Effect of Pelletized Diets and the Proportion of Fines on Performance of Broilers Raised in High-Density Conditions

Effect of Pelletized Diets and the Proportion of Fines on Performance of Broilers Raised in... SUMMARY The objective of the study was to evaluate some important parameters regarding production and welfare, as well as performance, uniformity, carcass yield and foot-pad lesions of broilers fed mash or pelleted diets with different concentrations and raised in different density conditions. The experimental design consisted of a 3 × 2 factorial scheme (3 diets: mash feed, pelleted feed with 50% of fines, and pelleted feed with 30% of fines vs. 2 stocking densities: 13 and 15 birds/m2) with six replications, totaling 1,746 male Cobb chicks. Besides the weight of the birds and feed intake for each replicate assessed weekly to evaluate performance, at 7 and 42 d of age all birds were individually weighed to assess uniformity within each replicate. Moreover, 12 birds/treatment were slaughtered to assess the yield for carcass and commercial cuts. To assess the incidence of food-pad dermatitis (FPD), all birds were evaluated for lesion score at 21 and 42 d of age. The intake of pelleted diets resulted in greater body weight gain and better feed conversion ratio in the first week. The reduction of stocking density resulted in greater weights of carcasses, legs, and wings as well as wing yield at the 46th day but did not alter FPD incidence. The performance during the grower/finisher phase and during all production phases was not affected by diet and stocking density, despite the greater performance that was observed for chicks supplemented with pelleted and ground diets in the starter phase. DESCRIPTON OF PROBLEM Physical treatments such as pelleting are used during feed processing to enhance feed efficiency. The process of starch gelatinization that may occur during the pelleting process (in the presence of heat and humidity) results in greater energy digestibility due to alterations on the physical characteristics of the diet [1, 2]. These benefits are in addition to greater microbiological quality, which is an important issue nowadays considering Salmonella infections, as well as decreased segregation of ingredients, and a reduction in time and energy spent during intake, therefore increasing growth efficiency [1, 3–6]. The low-quality pellets might disintegrate during processing, transportation, or conveying to the feeder, thus producing a mass known as “fines.” According to Mina-Boac et al., [7], these fine particles cause a nutrient imbalance in the feed composition, which can negatively affect animal performance. Due to the increase in intake of pelleted diets [8–10, 6], there is also an increase in the available energy production depending on environmental conditions, which can lead towards higher feed conversion ratios and greater fat deposition in the carcass. Brazilian poultry agribusiness has increased the stocking density while aiming to maximize production and decrease costs of broiler production. The increase in nutrient availability requires a greater oxygen demand for the physiological and metabolic processes associated with higher growth rates [11] and the high stocking rates can aggravate the situation because of low air and litter quality. Foot-pad dermatitis (FPD), characterized as an ulcerative lesion on the foot-pad, is a concern in poultry production that jeopardizes both animal welfare and company's profitability. Litter moisture, which is affected by stocking density, has been shown as a primary causal factor in high incidence rates of foot-pad lesions [12]. The aim of this study was to evaluate the animal performance, its uniformity within each experimental unit, carcass yield and incidence of FPD of broilers fed mash or pelleted diets with different fine concentrations and were raised in different stocking densities. MATERIALS AND METHODS Animal Care All procedures described below involving the animals used in this study were approved by the Ethics Committee in Animal Experimentation (Approval protocol of Ethics Committee: 01/2014), which are in accordance with the recommendations of Conselho Nacional de Controle de Experimentação Animal (CONCEA) [13]. The animals procedures used also met the guidelines approved by the institutional Animal Care and Use Committee. Experimental Design A total of 1,746 male Cobb broilers were randomly assigned (completely randomized design) using a 3 × 2 factorial scheme (3 diets: mash feed, pelleted feed with 50% fines, and pelleted feed with 30% fines vs. 2 stocking densities: 13 and 15 birds/m2) to total six treatments and six replications [14]. However, due to the need to grind the pelleted feed to supply the phase from 1 to 21 d, the factorial design that was considered for the statistical analysis of data obtained during this period was 2 × 2 (diets: mash and pelleted feed vs. stocking density: 13 and 15 birds/m2). The mash diet that was used throughout the experimental period was not submitted to any thermal processing. Corn/soybean meal-based diets were formulated considering the chemical composition of ingredients and the nutrient requirements for different bird phases, adopted by poultry integrators in the region (Table 1). The feeding program was composed of 4 phases: pre-starter (1 to 7 d), starter (8 to 21 d), grower (22 to 37 d), and finisher (38 to 46 d). Table 1. Composition and Calculated Nutritional Levels of the Experimental Diets. Pre-starter Starter Grower Finisher Ingredients, % 1–7 d 8–21 d 22–37 d 38–46 d Corn 54.05 56.30 56.66 57.78 Soybean meal 38.02 29.92 19.85 12.80 Integral soybean 2.00 8.00 18.00 25.04 Soybean oil 1.68 2.04 1.92 1.14 Dicalcium phosphate 1.27 1.20 1.17 1.02 Limestone 1.05 0.86 0.82 0.75 Salt 0.37 0.32 0.32 0.32 Vit/Min premix1 0.30 0.30 0.30 0.30 Sodium bicarbonate 0.20 0.10 0.04 – Choline chloride 0.08 0.07 0.05 0.03 Threonine (L-98%) 0.10 0.08 0.08 0.08 Valine (L-96.5%) 0.04 0.04 0.04 0.04 Methionine (DL-98%) 0.41 0.36 0.35 0.35 Lysine (L-50%) 0.38 0.36 0.35 0.35 Anticoccidial 0.05 0.05 0.05 – Calculated levels ME (Kcal/Kg) 2,980 3,099 3,235 3,280 CP (%) 23.90 22.30 21.00 20.16 Calcium (%) 1.000 0.890 0.870 0.810 Available P (%) 0.480 0.450 0.450 0.420 Dig. Lysine (%) 1.360 1.250 1.159 1.099 Dig. Met+Cys (%) 1.047 0.960 0.916 0.879 Pre-starter Starter Grower Finisher Ingredients, % 1–7 d 8–21 d 22–37 d 38–46 d Corn 54.05 56.30 56.66 57.78 Soybean meal 38.02 29.92 19.85 12.80 Integral soybean 2.00 8.00 18.00 25.04 Soybean oil 1.68 2.04 1.92 1.14 Dicalcium phosphate 1.27 1.20 1.17 1.02 Limestone 1.05 0.86 0.82 0.75 Salt 0.37 0.32 0.32 0.32 Vit/Min premix1 0.30 0.30 0.30 0.30 Sodium bicarbonate 0.20 0.10 0.04 – Choline chloride 0.08 0.07 0.05 0.03 Threonine (L-98%) 0.10 0.08 0.08 0.08 Valine (L-96.5%) 0.04 0.04 0.04 0.04 Methionine (DL-98%) 0.41 0.36 0.35 0.35 Lysine (L-50%) 0.38 0.36 0.35 0.35 Anticoccidial 0.05 0.05 0.05 – Calculated levels ME (Kcal/Kg) 2,980 3,099 3,235 3,280 CP (%) 23.90 22.30 21.00 20.16 Calcium (%) 1.000 0.890 0.870 0.810 Available P (%) 0.480 0.450 0.450 0.420 Dig. Lysine (%) 1.360 1.250 1.159 1.099 Dig. Met+Cys (%) 1.047 0.960 0.916 0.879 1Vitamin A (min) 9.000.000 UI/kg; vitamin D3 (min) 4.000.000 UI/kg; vitamin E (min) 30.000 UI/kg; vitamin K3 (min) 3.000 mg/kg; vitamin B1 (min) 2.000 mg/kg; vitamin B2 (min) 7.000 mg/kg; vitamin B6 (min) 4.000 mg/kg; vitamin B12 (min) 15.000 mcg/kg; niacin (min) 50 g/kg; pantothenic acid (min) 12 g/kg. folic acid (min) 3.000 mg/kg; biotin (min) 200 mg/kg. BHT 100 mg/kg. Manganese 90.00 ppm; zinc 80.5 ppm; iron 39.90 ppm; copper 10 ppm; iodine 0.71 ppm; selenium 0.30 ppm. View Large Table 1. Composition and Calculated Nutritional Levels of the Experimental Diets. Pre-starter Starter Grower Finisher Ingredients, % 1–7 d 8–21 d 22–37 d 38–46 d Corn 54.05 56.30 56.66 57.78 Soybean meal 38.02 29.92 19.85 12.80 Integral soybean 2.00 8.00 18.00 25.04 Soybean oil 1.68 2.04 1.92 1.14 Dicalcium phosphate 1.27 1.20 1.17 1.02 Limestone 1.05 0.86 0.82 0.75 Salt 0.37 0.32 0.32 0.32 Vit/Min premix1 0.30 0.30 0.30 0.30 Sodium bicarbonate 0.20 0.10 0.04 – Choline chloride 0.08 0.07 0.05 0.03 Threonine (L-98%) 0.10 0.08 0.08 0.08 Valine (L-96.5%) 0.04 0.04 0.04 0.04 Methionine (DL-98%) 0.41 0.36 0.35 0.35 Lysine (L-50%) 0.38 0.36 0.35 0.35 Anticoccidial 0.05 0.05 0.05 – Calculated levels ME (Kcal/Kg) 2,980 3,099 3,235 3,280 CP (%) 23.90 22.30 21.00 20.16 Calcium (%) 1.000 0.890 0.870 0.810 Available P (%) 0.480 0.450 0.450 0.420 Dig. Lysine (%) 1.360 1.250 1.159 1.099 Dig. Met+Cys (%) 1.047 0.960 0.916 0.879 Pre-starter Starter Grower Finisher Ingredients, % 1–7 d 8–21 d 22–37 d 38–46 d Corn 54.05 56.30 56.66 57.78 Soybean meal 38.02 29.92 19.85 12.80 Integral soybean 2.00 8.00 18.00 25.04 Soybean oil 1.68 2.04 1.92 1.14 Dicalcium phosphate 1.27 1.20 1.17 1.02 Limestone 1.05 0.86 0.82 0.75 Salt 0.37 0.32 0.32 0.32 Vit/Min premix1 0.30 0.30 0.30 0.30 Sodium bicarbonate 0.20 0.10 0.04 – Choline chloride 0.08 0.07 0.05 0.03 Threonine (L-98%) 0.10 0.08 0.08 0.08 Valine (L-96.5%) 0.04 0.04 0.04 0.04 Methionine (DL-98%) 0.41 0.36 0.35 0.35 Lysine (L-50%) 0.38 0.36 0.35 0.35 Anticoccidial 0.05 0.05 0.05 – Calculated levels ME (Kcal/Kg) 2,980 3,099 3,235 3,280 CP (%) 23.90 22.30 21.00 20.16 Calcium (%) 1.000 0.890 0.870 0.810 Available P (%) 0.480 0.450 0.450 0.420 Dig. Lysine (%) 1.360 1.250 1.159 1.099 Dig. Met+Cys (%) 1.047 0.960 0.916 0.879 1Vitamin A (min) 9.000.000 UI/kg; vitamin D3 (min) 4.000.000 UI/kg; vitamin E (min) 30.000 UI/kg; vitamin K3 (min) 3.000 mg/kg; vitamin B1 (min) 2.000 mg/kg; vitamin B2 (min) 7.000 mg/kg; vitamin B6 (min) 4.000 mg/kg; vitamin B12 (min) 15.000 mcg/kg; niacin (min) 50 g/kg; pantothenic acid (min) 12 g/kg. folic acid (min) 3.000 mg/kg; biotin (min) 200 mg/kg. BHT 100 mg/kg. Manganese 90.00 ppm; zinc 80.5 ppm; iron 39.90 ppm; copper 10 ppm; iodine 0.71 ppm; selenium 0.30 ppm. View Large Response Parameters For the evaluation of animal performance, the birds and feed orts from each experimental unit were assessed weekly. The feed conversion ratio was corrected by the mortality of birds according to the methodology described by Sakomura and Rostagno [15]. The record of daily mortality was also used for the calculation of feasibility. All chickens at 7 and 46 d of age were individually weighed to evaluate the effect of diets and stocking density on uniformity of the birds within the experimental unit, expressed by the coefficient of variation (%). At 46 d of age, the macroscopy scores of foot-pads from all chickens were evaluated, characterizing them as follows: Absence of lesions (A score), light lesion only in the center of foot-pad (B score), or serious and multiple lesions (C score). The carcass and commercial cuts yields were determined at 46 d of age when two chickens per experimental unit (12 birds/treatment) with body weights ± 2% of the average body weight of the pen were slaughtered. The chickens were identified, submitted to a fasting period of 6 h, and then slaughtered by electrical stunning and further bleeding. For the calculation of carcass yield, the hot eviscerated carcass weight (no feet, no head, and no abdominal fat) was considered in relation to the individual body weight that was obtained before slaughter. For the yield of prime cuts, the following cuts were calculated in relation to the eviscerated carcass weight: entire breast without skin and bones, legs (thigh and drumstick without skin and bones), back, and wings without skin. The abdominal fat around the cloaca, cloacal bursa, gizzard, proventriculus, and adjacent abdominal muscles was removed following methodology described by Smith [16]. Furthermore, it was weighed and calculated in relation to the eviscerated carcass weight. Statistical Procedures The data were submitted to analyses of variance using the general linear model procedure of SAS, as a 3 × 2 factorial arrangement of