta Sensing, Inc., Japan). A measuring area of 10 mm and illuminant D65 and 2° standard observer were used. The colorimeter was calibrated using a white tile (reference number 13,033,071; Y = 93.9, x = 0.3156, y = 0.3318). Pectoral Myopathies Sensorial analyses were performed on skinless breast fillets by experts in the field (College of Veterinary Medicine, North Carolina State University) to determine grade of severity for current pectoral myopathies. Spaghetti muscle (Baldi et al., 2018) was recorded as presence or absence of this abnormality, whereas WS and WB were scored based on severity. WB severity was evaluated based on a four-point scoring system. Score 1 represented a normal fillet with no WB signs, score 2 was considered a low severity, score 3 a medium and score 4 as severe (Tijare et al., 2016). WS was scored with a modified scale used by Kuttappan et al. (2016) which considered a four-point based scale of severity. Score 1 described a breast fillet with no white striations on the surface. Score 2 were the fillets with white striations less than 1 mm of thickness and easily observed in the surface, score 3 was represented by the white striation more than 1 mm of thickness and covering less than 50% of the breast's fillet area, and score 4 was considered the fillets with white striations with more than 1 mm of thickness and covering an area more than the 50% of the breast's fillet surface. Additionally, for WB and WS the distribution of the probability for each score were analyzed for both slaughter ages. Statistical Analysis Data were analyzed as completely randomized block design with a 2 × 2 factorial arrangement of treatments with grain (corn or sorghum) and supplementation or not of GAA as main effects to have a total of 4 treatments. Each treatment had 10 replicates distributed equally in two blocks (location of pens within the house) that were considered random effects. Data were analyzed in JMP 12 (SAS Inst. Inc., Cary, NC, 2016) using ANOVA in a mixed model. Differences between means were separated using Tukey's or t-student test at a level of significance of alpha = 0.05. Additionally, for carcass and cut up yields, meat quality and pectoral myopathies results, individual broiler's data from the same pen were nested within each corresponding treatment and considered as random effect. Cutter was also included in the model as random effect for carcass and cut up yields. Data of scores probability distribution for WB and WS were analyzed using GLIMMIX (SAS Institute, 2008). Results from each slaughter age were analyzed together and separately. RESULTS AND DISCUSSION Diets and Live Performance The analyzed GAA, and creatine concentration in the dietary treatments are shown in Table 3. The GAA concentration in diets supplemented with CreAMINO® showed slight differences compared to the intended dose (600 mg/kg). The CreAMINO® concentration was calculated using the standard concentration of GAA in the product (96%). As expected, low or absence of creatine was observed in all the diets. Crude protein and total amino acid, were similar to formulated values and these are presented in Table 2. Live performance results are shown in Table 4. No interactions effects (P > 0.05) of treatments were observed on BW or BW gain in any of the phases evaluated. An interaction effect (P < 0.05) on feed intake and FCR was observed only in the starter phase (0–14 d). In diets without GAA supplementation, chickens fed corn diets ate more (P < 0.05) than chickens fed sorghum diets resulting in higher BW and BWG, but no difference was observed when GAA was added. For the interaction results on FCR, no difference was observed when chickens were fed diets without GAA, but when GAA was added FCR of chickens fed corn diets was improved (1.242 vs. 1.333 g: g) as compared to broilers fed sorghum diets. At 35 d, feed intake was affected by grain source. Chickens fed corn diets had higher (P <0.01) feed intake than broilers fed sorghum diets. No differences (P > 0.05) due to GAA supplementation were detected at 50 d on feed intake. However, broilers fed corn diets ate more (P ≤ 0.05) than chickens fed sorghum diets, regardless of GAA supplementation. Table 4. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum based diets for Ross-708 male broilers on live performance up to 50 d of age.     BW  BW gain  Feed intake  FCR  Additive  Grain  Hatch  14d  35d  50d  CV1  0 - 14d  0 - 35d  0 - 50d  0 – 14d  0 –35d  0–50d  0 – 14d  0 –35d  0–50d      ——————– (g) ——————–  -(%)-  ——————————— (g) ——————————–  ———– (g:g) ————  GAA    39.9  468.5a  2,550a  4,167a  7.23  428.6a  2,509a  4111  551.2  3669  7030  1.288b  1.461b  1.682b  None    40.0  452.3b  2,498b  4,061b  8.44  412.3b  2,454b  4022  559.4  3693  7022  1.357a  1.499a  1.724a  SEM    0.1  3.2  12  51  0.35  3.1  11  57  6.7  25  43  0.016  0.007  0.009    Corn  40.0  470.4a  2,570a  4,172a  7.89  430.4a  2,528a  4,117a  561.5  3,741a  7,105a  1.306  1.478  1.700    Sorghum  39.9  450.4b  2,479b  4,056b  7.77  410.5b  2,435b  4,016b  549.0  3,621b  6,947b  1.339  1.482  1.706    SEM  0.13  3.1  12  51  0.35  3.1  11  5.72  6.7  25  43  0.016  0.007  0.009  GAA  Corn  39.9  479.1  2,590  4,237  6.92  439.2  2,550  4,168  545.4a,b  3,704  7,076  1.242b  1.453  1.675    Sorghum  39.9  457.9  2,510  4,096  7.54  418.0  2,467  4,054  556.9a,b  3,633  6,984  1.333a  1.469  1.689  None  Corn  40.2  461.8  2,549  4,106  8.86  421.6  2,506  4,065  577.9a  3,778  7,134  1.370a  1.504  1.725    Sorghum  39.9  442.9  2,447  4,016  8.01  403.0  2,403  3,978  541.0b  3,608  6,911  1.344a  1.495  1.723    SEM  0.2  4.3  16  60  0.57  4.3  16  66  9.5  38  70  0.023  0.011  0.014  CV%    1.39  3.01  1.96  3.45  24.70  3.32  1.99  3.62  5.46  3.55  3.44  5.71  2.77  2.71  Source of variation  ——————————————————————————— P—values ————————————————————————————  Additive  0.471  <0.001  0.002  0.027  0.071  <0.001  0.001  0.063  0.387  0.561  0.921  0.006  0.006  0.007  Grain  0.488  <0.001  <0.001  0.016  0.854  <0.001  <0.001  0.038  0.189  0.006  0.050  0.174  0.795  0.681  Additive*grain  0.505  0.793  0.496  0.569  0.252  0.773  0.498  0.774  0.015  0.244  0.405  0.017  0.339  0.604      BW  BW gain  Feed intake  FCR  Additive  Grain  Hatch  14d  35d  50d  CV1  0 - 14d  0 - 35d  0 - 50d  0 – 14d  0 –35d  0–50d  0 – 14d  0 –35d  0–50d      ——————– (g) ——————–  -(%)-  ——————————— (g) ——————————–  ———– (g:g) ————  GAA    39.9  468.5a  2,550a  4,167a  7.23  428.6a  2,509a  4111  551.2  3669  7030  1.288b  1.461b  1.682b  None    40.0  452.3b  2,498b  4,061b  8.44  412.3b  2,454b  4022  559.4  3693  7022  1.357a  1.499a  1.724a  SEM    0.1  3.2  12  51  0.35  3.1  11  57  6.7  25  43  0.016  0.007  0.009    Corn  40.0  470.4a  2,570a  4,172a  7.89  430.4a  2,528a  4,117a  561.5  3,741a  7,105a  1.306  1.478  1.700    Sorghum  39.9  450.4b  2,479b  4,056b  7.77  410.5b  2,435b  4,016b  549.0  3,621b  6,947b  1.339  1.482  1.706    SEM  0.13  3.1  12  51  0.35  3.1  11  5.72  6.7  25  43  0.016  0.007  0.009  GAA  Corn  39.9  479.1  2,590  4,237  6.92  439.2  2,550  4,168  545.4a,b  3,704  7,076  1.242b  1.453  1.675    Sorghum  39.9  457.9  2,510  4,096  7.54  418.0  2,467  4,054  556.9a,b  3,633  6,984  1.333a  1.469  1.689  None  Corn  40.2  461.8  2,549  4,106  8.86  421.6  2,506  4,065  577.9a  3,778  7,134  1.370a  1.504  1.725    Sorghum  39.9  442.9  2,447  4,016  8.01  403.0  2,403  3,978  541.0b  3,608  6,911  1.344a  1.495  1.723    SEM  0.2  4.3  16  60  0.57  4.3  16  66  9.5  38  70  0.023  0.011  0.014  CV%    1.39  3.01  1.96  3.45  24.70  3.32  1.99  3.62  5.46  3.55  3.44  5.71  2.77  2.71  Source of variation  ——————————————————————————— P—values ————————————————————————————  Additive  0.471  <0.001  0.002  0.027  0.071  <0.001  0.001  0.063  0.387  0.561  0.921  0.006  0.006  0.007  Grain  0.488  <0.001  <0.001  0.016  0.854  <0.001  <0.001  0.038  0.189  0.006  0.050  0.174  0.795  0.681  Additive*grain  0.505  0.793  0.496  0.569  0.252  0.773  0.498  0.774  0.015  0.244  0.405  0.017  0.339  0.604  Values are means of 10 pens per treatment combination with 20 male broiler chickens. a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Flock uniformity at 50 d of age. View Large Table 4. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum based diets for Ross-708 male broilers on live performance up to 50 d of age.     BW  BW gain  Feed intake  FCR  Additive  Grain  Hatch  14d  35d  50d  CV1  0 - 14d  0 - 35d  0 - 50d  0 – 14d  0 –35d  0–50d  0 – 14d  0 –35d  0–50d      ——————– (g) ——————–  -(%)-  ——————————— (g) ——————————–  ———– (g:g) ————  GAA    39.9  468.5a  2,550a  4,167a  7.23  428.6a  2,509a  4111  551.2  3669  7030  1.288b  1.461b  1.682b  None    40.0  452.3b  2,498b  4,061b  8.44  412.3b  2,454b  4022  559.4  3693  7022  1.357a  1.499a  1.724a  SEM    0.1  3.2  12  51  0.35  3.1  11  57  6.7  25  43  0.016  0.007  0.009    Corn  40.0  470.4a  2,570a  4,172a  7.89  430.4a  2,528a  4,117a  561.5  3,741a  7,105a  1.306  1.478  1.700    Sorghum  39.9  450.4b  2,479b  4,056b  7.77  410.5b  2,435b  4,016b  549.0  3,621b  6,947b  1.339  1.482  1.706    SEM  0.13  3.1  12  51  0.35  3.1  11  5.72  6.7  25  43  0.016  0.007  0.009  GAA  Corn  39.9  479.1  2,590  4,237  6.92  439.2  2,550  4,168  545.4a,b  3,704  7,076  1.242b  1.453  1.675    Sorghum  39.9  457.9  2,510  4,096  7.54  418.0  2,467  4,054  556.9a,b  3,633  6,984  1.333a  1.469  1.689  None  Corn  40.2  461.8  2,549  4,106  8.86  421.6  2,506  4,065  577.9a  3,778  7,134  1.370a  1.504  1.725    Sorghum  39.9  442.9  2,447  4,016  8.01  403.0  2,403  3,978  541.0b  3,608  6,911  1.344a  1.495  1.723    SEM  0.2  4.3  16  60  0.57  4.3  16  66  9.5  38  70  0.023  0.011  0.014  CV%    1.39  3.01  1.96  3.45  24.70  3.32  1.99  3.62  5.46  3.55  3.44  5.71  2.77  2.71  Source of variation  ——————————————————————————— P—values ————————————————————————————  Additive  0.471  <0.001  0.002  0.027  0.071  <0.001  0.001  0.063  0.387  0.561  0.921  0.006  0.006  0.007  Grain  0.488  <0.001  <0.001  0.016  