Age-related energy values of meat and bone meal for broiler chickens

Age-related energy values of meat and bone meal for broiler chickens Abstract Six hundred and eighty-four male Ross 308 broiler chicks were used to test the null hypothesis that post hatching age between day 0 and 21 does not affect utilization of energy in meat and bone meal (MBM). There were 6 replicate cages in each of 12 treatments consisting of 3 test diets (0, 40, or 80 g MBM/kg diets) at 4 feeding ages post hatching (day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 post hatching) for a total of 72 cages in a randomized complete block design. Birds were assigned to the 12 treatments on day 0, fed a standard starter diet until they were switched to the test diets on day 0, 6, 10, or 15, and the number of birds per cage for day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 were 12, 10, 8, or 8, respectively. Excreta were collected during the last 3 days of each feeding age post hatching and ileal digesta on the last day of each age. There was no interaction between dietary MBM level and feeding age post hatching for any of the response criteria. Weight gain and gain-to-feed ratio improved linearly (P < 0.001) with increasing dietary MBM and, expectedly, there was an increase (P < 0.001) in weight gain and a reduction (P < 0.001) in gain-to-feed ratio with bird feeding age post hatching. Ileal digestible energy (IDE), apparent metabolizable energy (AME), and nitrogen-corrected AME (AMEn) of the diet linearly increased (P < 0.001) with increasing dietary MBM. There were linear increases in dietary IDE (P < 0.05), AME (P < 0.001), and AMEn (P < 0.001) with bird feeding age post hatching. The IDE, ME, and MEn of MBM were determined by the regression procedure. During day 0 to 7, 6 to 11, 10 to 16, or 15 to 21, energy values increased (P < 0.05) with age and the respective IDE of MBM were 2.852, 2.962, 2.927, or 2.959 kcal/g DM. Corresponding ME of MBM were 2.909, 3.125, 3.083, or 3.075 kcal/g DM and those of MEn were 2.687, 2.887, 2.839, or 2.845 kcal/g DM. These results show that energy values of MBM increase with age post hatching and suggest the same energy value of MBM should not be used in formulating diets of broiler chickens during the first 3 weeks post hatching. INTRODUCTION Growth in early life period in animals is a critical time during which the animal must regulate nutrient supply to support growth and other metabolic functions. This regulation of nutrient supply involves both digestion and absorption of nutrients across the enterocyte brush border membrane. From hatching through the first week of life, the gut represents a small portion of the total body mass. When compared with the following 2 weeks, the first week of life is the time for maximal body growth along with corresponding demand for energy and amino acids (Obst and Diamond, 1992). During this time, the ability of the animal to extract nutrients may be limited and thus present a constraint to development. Because digestive enzyme production and absorptive capacity increase with age, the ability of animals to extract nutrients from feeds most likely increases with age and such age-related increases could be substrate-associated and therefore dependent on feed ingredient. From day 7 to 21 post hatching, there were effects of age on the total tract retention of dry matter, nitrogen, and energy, as well as dietary and ingredient ME (Olukosi et al. 2007; Stefanello et al., 2016), which are probably related to the development of digestive and absorptive capacities of the intestine, as has been demonstrated for pigs (Adeola and King, 2006). Birds undergo metabolic adaptations from embryonic yolk dependence to utilizing nutrients from exogenous feed (Noy and Sklan, 2001). The rendering of trimmings, bones, blood, heads, lean tissues, viscera, hooves, hide, feathers, and fat together with the differences in processing methods and conditions result in variations in the nutrient profile of meat and bone meal (MBM). In experiments with broiler chickens from day 14 to 21 post hatching, Bolarinwa et al. (2012) reported ME between 2.512 and 2.711 kcal/g and MEn between 2.127 and 2.345 kcal/g for MBM. Guirguis (1975) reported ME of 2.5 kcal/g MBM in older birds, whereas Oluyemi et al. (1976) reported ME of 2.14 kcal/g MBM for 9-day-old chicks. Factors such as the fat removal technique as observed by Dolz and De Blas (1992), cooking duration and temperature, and the ratio of bones to soft tissue in the MBM may also affect nutritional value. Increasing bone content has been reported by Dale (1997) and Wang and Parsons (1998) to have a negative effect on protein and energy concentration. The streamlining and standardization of processing methods and tissues processed for MBM could conceivably improve nutritional value. Because the effect of broiler chicken age during the first 21 d of life on energy value of MBM is not known, the current study was conducted to test the null hypothesis that post hatching age between day 0 and 21 does not affect utilization of energy in MBM. The