treatments that included feed form and stocking density as the fixed main effects and their respective interactions [17]. The treatment means were separated by the Tukey test at P < 0.05 statistical level. The frequency of birds within each weight category was analyzed by a nonparametric analysis. For the incidence of birds with different FPD scores, chi-square analyses were performed [17]. RESULTS AND DISCUSSION Uniformity and Performance In Figure 1, the variations in the distribution of individual body weight are characterized by five ranges during the first week of life of chickens in relation to mash or pelleted/ground diets. The treatment with mash feed resulted in a greater average percentage (21%) of very light birds (below 170 g) in relation to pelleted (5%), and there was a lower percentage of heavy chicks (above 210 g) for mash feed (9.4%) compared to pelleted (30%). Figure 1. View largeDownload slide Weight categories according to the diet at 7 d of age. Values represent the frequency (%) of birds within each weight category. Distinct letters statistically differ (P < 0.001) within each weight category. Figure 1. View largeDownload slide Weight categories according to the diet at 7 d of age. Values represent the frequency (%) of birds within each weight category. Distinct letters statistically differ (P < 0.001) within each weight category. In Table 2, values of coefficient of variation (CV) of individual body weights are shown at 7 and 46 d of age. When considering stocking density, the chicks presented with a uniform body weight (P > 0.05); however, the variation in body weight was statistically different (P < 0.05) when chicks were 7 d of age. The intake of pelleted diets resulted in lower CV (10.15%) of individual body weights of birds when compared to CV (12.99%) of chicks that were fed mash diets. Table 2. Coefficient of Variation of the Individual Body Weight at Housing, 7 And 46 d of Age of Broilers Fed Mash or Pelleted Diets, Raised in Different Stocking Densities. Coefficient of variation, %1 Diet Housing 7 d 46 d  Mash 8.55 12.99A 9.95  Pelleted 50:50 8.07 10.15B 11.84  Pelleted 70:30 10.97 Density  13 broilers/m² 8.32 11.45 11.00  15 broilers/m² 8.14 10.74 10.85 CV, % 10.55 28.93 16.69 Diet 0.321 0.025 0.070 Density 0.557 0.500 0.832 Diet × density 0.411 0.163 0.875 Coefficient of variation, %1 Diet Housing 7 d 46 d  Mash 8.55 12.99A 9.95  Pelleted 50:50 8.07 10.15B 11.84  Pelleted 70:30 10.97 Density  13 broilers/m² 8.32 11.45 11.00  15 broilers/m² 8.14 10.74 10.85 CV, % 10.55 28.93 16.69 Diet 0.321 0.025 0.070 Density 0.557 0.500 0.832 Diet × density 0.411 0.163 0.875 1Data are presented as means of the coefficient of variation (%) obtained using the individual birds’ weight at day 1, 7, and 46. CV = coefficient of variation. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). N = 6 replicates, totaling 1,746 birds. View Large Table 2. Coefficient of Variation of the Individual Body Weight at Housing, 7 And 46 d of Age of Broilers Fed Mash or Pelleted Diets, Raised in Different Stocking Densities. Coefficient of variation, %1 Diet Housing 7 d 46 d  Mash 8.55 12.99A 9.95  Pelleted 50:50 8.07 10.15B 11.84  Pelleted 70:30 10.97 Density  13 broilers/m² 8.32 11.45 11.00  15 broilers/m² 8.14 10.74 10.85 CV, % 10.55 28.93 16.69 Diet 0.321 0.025 0.070 Density 0.557 0.500 0.832 Diet × density 0.411 0.163 0.875 Coefficient of variation, %1 Diet Housing 7 d 46 d  Mash 8.55 12.99A 9.95  Pelleted 50:50 8.07 10.15B 11.84  Pelleted 70:30 10.97 Density  13 broilers/m² 8.32 11.45 11.00  15 broilers/m² 8.14 10.74 10.85 CV, % 10.55 28.93 16.69 Diet 0.321 0.025 0.070 Density 0.557 0.500 0.832 Diet × density 0.411 0.163 0.875 1Data are presented as means of the coefficient of variation (%) obtained using the individual birds’ weight at day 1, 7, and 46. CV = coefficient of variation. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). N = 6 replicates, totaling 1,746 birds. View Large These results are confirmed in the evaluation of animal performance (Table 3). There was better body weight gain and feed conversion ratio (P < 0.05) for chicks fed pelleted diets during the pre-starter phase (from 1 to 7 d). Penz [18] reported that in commercial conditions, the performance of broilers from 1 to 7 d of age that were fed pre-starter diets was better than the animals fed mash diets. Silva et al. [19] obtained greater body weight gain and better feed conversion ratio for birds fed pelleted/ground diets. Similar results were found by Jahan et al., [20] who reported that birds had greater feed intake with crumble or pellets than mash feeding. Other previous studies found similar results [21–23]. Table 3. Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Pre-Starter and Starter Phases of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 1 to 7 d 1 to 21 d Diet1 BWG FI FCR BWG FI FCR  Mash 139.19B 161.25 1.144B 831.17B 1,111.88B 1.338B  Pelleted 154.02A 163.39 1.061A 906.98A 1,179.42A 1.300A Density  13 broilers/m² 150.41 162.76 1.080 881.95 1,154.23 1.309  15 broilers/m² 148.36 162.59 1.086 881.47 1,159.58 1.316 CV, % 4.19 6.60 4.763 3.96 5.12 3.75 Diet 0.001 0.598 >0.001 0.001 0.003 0.034 Density 0.313 0.742 0.835 0.950 0.929 0.957 Diet × density 0.259 0.389 0.433 0.762 0.627 0.303 1 to 7 d 1 to 21 d Diet1 BWG FI FCR BWG FI FCR  Mash 139.19B 161.25 1.144B 831.17B 1,111.88B 1.338B  Pelleted 154.02A 163.39 1.061A 906.98A 1,179.42A 1.300A Density  13 broilers/m² 150.41 162.76 1.080 881.95 1,154.23 1.309  15 broilers/m² 148.36 162.59 1.086 881.47 1,159.58 1.316 CV, % 4.19 6.60 4.763 3.96 5.12 3.75 Diet 0.001 0.598 >0.001 0.001 0.003 0.034 Density 0.313 0.742 0.835 0.950 0.929 0.957 Diet × density 0.259 0.389 0.433 0.762 0.627 0.303 1From 1 to 21 d, pelleted diet was grounded to ensure proper feed intake. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 3. Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Pre-Starter and Starter Phases of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 1 to 7 d 1 to 21 d Diet1 BWG FI FCR BWG FI FCR  Mash 139.19B 161.25 1.144B 831.17B 1,111.88B 1.338B  Pelleted 154.02A 163.39 1.061A 906.98A 1,179.42A 1.300A Density  13 broilers/m² 150.41 162.76 1.080 881.95 1,154.23 1.309  15 broilers/m² 148.36 162.59 1.086 881.47 1,159.58 1.316 CV, % 4.19 6.60 4.763 3.96 5.12 3.75 Diet 0.001 0.598 >0.001 0.001 0.003 0.034 Density 0.313 0.742 0.835 0.950 0.929 0.957 Diet × density 0.259 0.389 0.433 0.762 0.627 0.303 1 to 7 d 1 to 21 d Diet1 BWG FI FCR BWG FI FCR  Mash 139.19B 161.25 1.144B 831.17B 1,111.88B 1.338B  Pelleted 154.02A 163.39 1.061A 906.98A 1,179.42A 1.300A Density  13 broilers/m² 150.41 162.76 1.080 881.95 1,154.23 1.309  15 broilers/m² 148.36 162.59 1.086 881.47 1,159.58 1.316 CV, % 4.19 6.60 4.763 3.96 5.12 3.75 Diet 0.001 0.598 >0.001 0.001 0.003 0.034 Density 0.313 0.742 0.835 0.950 0.929 0.957 Diet × density 0.259 0.389 0.433 0.762 0.627 0.303 1From 1 to 21 d, pelleted diet was grounded to ensure proper feed intake. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large The pelleting process alters both the consistency and conformation of the feed, which has considerable implications on the reduction of the partitioning effect; thus, the ingredients pass into the intestine under greater uniformity [24]. Moreover, in the initial growing phases, because of the incapacity of broilers to ingest whole pellets and then regulate the feed intake by energy level, a mash or crumbled diet is usually offered [25]. Gelatinizing cereal starch has generally been thought to improve enzymatic access to glucosidic linkages and consequent digestibility [3, 26], which contributes significantly to better efficiency of nutrient use in the diet, even when feed intake is similar among diets. The pelleted diet also has benefits on the intestinal mucosa of the animals. Amerah et al. [27] reported the presence of greater numbers of villi and deeper crypts in the duodenum and jejunum segments of birds fed pelleted diets, compared to those fed mash diets. This finding might be due to the combined effect of gelatinized starch and availability of nutrients other than starch. One strategy for producing high-quality pellets has been to gelatinize as much starch as possible. However, the improving pellet quality through increasing starch gelatinization may negatively affect nutrient utilization, thus antagonizing performance enhancements of pelleting. The processing conditions may generate retrograded starch, Maillard products, and loss of available amino acids or vitamins [28]. For the period from 1 to 21 d (Table 3), there was no interaction (P > 0.05) between stocking density and diets. However, we observed that feed intake was greater (P < 0.05) for chicks that were fed pelleted diets in relation to those that were fed mash feed, which resulted in greater (P < 0.05) body weight gains and better (P < 0.05) feed conversion ratio. A greater feed intake was also found by López and Baião [29] and may be attributed to a greater density of granulated diet, uniform particle size, and the obstruction of selective capture of feedstuffs [30, 31]. After 21 d of age, chickens started receiving 3 diets (mash, pelleted 50 : 50, and pelleted 70 : 30 diets). The results that were observed in the fourth week are similar to those described for the initial phase: greater feed intake and body weight gain of chickens fed pelleted diets, regardless of fine percentage. For the feed conversion ratio, a greater proportion of pellets to fines (70 : 30) resulted in a better index when compared with the use of mash feed (Table 4). Table 4. Weekly Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Grower Phase of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 22 to 28 d 29 to 35 d Diet1 BWG FI FCR BWG FI FCR  Mash 524.03B 851.28B 1.628B 666.26 1,064.26 1.605  Pelleted 50 : 50 576.32A 920.71A 1.600AB 646.06 1,084.71 1.682  Pelleted 70 : 30 597.23A 922.04A 1.546A 678.12 1,087.95 1.612 Density  13 broilers/m² 566.83 906.55 1.603 677.82 1,092.57 1.647  15 broilers/m² 564.88 889.46 1.579 649.13 1,065.38 1.619 CV, % 6.62 4.49 3.64 10.61 7.80 5.50 Diet 0.001 0.001 0.005 0.536 0.758 0.083 Density 0.876 0.213 0.231 0.231 0.341 0.369 Diet × density 0.923 0.334 0.334 0.848 0.612 0.051 22 to 28 d 29 to 35 d Diet1 BWG FI FCR BWG FI FCR  Mash 524.03B 851.28B 1.628B 666.26 1,064.26 1.605  Pelleted 50 : 50 576.32A 920.71A 1.600AB 646.06 1,084.71 1.682  Pelleted 70 : 30 597.23A 922.04A 1.546A 678.12 1,087.95 1.612 Density  13 broilers/m² 566.83 906.55 1.603 677.82 1,092.57 1.647  15 broilers/m² 564.88 889.46 1.579 649.13 1,065.38 1.619 CV, % 6.62 4.49 3.64 10.61 7.80 5.50 Diet 0.001 0.001 0.005 0.536 0.758 0.083 Density 0.876 0.213 0.231 0.231 0.341 0.369 Diet × density 0.923 0.334 0.334 0.848 0.612 0.051 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 4. Weekly Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Grower Phase of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 22 to 28 d 29 to 35 d Diet1 BWG FI FCR BWG FI FCR  Mash 524.03B 851.28B 1.628B 666.26 1,064.26 1.605  Pelleted 50 : 50 576.32A 920.71A 1.600AB 646.06 1,084.71 1.682  Pelleted 70 : 30 597.23A 922.04A 1.546A 678.12 1,087.95 1.612 Density  13 broilers/m² 566.83 906.55 1.603 677.82 1,092.57 1.647  15 broilers/m² 564.88 889.46 1.579 649.13 1,065.38 1.619 CV, % 6.62 4.49 3.64 10.61 7.80 5.50 Diet 0.001 0.001 0.005 0.536 0.758 0.083 Density 0.876 0.213 0.231 0.231 0.341 0.369 Diet × density 0.923 0.334 0.334 0.848 0.612 0.051 22 to 28 d 29 to 35 d Diet1 BWG FI FCR BWG FI FCR  Mash 524.03B 851.28B 1.628B 666.26 1,064.26 1.605  Pelleted 50 : 50 576.32A 920.71A 1.600AB 646.06 1,084.71 1.682  Pelleted 70 : 30 597.23A 922.04A 1.546A 678.12 1,087.95 1.612 Density  13 broilers/m² 566.83 906.55 1.603 677.82 1,092.57 1.647  15 broilers/m² 564.88 889.46 1.579 649.13 1,065.38 1.619 CV, % 6.62 4.49 3.64 10.61 7.80 5.50 Diet 0.001 0.001 0.005 0.536 0.758 0.083 Density 0.876 0.213 0.231 