0.854  <0.001  <0.001  0.038  0.189  0.006  0.050  0.174  0.795  0.681  Additive*grain  0.505  0.793  0.496  0.569  0.252  0.773  0.498  0.774  0.015  0.244  0.405  0.017  0.339  0.604      BW  BW gain  Feed intake  FCR  Additive  Grain  Hatch  14d  35d  50d  CV1  0 - 14d  0 - 35d  0 - 50d  0 – 14d  0 –35d  0–50d  0 – 14d  0 –35d  0–50d      ——————– (g) ——————–  -(%)-  ——————————— (g) ——————————–  ———– (g:g) ————  GAA    39.9  468.5a  2,550a  4,167a  7.23  428.6a  2,509a  4111  551.2  3669  7030  1.288b  1.461b  1.682b  None    40.0  452.3b  2,498b  4,061b  8.44  412.3b  2,454b  4022  559.4  3693  7022  1.357a  1.499a  1.724a  SEM    0.1  3.2  12  51  0.35  3.1  11  57  6.7  25  43  0.016  0.007  0.009    Corn  40.0  470.4a  2,570a  4,172a  7.89  430.4a  2,528a  4,117a  561.5  3,741a  7,105a  1.306  1.478  1.700    Sorghum  39.9  450.4b  2,479b  4,056b  7.77  410.5b  2,435b  4,016b  549.0  3,621b  6,947b  1.339  1.482  1.706    SEM  0.13  3.1  12  51  0.35  3.1  11  5.72  6.7  25  43  0.016  0.007  0.009  GAA  Corn  39.9  479.1  2,590  4,237  6.92  439.2  2,550  4,168  545.4a,b  3,704  7,076  1.242b  1.453  1.675    Sorghum  39.9  457.9  2,510  4,096  7.54  418.0  2,467  4,054  556.9a,b  3,633  6,984  1.333a  1.469  1.689  None  Corn  40.2  461.8  2,549  4,106  8.86  421.6  2,506  4,065  577.9a  3,778  7,134  1.370a  1.504  1.725    Sorghum  39.9  442.9  2,447  4,016  8.01  403.0  2,403  3,978  541.0b  3,608  6,911  1.344a  1.495  1.723    SEM  0.2  4.3  16  60  0.57  4.3  16  66  9.5  38  70  0.023  0.011  0.014  CV%    1.39  3.01  1.96  3.45  24.70  3.32  1.99  3.62  5.46  3.55  3.44  5.71  2.77  2.71  Source of variation  ——————————————————————————— P—values ————————————————————————————  Additive  0.471  <0.001  0.002  0.027  0.071  <0.001  0.001  0.063  0.387  0.561  0.921  0.006  0.006  0.007  Grain  0.488  <0.001  <0.001  0.016  0.854  <0.001  <0.001  0.038  0.189  0.006  0.050  0.174  0.795  0.681  Additive*grain  0.505  0.793  0.496  0.569  0.252  0.773  0.498  0.774  0.015  0.244  0.405  0.017  0.339  0.604  Values are means of 10 pens per treatment combination with 20 male broiler chickens. a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Flock uniformity at 50 d of age. View Large Consequent to higher feed consumption, broilers fed corn-based diets gain more BW (P < 0.05) throughout the whole experimental period than the ones fed sorghum diets. Therefore, chickens fed corn weighed more (P < 0.001) than broilers fed sorghum diets at 14 d, and remained heavier (P < 0.05) at 35 d (2570 vs. 2479 g), and 50 d (4172 vs. 4056 g) respectively. The GAA supplementation improved BW, and BW gain (P < 0.05) up to 35d, and FCR (P < 0.01) up to 50 d regardless of grain type. Improvements (P < 0.01) up to 4 points on FCR at 35 d (1.46 vs. 1.50 g: g), and 50 d (1.68 vs. 1.72 g: g) of age respectively, were attributed to GAA supplementation. No differences (P > 0.05) were detected on FCR at the end of each experimental phase due to grain source. Flock uniformity (CV%) at 50 d tended to be improved (P = 0.07) by GAA (7.33 vs. 8.44%) addition, while no interaction (P > 0.05) or effect of grain source was observed. Overall, total mortality was not affected (P > 0.05) either by grain source or GAA supplementation throughout the whole experimental period with no mortality in some replicates, but the average mortality rates per treatment were: 5, 3, 3 and 5% (corn-based diets with or without GAA; sorghum-based diets with or without GAA, respectively). Previous studies (Garcia et al., 2013; Torres et al., 2013; Tandiag et al., 2014) concluded that partial or total replacement of corn by sorghum did not depress (P > 0.05) FCR up to 42 d of age. Although FCR was not affected by grain source in the current study, there was a lower (P ≤ 0.05) feed intake in broilers fed sorghum-based diets that lowered BW gain and consequently BW. This could be attributed to the effects of the high tannin content in the sorghum (1.91% catechi equivalent) used for the experiment described herein. It has been reported that tannins lowered protein and starch digestion (Kumar et al., 2005; Del Puerto et al., 2016). Moreover, the fact that no significant differences were detected in FCR due to grain source in our study, suggests that the values used for digestible amino acids and available nutrients in the formulation were adequate. It has been reported a greater BW gain up to 70.2 g, when male Ross 308 broilers where fed corn-based supplemented diets with GAA and raised up to 39 d of age (Michiels et al., 2012). Several investigators have observed that GAA supplementation reduces FCR (P < 0.05), suggesting improvements up to five points on FCR due to GAA supplementation (Lemme et al., 2007a; Mousavi et al., 2013) in broilers fed corn-based or partially replaced with sorghum (20%) and raised up to 42 d. Ringel et al. (2007) observed improvements up to seven points in FCR with the same level of GAA (0.06%) inclusion, compared to a negative control diet that did not contain any animal by-product (“all vegetable diet”) without GAA supplementation. Findings in those studies concluded that GAA improved live performance in corn-based diets. In the present study, the improvement in BW gain was up to 55 g at 35 d, and FCR was improved by 7, 4, and 4 points at 14, 35 and 50 d, respectively, regardless of the type of grain source in the diet. Therefore, GAA could improve live performance in vegetable-based diets with either corn or sorghum as the base grain. The lack of interaction effects of GAA with grain source dismisses our hypothesis that GAA will have greater improvements on sorghum diets. Carcass and Cut up Parts Weights and Yields Results for the effect of grain source (corn or sorghum) on carcass and parts weights and yields for the selected broilers are shown in Table 5. These Ross-708 broilers were processed on two different days (51 and 55 d, 4 broilers/pen each time) to observe muscle development in two common stages in the US industry and meet experimental processing capabilities to evaluate all parameters at the same time. The four broilers used for processing were considered a subsample that represented each pen constituted of 20 chickens. Differences (P < 0.05) were observed between processing times and consequently data were analyzed separately. No differences (P > 0.05) on live BW of chickens selected for processing were detected due to either grain source or GAA supplementation for both slaughter ages. No interaction effects (P > 0.05) were observed at 51 d of age on carcass and cut up yields. However, at 55 d an interaction effect (P < 0.05) of grain source and GAA was detected on breast meat yield. Differences due to GAA supplementation at 55d were detected only in corn diets. In broilers fed corn diets, the addition of GAA improved breast meat yield (39.15 vs. 38.19%), compared to chickens fed corn non-supplemented diets, which attributed to an improvement of 96 g in breast meat per broiler at this age and weight (∼ 4521 g). Table 5. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum based diets for Ross-708 male broilers on carcass, breast meat, and cut up yields at 51 and 55 d of age.         Cut—up parts relative to carcass weight 51 d      Cut—up parts relative to carcass weight 55 d      Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Additive  Grain  weight  yield1  Wings  Quarters  major  minor  meat  Rack  weight  yield1  Wings  Quarters  major  minor  meat  Rack      –(g)–  ——————————————– % —————————————–  –(g)–  ——————————————– % —————————————–  GAA    4,148  78.28  9.50  30.63a  31.82  6.32  38.09  21.63  4,548  78.97  9.41  30.70  32.24  6.49  38.76  20.94  None    4,069  78.24  9.45  30.15b  31.93  6.30  38.15  21.91  4,464  78.72  9.39  30.94  32.02  6.45  38.43  21.94  SEM    50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.28  0.06  0.30  0.35    Corn  4,156  78.44a  9.43  30.23  32.11  6.37  38.42a  21.68  4,541  78.77  9.52a  30.77  32.21  6.45  38.67  20.95    Sorghum  4,060  78.08b  9.52  30.54  31.63  6.25  37.83b  21.86  4,470  78.92  9.28b  30.87  32.05  6.48  38.52  21.22    SEM  50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.27  0.06  0.30  0.35  GAA  Corn  4,217  78.33  9.49  30.42  31.93  6.36  38.21  21.61  4,597  79.02  9.48  30.47  32.59  6.51  39.15a  20.69    Sorghum  4,078  78.33  9.50  30.83  31.71  6.28  37.98  21.65  4,500  78.93  9.34  30.93  31.88  6.47  38.37a,b  21.18  None  Corn  4,095  78.54  9.37  30.05  32.30  6.37  38.63  21.75  4,486  78.52  9.56  31.06  31.82  6.40  38.19b  21.21    Sorghum  4,042  77.94  9.54  30.25  31.56  6.22  37.67  22.07  4,441  78.92  9.22  30.82  32.21  6.50  38.68a,b  21.27    SEM  62  0.16  0.11  0.23  0.27  0.08  0.28  0.28  63  0.21  0.13  0.24  0.34  0.08  0.37  0.37  CV%    5.32  1.30  6.15  4.98  5.89  6.34  5.06  5.84  4.81  1.18  5.53  4.45  5.63  7.39  5.34  5.35  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.136  0.781  0.325  0.043  0.710  0.756  0.839  0.236  0.158  0.123  0.865  0.236  0.435  0.570  0.274  0.085  Grain  0.072  0.025  0.635  0.170  0.091  0.112  0.044  0.435  0.235  0.352  0.035  0.594  0.573  0.662  0.627  0.123  Additive*grain  0.412  0.104  0.398  0.625  0.353  0.622  0.220  0.537  0.660  0.157  0.386  0.093  0.065  0.335  0.043  0.225          Cut—up parts relative to carcass weight 51 d      Cut—up parts relative to carcass weight 55 d      Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Additive  Grain  weight  yield1  Wings  Quarters  major  minor  meat  Rack  weight  yield1  Wings  Quarters  major  minor  meat  Rack      –(g)–  ——————————————– % —————————————–  –(g)–  ——————————————– % —————————————–  GAA    4,148  78.28  9.50  30.63a  31.82  6.32  38.09  21.63  4,548  78.97  9.41  30.70  32.24  6.49  38.76  20.94  None    4,069  78.24  9.45  30.15b  31.93  6.30  38.15  21.91  4,464  78.72  9.39  30.94  32.02  6.45  38.43  21.94  SEM    50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.28  0.06  0.30  0.35    Corn  4,156  78.44a  9.43  30.23  32.11  6.37  38.42a  21.68  