objective was to determine the effect of post hatching age between day 0 and 21 on ileal digestible energy (IDE), metabolizable energy (ME), and nitrogen-corrected ME (MEn) values for broiler chickens using the regression procedure. MATERIALS AND METHODS Animals, Experimental Periods, and Test Diets Experimental procedures were in accordance with the Massey University Animal Ethics Committee guidelines. Male Ross 308 broiler chicks were purchased from a commercial hatchery, tagged, weighed individually, sorted, and assigned to day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 post hatching age on day 0 in a randomized complete block design using initial weight as a blocking factor. Birds were offered a standard starter diet (Table 1) that was formulated to contain 230 g CP and 3100 kcal ME/kg until day 0, 6, 10, or 15, when they were switched to the test diets (Table 1). There were 6 replicate cages in each of 12 treatments in a 3 × 4 factorial arrangement consisting of 3 test diets (0, 40, or 80 g MBM/kg diet, Table 1) at each of 4 different feeding ages post hatching (day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 post hatching) for a total of 72 cages. The number of birds per cage for day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 post hatching were 12, 10, 8, or 8, respectively, for a total of 684 birds. Table 1. Ingredient composition of starter diet and experimental diets formulated with meat and bone meal.     Meat and bone meal, g/kg  Item  Starter diet  0  40  80  Ingredients, g/kg   Corn  545.9  518.7  505.1  491.4   Soybean meal  360  360  350.8  341.7   Soy oil  50  50  48.7  47.5   Monocalcium phosphate  15  18.2  9  0   Limestone  15  14  7.3  0.3   Salt  4  4  4  4   DL-Methionine  3.8  3.8  3.8  3.8   L-Lysine HCl  2.9  2.9  2.9  2.9   L-Threonine  1.1  1.1  1.1  1.1   Vitamin premix1  0.8  0.8  0.8  0.8   Mineral premix2  1.5  1.5  1.5  1.5   Titanium dioxide premix3  0  25  25  25   Meat and bone meal  0  0  40  80   Total  1,000  1,000  1,000  1,000  Calculated nutrient composition, g/kg   ME, kcal/kg  3,127  3,103  3,110  3,118   CP  226  225  239  254   Ca  8.3  8.3  9.1  9.8   Total P  6.1  6.6  7.2  7.8   Non-phytate P  3.6  4.0  4.7  5.4   Phytate P  2.5  2.5  2.5  2.4   Ca:P ratio  1.4  1.3  1.3  1.3   Crude fiber  24.8  24.7  24.0  23.4   NDF  79.3  78.6  89.6  100.6   ADF  34.7  34.5  35.7  36.8   Total amino acids    Arg  14.6  14.6  15.6  16.6    His  5.9  5.8  6.1  6.3    Ile  9.2  9.2  9.5  9.8    Leu  18.9  18.9  19.6  20.3    Lys  14.3  14.3  15.1  15.8    Met  7.2  7.2  7.4  7.6    Met + Cys  10.8  10.7  11.1  11.4    Phe  10.5  10.5  10.9  11.3    Phe + Tyr  19.2  19.1  19.7  20.4    Thr  9.4  9.4  9.8  10.2    Trp  3.0  3.0  3.0  3.1    Val  10.2  10.1  10.8  11.4      Meat and bone meal, g/kg  Item  Starter diet  0  40  80  Ingredients, g/kg   Corn  545.9  518.7  505.1  491.4   Soybean meal  360  360  350.8  341.7   Soy oil  50  50  48.7  47.5   Monocalcium phosphate  15  18.2  9  0   Limestone  15  14  7.3  0.3   Salt  4  4  4  4   DL-Methionine  3.8  3.8  3.8  3.8   L-Lysine HCl  2.9  2.9  2.9  2.9   L-Threonine  1.1  1.1  1.1  1.1   Vitamin premix1  0.8  0.8  0.8  0.8   Mineral premix2  1.5  1.5  1.5  1.5   Titanium dioxide premix3  0  25  25  25   Meat and bone meal  0  0  40  80   Total  1,000  1,000  1,000  1,000  Calculated nutrient composition, g/kg   ME, kcal/kg  3,127  3,103  3,110  3,118   CP  226  225  239  254   Ca  8.3  8.3  9.1  9.8   Total P  6.1  6.6  7.2  7.8   Non-phytate P  3.6  4.0  4.7  5.4   Phytate P  2.5  2.5  2.5  2.4   Ca:P ratio  1.4  1.3  1.3  1.3   Crude fiber  24.8  24.7  24.0  23.4   NDF  79.3  78.6  89.6  100.6   ADF  34.7  34.5  35.7  36.8   Total amino acids    Arg  14.6  14.6  15.6  16.6    His  5.9  5.8  6.1  6.3    Ile  9.2  9.2  9.5  9.8    Leu  18.9  18.9  19.6  20.3    Lys  14.3  14.3  15.1  15.8    Met  7.2  7.2  7.4  7.6    Met + Cys  10.8  10.7  11.1  11.4    Phe  10.5  10.5  10.9  11.3    Phe + Tyr  19.2  19.1  19.7  20.4    Thr  9.4  9.4  9.8  10.2    Trp  3.0  3.0  3.0  3.1    Val  10.2  10.1  10.8  11.4  1 Supplied the following per kilogram of diet: vitamin A (vitamin A acetate), 12,000 IU; vitamin D3 (cholcalciferol), 4,000 IU; vitamin E (DL-α-tocopherol), 80 IU; biotin, 0.25 mg; pantothenic acid (calcium-D-pantothenate), 15 mg; cyanocobalamin, 0.02 mg; folic acid, 3.0 mg; vitamin K3 (menadione nicotinamide bisulphite), 4.0 mg; niacin (nicotinic acid), 60 mg; pyridoxine (pyridoxine hydrochloride), 10 mg; riboflavin, 9.0 mg; thiamine (thiamine mononitrate), 3.0 mg; ethoxyquin, 100 mg. 2 Supplied the following per kilogram of diet: choline (choline chloride 60%), 360 mg; Co (cobalt sulfate), 0.15 mg; Cu (copper sulfate), 6.0 mg; organic Cu (B-TRAXIM 2C G/Cu), 3.0 mg; Fe (iron sulfate), 36 mg; I (calcium iodate), 0.93 mg; Mn (manganese oxide), 60 mg; Mo (sodium molybdate), 0.15 mg; Se (sodium selenite), 0.26 mg; organic Se (enriched yeast), 0.14 mg; Zn (zinc sulfate), 48 mg; organic Zn (B-TRAXIM 2C G/Zn), 24 mg. 3 Prepared as 1 g of titanium dioxide added to 4 g of corn. View Large Table 1. Ingredient composition of starter diet and experimental diets formulated with meat and bone meal.     