0.231 0.341 0.369 Diet × density 0.923 0.334 0.334 0.848 0.612 0.051 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large As the pellet quality is improved, chicks spend less time-consuming feed, which is represented by a reduction in activity, thereby improving energy use (greater real caloric value) and leading to greater tissue deposition [32]. McKinney and Teeter studied diets with different relationships between integral pellets and fines and determined that the effective caloric value of pelleting, which is defined as the caloric density of diet needed for birds to reach a determined body weight in relation to the determined feed conversion ratio. These authors concluded that the increase in pellet quality increases the apparent effective calorific value of the diet. Mckinney and Teeter [32] used diets containing different proportions of pellets to fines (100% pellet, 80% pellet, 60% pellet, 40% pellet, 20% pellet, and 100% fines) for broilers and found an increase in caloric effectiveness and frequency of rest since birds spent less time to consume the pelleted diets (integral pellets). The increasing proportions of integral pellets in diets (from 30% to 60% and 90%) resulted in increased feed intake and improved body weight gain [33]. Kenny [34] comparing a good pellet quality (control) in a wheat-based diet with 50% and 100% fines composition, showed that these two diets reduced the BW by 7.0% and 20%, respectively, compared to the control. When similar treatments were assessed using a corn-based diet, a similar effect on performance was shown, in which diets with 50% and 100% fines caused a reduction of 4.5% and 19% for BW and worsened the FCR by 2.2% and 6.1%, respectively. During the fifth and sixth weeks of life (Tables 4 and 5), these favorable results for feed processing were not observed (P > 0.05). However, for the evaluated period between 43 and 46 d of age, there was a significant effect of diet and stocking density. The supply of pelleted diets, independent of the proportion of fines in the diet, caused a lower (P < 0.05) feed intake without affecting body weight gain and feed conversion ratio (P > 0.05). Table 5. Weekly Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Finisher Phase of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 36 to 42 d 43 to 46 d Diet1 BWG FI FCR BWG FI FCR  Mash 604.12 1,199.25 1.992 309.71 677.38A 2.151  Pelleted 50 : 50 535.86 1,137.11 2.065 248.42 583.05B 2.324  Pelleted 70 : 30 553.27 1,119.92 2.044 276.96 589.01B 2.281 Density  13 broilers/m² 582.39 1,186.08 2.003 292.56 636.43 2.332B  15 broilers/m² 546.62 1,118.11 2.057 264.33 596.54 2.159A CV, % 13.81 8.81 7.00 21.72 12.90 7.74 Diet 0.099 0.149 0.510 0.062 0.010 0.264 Density 0.179 0.054 0.306 0.139 0.143 0.046 Diet × density 0.896 0.895 0.926 0.157 0.544 0.073 36 to 42 d 43 to 46 d Diet1 BWG FI FCR BWG FI FCR  Mash 604.12 1,199.25 1.992 309.71 677.38A 2.151  Pelleted 50 : 50 535.86 1,137.11 2.065 248.42 583.05B 2.324  Pelleted 70 : 30 553.27 1,119.92 2.044 276.96 589.01B 2.281 Density  13 broilers/m² 582.39 1,186.08 2.003 292.56 636.43 2.332B  15 broilers/m² 546.62 1,118.11 2.057 264.33 596.54 2.159A CV, % 13.81 8.81 7.00 21.72 12.90 7.74 Diet 0.099 0.149 0.510 0.062 0.010 0.264 Density 0.179 0.054 0.306 0.139 0.143 0.046 Diet × density 0.896 0.895 0.926 0.157 0.544 0.073 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 5. Weekly Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Finisher Phase of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 36 to 42 d 43 to 46 d Diet1 BWG FI FCR BWG FI FCR  Mash 604.12 1,199.25 1.992 309.71 677.38A 2.151  Pelleted 50 : 50 535.86 1,137.11 2.065 248.42 583.05B 2.324  Pelleted 70 : 30 553.27 1,119.92 2.044 276.96 589.01B 2.281 Density  13 broilers/m² 582.39 1,186.08 2.003 292.56 636.43 2.332B  15 broilers/m² 546.62 1,118.11 2.057 264.33 596.54 2.159A CV, % 13.81 8.81 7.00 21.72 12.90 7.74 Diet 0.099 0.149 0.510 0.062 0.010 0.264 Density 0.179 0.054 0.306 0.139 0.143 0.046 Diet × density 0.896 0.895 0.926 0.157 0.544 0.073 36 to 42 d 43 to 46 d Diet1 BWG FI FCR BWG FI FCR  Mash 604.12 1,199.25 1.992 309.71 677.38A 2.151  Pelleted 50 : 50 535.86 1,137.11 2.065 248.42 583.05B 2.324  Pelleted 70 : 30 553.27 1,119.92 2.044 276.96 589.01B 2.281 Density  13 broilers/m² 582.39 1,186.08 2.003 292.56 636.43 2.332B  15 broilers/m² 546.62 1,118.11 2.057 264.33 596.54 2.159A CV, % 13.81 8.81 7.00 21.72 12.90 7.74 Diet 0.099 0.149 0.510 0.062 0.010 0.264 Density 0.179 0.054 0.306 0.139 0.143 0.046 Diet × density 0.896 0.895 0.926 0.157 0.544 0.073 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large The probable reason for this might be that birds fed pelleted diets are more likely to remain inactive for a longer period. These birds also use less energy for consuming feed, and therefore the energy available for growth is increased. The average time spent at the feeder depends on the physical form of the feed, which could range from 56 s in pelleted feed to 114 s in a mash physical form [35]. During the last week, the environmental influence may have been preponderant in relation to diets. The experiment was conducted during the summer in a geographic region characterized by high environmental temperatures. Chickens that were fed pelleted diets and had greater growth rates, as observed at 21 d of age, were the animals that were most susceptible to metabolic disturbances due to heat stress [36]. This scenario with high temperatures generates a hyperthermia condition in the chickens, and consequently, there is greater carbon dioxide production due to increased respiratory rates, which then causes an electrolytic imbalance in the animals [37]. Once the negative effects are the most pronounced, chickens decrease intake trying to re-establish organic homeostasis. Feed form and stocking density had effects on broiler performance that were largely independent of each other. Chickens that were housed in greater densities (15/m2) presented a better (P < 0.05) feed conversion ratio when compared to chickens that were housed in lower densities during the period from 42 to 46 d (Table 5). Even though stocking density did not statistically affect feed intake and body weight gain, we observed that chickens that were housed in lower densities presented with lower numeric values for these characteristics. The performance during the grower/finisher phase, from 21 to 46 d, and during all production phases, from 1 to 46 d, was not affected by diet and stocking density, despite the greater performance that was observed for chicks supplemented with pelleted and ground diets in the starter phase (Table 6). Table 6. Cumulative Body Weight (BW), Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) From 22 to 46 d and 1 to 46 d of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 22 to 46 d 1 to 46 d Diet1 BWG FI FCR BW BWG FI FCR  Mash 2,104.38 3,792.20 1.804 3,022.44 2,942.16 4,913.30 1.671  Pelleted 50 : 50 2,006.66 3,725.60 1.864 3,021.39 2,916.88 4,852.30 1.684  Pelleted 70 : 30 2,072.64 3,718.90 1.803 3,103.36 2,995.99 4,922.30 1.646 Density  13 broilers/m² 2,108.59 3,821.63 1.822 3,100.18 3,001.14 4,959.54 1.666  15 broilers/m² 2,013.86 3,669.48 1.826 2,997.94 2,902.21 4,838.31 1.668 CV, % 9.93 6.78 4.65 7.12 7.29 5.30 2.85 Diet 0.498 0.739 0.151 0.576 0.659 0.815 0.212 Density 0.175 0.082 0.891 0.168 0.178 0.187 0.905 Diet × density 0.756 0.915 0.081 0.927 0.870 0.881 0.072 22 to 46 d 1 to 46 d Diet1 BWG FI FCR BW BWG FI FCR  Mash 2,104.38 3,792.20 1.804 3,022.44 2,942.16 4,913.30 1.671  Pelleted 50 : 50 2,006.66 3,725.60 1.864 3,021.39 2,916.88 4,852.30 1.684  Pelleted 70 : 30 2,072.64 3,718.90 1.803 3,103.36 2,995.99 4,922.30 1.646 Density  13 broilers/m² 2,108.59 3,821.63 1.822 3,100.18 3,001.14 4,959.54 1.666  15 broilers/m² 2,013.86 3,669.48 1.826 2,997.94 2,902.21 4,838.31 1.668 CV, % 9.93 6.78 4.65 7.12 7.29 5.30 2.85 Diet 0.498 0.739 0.151 0.576 0.659 0.815 0.212 Density 0.175 0.082 0.891 0.168 0.178 0.187 0.905 Diet × density 0.756 0.915 0.081 0.927 0.870 0.881 0.072 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 6. Cumulative Body Weight (BW), Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) From 22 to 46 d and 1 to 46 d of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 22 to 46 d 1 to 46 d Diet1 BWG FI FCR BW BWG FI FCR  Mash 2,104.38 3,792.20 1.804 3,022.44 2,942.16 4,913.30 1.671  Pelleted 50 : 50 2,006.66 3,725.60 1.864 3,021.39 2,916.88 4,852.30 1.684  Pelleted 70 : 30 2,072.64 3,718.90 1.803 3,103.36 2,995.99 4,922.30 1.646 Density  13 broilers/m² 2,108.59 3,821.63 1.822 3,100.18 3,001.14 4,959.54 1.666  15 broilers/m² 2,013.86 3,669.48 1.826 2,997.94 2,902.21 4,838.31 1.668 CV, % 9.93 6.78 4.65 7.12 7.29 5.30 2.85 Diet 0.498 0.739 0.151 0.576 0.659 0.815 0.212 Density 0.175 0.082 0.891 0.168 0.178 0.187 0.905 Diet × density 0.756 0.915 0.081 0.927 0.870 0.881 0.072 22 to 46 d 1 to 46 d Diet1 BWG FI FCR BW BWG FI FCR  Mash 2,104.38 3,792.20 1.804 3,022.44 2,942.16 4,913.30 1.671  Pelleted 50 : 50 2,006.66 3,725.60 1.864 3,021.39 2,916.88 4,852.30 1.684  Pelleted 70 : 30 2,072.64 3,718.90 1.803 3,103.36 2,995.99 4,922.30 1.646 Density  13 broilers/m² 2,108.59 3,821.63 1.822 3,100.18 3,001.14 4,959.54 1.666  15 broilers/m² 2,013.86 3,669.48 1.826 2,997.94 2,902.21 4,838.31 1.668 CV, % 9.93 6.78 4.65 7.12 7.29 5.30 2.85 Diet 0.498 0.739 0.151 0.576 0.659 0.815 0.212 Density 0.175 0.082 0.891 0.168 0.178 0.187 0.905 Diet × density 0.756 0.915 0.081 0.927 0.870 0.881 0.072 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Foot-Pad Dermatitis Assessment Evaluation of the foot-pad score at 21 d of age showed a greater incidence of C scores (serious and multiple lesions) in the foot-pad of chickens that received pelleted diets and were housed in greater densities (15 birds/m2). At 46 d, the incidence of FPD was different among the treatment combinations, consistently associated with stocking density. It means that within each feed form, birds housed at the highest stocking density (15 birds/m2), showed higher incidence of scores B and C compared to those housed at the lowest density (13 birds/m2) (Table 7). To confirm this, chi-square analyses were performed for both main effects (diets and stocking density). The results confirmed this assumption, as there was no significant effect for diets (P > 0.05) and there was a significant effect for stocking density (Table 8). There was a reduction in the incidence of score A paws in the order of 21.57% when stocking density was increased to 15 birds/m2. Confirming the negative effect of the highest density studied, the incidence of scores B and C was increased in 22.73% and 0.25%, respectively. It is not surprising that these lesions are a concern to the industry. Recently, chicken paws became the third most profitable part of chicken, following breast and wings [38]. FPD also jeopardizes animal welfare and food safety. Table 7. Percentage of Food-Pad Lesion of Broilers at 46 d of Age Fed Mash or Pelleted Diets, Raised in Different Stocking Densities. Treatment combination1 Score A, % Score B, % Score C, % Mash +13 broilers/m2 48.50 37.59B 13.91 Mash +15 broilers/m2 34.58 51.19A 14.24 Pelleted 50 : 50 +13 broilers/m2 44.79 44.79B 10.42 Pelleted 70 : 30 +15 broilers/m2 32.07 55.17A 12.76 Pelleted 50 : 50 +13 broilers/m2 42.58 46.48B 10.94 Pelleted 70 : 30 +15 broilers/m2 40.07 51.57A 8.36 P-value 0.221 <0.001 0.167 Treatment combination1 Score A, % Score B, % Score C, % Mash +13 broilers/m2 48.50 37.59B 13.91 Mash +15 broilers/m2 34.58 51.19A 14.24 Pelleted 50 : 50 +13 broilers/m2 44.79 44.79B 10.42 Pelleted 70 : 30 +15 broilers/m2 32.07 55.17A 12.76 Pelleted 50 : 50 +13 broilers/m2 42.58 46.48B 10.94 Pelleted 70 : 30 +15 broilers/m2 40.07 51.57A 8.36 P-value 0.221 <0.001 0.167 1Chi-square analyses performed considering the treatment combinations regardless of the three scores. N = pair of paws from 1,653 individually