4,541  78.77  9.52a  30.77  32.21  6.45  38.67  20.95    Sorghum  4,060  78.08b  9.52  30.54  31.63  6.25  37.83b  21.86  4,470  78.92  9.28b  30.87  32.05  6.48  38.52  21.22    SEM  50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.27  0.06  0.30  0.35  GAA  Corn  4,217  78.33  9.49  30.42  31.93  6.36  38.21  21.61  4,597  79.02  9.48  30.47  32.59  6.51  39.15a  20.69    Sorghum  4,078  78.33  9.50  30.83  31.71  6.28  37.98  21.65  4,500  78.93  9.34  30.93  31.88  6.47  38.37a,b  21.18  None  Corn  4,095  78.54  9.37  30.05  32.30  6.37  38.63  21.75  4,486  78.52  9.56  31.06  31.82  6.40  38.19b  21.21    Sorghum  4,042  77.94  9.54  30.25  31.56  6.22  37.67  22.07  4,441  78.92  9.22  30.82  32.21  6.50  38.68a,b  21.27    SEM  62  0.16  0.11  0.23  0.27  0.08  0.28  0.28  63  0.21  0.13  0.24  0.34  0.08  0.37  0.37  CV%    5.32  1.30  6.15  4.98  5.89  6.34  5.06  5.84  4.81  1.18  5.53  4.45  5.63  7.39  5.34  5.35  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.136  0.781  0.325  0.043  0.710  0.756  0.839  0.236  0.158  0.123  0.865  0.236  0.435  0.570  0.274  0.085  Grain  0.072  0.025  0.635  0.170  0.091  0.112  0.044  0.435  0.235  0.352  0.035  0.594  0.573  0.662  0.627  0.123  Additive*grain  0.412  0.104  0.398  0.625  0.353  0.622  0.220  0.537  0.660  0.157  0.386  0.093  0.065  0.335  0.043  0.225  Values are means of 10 pens per treatment combination with 4 male broiler chickens per pen selected for processing. Pen nested within each treatment and cutter (random effects). a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Relative to live weight of broilers selected for processing. View Large Table 5. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum based diets for Ross-708 male broilers on carcass, breast meat, and cut up yields at 51 and 55 d of age.         Cut—up parts relative to carcass weight 51 d      Cut—up parts relative to carcass weight 55 d      Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Additive  Grain  weight  yield1  Wings  Quarters  major  minor  meat  Rack  weight  yield1  Wings  Quarters  major  minor  meat  Rack      –(g)–  ——————————————– % —————————————–  –(g)–  ——————————————– % —————————————–  GAA    4,148  78.28  9.50  30.63a  31.82  6.32  38.09  21.63  4,548  78.97  9.41  30.70  32.24  6.49  38.76  20.94  None    4,069  78.24  9.45  30.15b  31.93  6.30  38.15  21.91  4,464  78.72  9.39  30.94  32.02  6.45  38.43  21.94  SEM    50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.28  0.06  0.30  0.35    Corn  4,156  78.44a  9.43  30.23  32.11  6.37  38.42a  21.68  4,541  78.77  9.52a  30.77  32.21  6.45  38.67  20.95    Sorghum  4,060  78.08b  9.52  30.54  31.63  6.25  37.83b  21.86  4,470  78.92  9.28b  30.87  32.05  6.48  38.52  21.22    SEM  50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.27  0.06  0.30  0.35  GAA  Corn  4,217  78.33  9.49  30.42  31.93  6.36  38.21  21.61  4,597  79.02  9.48  30.47  32.59  6.51  39.15a  20.69    Sorghum  4,078  78.33  9.50  30.83  31.71  6.28  37.98  21.65  4,500  78.93  9.34  30.93  31.88  6.47  38.37a,b  21.18  None  Corn  4,095  78.54  9.37  30.05  32.30  6.37  38.63  21.75  4,486  78.52  9.56  31.06  31.82  6.40  38.19b  21.21    Sorghum  4,042  77.94  9.54  30.25  31.56  6.22  37.67  22.07  4,441  78.92  9.22  30.82  32.21  6.50  38.68a,b  21.27    SEM  62  0.16  0.11  0.23  0.27  0.08  0.28  0.28  63  0.21  0.13  0.24  0.34  0.08  0.37  0.37  CV%    5.32  1.30  6.15  4.98  5.89  6.34  5.06  5.84  4.81  1.18  5.53  4.45  5.63  7.39  5.34  5.35  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.136  0.781  0.325  0.043  0.710  0.756  0.839  0.236  0.158  0.123  0.865  0.236  0.435  0.570  0.274  0.085  Grain  0.072  0.025  0.635  0.170  0.091  0.112  0.044  0.435  0.235  0.352  0.035  0.594  0.573  0.662  0.627  0.123  Additive*grain  0.412  0.104  0.398  0.625  0.353  0.622  0.220  0.537  0.660  0.157  0.386  0.093  0.065  0.335  0.043  0.225          Cut—up parts relative to carcass weight 51 d      Cut—up parts relative to carcass weight 55 d      Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Live  Carcass    Leg  Pectoralis  Pectoralis  Breast    Additive  Grain  weight  yield1  Wings  Quarters  major  minor  meat  Rack  weight  yield1  Wings  Quarters  major  minor  meat  Rack      –(g)–  ——————————————– % —————————————–  –(g)–  ——————————————– % —————————————–  GAA    4,148  78.28  9.50  30.63a  31.82  6.32  38.09  21.63  4,548  78.97  9.41  30.70  32.24  6.49  38.76  20.94  None    4,069  78.24  9.45  30.15b  31.93  6.30  38.15  21.91  4,464  78.72  9.39  30.94  32.02  6.45  38.43  21.94  SEM    50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.28  0.06  0.30  0.35    Corn  4,156  78.44a  9.43  30.23  32.11  6.37  38.42a  21.68  4,541  78.77  9.52a  30.77  32.21  6.45  38.67  20.95    Sorghum  4,060  78.08b  9.52  30.54  31.63  6.25  37.83b  21.86  4,470  78.92  9.28b  30.87  32.05  6.48  38.52  21.22    SEM  50  0.12  0.09  0.17  0.21  0.07  0.20  0.23  48  0.18  0.10  0.19  0.27  0.06  0.30  0.35  GAA  Corn  4,217  78.33  9.49  30.42  31.93  6.36  38.21  21.61  4,597  79.02  9.48  30.47  32.59  6.51  39.15a  20.69    Sorghum  4,078  78.33  9.50  30.83  31.71  6.28  37.98  21.65  4,500  78.93  9.34  30.93  31.88  6.47  38.37a,b  21.18  None  Corn  4,095  78.54  9.37  30.05  32.30  6.37  38.63  21.75  4,486  78.52  9.56  31.06  31.82  6.40  38.19b  21.21    Sorghum  4,042  77.94  9.54  30.25  31.56  6.22  37.67  22.07  4,441  78.92  9.22  30.82  32.21  6.50  38.68a,b  21.27    SEM  62  0.16  0.11  0.23  0.27  0.08  0.28  0.28  63  0.21  0.13  0.24  0.34  0.08  0.37  0.37  CV%    5.32  1.30  6.15  4.98  5.89  6.34  5.06  5.84  4.81  1.18  5.53  4.45  5.63  7.39  5.34  5.35  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.136  0.781  0.325  0.043  0.710  0.756  0.839  0.236  0.158  0.123  0.865  0.236  0.435  0.570  0.274  0.085  Grain  0.072  0.025  0.635  0.170  0.091  0.112  0.044  0.435  0.235  0.352  0.035  0.594  0.573  0.662  0.627  0.123  Additive*grain  0.412  0.104  0.398  0.625  0.353  0.622  0.220  0.537  0.660  0.157  0.386  0.093  0.065  0.335  0.043  0.225  Values are means of 10 pens per treatment combination with 4 male broiler chickens per pen selected for processing. Pen nested within each treatment and cutter (random effects). a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Relative to live weight of broilers selected for processing. View Large At 55 d of age, carcass and other cut up yields were not affected either by GAA addition or grain source, except for wing yield. Broilers fed corn diets had greater wing (P < 0.05) yield than broilers fed sorghum diets (9.52 vs. 9.28%). At 51 d of age (∼4108 g live weight), the addition of GAA improved (P < 0.05) leg quarter yield but not breast meat yield regardless of grain type. No effects (P > 0.05) of GAA addition were observed on carcass or other cut up yields. At this age, corn-based diets improved carcass and breast meat yield (P < 0.05). Broilers fed sorghum diets had less carcass yield (78.44% vs. 78.08%) and breast meat yield (38.42 vs. 37.83%) than broilers fed corn diets. No other differences in cut up yields were detected at 51 d attributed to grain type. Previous studies (Kwari et al., 2012; Garcia et al., 2013; Torres et al., 2013; Tandiang et al., 2014) reported that partial or total replacement of corn by sorghum did not affect (P > 0.05) carcass and cut up yields at different slaughter ages and in different genetic lines. On the other hand, Rodrigues et al. (2007) reported in a trial up to 42 d, that even though the relationships were not significant, increasing tannin levels still tended to depress breast meat yields (r = −0.513; P < 0.07). Nasr and Kheiri (2012) concluded that lysine availability in the diet affected carcass and breast meat yield. In agreement, Ebadi et al. (2005) observed that sorghum containing medium levels of tannins could adversely affect lysine availability. Therefore, our results of carcass and breast meat yield at this age may be explained by the possible effect of high tannin content (1.91% catechin equivalent) on dietary lysine bioavailability. It has been concluded (Lemme et al., 2007a; Michiels et al., 2012) that the use of GAA improved breast meat yield in vegetable-based diets. This response was observed even when corn was partially replaced by sorghum up to 20% (Lemme et al., 2007a). However, no improvements on whole carcass, and other cut up (upper leg, lower leg, wings) yields were observed. Our interaction effect detected only in corn diets at 55d suggested that the improvements on breast meat yield could depend on the type of grain base in the diet, specific content and/or digestibility of some amino acids. Meat Quality Results from meat quality parameters are shown in Table 6. No interactions effects (P > 0.05) were observed on drip and cook loss at any of the processing days. Drip and cook loss, and shear force were not affected (P > 0.05) by GAA supplementation or grain type main effects at any of the slaughter ages. Table 6. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum diets for Ross-708 male broilers on meat quality at 51 and 55 d of age.           