Meat and bone meal, g/kg  Item  Starter diet  0  40  80  Ingredients, g/kg   Corn  545.9  518.7  505.1  491.4   Soybean meal  360  360  350.8  341.7   Soy oil  50  50  48.7  47.5   Monocalcium phosphate  15  18.2  9  0   Limestone  15  14  7.3  0.3   Salt  4  4  4  4   DL-Methionine  3.8  3.8  3.8  3.8   L-Lysine HCl  2.9  2.9  2.9  2.9   L-Threonine  1.1  1.1  1.1  1.1   Vitamin premix1  0.8  0.8  0.8  0.8   Mineral premix2  1.5  1.5  1.5  1.5   Titanium dioxide premix3  0  25  25  25   Meat and bone meal  0  0  40  80   Total  1,000  1,000  1,000  1,000  Calculated nutrient composition, g/kg   ME, kcal/kg  3,127  3,103  3,110  3,118   CP  226  225  239  254   Ca  8.3  8.3  9.1  9.8   Total P  6.1  6.6  7.2  7.8   Non-phytate P  3.6  4.0  4.7  5.4   Phytate P  2.5  2.5  2.5  2.4   Ca:P ratio  1.4  1.3  1.3  1.3   Crude fiber  24.8  24.7  24.0  23.4   NDF  79.3  78.6  89.6  100.6   ADF  34.7  34.5  35.7  36.8   Total amino acids    Arg  14.6  14.6  15.6  16.6    His  5.9  5.8  6.1  6.3    Ile  9.2  9.2  9.5  9.8    Leu  18.9  18.9  19.6  20.3    Lys  14.3  14.3  15.1  15.8    Met  7.2  7.2  7.4  7.6    Met + Cys  10.8  10.7  11.1  11.4    Phe  10.5  10.5  10.9  11.3    Phe + Tyr  19.2  19.1  19.7  20.4    Thr  9.4  9.4  9.8  10.2    Trp  3.0  3.0  3.0  3.1    Val  10.2  10.1  10.8  11.4      Meat and bone meal, g/kg  Item  Starter diet  0  40  80  Ingredients, g/kg   Corn  545.9  518.7  505.1  491.4   Soybean meal  360  360  350.8  341.7   Soy oil  50  50  48.7  47.5   Monocalcium phosphate  15  18.2  9  0   Limestone  15  14  7.3  0.3   Salt  4  4  4  4   DL-Methionine  3.8  3.8  3.8  3.8   L-Lysine HCl  2.9  2.9  2.9  2.9   L-Threonine  1.1  1.1  1.1  1.1   Vitamin premix1  0.8  0.8  0.8  0.8   Mineral premix2  1.5  1.5  1.5  1.5   Titanium dioxide premix3  0  25  25  25   Meat and bone meal  0  0  40  80   Total  1,000  1,000  1,000  1,000  Calculated nutrient composition, g/kg   ME, kcal/kg  3,127  3,103  3,110  3,118   CP  226  225  239  254   Ca  8.3  8.3  9.1  9.8   Total P  6.1  6.6  7.2  7.8   Non-phytate P  3.6  4.0  4.7  5.4   Phytate P  2.5  2.5  2.5  2.4   Ca:P ratio  1.4  1.3  1.3  1.3   Crude fiber  24.8  24.7  24.0  23.4   NDF  79.3  78.6  89.6  100.6   ADF  34.7  34.5  35.7  36.8   Total amino acids    Arg  14.6  14.6  15.6  16.6    His  5.9  5.8  6.1  6.3    Ile  9.2  9.2  9.5  9.8    Leu  18.9  18.9  19.6  20.3    Lys  14.3  14.3  15.1  15.8    Met  7.2  7.2  7.4  7.6    Met + Cys  10.8  10.7  11.1  11.4    Phe  10.5  10.5  10.9  11.3    Phe + Tyr  19.2  19.1  19.7  20.4    Thr  9.4  9.4  9.8  10.2    Trp  3.0  3.0  3.0  3.1    Val  10.2  10.1  10.8  11.4  1 Supplied the following per kilogram of diet: vitamin A (vitamin A acetate), 12,000 IU; vitamin D3 (cholcalciferol), 4,000 IU; vitamin E (DL-α-tocopherol), 80 IU; biotin, 0.25 mg; pantothenic acid (calcium-D-pantothenate), 15 mg; cyanocobalamin, 0.02 mg; folic acid, 3.0 mg; vitamin K3 (menadione nicotinamide bisulphite), 4.0 mg; niacin (nicotinic acid), 60 mg; pyridoxine (pyridoxine hydrochloride), 10 mg; riboflavin, 9.0 mg; thiamine (thiamine mononitrate), 3.0 mg; ethoxyquin, 100 mg. 2 Supplied the following per kilogram of diet: choline (choline chloride 60%), 360 mg; Co (cobalt sulfate), 0.15 mg; Cu (copper sulfate), 6.0 mg; organic Cu (B-TRAXIM 2C G/Cu), 3.0 mg; Fe (iron sulfate), 36 mg; I (calcium iodate), 0.93 mg; Mn (manganese oxide), 60 mg; Mo (sodium molybdate), 0.15 mg; Se (sodium selenite), 0.26 mg; organic Se (enriched yeast), 0.14 mg; Zn (zinc sulfate), 48 mg; organic Zn (B-TRAXIM 2C G/Zn), 24 mg. 3 Prepared as 1 g of titanium dioxide added to 4 g of corn. View Large Test diets were based on corn-soybean meal in which corn, soybean meal, and soy oil were used as the sources of energy and MBM was added at 0, 40, or 80 g/kg diet to partly replace corn, soybean meal, and soy oil in a manner that maintained the same ratio of corn, soybean meal, and soy oil across the test diets (Table 1), which is important for the analysis (Zhang and Adeola, 2017a,b). These ratios were 1.4, 7.2, and 10.4 for corn: soybean meal, soybean meal:soy oil, and corn:soy oil, respectively. Because of the contribution of Ca and P from MBM, dietary levels of monocalcium phosphate and limestone were adjusted to maintain a total Ca:total P ratio of 1.3:1 across the 3 test diets (Table 1). Titanium dioxide was incorporated into the test diets as an indigestible marker at 5 g/kg on an as-fed basis. Sampling Procedures and Processing During day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 feeding ages post hatching, excreta collection trays underneath the cages were lined with waxed paper on day 4, 8, 13, or 18, respectively. Fresh excreta samples were collected twice daily during the subsequent 3 days, pooled by cage, and stored at –20°C until freeze-dried and ground. On day 7, 11, 16, or 21 post hatching, birds assigned to day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 feeding ages post hatching, respectively, were euthanized by intravenous injection of