assessed. View Large Table 7. Percentage of Food-Pad Lesion of Broilers at 46 d of Age Fed Mash or Pelleted Diets, Raised in Different Stocking Densities. Treatment combination1 Score A, % Score B, % Score C, % Mash +13 broilers/m2 48.50 37.59B 13.91 Mash +15 broilers/m2 34.58 51.19A 14.24 Pelleted 50 : 50 +13 broilers/m2 44.79 44.79B 10.42 Pelleted 70 : 30 +15 broilers/m2 32.07 55.17A 12.76 Pelleted 50 : 50 +13 broilers/m2 42.58 46.48B 10.94 Pelleted 70 : 30 +15 broilers/m2 40.07 51.57A 8.36 P-value 0.221 <0.001 0.167 Treatment combination1 Score A, % Score B, % Score C, % Mash +13 broilers/m2 48.50 37.59B 13.91 Mash +15 broilers/m2 34.58 51.19A 14.24 Pelleted 50 : 50 +13 broilers/m2 44.79 44.79B 10.42 Pelleted 70 : 30 +15 broilers/m2 32.07 55.17A 12.76 Pelleted 50 : 50 +13 broilers/m2 42.58 46.48B 10.94 Pelleted 70 : 30 +15 broilers/m2 40.07 51.57A 8.36 P-value 0.221 <0.001 0.167 1Chi-square analyses performed considering the treatment combinations regardless of the three scores. N = pair of paws from 1,653 individually assessed. View Large Table 8. Percentage of Food-Pad Lesion of Broilers at 46 d of Age for Each Main Effect. Main effects1 Score A, % Score B, % Score C, % Diet2  Mash 41.18 44.74 14.08  Pelleted 50 : 50 38.07 50.27 11.66  Pelleted 70 : 30 41.25 49.17 9.58 P-value 0.565 0.545 0.059 Stocking density  13 broilers/m2 45.33 42.89B 11.78  15 broilers/m2 35.55 52.64A 11.81 P-value 0.087 <0.001 0.430 Main effects1 Score A, % Score B, % Score C, % Diet2  Mash 41.18 44.74 14.08  Pelleted 50 : 50 38.07 50.27 11.66  Pelleted 70 : 30 41.25 49.17 9.58 P-value 0.565 0.545 0.059 Stocking density  13 broilers/m2 45.33 42.89B 11.78  15 broilers/m2 35.55 52.64A 11.81 P-value 0.087 <0.001 0.430 1Chi-square analyses performed considering the isolated main effects regardless of the three scores. N = pair of paws from 1,653 individually assessed. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 8. Percentage of Food-Pad Lesion of Broilers at 46 d of Age for Each Main Effect. Main effects1 Score A, % Score B, % Score C, % Diet2  Mash 41.18 44.74 14.08  Pelleted 50 : 50 38.07 50.27 11.66  Pelleted 70 : 30 41.25 49.17 9.58 P-value 0.565 0.545 0.059 Stocking density  13 broilers/m2 45.33 42.89B 11.78  15 broilers/m2 35.55 52.64A 11.81 P-value 0.087 <0.001 0.430 Main effects1 Score A, % Score B, % Score C, % Diet2  Mash 41.18 44.74 14.08  Pelleted 50 : 50 38.07 50.27 11.66  Pelleted 70 : 30 41.25 49.17 9.58 P-value 0.565 0.545 0.059 Stocking density  13 broilers/m2 45.33 42.89B 11.78  15 broilers/m2 35.55 52.64A 11.81 P-value 0.087 <0.001 0.430 1Chi-square analyses performed considering the isolated main effects regardless of the three scores. N = pair of paws from 1,653 individually assessed. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large The exact process that results in FPD are not clearly known, although most researchers agree that the quality and type of litter, and stocking density are important factors in the predisposition towards FPD [38]. Similar results were obtained by authors who studied prevalence and alternative to reduce the incidence of FPD in broiler flocks [12, 39, 40]. Carcass Yield There was no significant interaction (P > 0.05) for absolute and relative weights of carcass, commercial cuts, and abdominal fat deposition (Tables 9 and 10). Table 9. Weights of Carcass, Commercial Cuts, and Abdominal Fat Deposition of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. Absolute weight, g1 Diet2 Carcass Breast Legs Wings Abdominal Fat  Mash 2,380.00 857.75 646.08 249.83 48.07  Pelleted 50 : 50 2,448.17 860.17 657.17 258.91 47.21  Pelleted 70 : 30 2,476.92 882.78 661.42 261.00 51.87 Density  13 broilers/m² 2,486.55 885.14 667.44A 265.33A 47.32  15 broilers/m² 2,392.39 848.40 642.33B 247.83B 50.88 CV, % 6.30 9.40 6.44 7.41 27.43 Diet 0.151 0.480 0.438 0.104 0.464 Density 0.018 0.058 0.014 <0.001 0.274 Diet × density 0.577 0.933 0.945 0.368 0.643 Absolute weight, g1 Diet2 Carcass Breast Legs Wings Abdominal Fat  Mash 2,380.00 857.75 646.08 249.83 48.07  Pelleted 50 : 50 2,448.17 860.17 657.17 258.91 47.21  Pelleted 70 : 30 2,476.92 882.78 661.42 261.00 51.87 Density  13 broilers/m² 2,486.55 885.14 667.44A 265.33A 47.32  15 broilers/m² 2,392.39 848.40 642.33B 247.83B 50.88 CV, % 6.30 9.40 6.44 7.41 27.43 Diet 0.151 0.480 0.438 0.104 0.464 Density 0.018 0.058 0.014 <0.001 0.274 Diet × density 0.577 0.933 0.945 0.368 0.643 1Results expressed as absolute weights in grams. N = 6 replicates of 2 bird each per treatment combination. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 9. Weights of Carcass, Commercial Cuts, and Abdominal Fat Deposition of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. Absolute weight, g1 Diet2 Carcass Breast Legs Wings Abdominal Fat  Mash 2,380.00 857.75 646.08 249.83 48.07  Pelleted 50 : 50 2,448.17 860.17 657.17 258.91 47.21  Pelleted 70 : 30 2,476.92 882.78 661.42 261.00 51.87 Density  13 broilers/m² 2,486.55 885.14 667.44A 265.33A 47.32  15 broilers/m² 2,392.39 848.40 642.33B 247.83B 50.88 CV, % 6.30 9.40 6.44 7.41 27.43 Diet 0.151 0.480 0.438 0.104 0.464 Density 0.018 0.058 0.014 <0.001 0.274 Diet × density 0.577 0.933 0.945 0.368 0.643 Absolute weight, g1 Diet2 Carcass Breast Legs Wings Abdominal Fat  Mash 2,380.00 857.75 646.08 249.83 48.07  Pelleted 50 : 50 2,448.17 860.17 657.17 258.91 47.21  Pelleted 70 : 30 2,476.92 882.78 661.42 261.00 51.87 Density  13 broilers/m² 2,486.55 885.14 667.44A 265.33A 47.32  15 broilers/m² 2,392.39 848.40 642.33B 247.83B 50.88 CV, % 6.30 9.40 6.44 7.41 27.43 Diet 0.151 0.480 0.438 0.104 0.464 Density 0.018 0.058 0.014 <0.001 0.274 Diet × density 0.577 0.933 0.945 0.368 0.643 1Results expressed as absolute weights in grams. N = 6 replicates of 2 bird each per treatment combination. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 10. Relative Weights of Carcass, Commercial Cuts, and Fat Abdominal Deposition of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. Relative weight, %1 Diet2 Carcass Breast Legs Wings Abdominal fat  Mash 79.31B 35.80 26.98 10.41 2.01  Pelleted 50 : 50 81.10A 35.48 26.86 10.68 2.02  Pelleted 70 : 30 79.86AB 35.93 26.73 10.48 2.10 Density  13 broilers/m² 80.36 35.74 26.83 10.69A 1.90  15 broilers/m² 79.82 35.73 26.87 10.36B 2.18 CV, % 2.70 5.78 4.67 4.42 29.83 Diet 0.017 0.724 0.794 0.123 0.851 Density 0.287 0.944 0.896 0.004 0.059 Diet × density 0.465 0.561 0.435 0.856 0.599 Relative weight, %1 Diet2 Carcass Breast Legs Wings Abdominal fat  Mash 79.31B 35.80 26.98 10.41 2.01  Pelleted 50 : 50 81.10A 35.48 26.86 10.68 2.02  Pelleted 70 : 30 79.86AB 35.93 26.73 10.48 2.10 Density  13 broilers/m² 80.36 35.74 26.83 10.69A 1.90  15 broilers/m² 79.82 35.73 26.87 10.36B 2.18 CV, % 2.70 5.78 4.67 4.42 29.83 Diet 0.017 0.724 0.794 0.123 0.851 Density 0.287 0.944 0.896 0.004 0.059 Diet × density 0.465 0.561 0.435 0.856 0.599 1Results expressed as a percentage of the body weight. N = 6 replicates of 2 bird each per treatment combination. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 10. Relative Weights of Carcass, Commercial Cuts, and Fat Abdominal Deposition of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. Relative weight, %1 Diet2 Carcass Breast Legs Wings Abdominal fat  Mash 79.31B 35.80 26.98 10.41 2.01  Pelleted 50 : 50 81.10A 35.48 26.86 10.68 2.02  Pelleted 70 : 30 79.86AB 35.93 26.73 10.48 2.10 Density  13 broilers/m² 80.36 35.74 26.83 10.69A 1.90  15 broilers/m² 79.82 35.73 26.87 10.36B 2.18 CV, % 2.70 5.78 4.67 4.42 29.83 Diet 0.017 0.724 0.794 0.123 0.851 Density 0.287 0.944 0.896 0.004 0.059 Diet × density 0.465 0.561 0.435 0.856 0.599 Relative weight, %1 Diet2 Carcass Breast Legs Wings Abdominal fat  Mash 79.31B 35.80 26.98 10.41 2.01  Pelleted 50 : 50 81.10A 35.48 26.86 10.68 2.02  Pelleted 70 : 30 79.86AB 35.93 26.73 10.48 2.10 Density  13 broilers/m² 80.36 35.74 26.83 10.69A 1.90  15 broilers/m² 79.82 35.73 26.87 10.36B 2.18 CV, % 2.70 5.78 4.67 4.42 29.83 Diet 0.017 0.724 0.794 0.123 0.851 Density 0.287 0.944 0.896 0.004 0.059 Diet × density 0.465 0.561 0.435 0.856 0.599 1Results expressed as a percentage of the body weight. N = 6 replicates of 2 bird each per treatment combination. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large There was a greater (P < 0.05) carcass yield of chickens that were fed pelleted diets with 50% fines in relation to chickens that received mash feed (Table 10). There is an important relationship that should be considered when evaluating the results regarding muscle deposition in carcasses and the energy level of pelleted diets. As pellet quality is improved, birds spend less time consuming feed and thus, their level of activity decreases, which then leads to lower energy expenditures. However, when the energy levels are high, as seen in this study, this excess energy can lead to high body temperatures, which can interfere negatively with heat dissipation mechanisms and consequently reduce muscle deposition. Lara et al. [41] evaluated the effect of feed processing (mash and pelleted) on yield of cuts in broilers at 45 d of age and observed similar results. Pelleted/crumble diets over pre-starter phase (1 to 7 d) influence productive performance of broilers until the end of initial phase (21 d) [42], with an effect reduction until slaughter age and no effect on carcass yield [43]. There was an influence (P < 0.05) of stocking density on the weights of carcasses, legs, and wings (Table 9). Chicks that were housed in lower densities (13 birds/m2) presented with greater absolute body weights in relation to those that were housed in high densities (15 birds/m2). Similar results (P < 0.05) were observed for wing yield (Table 10). The lack of a density effect on breast yield was previously reported by [44–46]. Otherwise, [36] observed heavier carcasses and fillets in lower stocking densities. This effect is more evident because the densities that were used by these authors were lower than those used in commercial production systems, in addition to the difference between stocking rates that were used (3.11 and 6.7 birds/m2). Several factors are involved in the evaluation of ration processing; therefore, knowledge of these factors is important so that the benefits of pelleting can be enjoyed. It is important to consider that pelleting increases ration costs and is a process of high energy and capital demand. Thus, it can influence the yield of ration production, particularly if the manufacturing process is not adequately dimensioned. Furthermore, most of the Brazilian poultry industry supports production beyond its capacity that also influences in the yield of ration production [9]. Pellet quality depends on the pelletizer and the entire manufacturing system including formulation, milling, mixture, cooling, and transport. Moreover, acclimation of the farms can have a greater impact on production results than ration processing and all the systems involved. CONCLUSIONS AND APPLICATIONS The supply of crumble pelleted diet during the initial phase (1–21 d of age) allowed for better animal performance and lower incidences of FPD. During the grower and finisher phases, pelleted diets and pellet quality did not influence animal performance. The carcass yield of chickens that received pelleted diets with 50% fines was greater than that associated with the middling diet. The reduction in stocking density resulted in greater weights of carcasses, legs, and wings, as well as wing yield of chickens at 46 d of age. Footnotes Primary Audience: Poultry Nutritionists, Flock Supervisors and Poultry Researchers REFERENCES AND NOTES 1. Gadzirayi C. 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Effect of Pelletized Diets and the Proportion of Fines on Performance of Broilers Raised in High-Density Conditions

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Oxford University Press
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© 2018 Poultry Science Association Inc.