Post mortem pH  Color        Post mortem pH  Color  Additive  Grain  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*      –(g)–  (kg)            –(g)–  (kg)            GAA    1.24  28.67  4.60  5.91  6.01b  58.98  4.34  7.03b  1.31  31.01  4.58  5.88b  5.95b  59.49  3.90  7.23  None    1.28  28.57  4.35  5.94  6.08a  58.83  4.47  7.90a  1.19  30.52  4.67  5.92a  5.99a  58.57  3.81  7.55  SEM    0.06  0.46  0.18  0.01  0.02  0.33  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.34  0.17  0.22    Corn  1.28  28.30  4.50  5.92  6.05  58.61  4.17b  8.78a  1.26  30.97  4.59  5.88  5.95b  59.23  3.89  9.28a    Sorghum  1.24  28.94  4.45  5.93  6.04  59.21  4.64a  6.15b  1.24  30.57  4.66  5.91  5.99a  58.82  3.82  5.50b    SEM  0.06  0.46  0.18  0.01  0.02  0.34  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.35  0.17  0.22  GAA  Corn  1.28  28.14  4.57  5.90  6.03  58.50  3.78b  7.92b  1.31  30.98  4.54  5.87  5.95  59.85  4.02  9.34    Sorghum  1.20  29.19  4.62  5.91  5.99  59.46  4.91a  6.14c  1.31  31.04  4.62  5.88  5.96  59.13  3.78  5.13  None  Corn  1.29  28.47  4.43  5.94  6.07  58.71  4.56a,b  9.64a  1.21  30.96  4.64  5.90  5.96  58.62  3.76  9.23    Sorghum  1.27  28.68  4.27  5.95  6.09  58.95  4.38a,b  6.17c  1.17  30.09  4.70  5.95  6.03  58.52  3.85  5.87    SEM  0.09  0.65  0.22  0.02  0.03  0.48  0.23  0.33  0.07  0.72  0.17  0.02  0.02  0.50  0.24  0.31  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.674  0.887  0.182  0.100  0.015  0.753  0.592  0.009  0.078  0.499  0.637  0.008  0.009  0.068  0.691  0.310  Grain  0.630  0.333  0.692  0.626  0.719  0.211  0.049  <0.001  0.728  0.579  0.637  0.068  0.020  0.411  0.753  <0.001  Additive*grain  0.741  0.521  0.544  0.942  0.256  0.455  0.007  0.011  0.785  0.516  0.965  0.330  0.139  0.539  0.478  0.173            Post mortem pH  Color        Post mortem pH  Color  Additive  Grain  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*      –(g)–  (kg)            –(g)–  (kg)            GAA    1.24  28.67  4.60  5.91  6.01b  58.98  4.34  7.03b  1.31  31.01  4.58  5.88b  5.95b  59.49  3.90  7.23  None    1.28  28.57  4.35  5.94  6.08a  58.83  4.47  7.90a  1.19  30.52  4.67  5.92a  5.99a  58.57  3.81  7.55  SEM    0.06  0.46  0.18  0.01  0.02  0.33  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.34  0.17  0.22    Corn  1.28  28.30  4.50  5.92  6.05  58.61  4.17b  8.78a  1.26  30.97  4.59  5.88  5.95b  59.23  3.89  9.28a    Sorghum  1.24  28.94  4.45  5.93  6.04  59.21  4.64a  6.15b  1.24  30.57  4.66  5.91  5.99a  58.82  3.82  5.50b    SEM  0.06  0.46  0.18  0.01  0.02  0.34  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.35  0.17  0.22  GAA  Corn  1.28  28.14  4.57  5.90  6.03  58.50  3.78b  7.92b  1.31  30.98  4.54  5.87  5.95  59.85  4.02  9.34    Sorghum  1.20  29.19  4.62  5.91  5.99  59.46  4.91a  6.14c  1.31  31.04  4.62  5.88  5.96  59.13  3.78  5.13  None  Corn  1.29  28.47  4.43  5.94  6.07  58.71  4.56a,b  9.64a  1.21  30.96  4.64  5.90  5.96  58.62  3.76  9.23    Sorghum  1.27  28.68  4.27  5.95  6.09  58.95  4.38a,b  6.17c  1.17  30.09  4.70  5.95  6.03  58.52  3.85  5.87    SEM  0.09  0.65  0.22  0.02  0.03  0.48  0.23  0.33  0.07  0.72  0.17  0.02  0.02  0.50  0.24  0.31  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.674  0.887  0.182  0.100  0.015  0.753  0.592  0.009  0.078  0.499  0.637  0.008  0.009  0.068  0.691  0.310  Grain  0.630  0.333  0.692  0.626  0.719  0.211  0.049  <0.001  0.728  0.579  0.637  0.068  0.020  0.411  0.753  <0.001  Additive*grain  0.741  0.521  0.544  0.942  0.256  0.455  0.007  0.011  0.785  0.516  0.965  0.330  0.139  0.539  0.478  0.173  Values are means of 10 pens per treatment combination with 4 male broiler chickens per pen selected for processing. Pen nested within each treatment (random effects). a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Warner-Bratzler; Color: L* = lightness, a* = redness, b* = yellowness. View Large Table 6. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum diets for Ross-708 male broilers on meat quality at 51 and 55 d of age.           Post mortem pH  Color        Post mortem pH  Color  Additive  Grain  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*      –(g)–  (kg)            –(g)–  (kg)            GAA    1.24  28.67  4.60  5.91  6.01b  58.98  4.34  7.03b  1.31  31.01  4.58  5.88b  5.95b  59.49  3.90  7.23  None    1.28  28.57  4.35  5.94  6.08a  58.83  4.47  7.90a  1.19  30.52  4.67  5.92a  5.99a  58.57  3.81  7.55  SEM    0.06  0.46  0.18  0.01  0.02  0.33  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.34  0.17  0.22    Corn  1.28  28.30  4.50  5.92  6.05  58.61  4.17b  8.78a  1.26  30.97  4.59  5.88  5.95b  59.23  3.89  9.28a    Sorghum  1.24  28.94  4.45  5.93  6.04  59.21  4.64a  6.15b  1.24  30.57  4.66  5.91  5.99a  58.82  3.82  5.50b    SEM  0.06  0.46  0.18  0.01  0.02  0.34  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.35  0.17  0.22  GAA  Corn  1.28  28.14  4.57  5.90  6.03  58.50  3.78b  7.92b  1.31  30.98  4.54  5.87  5.95  59.85  4.02  9.34    Sorghum  1.20  29.19  4.62  5.91  5.99  59.46  4.91a  6.14c  1.31  31.04  4.62  5.88  5.96  59.13  3.78  5.13  None  Corn  1.29  28.47  4.43  5.94  6.07  58.71  4.56a,b  9.64a  1.21  30.96  4.64  5.90  5.96  58.62  3.76  9.23    Sorghum  1.27  28.68  4.27  5.95  6.09  58.95  4.38a,b  6.17c  1.17  30.09  4.70  5.95  6.03  58.52  3.85  5.87    SEM  0.09  0.65  0.22  0.02  0.03  0.48  0.23  0.33  0.07  0.72  0.17  0.02  0.02  0.50  0.24  0.31  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.674  0.887  0.182  0.100  0.015  0.753  0.592  0.009  0.078  0.499  0.637  0.008  0.009  0.068  0.691  0.310  Grain  0.630  0.333  0.692  0.626  0.719  0.211  0.049  <0.001  0.728  0.579  0.637  0.068  0.020  0.411  0.753  <0.001  Additive*grain  0.741  0.521  0.544  0.942  0.256  0.455  0.007  0.011  0.785  0.516  0.965  0.330  0.139  0.539  0.478  0.173            Post mortem pH  Color        Post mortem pH  Color  Additive  Grain  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*  Drip loss  Cook loss  Shear force1  6 h  24 h  L*  a*  b*      –(g)–  (kg)            –(g)–  (kg)            GAA    1.24  28.67  4.60  5.91  6.01b  58.98  4.34  7.03b  1.31  31.01  4.58  5.88b  5.95b  59.49  3.90  7.23  None    1.28  28.57  4.35  5.94  6.08a  58.83  4.47  7.90a  1.19  30.52  4.67  5.92a  5.99a  58.57  3.81  7.55  SEM    0.06  0.46  0.18  0.01  0.02  0.33  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.34  0.17  0.22    Corn  1.28  28.30  4.50  5.92  6.05  58.61  4.17b  8.78a  1.26  30.97  4.59  5.88  5.95b  59.23  3.89  9.28a    Sorghum  1.24  28.94  4.45  5.93  6.04  59.21  4.64a  6.15b  1.24  30.57  4.66  5.91  5.99a  58.82  3.82  5.50b    SEM  0.06  0.46  0.18  0.01  0.02  0.34  0.17  0.23  0.05  0.51  0.14  0.01  0.01  0.35  0.17  0.22  GAA  Corn  1.28  28.14  4.57  5.90  6.03  58.50  3.78b  7.92b  1.31  30.98  4.54  5.87  5.95  59.85  4.02  9.34    Sorghum  1.20  29.19  4.62  5.91  5.99  59.46  4.91a  6.14c  1.31  31.04  4.62  5.88  5.96  59.13  3.78  5.13  None  Corn  1.29  28.47  4.43  5.94  6.07  58.71  4.56a,b  9.64a  1.21  30.96  4.64  5.90  5.96  58.62  3.76  9.23    Sorghum  1.27  28.68  4.27  5.95  6.09  58.95  4.38a,b  6.17c  1.17  30.09  4.70  5.95  6.03  58.52  3.85  5.87    SEM  0.09  0.65  0.22  0.02  0.03  0.48  0.23  0.33  0.07  0.72  0.17  0.02  0.02  0.50  0.24  0.31  Source of variation  ———————————————————————————————- P—values ——————————————————————————————————-  Additive  0.674  0.887  0.182  0.100  0.015  0.753  0.592  0.009  0.078  0.499  0.637  0.008  0.009  0.068  0.691  0.310  Grain  0.630  0.333  0.692  0.626  0.719  0.211  0.049  <0.001  0.728  0.579  0.637  0.068  0.020  0.411  0.753  <0.001  Additive*grain  0.741  0.521  0.544  0.942  0.256  0.455  0.007  0.011  0.785  0.516  0.965  0.330  0.139  0.539  0.478  0.173  Values are means of 10 pens per treatment combination with 4 male broiler chickens per pen selected for processing. Pen nested within each treatment (random effects). a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. 1Warner-Bratzler; Color: L* = lightness, a* = redness, b* = yellowness. View Large Postmortem pH values of breast muscle showed no interaction effects (P > 0.05) in both processing days. The pH of breast meat, 1 h post-processing, was not affected (P > 0.05) either by grain type or GAA supplementation for both slaughter ages (data not shown). In contrast, grain source affected (P < 0.05) the ultimate pH (24 h after slaughter) at 55 d only. Samples from chickens fed corn diets had lower pH than samples from broilers fed sorghum diets (5.95 vs. 5.99). On the other hand, GAA supplementation lowered (P < 0.05) pH of breast meat after 24 h of slaughter at 51 d (6.01 vs. 6.08) compared to samples from chickens fed non-supplemented diets. Similarly, GAA supplementation reduced (P < 0.01) pH after six (5.88 vs. 5.92) and 24 h (5.95 vs. 5.99) post-slaughter at 55 d of age. An interaction effect was observed on redness (a*) value at 51 d only. Differences were detected only in the supplemented diets with GAA, where chickens fed sorghum-supplemented diets had higher (P < 0.01) a* value than breast meat from chickens fed corn-supplemented diets (4.91 vs. 3.78). While samples of broilers fed corn or sorghum non-supplemented diets had intermediate results. At 51 d only, an interaction effect (P < 0.05) was found on yellowness (b*) value. Samples from broilers fed corn non-supplemented diets had the highest b* value. At 55 d of processing the b* value was affected (P < 0.001) by grain type. Breast fillets from broilers fed corn diets had greater b* values (9.28 vs. 5.50) than samples from broilers fed sorghum diets. Opposite response was observed for lightness (L*), where no differences (P > 0.05) between treatments were detected due to grain type or GAA supplementation at any processing days. It has been reported (Garcia et al., 2005; Del Puerto et al., 2016) that drip and cook loss were not affected (P > 0.05) by partial or total replacement of corn by sorghum. Likewise, GAA did not improve (P > 0.05) drip loss in a previous study (Michiels et al., 2012). On the other hand, Michiels et al. (2012) observed that cook loss was increased (P < 0.05) in diets containing GAA compared to a negative control (corn-soybean meal diets). Garcia et al. (2013) observed that breast meat pH was not affected (P > 0.05) by the substitution (50 and 100%) of corn with sorghum. In addition, Garcia et al. (2005) reported that the replacement of 100% of corn by sorghum lowered (P < 0.05) breast meat pH. Del Puerto et al. (2016) found no differences (P > 0.05) in ultimate pH when comparing samples of Pectoralis major from chickens fed corn or sorghum-based diets. However, they observed differences on pH after 45 and 90 min of slaughter, where samples from broilers fed corn diets had lower (P < 0.05) pH values than samples from broilers fed sorghum. These