sodium pentobarbitone (Provet NZ Pty. Ltd., Auckland, New Zealand) at 0.5 mL/kg BW. Ileal digesta in the distal two-thirds from the Meckel's diverticulum to approximately 2 cm cranial to the ileo-cecal junction from all birds in each cage were flushed with distilled water into plastic bags, pooled by cage, and stored at –20°C until freeze-dried and ground. Pooled excreta and ileal digesta were freeze-dried (Model 0610, Cuddon Engineering, Blenheim, New Zealand), and the diet, excreta, and ileal digesta were subsequently ground to a homogenous mixture through a 0.50-mm screen and stored at 4°C until laboratory analysis. Analyses Samples of ground diets, excreta, and ileal digesta were analyzed for dry matter (DM), titanium (Ti), gross energy, and N. Ground MBM sample was analyzed for DM, Ti, gross energy, and N, crude fat, Ca, P, amino acids, and particle size. All analyses were conducted in an ISO17025 accredited laboratory (Nutrition Laboratory, Massey University). Dry matter content was determined using standard procedures (methods 930.15 and 925.10; AOAC International, 2005). Gross energy was determined using an adiabatic bomb calorimeter (Gallenkamp Autobomb, London, UK) standardized with benzoic acid. Nitrogen content was determined by the combustion method using a CNS-2000 carbon, nitrogen and sulfur analyzer (LECO Corporation, St. Joseph, MI). Fat content was determined using the Soxhlet extraction procedure (method 991.36; AOAC International, 2005). Samples were assayed for Ti on a UV spectrophotometer following the method of Short et al. (1996). Amino acids were determined as described by Ravindran et al. (2009). Briefly, the samples were hydrolyzed with 6 N HCl (containing phenol) for 24 h at 110 ± 2°C in glass tubes sealed under vacuum. Amino acids were detected on a Waters ion-exchange HPLC system, and the chromatograms were integrated using dedicated software (Millennium, Version 3.05.01, Waters, Millipore, Milford, MA) with the AA identified and quantified using a standard AA mixture (Product no. A2908, Sigma, St. Louis, MO). The HPLC system consisted of an ion-exchange column, two 510 pumps, Waters 715 ultra-WISP sample processor, a column heater, a post column reaction coil heater, a ninhydrin pump, and a dual wavelength detector. Amino acids were eluted by a gradient of pH 3.3 sodium citrate eluent to pH 9.8 sodium borate eluent at a flow rate of 0.4 mL/min and a column temperature of 60°C. Cysteine and methionine were analyzed as cysteic acid and methionine sulfone, respectively, by oxidation with performic acid for 16 h at 0°C and neutralization with hydrobromic acid prior to hydrolysis. For mineral analysis, the samples were wet acid digested with nitric and perchloric acid mixture, and concentrations of P and Ca were determined by Inductively Coupled Plasma-Optical Emission Spectroscopy using a Thermo Jarrell Ash IRIS instrument (Thermo Jarrell Ash Corporation, Franklin, MA). The dry sieving method was used to determine the particle size distribution of MBM sample using the method described by Baker and Herrman (2002). Calculations and Statistical Analysis The ileal digestibility and total tract metabolizability coefficients (C) of nutrients and energy were determined (McCormick et al., 2017; Zhang and Adeola, 2017) and calculated as C = 1 − [(Cd/Co) × (Eo/Ed)], where Cd is the concentration of Ti in the diet; Co is the concentration of Ti in the ileal digesta or excreta output; Eo is the concentration of nutrient or energy in the ileal digesta or excreta output; and Ed is the concentration of nutrient or energy in the diet. The IDE (kcal/kg) or AME (kcal/g) of the diets were calculated as the product of C and the gross energy concentration (kcal/g) of the diet. Because catabolic compounds in excreted N can contribute to energy loss, ME was corrected to zero N retention using a factor of 8.22 kcal/g (Hill and Anderson, 1958) as MEn = ME − (8.22 × Nret), where Nret is N retention in g/g of DM intake. The Nret was calculated as Nret = Ni – (No × Cd/Co), where Ni and No are the N concentrations (g/g of DM) in the diet and excreta, respectively. The C of IDE, ME, or MEn for reference diet (0 g MBM/kg), test diets (40 or 80 g MBM/kg), and MBM are Crd, Ctd, and Cmbm, respectively. The definition that the test diet energy consists of energy from reference diet (0 g MBM/kg) and the energy from MBM make the sum of proportional contribution of energy of the reference diet and the test ingredient equal to 1: Prd + Pmbm = 1, where Prd and Pmbm represent the proportion of energy contribution from reference diet and MBM, respectively. The assumption of additivity in diet formulation gives: Ctd = (Crd × Prd) + (Cmbm × Pmbm); solving for Cmbm gives: Cmbm = [Ctd − (Crd × Prd)]/Pmbm; substituting 1− Pmbm for Prd gives: Cmbm = [Crd + (Ctd − Crd)/Pmbm]. The product of Cmbm at each level of MBM substitution rate (0, 40, or 80 g/kg), grams of dry MBM intake (product of 0, 0.04, or 0.08 and dry feed intake), and the gross energy of test ingredient are the MBM-associated IDE, ME, or MEn in kilocalories (Bolarinwa and