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1056-6171
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1537-0437
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10.3382/japr/pfy015
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Abstract

SUMMARY The objective of the study was to evaluate some important parameters regarding production and welfare, as well as performance, uniformity, carcass yield and foot-pad lesions of broilers fed mash or pelleted diets with different concentrations and raised in different density conditions. The experimental design consisted of a 3 × 2 factorial scheme (3 diets: mash feed, pelleted feed with 50% of fines, and pelleted feed with 30% of fines vs. 2 stocking densities: 13 and 15 birds/m2) with six replications, totaling 1,746 male Cobb chicks. Besides the weight of the birds and feed intake for each replicate assessed weekly to evaluate performance, at 7 and 42 d of age all birds were individually weighed to assess uniformity within each replicate. Moreover, 12 birds/treatment were slaughtered to assess the yield for carcass and commercial cuts. To assess the incidence of food-pad dermatitis (FPD), all birds were evaluated for lesion score at 21 and 42 d of age. The intake of pelleted diets resulted in greater body weight gain and better feed conversion ratio in the first week. The reduction of stocking density resulted in greater weights of carcasses, legs, and wings as well as wing yield at the 46th day but did not alter FPD incidence. The performance during the grower/finisher phase and during all production phases was not affected by diet and stocking density, despite the greater performance that was observed for chicks supplemented with pelleted and ground diets in the starter phase. DESCRIPTON OF PROBLEM Physical treatments such as pelleting are used during feed processing to enhance feed efficiency. The process of starch gelatinization that may occur during the pelleting process (in the presence of heat and humidity) results in greater energy digestibility due to alterations on the physical characteristics of the diet [1, 2]. These benefits are in addition to greater microbiological quality, which is an important issue nowadays considering Salmonella infections, as well as decreased segregation of ingredients, and a reduction in time and energy spent during intake, therefore increasing growth efficiency [1, 3–6]. The low-quality pellets might disintegrate during processing, transportation, or conveying to the feeder, thus producing a mass known as “fines.” According to Mina-Boac et al., [7], these fine particles cause a nutrient imbalance in the feed composition, which can negatively affect animal performance. Due to the increase in intake of pelleted diets [8–10, 6], there is also an increase in the available energy production depending on environmental conditions, which can lead towards higher feed conversion ratios and greater fat deposition in the carcass. Brazilian poultry agribusiness has increased the stocking density while aiming to maximize production and decrease costs of broiler production. The increase in nutrient availability requires a greater oxygen demand for the physiological and metabolic processes associated with higher growth rates [11] and the high stocking rates can aggravate the situation because of low air and litter quality. Foot-pad dermatitis (FPD), characterized as an ulcerative lesion on the foot-pad, is a concern in poultry production that jeopardizes both animal welfare and company's profitability. Litter moisture, which is affected by stocking density, has been shown as a primary causal factor in high incidence rates of foot-pad lesions [12]. The aim of this study was to evaluate the animal performance, its uniformity within each experimental unit, carcass yield and incidence of FPD of broilers fed mash or pelleted diets with different fine concentrations and were raised in different stocking densities. MATERIALS AND METHODS Animal Care All procedures described below involving the animals used in this study were approved by the Ethics Committee in Animal Experimentation (Approval protocol of Ethics Committee: 01/2014), which are in accordance with the recommendations of Conselho Nacional de Controle de Experimentação Animal (CONCEA) [13]. The animals procedures used also met the guidelines approved by the institutional Animal Care and Use Committee. Experimental Design A total of 1,746 male Cobb broilers were randomly assigned (completely randomized design) using a 3 × 2 factorial scheme (3 diets: mash feed, pelleted feed with 50% fines, and pelleted feed with 30% fines vs. 2 stocking densities: 13 and 15 birds/m2) to total six treatments and six replications [14]. However, due to the need to grind the pelleted feed to supply the phase from 1 to 21 d, the factorial design that was considered for the statistical analysis of data obtained during this period was 2 × 2 (diets: mash and pelleted feed vs. stocking density: 13 and 15 birds/m2). The mash diet that was used throughout the experimental period was not submitted to any thermal processing. Corn/soybean meal-based diets were formulated considering the chemical composition of ingredients and the nutrient requirements for different bird phases, adopted by poultry integrators in the region (Table 1). The feeding program was composed of 4 phases: pre-starter (1 to 7 d), starter (8 to 21 d), grower (22 to 37 d), and finisher (38 to 46 d). Table 1. Composition and Calculated Nutritional Levels of the Experimental Diets. Pre-starter Starter Grower Finisher Ingredients, % 1–7 d 8–21 d 22–37 d 38–46 d Corn 54.05 56.30 56.66 57.78 Soybean meal 38.02 29.92 19.85 12.80 Integral soybean 2.00 8.00 18.00 25.04 Soybean oil 1.68 2.04 1.92 1.14 Dicalcium phosphate 1.27 1.20 1.17 1.02 Limestone 1.05 0.86 0.82 0.75 Salt 0.37 0.32 0.32 0.32 Vit/Min premix1 0.30 0.30 0.30 0.30 Sodium bicarbonate 0.20 0.10 0.04 – Choline chloride 0.08 0.07 0.05 0.03 Threonine (L-98%) 0.10 0.08 0.08 0.08 Valine (L-96.5%) 0.04 0.04 0.04 0.04 Methionine (DL-98%) 0.41 0.36 0.35 0.35 Lysine (L-50%) 0.38 0.36 0.35 0.35 Anticoccidial 0.05 0.05 0.05 – Calculated levels ME (Kcal/Kg) 2,980 3,099 3,235 3,280 CP (%) 23.90 22.30 21.00 20.16 Calcium (%) 1.000 0.890 0.870 0.810 Available P (%) 0.480 0.450 0.450 0.420 Dig. Lysine (%) 1.360 1.250 1.159 1.099 Dig. Met+Cys (%) 1.047 0.960 0.916 0.879 Pre-starter Starter Grower Finisher Ingredients, % 1–7 d 8–21 d 22–37 d 38–46 d Corn 54.05 56.30 56.66 57.78 Soybean meal 38.02 29.92 19.85 12.80 Integral soybean 2.00 8.00 18.00 25.04 Soybean oil 1.68 2.04 1.92 1.14 Dicalcium phosphate 1.27 1.20 1.17 1.02 Limestone 1.05 0.86 0.82 0.75 Salt 0.37 0.32 0.32 0.32 Vit/Min premix1 0.30 0.30 0.30 0.30 Sodium bicarbonate 0.20 0.10 0.04 – Choline chloride 0.08 0.07 0.05 0.03 Threonine (L-98%) 0.10 0.08 0.08 0.08 Valine (L-96.5%) 0.04 0.04 0.04 0.04 Methionine (DL-98%) 0.41 0.36 0.35 0.35 Lysine (L-50%) 0.38 0.36 0.35 0.35 Anticoccidial 0.05 0.05 0.05 – Calculated levels ME (Kcal/Kg) 2,980 3,099 3,235 3,280 CP (%) 23.90 22.30 21.00 20.16 Calcium (%) 1.000 0.890 0.870 0.810 Available P (%) 0.480 0.450 0.450 0.420 Dig. Lysine (%) 1.360 1.250 1.159 1.099 Dig. Met+Cys (%) 1.047 0.960 0.916 0.879 1Vitamin A (min) 9.000.000 UI/kg; vitamin D3 (min) 4.000.000 UI/kg; vitamin E (min) 30.000 UI/kg; vitamin K3 (min) 3.000 mg/kg; vitamin B1 (min) 2.000 mg/kg; vitamin B2 (min) 7.000 mg/kg; vitamin B6 (min) 4.000 mg/kg; vitamin B12 (min) 15.000 mcg/kg; niacin (min) 50 g/kg; pantothenic acid (min) 12 g/kg. folic acid (min) 3.000 mg/kg; biotin (min) 200 mg/kg. BHT 100 mg/kg. Manganese 90.00 ppm; zinc 80.5 ppm; iron 39.90 ppm; copper 10 ppm; iodine 0.71 ppm; selenium 0.30 ppm. View Large Table 1. Composition and Calculated Nutritional Levels of the Experimental Diets. Pre-starter Starter Grower Finisher Ingredients, % 1–7 d 8–21 d 22–37 d 38–46 d Corn 54.05 56.30 56.66 57.78 Soybean meal 38.02 29.92 19.85 12.80 Integral soybean 2.00 8.00 18.00 25.04 Soybean oil 1.68 2.04 1.92 1.14 Dicalcium phosphate 1.27 1.20 1.17 1.02 Limestone 1.05 0.86 0.82 0.75 Salt 0.37 0.32 0.32 0.32 Vit/Min premix1 0.30 0.30 0.30 0.30 Sodium bicarbonate 0.20 0.10 0.04 – Choline chloride 0.08 0.07 0.05 0.03 Threonine (L-98%) 0.10 0.08 0.08 0.08 Valine (L-96.5%) 0.04 0.04 0.04 0.04 Methionine (DL-98%) 0.41 0.36 0.35 0.35 Lysine (L-50%) 0.38 0.36 0.35 0.35 Anticoccidial 0.05 0.05 0.05 – Calculated levels ME (Kcal/Kg) 2,980 3,099 3,235 3,280 CP (%) 23.90 22.30 21.00 20.16 Calcium (%) 1.000 0.890 0.870 0.810 Available P (%) 0.480 0.450 0.450 0.420 Dig. Lysine (%) 1.360 1.250 1.159 1.099 Dig. Met+Cys (%) 1.047 0.960 0.916 0.879 Pre-starter Starter Grower Finisher Ingredients, % 1–7 d 8–21 d 22–37 d 38–46 d Corn 54.05 56.30 56.66 57.78 Soybean meal 38.02 29.92 19.85 12.80 Integral soybean 2.00 8.00 18.00 25.04 Soybean oil 1.68 2.04 1.92 1.14 Dicalcium phosphate 1.27 1.20 1.17 1.02 Limestone 1.05 0.86 0.82 0.75 Salt 0.37 0.32 0.32 0.32 Vit/Min premix1 0.30 0.30 0.30 0.30 Sodium bicarbonate 0.20 0.10 0.04 – Choline chloride 0.08 0.07 0.05 0.03 Threonine (L-98%) 0.10 0.08 0.08 0.08 Valine (L-96.5%) 0.04 0.04 0.04 0.04 Methionine (DL-98%) 0.41 0.36 0.35 0.35 Lysine (L-50%) 0.38 0.36 0.35 0.35 Anticoccidial 0.05 0.05 0.05 – Calculated levels ME (Kcal/Kg) 2,980 3,099 3,235 3,280 CP (%) 23.90 22.30 21.00 20.16 Calcium (%) 1.000 0.890 0.870 0.810 Available P (%) 0.480 0.450 0.450 0.420 Dig. Lysine (%) 1.360 1.250 1.159 1.099 Dig. Met+Cys (%) 1.047 0.960 0.916 0.879 1Vitamin A (min) 9.000.000 UI/kg; vitamin D3 (min) 4.000.000 UI/kg; vitamin E (min) 30.000 UI/kg; vitamin K3 (min) 3.000 mg/kg; vitamin B1 (min) 2.000 mg/kg; vitamin B2 (min) 7.000 mg/kg; vitamin B6 (min) 4.000 mg/kg; vitamin B12 (min) 15.000 mcg/kg; niacin (min) 50 g/kg; pantothenic acid (min) 12 g/kg. folic acid (min) 3.000 mg/kg; biotin (min) 200 mg/kg. BHT 100 mg/kg. Manganese 90.00 ppm; zinc 80.5 ppm; iron 39.90 ppm; copper 10 ppm; iodine 0.71 ppm; selenium 0.30 ppm. View Large Response Parameters For the evaluation of animal performance, the birds and feed orts from each experimental unit were assessed weekly. The feed conversion ratio was corrected by the mortality of birds according to the methodology described by Sakomura and Rostagno [15]. The record of daily mortality was also used for the calculation of feasibility. All chickens at 7 and 46 d of age were individually weighed to evaluate the effect of diets and stocking density on uniformity of the birds within the experimental unit, expressed by the coefficient of variation (%). At 46 d of age, the macroscopy scores of foot-pads from all chickens were evaluated, characterizing them as follows: Absence of lesions (A score), light lesion only in the center of foot-pad (B score), or serious and multiple lesions (C score). The carcass and commercial cuts yields were determined at 46 d of age when two chickens per experimental unit (12 birds/treatment) with body weights ± 2% of the average body weight of the pen were slaughtered. The chickens were identified, submitted to a fasting period of 6 h, and then slaughtered by electrical stunning and further bleeding. For the calculation of carcass yield, the hot eviscerated carcass weight (no feet, no head, and no abdominal fat) was considered in relation to the individual body weight that was obtained before slaughter. For the yield of prime cuts, the following cuts were calculated in relation to the eviscerated carcass weight: entire breast without skin and bones, legs (thigh and drumstick without skin and bones), back, and wings without skin. The abdominal fat around the cloaca, cloacal bursa, gizzard, proventriculus, and adjacent abdominal muscles was removed following methodology described by Smith [16]. Furthermore, it was weighed and calculated in relation to the eviscerated carcass weight. Statistical Procedures The data were submitted to analyses of variance using the general linear model procedure of SAS, as a 3 × 2 factorial arrangement of