researchers suggested that the effect of sorghum to reduce the pH drop in the breast muscle as compared to corn, and this could be due to the difference in starch digestibility. Corn has higher digestibility than sorghum because anti-nutritional factors contained in sorghum grain such as tannins and kafirin proteins reduce the availability of amino acids and starch (Garcia et al., 2005). This effect associated with tannins in sorghum has been observed to differ among broilers, layers, and roosters (Huang et al., 2006; Moughan et al., 2014). A previous study conducted by Michiels et al. (2012) found that GAA supplementation lowered (P < 0.05) breast meat pH after 4 and 24 h post-slaughter of broilers fed supplemented diets in comparison with chickens fed non-supplemented diets. Our findings would suggest that GAA supplementation lowered the pH of breast meat to levels close to what is has been reported to be normal values (Fletcher et al., 2000), which could be beneficial for water holding capacity and therefore breast meat tenderness. However, no differences were detected on drip and cook loss, and shear force in both processing days. The water-holding capacity of marinated meat was not evaluated in the present study. Michiels et al. (2012) reported that when chickens were fed diets containing GAA, the ratios of phosphocreatine: ATP were higher than those fed a negative control without GAA supplementation, indicating the buffer capacity of ATP for hydrolysis by phosphocreatine which represent higher energy availability for muscle development. Moreover, intramuscular phosphocreatine can attract water into the muscle cell and increase the cell volume (Hultman et al., 1996). Haussinger (1996) found that a super-hydrated muscle may trigger protein synthesis, minimize protein breakdown, and increase glycogen synthesis, as partly demonstrated by Young et al. (2007). Abasht et al. (2016) observed that breast meat affected with wooden breast myopathy had lower (P < 0.001) glycogen content in muscle than samples from unaffected chickens. A significant higher ultimate pH (24 h after slaughter) observed in affected tissues may also be related to glycogen depletion and reduced glycolytic potential within affected muscle at the time of slaughtering (Sante et al., 2001; Del Puerto el al., 2016). A recent study (Majdeddin et al., 2017) concluded that higher phosphocreatine, creatine and glycogen concentrations in breast muscle of broilers were observed with increasing dietary GAA levels (0.06 and 0.12%). Shear force (Warner-Bratzler) was not affected either by grain source or GAA supplementation in the present experiment. Generally, results ranged between 41.87 to 46.09 N (4.27 to 4.70 kg respectively, Warner-Bratzler). According to different authors (Owens et al., 2000; Schilling et al., 2003; Corzo et al., 2009) these values have been considered as low tender, resulting in less acceptability by the consumer. However, Schilling et al. (2003) suggested that independently of the shear force value in samples considered as low tender, not many consumers would find these samples as unacceptable. The values obtained in the present experiment showed similar results as observed by Poole et al. (1999), who observed that broilers at 7 wk old had an average of 4.64 ± 0.18 kg shear force values (Warner-Bratzler). These authors concluded that shear force values of cooked breast meat changes, depending on age of the broilers. They suggested that shear force values of breast fillets in the scale from 3.46 to 6.41 kg (Warner-Bratzler) are considered “moderately tender”. According to Garcia et al. (2005), no differences (P > 0.05) in shear force were observed when corn was replaced by sorghum up to 100% in the diet. In agreement with our findings, Michiels et al. (2012) reported that shear force was not affected (P > 0.05) by up to 1.2% GAA dietary supplementation. Therefore, the shear force values obtained in our experiment were more likely due to age of the broilers than related to dietary grain source or GAA supplementation. Zotte et al. (2017) found no differences in shear force when comparing breast fillets affected by WB myopathy with non-affected breast fillets. According to Fletcher (2002), differences in tenderness can be due to the fact that older birds are more mature at the time of harvest and have more cross-linked collagen. Considering the age of broilers at processing in the experiment described herein, the incidence of WB is related to increased cross-linked collagen in the pectoral muscle. Results from the present study related to color in breast meat, are consistent with those detected by Garcia et al. (2013) and Harder et al. (2010), who evaluated the effects of sorghum replacing corn in the diet for broilers. These authors concluded that the L* value of broiler breast meat depends on the carotenoid content in the diet. In the same study, breast meat b* value decreased gradually as sorghum replaced corn in the diets. According to Etuk et al. (2012) and Garcia et al. (2013), grain sorghum is deficient in carotene and contains less yellow xanthophylls than corn. Therefore, the findings of b* value in the present study may be due to carotenoid content in the diets considering its grain-based origin; thus, breast meat from chickens fed corn diets had higher b* values at both processing days. Garcia et al. (2013) also concluded that breast meat redness (a*) decreased, and lightness (L*) increased when corn was replaced by sorghum at 50 and 100% level. However, results from our experiment showed no effect (P > 0.05) of grain source or GAA supplementation on L* value for both slaughter ages, and a* value was affected by grain type only at 51 d. Garcia et al. (2005) reported similar results as findings detected in the present study. Breast meat L* values were not affected when corn was replaced 100% by sorghum. Michiels et al. (2012) observed that L* and b* values were increased (P < 0.05) by GAA supplementation of corn-based diets. In contrast, we observed that dietary GAA supplementation reduced (P < 0.05) b* values. Zotte et al. (2017) found differences (P < 0.01) in color between breast meat of chickens affected with WB and non-affected samples. Breast meat with WB abnormality had higher (P < 0.01) L*, a*, and b* values, than those without the abnormality. According to several researchers, the impairment of the homeostasis of lipids and proteins leads to oxidation in muscle promoting changes in meat color due to modification of heme pigments state (Estevez, 2011; Xiao et al., 2011; Zhang et al., 2011). Poultry meat color depends mainly on myoglobin concentration and chemical state, while it is affected by numerous factors such as bird age, gender, genetic background, diet, intramuscular fat, meat moisture content, preslaughter conditions, and processing variables (Totosaus et al., 2007). In the project described herein, at 51 d of age only, an effect of GAA supplementation was observed on b* value (Table 6) and on WB average score (Table 7). At this age a positive correlation (P < 0.05; r = 0.238) between b* value and WB was detected and it is shown in Table 8. These findings support the results obtained by other researchers (Mudalal et al., 2015; and Wold et al., 2017) in which WB was associated with higher b* values. In addition, altered color with higher b* value has been related with breast meat abnormalities (Petracci et al., 2017), having an important potential to identify fillets with WB myopathy in an industrial scale (Wold et al., 2017). Differences as compared to the quoted references can be due to dose, age of chickens, diet and standardization of the applied technique. Table 7. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum diets for Ross-708 male broilers on pectoral myophaties sensorial average score severity at 51 and 55 d of age.     White striping  Wooden breast  Spaghetti muscle  Additive  Grain  51d  55d  51d  55d  51d  55d      — (1–4) —  — (1–4) —  — (1–2) —  GAA    2.24  2.30  2.33b  2.37  1.14  1.02  None    2.17  2.21  2.76a  2.41  1.09  1.04  SEM    0.09  0.08  0.10  0.08  0.03  0.02    Corn  2.16  2.29  2.51  2.58a  1.10  1.03    Sorghum  2.25  2.23  2.57  2.19b  1.14  1.03    SEM  0.08  0.08  0.10  0.08  0.03  0.02  GAA  Corn  2.20  2.30  2.18  2.58  1.13  1.02    Sorghum  2.27  2.31  2.48  2.15  1.16  1.03  None  Corn  2.13  2.27  2.85  2.59  1.08  1.05    Sorghum  2.22  2.15  2.67  2.23  1.11  1.04    SEM  0.11  0.11  0.14  0.11  0.04  0.03  Source of variation  ———————– P—values ———————–  Additive  0.573  0.417  0.003  0.723  0.279  0.411  Grain  0.447  0.610  0.667  0.001  0.436  0.973  Additive*grain  0.912  0.565  0.085  0.745  0.982  0.621      White striping  Wooden breast  Spaghetti muscle  Additive  Grain  51d  55d  51d  55d  51d  55d      — (1–4) —  — (1–4) —  — (1–2) —  GAA    2.24  2.30  2.33b  2.37  1.14  1.02  None    2.17  2.21  2.76a  2.41  1.09  1.04  SEM    0.09  0.08  0.10  0.08  0.03  0.02    Corn  2.16  2.29  2.51  2.58a  1.10  1.03    Sorghum  2.25  2.23  2.57  2.19b  1.14  1.03    SEM  0.08  0.08  0.10  0.08  0.03  0.02  GAA  Corn  2.20  2.30  2.18  2.58  1.13  1.02    Sorghum  2.27  2.31  2.48  2.15  1.16  1.03  None  Corn  2.13  2.27  2.85  2.59  1.08  1.05    Sorghum  2.22  2.15  2.67  2.23  1.11  1.04    SEM  0.11  0.11  0.14  0.11  0.04  0.03  Source of variation  ———————– P—values ———————–  Additive  0.573  0.417  0.003  0.723  0.279  0.411  Grain  0.447  0.610  0.667  0.001  0.436  0.973  Additive*grain  0.912  0.565  0.085  0.745  0.982  0.621  Values are means of 10 pens per treatment combination with 4 male broiler chickens selected for processing. a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. View Large Table 7. Effect of supplementation of guanidinoacetic acid (GAA) in corn or sorghum diets for Ross-708 male broilers on pectoral myophaties sensorial average score severity at 51 and 55 d of age.     