Adeola, 2012). The data were analyzed as a 3 × 4 factorial arrangement in a randomized complete block design using the GLM of SAS (SAS Inst. Inc., Cary, NC). The model included two main effects of dietary MBM level (0, 40, or 80 g/kg) with 2 degrees of freedom (df), feeding age post hatching (day 0 to 7, 6 to 11, 10 to 16, or 15 to 21) with 3 df, and the interaction effects with 6 df as fixed effects, and block with 5 df as a random effect. Cage served as the experimental unit for all statistical analyses. Where there was no interaction between dietary MBM level and feeding age post hatching in the initial analyses, interaction term was pooled into the error term. Main effect means were separated using linear and quadratic contrasts. Regression of the MBM-associated IDE, ME, or MEn intake in kilocalories against grams of MBM intake for cage of birds was conducted. The SLOPE and INTERCEPT functions of Microsoft Office Excel 2010 (Microsoft Corp., Redmond, WA) were used to generate the respective slopes and intercepts from 3 cages of 0, 40, or 80 g MBM/kg diet in each of 6 blocks. One-way ANOVA was then performed to determine the differences in slopes among the 4 feeding ages post hatching of day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 using the PROC GLM of SAS. Feeding age post hatching was considered an independent variable, whereas the slope was used as dependent variable (Adeola and Kong, 2014). Statistical significance was determined at a probability level of 0.05. RESULTS AND DISCUSSION Birds remained healthy throughout the experiment and 6 of the 684 birds that were started on the study died from causes unrelated to the experimental treatments. Table 2 provides the analyzed nutritional characteristics of the corn, soybean meal, limestone, and monocalcium phosphate used in starter and experimental diets as well as those of the meat and bone meal. The analyzed gross energy of corn (3.9 Mcal/kg) and the analyzed N of soybean meal (74 g/kg) are similar to the average values previously reported (NRC, 2012), but the N in corn at 1.95 g/kg and energy in soybean meal at 4.1 Mcal/kg are higher and lower, respectively, than the previously reported (NRC, 2012) average values. Analyzed Ca in limestone is consistent, but Ca and P in monocalcium phosphate are lower than expected. Nutritional characteristics, including N, amino acids, crude fat, Ca, and P of MBM presented in Table 2, are similar to the average values reported in NRC (2012) for MBM containing more than 4% P. Furthermore, the N, Ca, and P are in the range of values in Anwar et al. (2015, 2016). The gross energy of the MBM sample at 3.7 Mcal/kg, assessed for energy value in the current broiler chicken study, is in the range of values previously reported for a variety of MBM samples (Adedokun and Adeola, 2005a,b; Olukosi and Adeola, 2009; Kerr et al., 2017). Geometric mean diameter of the MBM sample was 533 μm with SD of 1.9 based on 3 observations (Table 2). For the particle size distribution, approximately 75% of the MBM sample used was between 250 and 1,000 μm with more than 29% in the particle size bracket of 500 and 1,000 μm and the geometric mean diameter between 250 and 500 μm accounted for slightly more than 45%. The geometric mean diameter of 533 μm for the MBM sample used in the current study is smaller than and the particle size distribution is different from those reported by Anwar et al. (2015, 2016) for 7 MBM samples, but both the geometric mean diameter and particle size distribution are similar to those reported for 1 of the 3 MBM samples in Mutucumarana et al. (2015). Table 2. Nutritional characteristics of the test ingredient—meat and bone meal, corn, soybean meal, limestone and monocalcium phosphate used in starter and experimental diets on an as-is basis. Item, g/kg  Meat and bone meal  Corn  Soybean meal  Limestone  Monocalcium phosphate  DM  925.1  885.4  892.4  999  943.6  Gross energy (kcal/kg)  3,678  3,873  4,113      N  78.8  15.3  74.1      Crude fat  114.5          Calcium  107.7      370.9  113.1  Phosphorus  53.1      0.3  154.5  Indispensable AA   Arg  34.2           His  8.8           Ile  12.9           Leu  29.6           Lys  26.1           Met  7.8           Phe  16.9           Thr  16.0           Val  21.9          Dispensable AA             Ala  35.5           Asp  36.2           Cys  4.9           Glu  55.8           Gly  70.3           Pro  42.4           Ser  19.8           Tyr  10.9          Particle size             Geometric mean diameter (GMD), μm  533           GMD standard deviation, μm  1.9          Particle size distribution, %             >2,000 μm  3.71           1,000 to 2,000 μm  16.2           500 to 1,000 μm  28.66           250 to 500 μm  45.71           125 to 250 μm  5.4           75 to 125 μm  0.12           <75 μm  0.02          Item, g/kg  Meat and bone meal  Corn  Soybean meal  Limestone  Monocalcium phosphate  DM  925.1  885.4  892.4  999  943.6  Gross energy (kcal/kg)  3,678  3,873  4,113      N  78.8  15.3  74.1      Crude fat  114.5          Calcium  107.7      370.9  113.1  Phosphorus  