treatments that included feed form and stocking density as the fixed main effects and their respective interactions [17]. The treatment means were separated by the Tukey test at P < 0.05 statistical level. The frequency of birds within each weight category was analyzed by a nonparametric analysis. For the incidence of birds with different FPD scores, chi-square analyses were performed [17]. RESULTS AND DISCUSSION Uniformity and Performance In Figure 1, the variations in the distribution of individual body weight are characterized by five ranges during the first week of life of chickens in relation to mash or pelleted/ground diets. The treatment with mash feed resulted in a greater average percentage (21%) of very light birds (below 170 g) in relation to pelleted (5%), and there was a lower percentage of heavy chicks (above 210 g) for mash feed (9.4%) compared to pelleted (30%). Figure 1. View largeDownload slide Weight categories according to the diet at 7 d of age. Values represent the frequency (%) of birds within each weight category. Distinct letters statistically differ (P < 0.001) within each weight category. Figure 1. View largeDownload slide Weight categories according to the diet at 7 d of age. Values represent the frequency (%) of birds within each weight category. Distinct letters statistically differ (P < 0.001) within each weight category. In Table 2, values of coefficient of variation (CV) of individual body weights are shown at 7 and 46 d of age. When considering stocking density, the chicks presented with a uniform body weight (P > 0.05); however, the variation in body weight was statistically different (P < 0.05) when chicks were 7 d of age. The intake of pelleted diets resulted in lower CV (10.15%) of individual body weights of birds when compared to CV (12.99%) of chicks that were fed mash diets. Table 2. Coefficient of Variation of the Individual Body Weight at Housing, 7 And 46 d of Age of Broilers Fed Mash or Pelleted Diets, Raised in Different Stocking Densities. Coefficient of variation, %1 Diet Housing 7 d 46 d  Mash 8.55 12.99A 9.95  Pelleted 50:50 8.07 10.15B 11.84  Pelleted 70:30 10.97 Density  13 broilers/m² 8.32 11.45 11.00  15 broilers/m² 8.14 10.74 10.85 CV, % 10.55 28.93 16.69 Diet 0.321 0.025 0.070 Density 0.557 0.500 0.832 Diet × density 0.411 0.163 0.875 Coefficient of variation, %1 Diet Housing 7 d 46 d  Mash 8.55 12.99A 9.95  Pelleted 50:50 8.07 10.15B 11.84  Pelleted 70:30 10.97 Density  13 broilers/m² 8.32 11.45 11.00  15 broilers/m² 8.14 10.74 10.85 CV, % 10.55 28.93 16.69 Diet 0.321 0.025 0.070 Density 0.557 0.500 0.832 Diet × density 0.411 0.163 0.875 1Data are presented as means of the coefficient of variation (%) obtained using the individual birds’ weight at day 1, 7, and 46. CV = coefficient of variation. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). N = 6 replicates, totaling 1,746 birds. View Large Table 2. Coefficient of Variation of the Individual Body Weight at Housing, 7 And 46 d of Age of Broilers Fed Mash or Pelleted Diets, Raised in Different Stocking Densities. Coefficient of variation, %1 Diet Housing 7 d 46 d  Mash 8.55 12.99A 9.95  Pelleted 50:50 8.07 10.15B 11.84  Pelleted 70:30 10.97 Density  13 broilers/m² 8.32 11.45 11.00  15 broilers/m² 8.14 10.74 10.85 CV, % 10.55 28.93 16.69 Diet 0.321 0.025 0.070 Density 0.557 0.500 0.832 Diet × density 0.411 0.163 0.875 Coefficient of variation, %1 Diet Housing 7 d 46 d  Mash 8.55 12.99A 9.95  Pelleted 50:50 8.07 10.15B 11.84  Pelleted 70:30 10.97 Density  13 broilers/m² 8.32 11.45 11.00  15 broilers/m² 8.14 10.74 10.85 CV, % 10.55 28.93 16.69 Diet 0.321 0.025 0.070 Density 0.557 0.500 0.832 Diet × density 0.411 0.163 0.875 1Data are presented as means of the coefficient of variation (%) obtained using the individual birds’ weight at day 1, 7, and 46. CV = coefficient of variation. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). N = 6 replicates, totaling 1,746 birds. View Large These results are confirmed in the evaluation of animal performance (Table 3). There was better body weight gain and feed conversion ratio (P < 0.05) for chicks fed pelleted diets during the pre-starter phase (from 1 to 7 d). Penz [18] reported that in commercial conditions, the performance of broilers from 1 to 7 d of age that were fed pre-starter diets was better than the animals fed mash diets. Silva et al. [19] obtained greater body weight gain and better feed conversion ratio for birds fed pelleted/ground diets. Similar results were found by Jahan et al., [20] who reported that birds had greater feed intake with crumble or pellets than mash feeding. Other previous studies found similar results [21–23]. Table 3. Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Pre-Starter and Starter Phases of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 1 to 7 d 1 to 21 d Diet1 BWG FI FCR BWG FI FCR  Mash 139.19B 161.25 1.144B 831.17B 1,111.88B 1.338B  Pelleted 154.02A 163.39 1.061A 906.98A 1,179.42A 1.300A Density  13 broilers/m² 150.41 162.76 1.080 881.95 1,154.23 1.309  15 broilers/m² 148.36 162.59 1.086 881.47 1,159.58 1.316 CV, % 4.19 6.60 4.763 3.96 5.12 3.75 Diet 0.001 0.598 >0.001 0.001 0.003 0.034 Density 0.313 0.742 0.835 0.950 0.929 0.957 Diet × density 0.259 0.389 0.433 0.762 0.627 0.303 1 to 7 d 1 to 21 d Diet1 BWG FI FCR BWG FI FCR  Mash 139.19B 161.25 1.144B 831.17B 1,111.88B 1.338B  Pelleted 154.02A 163.39 1.061A 906.98A 1,179.42A 1.300A Density  13 broilers/m² 150.41 162.76 1.080 881.95 1,154.23 1.309  15 broilers/m² 148.36 162.59 1.086 881.47 1,159.58 1.316 CV, % 4.19 6.60 4.763 3.96 5.12 3.75 Diet 0.001 0.598 >0.001 0.001 0.003 0.034 Density 0.313 0.742 0.835 0.950 0.929 0.957 Diet × density 0.259 0.389 0.433 0.762 0.627 0.303 1From 1 to 21 d, pelleted diet was grounded to ensure proper feed intake. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 3. Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Pre-Starter and Starter Phases of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 1 to 7 d 1 to 21 d Diet1 BWG FI FCR BWG FI FCR  Mash 139.19B 161.25 1.144B 831.17B 1,111.88B 1.338B  Pelleted 154.02A 163.39 1.061A 906.98A 1,179.42A 1.300A Density  13 broilers/m² 150.41 162.76 1.080 881.95 1,154.23 1.309  15 broilers/m² 148.36 162.59 1.086 881.47 1,159.58 1.316 CV, % 4.19 6.60 4.763 3.96 5.12 3.75 Diet 0.001 0.598 >0.001 0.001 0.003 0.034 Density 0.313 0.742 0.835 0.950 0.929 0.957 Diet × density 0.259 0.389 0.433 0.762 0.627 0.303 1 to 7 d 1 to 21 d Diet1 BWG FI FCR BWG FI FCR  Mash 139.19B 161.25 1.144B 831.17B 1,111.88B 1.338B  Pelleted 154.02A 163.39 1.061A 906.98A 1,179.42A 1.300A Density  13 broilers/m² 150.41 162.76 1.080 881.95 1,154.23 1.309  15 broilers/m² 148.36 162.59 1.086 881.47 1,159.58 1.316 CV, % 4.19 6.60 4.763 3.96 5.12 3.75 Diet 0.001 0.598 >0.001 0.001 0.003 0.034 Density 0.313 0.742 0.835 0.950 0.929 0.957 Diet × density 0.259 0.389 0.433 0.762 0.627 0.303 1From 1 to 21 d, pelleted diet was grounded to ensure proper feed intake. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large The pelleting process alters both the consistency and conformation of the feed, which has considerable implications on the reduction of the partitioning effect; thus, the ingredients pass into the intestine under greater uniformity [24]. Moreover, in the initial growing phases, because of the incapacity of broilers to ingest whole pellets and then regulate the feed intake by energy level, a mash or crumbled diet is usually offered [25]. Gelatinizing cereal starch has generally been thought to improve enzymatic access to glucosidic linkages and consequent digestibility [3, 26], which contributes significantly to better efficiency of nutrient use in the diet, even when feed intake is similar among diets. The pelleted diet also has benefits on the intestinal mucosa of the animals. Amerah et al. [27] reported the presence of greater numbers of villi and deeper crypts in the duodenum and jejunum segments of birds fed pelleted diets, compared to those fed mash diets. This finding might be due to the combined effect of gelatinized starch and availability of nutrients other than starch. One strategy for producing high-quality pellets has been to gelatinize as much starch as possible. However, the improving pellet quality through increasing starch gelatinization may negatively affect nutrient utilization, thus antagonizing performance enhancements of pelleting. The processing conditions may generate retrograded starch, Maillard products, and loss of available amino acids or vitamins [28]. For the period from 1 to 21 d (Table 3), there was no interaction (P > 0.05) between stocking density and diets. However, we observed that feed intake was greater (P < 0.05) for chicks that were fed pelleted diets in relation to those that were fed mash feed, which resulted in greater (P < 0.05) body weight gains and better (P < 0.05) feed conversion ratio. A greater feed intake was also found by López and Baião [29] and may be attributed to a greater density of granulated diet, uniform particle size, and the obstruction of selective capture of feedstuffs [30, 31]. After 21 d of age, chickens started receiving 3 diets (mash, pelleted 50 : 50, and pelleted 70 : 30 diets). The results that were observed in the fourth week are similar to those described for the initial phase: greater feed intake and body weight gain of chickens fed pelleted diets, regardless of fine percentage. For the feed conversion ratio, a greater proportion of pellets to fines (70 : 30) resulted in a better index when compared with the use of mash feed (Table 4). Table 4. Weekly Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Grower Phase of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 22 to 28 d 29 to 35 d Diet1 BWG FI FCR BWG FI FCR  Mash 524.03B 851.28B 1.628B 666.26 1,064.26 1.605  Pelleted 50 : 50 576.32A 920.71A 1.600AB 646.06 1,084.71 1.682  Pelleted 70 : 30 597.23A 922.04A 1.546A 678.12 1,087.95 1.612 Density  13 broilers/m² 566.83 906.55 1.603 677.82 1,092.57 1.647  15 broilers/m² 564.88 889.46 1.579 649.13 1,065.38 1.619 CV, % 6.62 4.49 3.64 10.61 7.80 5.50 Diet 0.001 0.001 0.005 0.536 0.758 0.083 Density 0.876 0.213 0.231 0.231 0.341 0.369 Diet × density 0.923 0.334 0.334 0.848 0.612 0.051 22 to 28 d 29 to 35 d Diet1 BWG FI FCR BWG FI FCR  Mash 524.03B 851.28B 1.628B 666.26 1,064.26 1.605  Pelleted 50 : 50 576.32A 920.71A 1.600AB 646.06 1,084.71 1.682  Pelleted 70 : 30 597.23A 922.04A 1.546A 678.12 1,087.95 1.612 Density  13 broilers/m² 566.83 906.55 1.603 677.82 1,092.57 1.647  15 broilers/m² 564.88 889.46 1.579 649.13 1,065.38 1.619 CV, % 6.62 4.49 3.64 10.61 7.80 5.50 Diet 0.001 0.001 0.005 0.536 0.758 0.083 Density 0.876 0.213 0.231 0.231 0.341 0.369 Diet × density 0.923 0.334 0.334 0.848 0.612 0.051 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 4. Weekly Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Grower Phase of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 22 to 28 d 29 to 35 d Diet1 BWG FI FCR BWG FI FCR  Mash 524.03B 851.28B 1.628B 666.26 1,064.26 1.605  Pelleted 50 : 50 576.32A 920.71A 1.600AB 646.06 1,084.71 1.682  Pelleted 70 : 30 597.23A 922.04A 1.546A 678.12 1,087.95 1.612 Density  13 broilers/m² 566.83 906.55 1.603 677.82 1,092.57 1.647  15 broilers/m² 564.88 889.46 1.579 649.13 1,065.38 1.619 CV, % 6.62 4.49 3.64 10.61 7.80 5.50 Diet 0.001 0.001 0.005 0.536 0.758 0.083 Density 0.876 0.213 0.231 0.231 0.341 0.369 Diet × density 0.923 0.334 0.334 0.848 0.612 0.051 22 to 28 d 29 to 35 d Diet1 BWG FI FCR BWG FI FCR  Mash 524.03B 851.28B 1.628B 666.26 1,064.26 1.605  Pelleted 50 : 50 576.32A 920.71A 1.600AB 646.06 1,084.71 1.682  Pelleted 70 : 30 597.23A 922.04A 1.546A 678.12 1,087.95 1.612 Density  13 broilers/m² 566.83 906.55 1.603 677.82 1,092.57 1.647  15 broilers/m² 564.88 889.46 1.579 649.13 1,065.38 1.619 CV, % 6.62 4.49 3.64 10.61 7.80 5.50 Diet 0.001 0.001 0.005 0.536 0.758 0.083 Density 0.876 0.213 0.231 0.231 0.341 0.369 Diet × density 0.923 0.334 0.334 0.848 0.612 