White striping  Wooden breast  Spaghetti muscle  Additive  Grain  51d  55d  51d  55d  51d  55d      — (1–4) —  — (1–4) —  — (1–2) —  GAA    2.24  2.30  2.33b  2.37  1.14  1.02  None    2.17  2.21  2.76a  2.41  1.09  1.04  SEM    0.09  0.08  0.10  0.08  0.03  0.02    Corn  2.16  2.29  2.51  2.58a  1.10  1.03    Sorghum  2.25  2.23  2.57  2.19b  1.14  1.03    SEM  0.08  0.08  0.10  0.08  0.03  0.02  GAA  Corn  2.20  2.30  2.18  2.58  1.13  1.02    Sorghum  2.27  2.31  2.48  2.15  1.16  1.03  None  Corn  2.13  2.27  2.85  2.59  1.08  1.05    Sorghum  2.22  2.15  2.67  2.23  1.11  1.04    SEM  0.11  0.11  0.14  0.11  0.04  0.03  Source of variation  ———————– P—values ———————–  Additive  0.573  0.417  0.003  0.723  0.279  0.411  Grain  0.447  0.610  0.667  0.001  0.436  0.973  Additive*grain  0.912  0.565  0.085  0.745  0.982  0.621      White striping  Wooden breast  Spaghetti muscle  Additive  Grain  51d  55d  51d  55d  51d  55d      — (1–4) —  — (1–4) —  — (1–2) —  GAA    2.24  2.30  2.33b  2.37  1.14  1.02  None    2.17  2.21  2.76a  2.41  1.09  1.04  SEM    0.09  0.08  0.10  0.08  0.03  0.02    Corn  2.16  2.29  2.51  2.58a  1.10  1.03    Sorghum  2.25  2.23  2.57  2.19b  1.14  1.03    SEM  0.08  0.08  0.10  0.08  0.03  0.02  GAA  Corn  2.20  2.30  2.18  2.58  1.13  1.02    Sorghum  2.27  2.31  2.48  2.15  1.16  1.03  None  Corn  2.13  2.27  2.85  2.59  1.08  1.05    Sorghum  2.22  2.15  2.67  2.23  1.11  1.04    SEM  0.11  0.11  0.14  0.11  0.04  0.03  Source of variation  ———————– P—values ———————–  Additive  0.573  0.417  0.003  0.723  0.279  0.411  Grain  0.447  0.610  0.667  0.001  0.436  0.973  Additive*grain  0.912  0.565  0.085  0.745  0.982  0.621  Values are means of 10 pens per treatment combination with 4 male broiler chickens selected for processing. a,bMeans in a column not sharing a common superscript are significantly different (P ≤ 0.05) by Student's t or Tukey's test. View Large Table 8. Pearson correlation coefficients between breast meat quality parameters Ross-708 male broilers raised up to 51d.   Drip Loss  Cook Loss  Wooden Breast  pH (t = 6 h)  pH (t = 24 h)  Shear force1  L*  a*  Drip Loss  1                Cook Loss  0.313**  1              Wooden Breast  0.231*  0.355**  1            pH (t = 6 h)  0.209*  0.048  0.236*  1          pH (t = 24 h)  0.050  0.176*  0.195*  0.210*  1        Shear force1  -0.202*  0.070  0.144  -0.162*  -0.078  1      L*  0.302**  0.495**  0.341**  0.094  0.010  0.054  1    a*  0.144  0.124  0.156*  0.008  0.039  -0.057  -0.068  1  b*  0.151  0.132  0.238*  0.093  -0.002  -0.087  0.423**  0.136    Drip Loss  Cook Loss  Wooden Breast  pH (t = 6 h)  pH (t = 24 h)  Shear force1  L*  a*  Drip Loss  1                Cook Loss  0.313**  1              Wooden Breast  0.231*  0.355**  1            pH (t = 6 h)  0.209*  0.048  0.236*  1          pH (t = 24 h)  0.050  0.176*  0.195*  0.210*  1        Shear force1  -0.202*  0.070  0.144  -0.162*  -0.078  1      L*  0.302**  0.495**  0.341**  0.094  0.010  0.054  1    a*  0.144  0.124  0.156*  0.008  0.039  -0.057  -0.068  1  b*  0.151  0.132  0.238*  0.093  -0.002  -0.087  0.423**  0.136  **P < 0.001. *P < 0.05. 1 Warner-Bratzler; Color: L* = lightness, a* = redness, b* = yellowness View Large Table 8. Pearson correlation coefficients between breast meat quality parameters Ross-708 male broilers raised up to 51d.   Drip Loss  Cook Loss  Wooden Breast  pH (t = 6 h)  pH (t = 24 h)  Shear force1  L*  a*  Drip Loss  1                Cook Loss  0.313**  1              Wooden Breast  0.231*  0.355**  1            pH (t = 6 h)  0.209*  0.048  0.236*  1          pH (t = 24 h)  0.050  0.176*  0.195*  0.210*  1        Shear force1  -0.202*  0.070  0.144  -0.162*  -0.078  1      L*  0.302**  0.495**  0.341**  0.094  0.010  0.054  1    a*  0.144  0.124  0.156*  0.008  0.039  -0.057  -0.068  1  b*  0.151  0.132  0.238*  0.093  -0.002  -0.087  0.423**  0.136    Drip Loss  Cook Loss  Wooden Breast  pH (t = 6 h)  pH (t = 24 h)  Shear force1  L*  a*  Drip Loss  1                Cook Loss  0.313**  1              Wooden Breast  0.231*  0.355**  1            pH (t = 6 h)  0.209*  0.048  0.236*  1          pH (t = 24 h)  0.050  0.176*  0.195*  0.210*  1        Shear force1  -0.202*  0.070  0.144  -0.162*  -0.078  1      L*  0.302**  0.495**  0.341**  0.094  0.010  0.054  1    a*  0.144  0.124  0.156*  0.008  0.039  -0.057  -0.068  1  b*  0.151  0.132  0.238*  0.093  -0.002  -0.087  0.423**  0.136  **P < 0.001. *P < 0.05. 1 Warner-Bratzler; Color: L* = lightness, a* = redness, b* = yellowness View Large Pectoral Myopathies The average score of each myopathy is presented in Table 7, and the distribution of the probability for each WB score for both processing days are shown in Figures 1 and 2. No effects (P > 0.05) of grain type or GAA supplementation were detected on spaghetti muscle and WS for both slaughter ages. However, dietary supplementation of GAA decreased (P < 0.01) the severity of WB at 51 d of age, but not at 55 d. At this age (55 d), broilers fed sorghum based diets had lower (P < 0.01) WB average score severity compared to chickens fed corn-based diets, which may be related to a higher BW gain in broilers fed corn-based diets. Results of the probability distribution for each WB score at 51 d showed an interaction effect on WB score 2 (Figure 1). Dietary supplementation with GAA in corn-based diets, increased (P < 0.05) the probability of having breast meat samples with low severity of WB (score 2), mainly due to the reduction of probability for scores 3 and 4, whereas in sorghum diets the addition of the feed additive decreased the WB score 2 principally due to an increment of the probability for having breast meat with no WB myopathy (score 1). At 55 d, broilers fed sorghum had fewer (P < 0.05) breast meat samples with score 3 (medium severity) for WB myopathy compared to broilers fed corn-based diets (Figure 2). The differences in responses to GAA on myopathies between the two processing times could be due to a higher breast meat yield driven by GAA at 55d only in chickens fed corn-based diets (Table 5) that may promote the occurrence of myopathies compared to broilers non-supplemented with GAA that had even lower breast meat yield at 55 d compared to 51 d (38.19 vs. 38.63%) leading to a similar average score (2.58 vs. 2.59) of myopathies (Table 7). Figure 1. View largeDownload slide Interaction effect of grain source and GAA supplementation on probability distribution (0.00–1.00) for each wooden breast severity score in Ross-708 male broilers at 51 d of age. Means not sharing a common superscript (a-b) are significantly different (P < 0.05) by Tukey's test. Each value represents the probability (0 -1) of developing each severity score according to main factors or factorial arrangement of treatments, n = 40 broilers within 10 pens per treatment. Scores are based on a 4-point scale (4 = severe, 3 = medium, 2 = low, 1 = normal). Figure 1. View largeDownload slide Interaction effect of grain source and GAA supplementation on probability distribution (0.00–1.00) for each wooden breast severity score in Ross-708 male broilers at 51 d of age. Means not sharing a common superscript (a-b) are significantly different (P < 0.05) by Tukey's test. Each value represents the probability (0 -1) of developing each severity score according to main factors or factorial arrangement of treatments, n = 40 broilers within 10 pens per treatment. Scores are based on a 4-point scale (4 = severe, 3 = medium, 2 = low, 1 = normal). Figure 2. View largeDownload slide Effect of grain source on probability distribution (0.00–1.00) for each wooden breast severity score in Ross-708 male broilers at 55 d of age. Means not sharing a common superscript (a-b) are significantly different (P < 0.05) by t-student's test. Each value represents the probability (0–1) of developing each severity score according to main factors or factorial arrangement of treatments, n = 40 within 10 pens per treatment. Scores are based on a 4-point scale (4 = severe, 3 = medium, 2 = low, 1 = normal). Figure 2. View largeDownload slide Effect of grain source on probability distribution (0.00–1.00) for each wooden breast severity score in Ross-708 male broilers at 55 d of age. Means not sharing a common superscript (a-b) are significantly different (P < 0.05) by t-student's test. Each value represents the probability (0–1) of developing each severity score according to main factors or factorial arrangement of treatments, n = 40 within 10 pens per treatment. Scores are based on a 4-point scale (4 = severe, 3 = medium, 2 = low, 1 = normal). A previous trial (Mudalal et al., 2015; Mutryn et al., 2015) suggested that these abnormalities might be related to a reduced level of glycogen in the muscle. Additionally, Zotte et al. (2017) reported higher (P < 0.01) ultimate pH values of breast meat affected by WB than breast meat samples from non-affected broilers (6.30 vs. 5.92). Soglia et al. (2016) observed that ultimate pH of breast meat affected by WB was higher (P < 0.01) than fillets samples considered normal (pH: 5.87 vs. 5.82). Considering the results of the present study at slaughter age 51 d, dietary GAA supplementation reduced (P < 0.05) the ultimate pH and doubled the probability of having breast meat considered as normal or with no signs of WB (score 1). Evidently, dietary GAA supplementation helped to prevent myopathies in broilers fed vegetable-based diets or ameliorates the severity of WB. Apparently, the improvement on concentration of metabolites involved in muscle energy metabolism (creatine, phosphocreatine, and phosphocreatine: ATP) and the increase creatine and glycogen content by dietary GAA supplementation (Lemme et al., 2007a; Majdeddin et al., 2017; DeGroot et al., 2018) in muscle, may have a supportive effect on muscle energy metabolism (Balsom et al., 1994; Kolling et al., 2013; Nabuurs et al., 2013) as observed in previous trials conducted in rats with muscle dystrophies (Pearlman and Fielding, 2006; Chung et al., 2007; Tarnopolsky, 2007). Kolling et al. (2013) explained the effect of creatine and associated it with homocysteine-altered glucose oxidation that protects muscle from energy imbalances