53.1      0.3  154.5  Indispensable AA   Arg  34.2           His  8.8           Ile  12.9           Leu  29.6           Lys  26.1           Met  7.8           Phe  16.9           Thr  16.0           Val  21.9          Dispensable AA             Ala  35.5           Asp  36.2           Cys  4.9           Glu  55.8           Gly  70.3           Pro  42.4           Ser  19.8           Tyr  10.9          Particle size             Geometric mean diameter (GMD), μm  533           GMD standard deviation, μm  1.9          Particle size distribution, %             >2,000 μm  3.71           1,000 to 2,000 μm  16.2           500 to 1,000 μm  28.66           250 to 500 μm  45.71           125 to 250 μm  5.4           75 to 125 μm  0.12           <75 μm  0.02          View Large Table 2. Nutritional characteristics of the test ingredient—meat and bone meal, corn, soybean meal, limestone and monocalcium phosphate used in starter and experimental diets on an as-is basis. Item, g/kg  Meat and bone meal  Corn  Soybean meal  Limestone  Monocalcium phosphate  DM  925.1  885.4  892.4  999  943.6  Gross energy (kcal/kg)  3,678  3,873  4,113      N  78.8  15.3  74.1      Crude fat  114.5          Calcium  107.7      370.9  113.1  Phosphorus  53.1      0.3  154.5  Indispensable AA   Arg  34.2           His  8.8           Ile  12.9           Leu  29.6           Lys  26.1           Met  7.8           Phe  16.9           Thr  16.0           Val  21.9          Dispensable AA             Ala  35.5           Asp  36.2           Cys  4.9           Glu  55.8           Gly  70.3           Pro  42.4           Ser  19.8           Tyr  10.9          Particle size             Geometric mean diameter (GMD), μm  533           GMD standard deviation, μm  1.9          Particle size distribution, %             >2,000 μm  3.71           1,000 to 2,000 μm  16.2           500 to 1,000 μm  28.66           250 to 500 μm  45.71           125 to 250 μm  5.4           75 to 125 μm  0.12           <75 μm  0.02          Item, g/kg  Meat and bone meal  Corn  Soybean meal  Limestone  Monocalcium phosphate  DM  925.1  885.4  892.4  999  943.6  Gross energy (kcal/kg)  3,678  3,873  4,113      N  78.8  15.3  74.1      Crude fat  114.5          Calcium  107.7      370.9  113.1  Phosphorus  53.1      0.3  154.5  Indispensable AA   Arg  34.2           His  8.8           Ile  12.9           Leu  29.6           Lys  26.1           Met  7.8           Phe  16.9           Thr  16.0           Val  21.9          Dispensable AA             Ala  35.5           Asp  36.2           Cys  4.9           Glu  55.8           Gly  70.3           Pro  42.4           Ser  19.8           Tyr  10.9          Particle size             Geometric mean diameter (GMD), μm  533           GMD standard deviation, μm  1.9          Particle size distribution, %             >2,000 μm  3.71           1,000 to 2,000 μm  16.2           500 to 1,000 μm  28.66           250 to 500 μm  45.71           125 to 250 μm  5.4           75 to 125 μm  0.12           <75 μm  0.02          View Large Initial statistical analysis of the growth performance data revealed the absence of interaction between dietary MBM concentration and feeding age post hatching. Therefore, the df and sums of squares of the interaction term were pooled into the error term. Thus, the body weight (BW) gain, feed intake, and gain-to-feed ratio data presented in Table 3 are the main effects of dietary MBM concentration and feeding age post hatching. Proportional substitution of corn, soybean meal, and soy oil, which are the energy-contributing ingredients in the reference diet, with 0, 40, or 80 g MBM/kg diet linearly improved (P < 0.001) weight gain and gain-to-feed ratio (Table 3). Dietary protein and amino acids increased with increasing addition of MBM. In addition, both dietary non-phytate P and Ca increased with increasing supplementation of MBM. It is not known whether the improvement in weight gain and gain-to-feed ratio in the current study resulted from one of or a combination of the increase in dietary amino acids, P, and Ca. Feeding a 216 g CP/kg corn-soybean meal-based diet, Drewyor and Waldroup (2000) reported that substitution of 75 g high-ash MBM/kg diet improved BW by 8%, which was attributed to an increase in dietary non-phytate P from 4.5 to 5.5 g/kg. There were the expected and predictable increases (P < 0.001) in weight gain, feed intake, and gain-to-feed ratio with increasing feeding age post hatching (Table 3). Except for the feeding age post hatching between day 0 and 7, where weight gain, feed intake, and gain-to-feed ratio were approximately 97.5% of the Aviagen (2014) Ross 308 broiler performance objectives, subsequent growth performance for day 6 to 11, 10 to 16, or 15 to 21 feeding ages post hatching data were numerically superior to Aviagen (2014) Ross 308 broiler performance objectives. Table 3. Growth performance response to the main effect of dietary meat and bone meal and feeding age post hatching.   