0.051 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large As the pellet quality is improved, chicks spend less time-consuming feed, which is represented by a reduction in activity, thereby improving energy use (greater real caloric value) and leading to greater tissue deposition [32]. McKinney and Teeter studied diets with different relationships between integral pellets and fines and determined that the effective caloric value of pelleting, which is defined as the caloric density of diet needed for birds to reach a determined body weight in relation to the determined feed conversion ratio. These authors concluded that the increase in pellet quality increases the apparent effective calorific value of the diet. Mckinney and Teeter [32] used diets containing different proportions of pellets to fines (100% pellet, 80% pellet, 60% pellet, 40% pellet, 20% pellet, and 100% fines) for broilers and found an increase in caloric effectiveness and frequency of rest since birds spent less time to consume the pelleted diets (integral pellets). The increasing proportions of integral pellets in diets (from 30% to 60% and 90%) resulted in increased feed intake and improved body weight gain [33]. Kenny [34] comparing a good pellet quality (control) in a wheat-based diet with 50% and 100% fines composition, showed that these two diets reduced the BW by 7.0% and 20%, respectively, compared to the control. When similar treatments were assessed using a corn-based diet, a similar effect on performance was shown, in which diets with 50% and 100% fines caused a reduction of 4.5% and 19% for BW and worsened the FCR by 2.2% and 6.1%, respectively. During the fifth and sixth weeks of life (Tables 4 and 5), these favorable results for feed processing were not observed (P > 0.05). However, for the evaluated period between 43 and 46 d of age, there was a significant effect of diet and stocking density. The supply of pelleted diets, independent of the proportion of fines in the diet, caused a lower (P < 0.05) feed intake without affecting body weight gain and feed conversion ratio (P > 0.05). Table 5. Weekly Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Finisher Phase of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 36 to 42 d 43 to 46 d Diet1 BWG FI FCR BWG FI FCR  Mash 604.12 1,199.25 1.992 309.71 677.38A 2.151  Pelleted 50 : 50 535.86 1,137.11 2.065 248.42 583.05B 2.324  Pelleted 70 : 30 553.27 1,119.92 2.044 276.96 589.01B 2.281 Density  13 broilers/m² 582.39 1,186.08 2.003 292.56 636.43 2.332B  15 broilers/m² 546.62 1,118.11 2.057 264.33 596.54 2.159A CV, % 13.81 8.81 7.00 21.72 12.90 7.74 Diet 0.099 0.149 0.510 0.062 0.010 0.264 Density 0.179 0.054 0.306 0.139 0.143 0.046 Diet × density 0.896 0.895 0.926 0.157 0.544 0.073 36 to 42 d 43 to 46 d Diet1 BWG FI FCR BWG FI FCR  Mash 604.12 1,199.25 1.992 309.71 677.38A 2.151  Pelleted 50 : 50 535.86 1,137.11 2.065 248.42 583.05B 2.324  Pelleted 70 : 30 553.27 1,119.92 2.044 276.96 589.01B 2.281 Density  13 broilers/m² 582.39 1,186.08 2.003 292.56 636.43 2.332B  15 broilers/m² 546.62 1,118.11 2.057 264.33 596.54 2.159A CV, % 13.81 8.81 7.00 21.72 12.90 7.74 Diet 0.099 0.149 0.510 0.062 0.010 0.264 Density 0.179 0.054 0.306 0.139 0.143 0.046 Diet × density 0.896 0.895 0.926 0.157 0.544 0.073 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 5. Weekly Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) at Finisher Phase of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 36 to 42 d 43 to 46 d Diet1 BWG FI FCR BWG FI FCR  Mash 604.12 1,199.25 1.992 309.71 677.38A 2.151  Pelleted 50 : 50 535.86 1,137.11 2.065 248.42 583.05B 2.324  Pelleted 70 : 30 553.27 1,119.92 2.044 276.96 589.01B 2.281 Density  13 broilers/m² 582.39 1,186.08 2.003 292.56 636.43 2.332B  15 broilers/m² 546.62 1,118.11 2.057 264.33 596.54 2.159A CV, % 13.81 8.81 7.00 21.72 12.90 7.74 Diet 0.099 0.149 0.510 0.062 0.010 0.264 Density 0.179 0.054 0.306 0.139 0.143 0.046 Diet × density 0.896 0.895 0.926 0.157 0.544 0.073 36 to 42 d 43 to 46 d Diet1 BWG FI FCR BWG FI FCR  Mash 604.12 1,199.25 1.992 309.71 677.38A 2.151  Pelleted 50 : 50 535.86 1,137.11 2.065 248.42 583.05B 2.324  Pelleted 70 : 30 553.27 1,119.92 2.044 276.96 589.01B 2.281 Density  13 broilers/m² 582.39 1,186.08 2.003 292.56 636.43 2.332B  15 broilers/m² 546.62 1,118.11 2.057 264.33 596.54 2.159A CV, % 13.81 8.81 7.00 21.72 12.90 7.74 Diet 0.099 0.149 0.510 0.062 0.010 0.264 Density 0.179 0.054 0.306 0.139 0.143 0.046 Diet × density 0.896 0.895 0.926 0.157 0.544 0.073 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large The probable reason for this might be that birds fed pelleted diets are more likely to remain inactive for a longer period. These birds also use less energy for consuming feed, and therefore the energy available for growth is increased. The average time spent at the feeder depends on the physical form of the feed, which could range from 56 s in pelleted feed to 114 s in a mash physical form [35]. During the last week, the environmental influence may have been preponderant in relation to diets. The experiment was conducted during the summer in a geographic region characterized by high environmental temperatures. Chickens that were fed pelleted diets and had greater growth rates, as observed at 21 d of age, were the animals that were most susceptible to metabolic disturbances due to heat stress [36]. This scenario with high temperatures generates a hyperthermia condition in the chickens, and consequently, there is greater carbon dioxide production due to increased respiratory rates, which then causes an electrolytic imbalance in the animals [37]. Once the negative effects are the most pronounced, chickens decrease intake trying to re-establish organic homeostasis. Feed form and stocking density had effects on broiler performance that were largely independent of each other. Chickens that were housed in greater densities (15/m2) presented a better (P < 0.05) feed conversion ratio when compared to chickens that were housed in lower densities during the period from 42 to 46 d (Table 5). Even though stocking density did not statistically affect feed intake and body weight gain, we observed that chickens that were housed in lower densities presented with lower numeric values for these characteristics. The performance during the grower/finisher phase, from 21 to 46 d, and during all production phases, from 1 to 46 d, was not affected by diet and stocking density, despite the greater performance that was observed for chicks supplemented with pelleted and ground diets in the starter phase (Table 6). Table 6. Cumulative Body Weight (BW), Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) From 22 to 46 d and 1 to 46 d of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 22 to 46 d 1 to 46 d Diet1 BWG FI FCR BW BWG FI FCR  Mash 2,104.38 3,792.20 1.804 3,022.44 2,942.16 4,913.30 1.671  Pelleted 50 : 50 2,006.66 3,725.60 1.864 3,021.39 2,916.88 4,852.30 1.684  Pelleted 70 : 30 2,072.64 3,718.90 1.803 3,103.36 2,995.99 4,922.30 1.646 Density  13 broilers/m² 2,108.59 3,821.63 1.822 3,100.18 3,001.14 4,959.54 1.666  15 broilers/m² 2,013.86 3,669.48 1.826 2,997.94 2,902.21 4,838.31 1.668 CV, % 9.93 6.78 4.65 7.12 7.29 5.30 2.85 Diet 0.498 0.739 0.151 0.576 0.659 0.815 0.212 Density 0.175 0.082 0.891 0.168 0.178 0.187 0.905 Diet × density 0.756 0.915 0.081 0.927 0.870 0.881 0.072 22 to 46 d 1 to 46 d Diet1 BWG FI FCR BW BWG FI FCR  Mash 2,104.38 3,792.20 1.804 3,022.44 2,942.16 4,913.30 1.671  Pelleted 50 : 50 2,006.66 3,725.60 1.864 3,021.39 2,916.88 4,852.30 1.684  Pelleted 70 : 30 2,072.64 3,718.90 1.803 3,103.36 2,995.99 4,922.30 1.646 Density  13 broilers/m² 2,108.59 3,821.63 1.822 3,100.18 3,001.14 4,959.54 1.666  15 broilers/m² 2,013.86 3,669.48 1.826 2,997.94 2,902.21 4,838.31 1.668 CV, % 9.93 6.78 4.65 7.12 7.29 5.30 2.85 Diet 0.498 0.739 0.151 0.576 0.659 0.815 0.212 Density 0.175 0.082 0.891 0.168 0.178 0.187 0.905 Diet × density 0.756 0.915 0.081 0.927 0.870 0.881 0.072 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 6. Cumulative Body Weight (BW), Body Weight Gain (BWG), Feed Intake (FI), and Feed Conversion Ratio (FCR) From 22 to 46 d and 1 to 46 d of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. 22 to 46 d 1 to 46 d Diet1 BWG FI FCR BW BWG FI FCR  Mash 2,104.38 3,792.20 1.804 3,022.44 2,942.16 4,913.30 1.671  Pelleted 50 : 50 2,006.66 3,725.60 1.864 3,021.39 2,916.88 4,852.30 1.684  Pelleted 70 : 30 2,072.64 3,718.90 1.803 3,103.36 2,995.99 4,922.30 1.646 Density  13 broilers/m² 2,108.59 3,821.63 1.822 3,100.18 3,001.14 4,959.54 1.666  15 broilers/m² 2,013.86 3,669.48 1.826 2,997.94 2,902.21 4,838.31 1.668 CV, % 9.93 6.78 4.65 7.12 7.29 5.30 2.85 Diet 0.498 0.739 0.151 0.576 0.659 0.815 0.212 Density 0.175 0.082 0.891 0.168 0.178 0.187 0.905 Diet × density 0.756 0.915 0.081 0.927 0.870 0.881 0.072 22 to 46 d 1 to 46 d Diet1 BWG FI FCR BW BWG FI FCR  Mash 2,104.38 3,792.20 1.804 3,022.44 2,942.16 4,913.30 1.671  Pelleted 50 : 50 2,006.66 3,725.60 1.864 3,021.39 2,916.88 4,852.30 1.684  Pelleted 70 : 30 2,072.64 3,718.90 1.803 3,103.36 2,995.99 4,922.30 1.646 Density  13 broilers/m² 2,108.59 3,821.63 1.822 3,100.18 3,001.14 4,959.54 1.666  15 broilers/m² 2,013.86 3,669.48 1.826 2,997.94 2,902.21 4,838.31 1.668 CV, % 9.93 6.78 4.65 7.12 7.29 5.30 2.85 Diet 0.498 0.739 0.151 0.576 0.659 0.815 0.212 Density 0.175 0.082 0.891 0.168 0.178 0.187 0.905 Diet × density 0.756 0.915 0.081 0.927 0.870 0.881 0.072 1From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Foot-Pad Dermatitis Assessment Evaluation of the foot-pad score at 21 d of age showed a greater incidence of C scores (serious and multiple lesions) in the foot-pad of chickens that received pelleted diets and were housed in greater densities (15 birds/m2). At 46 d, the incidence of FPD was different among the treatment combinations, consistently associated with stocking density. It means that within each feed form, birds housed at the highest stocking density (15 birds/m2), showed higher incidence of scores B and C compared to those housed at the lowest density (13 birds/m2) (Table 7). To confirm this, chi-square analyses were performed for both main effects (diets and stocking density). The results confirmed this assumption, as there was no significant effect for diets (P > 0.05) and there was a significant effect for stocking density (Table 8). There was a reduction in the incidence of score A paws in the order of 21.57% when stocking density was increased to 15 birds/m2. Confirming the negative effect of the highest density studied, the incidence of scores B and C was increased in 22.73% and 0.25%, respectively. It is not surprising that these lesions are a concern to the industry. Recently, chicken paws became the third most profitable part of chicken, following breast and wings [38]. FPD also jeopardizes animal welfare and food safety. Table 7. Percentage of Food-Pad Lesion of Broilers at 46 d of Age Fed Mash or Pelleted Diets, Raised in Different Stocking Densities. Treatment combination1 Score A, % Score B, % Score C, % Mash +13 broilers/m2 48.50 37.59B 13.91 Mash +15 broilers/m2 34.58 51.19A 14.24 Pelleted 50 : 50 +13 broilers/m2 44.79 44.79B 10.42 Pelleted 70 : 30 +15 broilers/m2 32.07 55.17A 12.76 Pelleted 50 : 50 +13 broilers/m2 42.58 46.48B 10.94 Pelleted 70 : 30 +15 broilers/m2 40.07 51.57A 8.36 P-value 0.221 <0.001 0.167 Treatment combination1 Score A, % Score B, % Score C, % Mash +13 broilers/m2 48.50 37.59B 13.91 Mash +15 broilers/m2 34.58 51.19A 14.24 Pelleted 50 : 50 +13 broilers/m2 44.79 44.79B 10.42 Pelleted 70 : 30 +15 broilers/m2 32.07 55.17A 12.76 Pelleted 50 : 50 +13 broilers/m2 42.58 46.48B 10.94 Pelleted 70 : 30 +15 broilers/m2 40.07 51.57A 8.36 P-value 0.221 <0.001 0.167 1Chi-square analyses performed considering the treatment combinations regardless of the three scores. N = pair of paws from 1,653 individually assessed. View Large Table 7. Percentage of Food-Pad Lesion of Broilers at 46 d of Age Fed Mash or Pelleted Diets, Raised in Different Stocking Densities. Treatment combination1 Score A, % Score B, % Score C, % Mash +13 broilers/m2 48.50 37.59B 13.91 Mash +15 broilers/m2 34.58 51.19A 14.24 Pelleted 50 : 50 +13 broilers/m2 44.79 44.79B 10.42 Pelleted 70 : 30 +15 broilers/m2 32.07 55.17A 12.76 Pelleted 50 : 50 +13 broilers/m2 42.58 46.48B 10.94 Pelleted 70 : 30 +15 broilers/m2 40.07 51.57A 8.36 P-value 0.221 <0.001 0.167 Treatment combination1 Score A, % Score B, % Score C, % Mash +13 broilers/m2 48.50 37.59B 13.91 Mash +15 broilers/m2 34.58 51.19A 14.24 Pelleted 50 : 50 +13 broilers/m2 44.79 44.79B 10.42 Pelleted 70 : 30 +15 broilers/m2 32.07 55.17A 12.76 Pelleted 50 : 50 +13 broilers/m2 42.58 46.48B 10.94 Pelleted 70 : 30 +15 broilers/m2 40.07 51.57A 8.36 P-value 0.221 <0.001 0.167 1Chi-square analyses performed considering the treatment combinations regardless of the three scores. N = pair of paws from 1,653 individually assessed. View Large Table 8. Percentage of Food-Pad Lesion of Broilers at 46 d of Age for Each Main Effect. Main effects1 Score A, % Score B, % Score C, % Diet2  Mash 41.18 44.74 14.08  Pelleted 50 : 50 38.07 50.27 11.66  Pelleted 70 : 30 41.25 49.17 9.58 P-value 0.565 0.545 0.059 Stocking density  13 broilers/m2 45.33 42.89B 11.78  15 broilers/m2 35.55 52.64A 11.81 P-value 0.087 <0.001 0.430 Main effects1 Score A, % Score B, % Score C, % Diet2  Mash 41.18 44.74 14.08  Pelleted 50 : 50 38.07 50.27 11.66  Pelleted 70 : 30 41.25 49.17 9.58 P-value 0.565 0.545 0.059 Stocking density  13 broilers/m2 45.33 42.89B 11.78  15 broilers/m2 35.55 52.64A 11.81 P-value 0.087 <0.001 0.430 1Chi-square analyses performed considering the isolated main effects regardless of the three scores. N = pair of paws from 1,653 individually assessed. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 8. Percentage of Food-Pad Lesion of Broilers at 46 d of Age for Each Main Effect. Main effects1 Score A, % Score B, % Score C, % Diet2  Mash 41.18 44.74 14.08  Pelleted 50 : 50 38.07 50.27 11.66  Pelleted 70 : 30 41.25 49.17 9.58 P-value 0.565 0.545 0.059 Stocking density  13 broilers/m2 45.33 42.89B 11.78  15 broilers/m2 35.55 52.64A 11.81 P-value 0.087 <0.001 0.430 Main effects1 Score A, % Score B, % Score C, % Diet2  Mash 41.18 44.74 14.08  Pelleted 50 : 50 38.07 50.27 11.66  Pelleted 70 : 30 41.25 49.17 9.58 P-value 0.565 0.545 0.059 Stocking density  13 broilers/m2 45.33 42.89B 11.78  15 broilers/m2 35.55 52.64A 11.81 P-value 0.087 <0.001 0.430 1Chi-square analyses performed considering the isolated main effects regardless of the three scores. N = pair of paws from 1,653 individually assessed. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large The exact process that results in FPD are not clearly known, although most researchers agree that the quality and type of litter, and stocking density are important factors in the predisposition towards FPD [38]. Similar results were obtained by authors who studied prevalence and alternative to reduce the incidence of FPD in broiler flocks [12, 39, 40]. Carcass Yield There was no significant interaction (P > 0.05) for absolute and relative weights of carcass, commercial cuts, and abdominal fat deposition (Tables 9 and 10). Table 9. Weights of Carcass, Commercial Cuts, and Abdominal Fat Deposition of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. Absolute weight, g1 Diet2 Carcass Breast Legs Wings Abdominal Fat  Mash 2,380.00 857.75 646.08 249.83 48.07  Pelleted 50 : 50 2,448.17 860.17 657.17 258.91 47.21  Pelleted 70 : 30 2,476.92 882.78 661.42 261.00 51.87 Density  13 broilers/m² 2,486.55 885.14 667.44A 265.33A 47.32  15 broilers/m² 2,392.39 848.40 642.33B 247.83B 50.88 CV, % 6.30 9.40 6.44 7.41 27.43 Diet 0.151 0.480 0.438 0.104 0.464 Density 0.018 0.058 0.014 <0.001 0.274 Diet × density 0.577 0.933 0.945 0.368 0.643 Absolute weight, g1 Diet2 Carcass Breast Legs Wings Abdominal Fat  Mash 2,380.00 857.75 646.08 249.83 48.07  Pelleted 50 : 50 2,448.17 860.17 657.17 258.91 47.21  Pelleted 70 : 30 2,476.92 882.78 661.42 261.00 51.87 Density  13 broilers/m² 2,486.55 885.14 667.44A 265.33A 47.32  15 broilers/m² 2,392.39 848.40 642.33B 247.83B 50.88 CV, % 6.30 9.40 6.44 7.41 27.43 Diet 0.151 0.480 0.438 0.104 0.464 Density 0.018 0.058 0.014 <0.001 0.274 Diet × density 0.577 0.933 0.945 0.368 0.643 1Results expressed as absolute weights in grams. N = 6 replicates of 2 bird each per treatment combination. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 9. Weights of Carcass, Commercial Cuts, and Abdominal Fat Deposition of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. Absolute weight, g1 Diet2 Carcass Breast Legs Wings Abdominal Fat  Mash 2,380.00 857.75 646.08 249.83 48.07  Pelleted 50 : 50 2,448.17 860.17 657.17 258.91 47.21  Pelleted 70 : 30 2,476.92 882.78 661.42 261.00 51.87 Density  13 broilers/m² 2,486.55 885.14 667.44A 265.33A 47.32  15 broilers/m² 2,392.39 848.40 642.33B 247.83B 50.88 CV, % 6.30 9.40 6.44 7.41 27.43 Diet 0.151 0.480 0.438 0.104 0.464 Density 0.018 0.058 0.014 <0.001 0.274 Diet × density 0.577 0.933 0.945 0.368 0.643 Absolute weight, g1 Diet2 Carcass Breast Legs Wings Abdominal Fat  Mash 2,380.00 857.75 646.08 249.83 48.07  Pelleted 50 : 50 2,448.17 860.17 657.17 258.91 47.21  Pelleted 70 : 30 2,476.92 882.78 661.42 261.00 51.87 Density  13 broilers/m² 2,486.55 885.14 667.44A 265.33A 47.32  15 broilers/m² 2,392.39 848.40 642.33B 247.83B 50.88 CV, % 6.30 9.40 6.44 7.41 27.43 Diet 0.151 0.480 0.438 0.104 0.464 Density 0.018 0.058 0.014 <0.001 0.274 Diet × density 0.577 0.933 0.945 0.368 0.643 1Results expressed as absolute weights in grams. N = 6 replicates of 2 bird each per treatment combination. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 10. Relative Weights of Carcass, Commercial Cuts, and Fat Abdominal Deposition of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. Relative weight, %1 Diet2 Carcass Breast Legs Wings Abdominal fat  Mash 79.31B 35.80 26.98 10.41 2.01  Pelleted 50 : 50 81.10A 35.48 26.86 10.68 2.02  Pelleted 70 : 30 79.86AB 35.93 26.73 10.48 2.10 Density  13 broilers/m² 80.36 35.74 26.83 10.69A 1.90  15 broilers/m² 79.82 35.73 26.87 10.36B 2.18 CV, % 2.70 5.78 4.67 4.42 29.83 Diet 0.017 0.724 0.794 0.123 0.851 Density 0.287 0.944 0.896 0.004 0.059 Diet × density 0.465 0.561 0.435 0.856 0.599 Relative weight, %1 Diet2 Carcass Breast Legs Wings Abdominal fat  Mash 79.31B 35.80 26.98 10.41 2.01  Pelleted 50 : 50 81.10A 35.48 26.86 10.68 2.02  Pelleted 70 : 30 79.86AB 35.93 26.73 10.48 2.10 Density  13 broilers/m² 80.36 35.74 26.83 10.69A 1.90  15 broilers/m² 79.82 35.73 26.87 10.36B 2.18 CV, % 2.70 5.78 4.67 4.42 29.83 Diet 0.017 0.724 0.794 0.123 0.851 Density 0.287 0.944 0.896 0.004 0.059 Diet × density 0.465 0.561 0.435 0.856 0.599 1Results expressed as a percentage of the body weight. N = 6 replicates of 2 bird each per treatment combination. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large Table 10. Relative Weights of Carcass, Commercial Cuts, and Fat Abdominal Deposition of Broilers Fed Mash and Pelleted Diets, Raised in Different Stocking Densities. Relative weight, %1 Diet2 Carcass Breast Legs Wings Abdominal fat  Mash 79.31B 35.80 26.98 10.41 2.01  Pelleted 50 : 50 81.10A 35.48 26.86 10.68 2.02  Pelleted 70 : 30 79.86AB 35.93 26.73 10.48 2.10 Density  13 broilers/m² 80.36 35.74 26.83 10.69A 1.90  15 broilers/m² 79.82 35.73 26.87 10.36B 2.18 CV, % 2.70 5.78 4.67 4.42 29.83 Diet 0.017 0.724 0.794 0.123 0.851 Density 0.287 0.944 0.896 0.004 0.059 Diet × density 0.465 0.561 0.435 0.856 0.599 Relative weight, %1 Diet2 Carcass Breast Legs Wings Abdominal fat  Mash 79.31B 35.80 26.98 10.41 2.01  Pelleted 50 : 50 81.10A 35.48 26.86 10.68 2.02  Pelleted 70 : 30 79.86AB 35.93 26.73 10.48 2.10 Density  13 broilers/m² 80.36 35.74 26.83 10.69A 1.90  15 broilers/m² 79.82 35.73 26.87 10.36B 2.18 CV, % 2.70 5.78 4.67 4.42 29.83 Diet 0.017 0.724 0.794 0.123 0.851 Density 0.287 0.944 0.896 0.004 0.059 Diet × density 0.465 0.561 0.435 0.856 0.599 1Results expressed as a percentage of the body weight. N = 6 replicates of 2 bird each per treatment combination. 2From 21 to 46 d, the experimental diets were composed by three diets: mash, pelleted with 50% of fines, and pelleted with 30% of fines. The mash diet was not submitted to thermal processing. Means followed by distinct superscript letters statistically differ by the Tukey test (P < 0.05). View Large There was a greater (P < 0.05) carcass yield of chickens that were fed pelleted diets with 50% fines in relation to chickens that received mash feed (Table 10). There is an important relationship that should be considered when evaluating the results regarding muscle deposition in carcasses and the energy level of pelleted diets. As pellet quality is improved, birds spend less time consuming feed and thus, their level of activity decreases, which then leads to lower energy expenditures. However, when the energy levels are high, as seen in this study, this excess energy can lead to high body temperatures, which can interfere negatively with heat dissipation mechanisms and consequently reduce muscle deposition. Lara et al. [41] evaluated the effect of feed processing (mash and pelleted) on yield of cuts in broilers at 45 d of age and observed similar results. Pelleted/crumble diets over pre-starter phase (1 to 7 d) influence productive performance of broilers until the end of initial phase (21 d) [42], with an effect reduction until slaughter age and no effect on carcass yield [43]. There was an influence (P < 0.05) of stocking density on the weights of carcasses, legs, and wings (Table 9). Chicks that were housed in lower densities (13 birds/m2) presented with greater absolute body weights in relation to those that were housed in high densities (15 birds/m2). Similar results (P < 0.05) were observed for wing yield (Table 10). The lack of a density effect on breast yield was previously reported by [44–46]. Otherwise, [36] observed heavier carcasses and fillets in lower stocking densities. This effect is more evident because the densities that were used by these authors were lower than those used in commercial production systems, in addition to the difference between stocking rates that were used (3.11 and 6.7 birds/m2). Several factors are involved in the evaluation of ration processing; therefore, knowledge of these factors is important so that the benefits of pelleting can be enjoyed. It is important to consider that pelleting increases ration costs and is a process of high energy and capital demand. Thus, it can influence the yield of ration production, particularly if the manufacturing process is not adequately dimensioned. Furthermore, most of the Brazilian poultry industry supports production beyond its capacity that also influences in the yield of ration production [9]. Pellet quality depends on the pelletizer and the entire manufacturing system including formulation, milling, mixture, cooling, and transport. Moreover, acclimation of the farms can have a greater impact on production results than ration processing and all the systems involved. CONCLUSIONS AND APPLICATIONS The supply of crumble pelleted diet during the initial phase (1–21 d of age) allowed for better animal performance and lower incidences of FPD. During the grower and finisher phases, pelleted diets and pellet quality did not influence animal performance. The carcass yield of chickens that received pelleted diets with 50% fines was greater than that associated with the middling diet. The reduction in stocking density resulted in greater weights of carcasses, legs, and wings, as well as wing yield of chickens at 46 d of age. Footnotes Primary Audience: Poultry Nutritionists, Flock Supervisors and Poultry Researchers REFERENCES AND NOTES 1. Gadzirayi C. 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Journal

Journal of Applied Poultry ResearchOxford University Press

Published: May 11, 2018

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