in rats. An impaired energy metabolism may trigger proapoptotic signaling (programmed cell death), oxidative damage to lipids, protein and DNA, and impair mitochondrial DNA repair. It has been demonstrated that alterations in energy metabolism seem to be implicated in the pathogenesis of several muscle and neurological complications, metabolic disorders, aging and neuromuscular diseases. Nabuurs et al. (2013) also observed similar effect reversing muscular dystrophy effects of creatine deficiency by providing creatine in diets to rats. Therefore, we could speculate that dietary supplementation with GAA as precursor of creatine may prevent or reduce the occurrence of WB myopathy by modulating intermediate metabolites related with muscle and energy metabolism. In addition, we could suggest that the response observed on b* value may be related to a protective effect of GAA supplementation on heme pigments reducing the fibrotic response that has been observed in muscle myopathies (Petracci et al., 2017). In conclusion, results of the current study indicated that dietary supplementation of GAA (600 g/ton) improved BW gain and FCR of broilers fed either corn or sorghum-based diets throughout their life to market age. An improvement in breast meat yield was observed at 55d when adding GAA to corn diets, but not when added to sorghum diets. GAA supplementation reduced the severity of WB at 51 d and reduced the breast meat ultimate pH. Findings associated with b* value of color and WB suggest that GAA as precursor of creatine may have a potential benefit in lowering the severity of this myopathy. Notes Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by North Carolina State University. REFERENCES Abasht B., Mutryn M. F., Michalek R. D., Lee W. R.. 2016. Oxidative stress and metabolic perturbations in wooden breast disorder in chickens. PLoS One  11: e0153750. Google Scholar CrossRef Search ADS PubMed  AminoDat 5.0. 2015. Evonik Industries , Evonik Degussa GmbH, Hanau-Wolfgang, Germany. PubMed PubMed  AgriStats. 2016. AgriStats Monthly Live Production, April . AgriStats, Inc. Fort Wayne, Indiana. Baldi G., Soglia F., Mazzoni M., Sirri F., Canonico L., Babini E., Laghi L., Cavani C., Petracci M.. 2018. Implications of white striping and spaghetti meat abnormalities on meat quality and histological features in broilers. Animal . 12: 164– 173. Google Scholar CrossRef Search ADS PubMed  Balsom P. D., Soderlund K., Ekblom B.. 1994. Creatine in humans with special reference to creatine supplementation. Sports Medicine . 18: 268– 280. Google Scholar CrossRef Search ADS PubMed  Beal F. M. 2011. Neuroprotective effects of creatine. Amino Acids . 40: 1305– 1313. Google Scholar CrossRef Search ADS PubMed  Bender A., Koch W., Elstner M.. 2006. Creatine supplementation in Parkinson disease: a placebo-controlled randomized pilot trial. Neurology . 67: 1262– 1264. Google Scholar CrossRef Search ADS PubMed  Bozutti S. R. A. 2009. Avaliacao de ingredients alternativos na alimentacao de frangos de corte com a adicao de enzimas . MSci. Diss. Faculdade de Zootecnia e Engenharia de Alimentos/Universidade de Sao Paulo, Pirassununga, Sao Paulo, Brazil. Brenes A., Viveros A., Goñi I., Centeno C., Sayago-Ayerdy S. G., Arija I., Saura-Calixto F.. 2008. Effect of grape pomace concentrate and vitamin E on digestibility of polyphenols and antioxidant activity in chickens. Poult. Sci.  87: 307– 316. Google Scholar CrossRef Search ADS PubMed  Bryden W. L., Li X.. 2010. Amino acid digestibility and poultry feed formulation: expression, limitations and application. R. Bras. Zootec.  39: 279– 287. Google Scholar CrossRef Search ADS   Campos D. M. B. 2006. Efeito do sorgo sobre o desempenho zootecnico, caracteristicas da caracca e o desenvolvimiento da mucosa intestinal de frangos . MSci Diss. Faculdade de Ciencias Agrarias e Veterinarias/Universidade Estadual Paulista, Jaboticabal, Sao Paulo, Brazil. Chung Y. L., Alexanderson H., Pipitone N.. 2007. Creatine supplements in patients with idiopathic inflammatory myopathies who are clinically weak after conventional pharmacologic treatment: Six-month, double-blind, randomized, placebo-controlled trial. Arthritis Rheum.  57: 694– 702. Google Scholar CrossRef Search ADS PubMed  Community Reference Laboratory Feed Additives (CRL Feed Additives). 2007. CRL Evaluation Report on Guanidinoacetic acid (CreAmino™ ). FAD-2007–0003. European Food Safety Authority (EFSA). The European Commission's science an knowledge service, EU SCIENCE HUB. EFSA-Q-2007-050. Corzo A., Schilling M. W., Loar R. E. II, Jackson V., Kin S., Radhakrishnan V.. 2009. The effects of feeding distillers dried grains with solubles on broiler meat quality. Poult. Sci.  88: 432– 439. Google Scholar CrossRef Search ADS PubMed  DeGroot A. A. 2014. Efficacy of dietary guanidinoacetic acid in broilers chicks . Master Diss. Univ. of Illinois at Urbana-Champaign, Illinois. DeGroot A. A., Braun U., Dilger R. N.. 2018. Efficacy of guanidinoacetic acid on growth and muscle energy metabolism in broiler chicks receiving arginine-deficient diets. Poult. Sci.  0: 1– 11. Del Puerto M., Terevinto A., Saadoun A., Olivero R., Cabrera M. C.. 2016. Effect of different sources of dietary starch on meat quality, oxidative status and glycogen and lactate kinetic in chicken Pectoralis muscle. J. Food Nutr. Res.  4: 185– 194. Dilger R. N., Bryant-Angeoni K., Payne R. L., Lemme A., Parsons C. M.. 2013. Dietary guanidino acetic acid is an efficacious replacement for arginine for young chicks. Poult. Sci.  92: 171– 177. Google Scholar CrossRef Search ADS PubMed  Douglas J. H., Sullivan T. W., Bond P. L., Struwe F. J.. 1990. Nutrient composition and metabolizable energy values of selected grain sorghum varieties and yellow corn. Poult. Sci.  69: 1147– 1155. Google Scholar CrossRef Search ADS   Ebadi M. R., Pourreza J., Jamalian J., Edriss M. A., Samie A. H., Mirhadi S. A.. 2005. Amino acid content and availability in low, medium and high tannin sorghum grain for poultry. International J. Poul. Sci.  4: 27– 31. Google Scholar CrossRef Search ADS   Esser A. F. G., Goncalves D. R. M., Rorig A., Cristo A. B., Perini R., Fernandes J. I. M.. 2017. Effects of guanidionoacetic acid and arginine supplementation to vegetable diets fed to broiler chickens subjected to heat stress before slaughter. Braz. J. Poult. Sc.  19: 429– 436. Estevez M. 2011. Protein carbonyls in meat systems: a review. Meat Sci.  89: 259– 279. Google Scholar CrossRef Search ADS PubMed  Etuk E. B., Ifeduba A. V., Okata U. E., Chiaka I., Ifeanyi C. O., Okeudo N. J., Esonu B. O., Udedibie A. B. I., Moreki J. C.. 2012. Nutrient composition and feeding value of sorghum for livestock and poultry: a review. J. Anim. Sci. Adv.  2: 510– 524. Fletcher D. L. 2002. Poultry meat quality. Worlds Poult. Sci. J.  58: 131– 145. Google Scholar CrossRef Search ADS   Fletcher D. L., Giao M., Smith D. P.. 2000. The relationship of raw broiler breast meat color and pH to cooked meat color and pH. Poult. Sci.  79: 784– 788. Google Scholar CrossRef Search ADS PubMed  Gabor E., Gaspar O., Vamos E.. 1984. Quantitative determination of muscle protein in meat products by measuring creatine content. Acta alimentaria.  13: 13– 22. Garcia R. G., Mendes A. A., Costa C., Paz I. C. L. A., Takahashi S. E.. 2005. Desempenho e qualidade da carne de frangos de corte alimentados com diferentes níveis de sorgo em substituição ao milho. Arq. Bras. Med. Vet. Zootec.  57: 634– 643. Google Scholar CrossRef Search ADS   Garcia A. R., Batal A. B., Dale N. M.. 2007. A comparison of methods to determine amino acid digestibility of feed ingredients for chickens. Poult. Sci.  86: 94– 101. Google Scholar CrossRef Search ADS PubMed  Garcia R., Mendes A., Almeida P., Komiyama C., Caldara F., Naas I., Mariano W.. 2013. Implications of the use of sorghum in broiler production. Braz. J. Poult. Sci.  15: 169– 286. Harder M. N. C., Spada F. P., Savino V. J. M., Coelho A. A. D., Correr E., Martins E.. 2010. Coloração de cortes cozidos de frangos alimentados com urucum. Ciênc. Tecnol. Aliment.  30: 507– 509. Google Scholar CrossRef Search ADS   Haussinger D. 1996. The role of cellular hydration in the regulation of cell function. Biochem. J.  313: 697– 710. Google Scholar CrossRef Search ADS PubMed  Heger J., Zelenka J., Machander V., de la Cruz C., Lestak M., Hample D.. 2014. Effects of guanidinoacetic acid supplementation to broiler diets with varying energy content. Acta Univ. Agric. Silvic. Mendelianae Brun.  62: 477– 485. Google Scholar CrossRef Search ADS   Huang K. H., Li X., Ravindran V., Bryden W. L.. 2006. Comparison of apparent ileal amino acid digestibility of feed ingredients measured with broilers, layers, and roosters. Poult. Sci.  85: 625– 634. Google Scholar CrossRef Search ADS PubMed  Hultman E., Soderlund K., Timmons J. A., Cederblad G., Greenhaff P. L.. 1996. Muscle creatine loading in men. J. Appl. Physiol.  81: 232– 237. Google Scholar CrossRef Search ADS PubMed  Khan A. W., Cowen D. C.. 1977. Rapid estimation of muscle proteins in beef-vegetable protein mixtures. J. Agric. Food Chem.  25: 236– 238. Google Scholar CrossRef Search ADS PubMed  Kolling J., Wyse A. T. S.. 2010. Creatine prevents the inhibition of energy metabolism and lipid peroxidation in rats subjected to GAA administration. Metab. Brain Dis.  25: 331– 338. Google Scholar CrossRef Search ADS PubMed  Kolling J., Scherer E. B. S., Siebert C., Hansen F., Torres F. V., Scaini G., Ferreira G., De Andrade R. B., Goncalves C. A. S., Streck E. L., Wannmacher C. M. D., Wyse A. T. S.. 2013. Homocysteine induces energy imbalance in rat skeletal muscle: is creatine a protector?. Cell Biochem. Funct.  