Weight gain,  Feed intake,  Gain/feed,  Item  g  g  g/kg  Dietary meat and bone meal (diet), g/kg1   0  269  318  890   40  277  314  927   80  297  320  976  Feeding age post hatching (age), d2   0 to 7  143  133  1,076   6 to 11  229  236  972   10 to 16  314  370  851   15 to 21  438  531  826  SD  17.1  17.3  39.4   P-value    Diet  <0.001  0.421  <0.001     Linear effect of diet  <0.001  0.560  <0.001     Quadratic effect of diet  0.136  0.240  0.516    Age  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001     Quadratic effect of age  0.019  <0.001  <0.001    Weight gain,  Feed intake,  Gain/feed,  Item  g  g  g/kg  Dietary meat and bone meal (diet), g/kg1   0  269  318  890   40  277  314  927   80  297  320  976  Feeding age post hatching (age), d2   0 to 7  143  133  1,076   6 to 11  229  236  972   10 to 16  314  370  851   15 to 21  438  531  826  SD  17.1  17.3  39.4   P-value    Diet  <0.001  0.421  <0.001     Linear effect of diet  <0.001  0.560  <0.001     Quadratic effect of diet  0.136  0.240  0.516    Age  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001     Quadratic effect of age  0.019  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 3. Growth performance response to the main effect of dietary meat and bone meal and feeding age post hatching.   Weight gain,  Feed intake,  Gain/feed,  Item  g  g  g/kg  Dietary meat and bone meal (diet), g/kg1   0  269  318  890   40  277  314  927   80  297  320  976  Feeding age post hatching (age), d2   0 to 7  143  133  1,076   6 to 11  229  236  972   10 to 16  314  370  851   15 to 21  438  531  826  SD  17.1  17.3  39.4   P-value    Diet  <0.001  0.421  <0.001     Linear effect of diet  <0.001  0.560  <0.001     Quadratic effect of diet  0.136  0.240  0.516    Age  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001     Quadratic effect of age  0.019  <0.001  <0.001    Weight gain,  Feed intake,  Gain/feed,  Item  g  g  g/kg  Dietary meat and bone meal (diet), g/kg1   0  269  318  890   40  277  314  927   80  297  320  976  Feeding age post hatching (age), d2   0 to 7  143  133  1,076   6 to 11  229  236  972   10 to 16  314  370  851   15 to 21  438  531  826  SD  17.1  17.3  39.4   P-value    Diet  <0.001  0.421  <0.001     Linear effect of diet  <0.001  0.560  <0.001     Quadratic effect of diet  0.136  0.240  0.516    Age  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001     Quadratic effect of age  0.019  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 4 shows the main effects of dietary MBM concentration and feeding age post hatching on ileal DM, N, and energy digestibility as there were no interactions between dietary MBM concentration and feeding age post hatching for those response criteria. When 0, 40, or 80 g MBM/kg diet were proportionally substituted with corn, soybean meal, and soy oil, there were responses (P < 0.01) in ileal digestibility of DM, N, and energy as well as IDE. Furthermore, responses to dietary substitution were quadratic (P < 0.01), whereas only the responses in ileal digestibility of N and IDE were linear (P < 0.01). There were both linear and quadratic decreases (P < 0.05) in ileal digestibility of N, and energy as well as IDE with advancing age, but only a linear (P < 0.05) response in ileal digestibility of DM to age (Table 4). Corn, soybean meal, and MBM supply N in the experimental diets with MBM proportionally replacing corn and soybean meal. Comparative ileal digestibility of N in studies (Bolarinwa et al., 2012; Adedokun et el., 2014) has shown lower N digestibility in MBM than soybean meal, and thus the reduction in ileal N digestibility with proportional substitution of 0, 40, or 80 g MBM/kg into the diets. As with growth performance and ileal DM, N, and energy utilization, there was no interaction between dietary MBM concentration and feeding age post hatching. Thus, the main effects of dietary MBM concentration and feeding age post hatching on total tract DM, N, and energy utilization responses are presented in Table 5. Proportionally substituting 0, 40, or 80 g MBM/kg into the diets resulted in linear effects (P < 0.01) of diet on AME, AMEn, and total tract retention of N. Total tract retention of N was linearly increased (P < 0.05) with feeding age post hatching. In addition, there were quadratic increases (P < 0.001) in metabolizability of energy, AME, and AMEn with increase in feeding age post hatching. There are no studies reported in the literature on age-related energy utilization responses of broiler chickens to MBM supplementation. For diets and bakery meal, age-related increases in energy utilization that are similar to observations in the current study have been reported (Sulistiyanto et al., 1999; Olukosi et al. 2007; Stefanello et al., 2016). Efficiency with which nitrogen and energy are utilized for BW gain is presented in Tables 6 and 7, respectively. Although there were predictable effects of diet on nitrogen intake (due to dietary nitrogen concentration), proportional substitution of corn, soybean meal, and soy oil with 0, 40, or 80 g MBM/kg diet did not affect the efficiency of ileal digestible N intake for BW gain. Increase in N intake as total, digestible, or retainable did not affect the efficiency of utilization for BW gain, which concurs with previous reports (Xue et al., 2016; Adedokun and Adeola, 2017). Efficiency of IDE, AME, and AMEn utilization for BW gain were linearly (P < 0.001) improved with the addition of 0, 40, or 80 g MBM/kg diet (Table 7). There were both linear and quadratic reductions (P < 0.001) in the efficiency of utilization of intakes of ileal digestible nitrogen, retainable nitrogen, IDE, and AME for BW gain with feeding age post hatching. Table 4. Ileal dry matter (DM), nitrogen (N), and energy digestibility responses to dietary meat and bone meal and feeding age post hatching.   