31: 575– 584. Google Scholar PubMed  Kumar V., Elangovan A. V., Mandal A. B.. 2005. Utilization of reconstituted high-tannin sorghum in the diets of broiler chickens. Asian-Australas. J. Anim. Sci.  18: 538– 544. Google Scholar CrossRef Search ADS   Kuttappan V. A., Hargis B. M., Owens C. M.. 2016. White striping and woody breast myopathies in the modern poultry industry: a review. Poult. Sci.  95: 2724– 2733. Google Scholar CrossRef Search ADS PubMed  Kwari I. D., Diarra S. S., Igwebuike J. U., Nkama I., Issa S., Hamaker B. R., Hancock J. D., Jauro M., Seriki O. A., Murphy I.. 2012. Replacement value of low tannin sorghum (Sorghum bicolor) for maize in broiler chickens' diets in the semi-arid zone of nigeria. International J. Poult. Sci.  11: 333– 337. Google Scholar CrossRef Search ADS   Lemme A., Ringel J., Sterk A., Young J.. 2007a. Supplemental guanidino acetic acid affects energy metabolism of broilers. Proc. 16th Eur. Symp. Poult. Nut., Strasbourg, France . World's Poult. Sci. Assoc., Beekbergen, the Netherlands. Lemme A., Ringel J., Rostagno H. S., Redshaw M. S.. 2007b. Supplemental guanidine acetic acid improved feed conversion, weight gain, and breast meat yield in male and female broilers. Proc. 16th Eur. Symp. Poult. Nut., Strasbourg, France . World's Poult. Sci. Assoc., Beekbergen, the Netherlands. Li X., Rezaeri R., Li P., Wu G.. 2011. Composition of amino acids in feed ingredients for animal diets. Amino Acids . 40: 1159– 1168. Google Scholar CrossRef Search ADS PubMed  Majdeddin M., Braun U., Lemme A., Golian A., Kermanshahi H., De Smet S., Michielis J.. 2017. Guanidinoacetic acid supplementation improves feed conversion in broilers subjected to chronic cyclic heat stress in the finishing phase associated with improved energy and arginine metabolism. Proc. 21st Eur. Symp. Poult. Nut., Salout/Vila-seca, Spain . World's Poult. Sci. Assoc. Wageningen Academic Publishers, Wageningen, the Netherlands. Makkar H. P., Becker K.. 1993. Vanillin-HCl method for condensed tannins: Effect of organic solvents used for extraction of tannins. J. Chem. Ecol.  19: 613– 621. Google Scholar CrossRef Search ADS PubMed  Michiels J., Maertens L., Buyse J., Lemme A., Rademacher M., Dierick N., De Smet S.. 2012. Supplementation of guanidinoacetic acid to broiler diets: Effects on performance, carcass characteristics, meat quality, and energy metabolism. Poult. Sci.  91: 402– 412. Google Scholar CrossRef Search ADS PubMed  Mohamed A., Urge M., Gebeyew K.. 2015. Effects of replacing maize with sorghum on growth and feed efficiency of commercial broiler chicken. J. Vet. Sci. Technol.  6: 224. Moughan P. J., Ravindran V., Sorbara J. O. B.. 2014. Dietary protein and amino acids—Consideration of the undigestible fraction. Poult. Sci.  93: 2400– 2410. Google Scholar CrossRef Search ADS PubMed  Mousavi S., Afsar A., Lotfollahian H.. 2013. Effects of guanidinoacetic acid supplementation to broiler diets with varying energy contents. J. Appl. Poul. Res.  22: 47– 54. Google Scholar CrossRef Search ADS   Mudalal S., Lorenzi M., Soglia F., Cavani C., Petracci M.. 2015. Implications of white striping and wooden breast abnormalities on quality traits of raw and marinated chicken meat. Animal . 9: 728– 734. Google Scholar CrossRef Search ADS PubMed  Mutryn M. F., Brannick E. M., Fu W., Lee W. L., Abasht B.. 2015. Characterization of a novel chiken muscle disorder through differential gene expression and pathway analysis using RNA-sequencing. Genomics . 16: 399. Google Scholar PubMed  Nabuurs C. I., Choe C. U., Veltien A., Kan H. E., VanLoon L. J. C., Rodenburg R. J. T., Matschke J., Wieringa B., Kemp G. J., Isbrandt D., Heerschap A.. 2013. Disturbed energy metabolism and muscular dystrophy caused by pure creatine deficiency are reversible by creatine intake. J. Physiol.  591: 571– 592. Google Scholar CrossRef Search ADS PubMed  Nasr J., Kheiri F.. 2012. Effects of lysine levels of diets formulated based on total or digestible amino acids on broiler carcass composition. Braz. J. Poult. Sci.  14: 233– 304. Owens C. M., Hirschler E. M., McKee S. R., Martinez-Dawson R., Sams A. R.. 2000. The characterization and incidence of pale, soft, exudative turkey meat in a commercial plant. Poult. Sci.  79: 553– 558. Google Scholar CrossRef Search ADS PubMed  Parsons C. M. 1985. Influence of caecectomy on digestibility of amino acids by roosters fed distillers' dried grains with solubles. J. Agric. Sci.  104: 469– 472. Google Scholar CrossRef Search ADS   Pearlman J. P., Fielding R. A.. 2006. Creatine monohydrate as a therapeutic aid in muscular dystrophy. Nutr. Rev.  64: 80– 88. Google Scholar CrossRef Search ADS PubMed  Petracci M., Soglia F., Berri C.. 2017. Muscle metabolism and meat quality abnormalities. Pages 51– 75 in Poultry Quality Evaluation, quality attributes and consumer values , Petracci M., Berri C., ed. Woodhead Publishing Series in Food Science, Technology and Nutrition. Woodhead Publishing Limited, Cambridge, UK. Google Scholar CrossRef Search ADS   Poole G. H., Lyon C. E., Buhr R. J., Young L. L.. 1999. Evaluation of age, gender, strain, and diet on the cooked yield and shear values of broiler breast fillets. J. Appl. Poult. Res.  8: 170– 176. Google Scholar CrossRef Search ADS   Pour-Reza J., Edriss M. A.. 1997. Effects of dietary sorghum of different tannin concentrations and tallow supplementation on the performance of broiler chicks. Br. Poult. Sci.  38: 512– 517. Google Scholar CrossRef Search ADS PubMed  Rodrigues H. D., Perez-Maldonado R. A., Trappett P., Barram K. M., Kemsley M.. 2007. Broiler performance in Australian sorghum-based starter and finisher diets (2005 harvest). Proc. 19th Aust. Poult. Sci. Symp., Sidney, Australia . World's Poult. Sci. Assoc., Australia. Ringel J., Lemme A., Knox A., Mc Nab J., Redshaw M. S.. 2007. Effects of graded levels of creatine and guanidinoacetic acid in vegetable-based diets on performance and biochemical parameters in muscle tissue. Proc. 16th Eur. Symp. Poult. Nut., Strasbourg, France . World's Poult. Sci. Assoc., Beekbergen, the Netherlands. Sante V., Fernandez X., Monin G., Renou J. P.. 2001. Nouvelles méthodes de mesure de la qualité de la viande de volaille. INRA Productions Animales  14: 247– 254. SAS Institute. 2016. A User's Guide to SAS . Sparks Press, Inc., Cary, NC. SAS Institute. 2008. SAS/STAT Users Guide . Version 9.2. SAS Inst. Inc., Cary, NC. Schilling M. W., Schilling J. K., Claus J. R., Marriott N. G., Duncan S. E., Wang H.. 2003. Instrumental texture assessment and consumer acceptability of cooked broiler breast evaluated using a geometrically uniform-shaped sample. J Muscle Foods . 14: 11– 23. Google Scholar CrossRef Search ADS   Soglia F., Mudalal S., Babini E., Di Nunzio M., Mazzoni M., Sirri F., Cavani C., Petracci M.. 2016. Histology, composition, and quality traits of chicken Pectoralis major muscle affected by wooden breast abnormality. Poult. Sci.  95: 651– 659. Google Scholar CrossRef Search ADS PubMed  Tandiang D., Diop M., Dieng A., Louis G., Cisse N., Nassim M.. 2014. Effect of corn substitution by sorghum grain with low tannin content on broiler production: animal performance, nutrient digestibility and carcass characteristics. International J. Poult. Sci.  13: 568– 574. Google Scholar CrossRef Search ADS   Tarnopolsky M. A. 2007. Clinical use of creatine in neuromuscular and neurometabolic disorders. Subcell. Biochem.  46: 183– 204. Google Scholar CrossRef Search ADS PubMed  Tasoniero G., Cullere M., Cecchinato M., Puolanne E., Dalle Zotte A.. 2016. Technological quality, mineral profile, and sensory attributes of broiler chicken breasts affected by white striping and wooden breast myopathies. Poult. Sci.  95: 2707– 2714. Google Scholar CrossRef Search ADS PubMed  Tijare V. V., Yang F. L., Kuttappan V. A., Alvarado C. Z., Coon C. N., Owens C. M.. 2016. Meat quality of broiler breast fillets with white striping and woody breast muscle myopathies. Poult. Sci.  95: 2167– 2173. Google Scholar CrossRef Search ADS PubMed  Torres K., Pizauro J., Soares C., Silva T., Nogueira W., Campos D., Furlan R., Macari M.. 2013. Effects of corn replacement by sorghum in broiler diets on performance and intestinal mucosa integrity. Poult. Sci.  92: 1564– 1571. Google Scholar CrossRef Search ADS PubMed  Totosaus A., Perez-Chabela M. L., Guerrero I., 2007. Color of fresh and frozen poultry. Pages 455– 466 in Handbook of Meat, Poultry and Seafood Quality , Nollet L. M. L. ed. Blackwell Publishing Ltd, Ames, IA. Google Scholar CrossRef Search ADS   Vieira S. L., Lima I. L.. 2005. Live performance, water intake and excreta characteristics of broilers fed all vegetable diets based on corn and soybean meal. International J. Poult. Sci.  4: 365– 368. Google Scholar CrossRef Search ADS   Wold J. P., Veiseth-Kent E., Host V., Lovland A.. 2017. Rapid on-line detection and grading of wooden breast myopathy in chicken fillets by near-infrared spectroscopy. PLoS One . 12: 1– 16. Google Scholar CrossRef Search ADS   Young J. F., Bertram H. C., Theil P. K., Petersen A. G. D., Poulsen K. A., Rasmussen M., Malmendal A., Nielsen N. C., Vestergaard M., Oksbjerg N.. 2007. In vitro and in vivo studies of creatine monohydrate supplementation to Duroc and Landrace pigs. Meat Sci.  76: 342– 351. Google Scholar CrossRef Search ADS PubMed  Wyss M., Kaddurah-Daouk R.. 2000. Creatine and creatinine metabolism. Physiol. Rev.  80: 1107– 1213. Google Scholar CrossRef Search ADS PubMed  Xiao S., Zhang W. G., Lee E. J., Ma C. W., Ahn D. U.. 2011. Effects of diet, packaging, and irradiation on protein oxidation, lipid oxidation, and color of raw broiler thigh meat during refrigerated storage. Poult. Sci.  90: 1348– 1357. Google Scholar CrossRef Search ADS PubMed  Zhang W., Xiao S., Lee E. J., Ahn D. U.. 2011. Consumption of oxidized oil increases oxidative stress in broilers and affects the quality of breast meat. J. Agric. Food Chem.  59: 969– 974. Google Scholar CrossRef Search ADS PubMed  Zotte A. D., Tasoniero G., Poulanne E., Remignon H., Cecchinato M., Catelli E., Cullere M.. 2017. Effect of Wooden Breast appearance on poultry meat quality, histological traits, and lesions characterization. Czech J. Anim. Sci.  62: 51– 57. Google Scholar CrossRef Search ADS   © 2018 Poultry Science Association Inc.

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Poultry ScienceOxford University Press

Published: Apr 13, 2018

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