Ileal DM  Ileal  Ileal energy  Ileal digestible    digestibility,  N digestibility,  digestibility,  energy,  Item  g/g DM  g/g N  kcal/kcal  kcal/g DM  Dietary meat and bone meal, (diet) g/kg1   0  0.709  0.831  0.735  3.337   40  0.694  0.809  0.724  3.329   80  0.706  0.809  0.734  3.405  Feeding age post hatching (age), d2   0 to 7  0.708  0.828  0.732  3.361   6 to 11  0.703  0.827  0.735  3.376   10 to 16  0.707  0.815  0.734  3.374   15 to 21  0.692  0.796  0.722  3.372  SD  0.0134  0.0145  0.0134  0.0613   P-value    Diet  <0.001  <0.001  <0.01  <0.01     Linear effect of diet  0.391  <0.001  0.618  <0.01     Quadratic effect of diet  <0.001  <0.01  <0.01  <0.01    Age  <0.01  <0.001  0.019  0.018     Linear effect of age  <0.01  <0.001  0.034  0.034     Quadratic effect of age  0.116  0.025  0.019  0.018    Ileal DM  Ileal  Ileal energy  Ileal digestible    digestibility,  N digestibility,  digestibility,  energy,  Item  g/g DM  g/g N  kcal/kcal  kcal/g DM  Dietary meat and bone meal, (diet) g/kg1   0  0.709  0.831  0.735  3.337   40  0.694  0.809  0.724  3.329   80  0.706  0.809  0.734  3.405  Feeding age post hatching (age), d2   0 to 7  0.708  0.828  0.732  3.361   6 to 11  0.703  0.827  0.735  3.376   10 to 16  0.707  0.815  0.734  3.374   15 to 21  0.692  0.796  0.722  3.372  SD  0.0134  0.0145  0.0134  0.0613   P-value    Diet  <0.001  <0.001  <0.01  <0.01     Linear effect of diet  0.391  <0.001  0.618  <0.01     Quadratic effect of diet  <0.001  <0.01  <0.01  <0.01    Age  <0.01  <0.001  0.019  0.018     Linear effect of age  <0.01  <0.001  0.034  0.034     Quadratic effect of age  0.116  0.025  0.019  0.018  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 4. Ileal dry matter (DM), nitrogen (N), and energy digestibility responses to dietary meat and bone meal and feeding age post hatching.   Ileal DM  Ileal  Ileal energy  Ileal digestible    digestibility,  N digestibility,  digestibility,  energy,  Item  g/g DM  g/g N  kcal/kcal  kcal/g DM  Dietary meat and bone meal, (diet) g/kg1   0  0.709  0.831  0.735  3.337   40  0.694  0.809  0.724  3.329   80  0.706  0.809  0.734  3.405  Feeding age post hatching (age), d2   0 to 7  0.708  0.828  0.732  3.361   6 to 11  0.703  0.827  0.735  3.376   10 to 16  0.707  0.815  0.734  3.374   15 to 21  0.692  0.796  0.722  3.372  SD  0.0134  0.0145  0.0134  0.0613   P-value    Diet  <0.001  <0.001  <0.01  <0.01     Linear effect of diet  0.391  <0.001  0.618  <0.01     Quadratic effect of diet  <0.001  <0.01  <0.01  <0.01    Age  <0.01  <0.001  0.019  0.018     Linear effect of age  <0.01  <0.001  0.034  0.034     Quadratic effect of age  0.116  0.025  0.019  0.018    Ileal DM  Ileal  Ileal energy  Ileal digestible    digestibility,  N digestibility,  digestibility,  energy,  Item  g/g DM  g/g N  kcal/kcal  kcal/g DM  Dietary meat and bone meal, (diet) g/kg1   0  0.709  0.831  0.735  3.337   40  0.694  0.809  0.724  3.329   80  0.706  0.809  0.734  3.405  Feeding age post hatching (age), d2   0 to 7  0.708  0.828  0.732  3.361   6 to 11  0.703  0.827  0.735  3.376   10 to 16  0.707  0.815  0.734  3.374   15 to 21  0.692  0.796  0.722  3.372  SD  0.0134  0.0145  0.0134  0.0613   P-value    Diet  <0.001  <0.001  <0.01  <0.01     Linear effect of diet  0.391  <0.001  0.618  <0.01     Quadratic effect of diet  <0.001  <0.01  <0.01  <0.01    Age  <0.01  <0.001  0.019  0.018     Linear effect of age  <0.01  <0.001  0.034  0.034     Quadratic effect of age  0.116  0.025  0.019  0.018  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 5. Total tract dry matter (DM), nitrogen (N), and energy utilization responses to dietary meat and bone meal and feeding age post hatching.   Total tract DM  Total tract N  Total tract N  Energy  N-corrected energy        retention,  retention,  retention,  metabolizability,  metabolizability,  AME,  AMEn,  Item  g/g DM  g/g N  g/g DM intake  kcal/kcal  kcal/kcal  kcal/g  kcal/g  Dietary meat and bone meal (diet), g/kg1   0  0.724  0.715  0.029  0.759  0.706  3.443  3.203   40  0.712  0.691  0.030  0.751  0.698  3.457  3.210   80  0.725  0.701  0.032  0.762  0.705  3.538  3.273  Feeding age post hatching (age), d2   0 to 7  0.707  0.699  0.030  0.736  0.682  3.380  3.131   6 to 11  0.738  0.732  0.032  0.774  0.717  3.556  3.295   10 to 16  0.712  0.676  0.029  0.755  0.702  3.466  3.225   15 to 21  0.724  0.703  0.030  0.765  0.711  3.515  3.265  SD  0.0163  0.0210  0.0009  0.0142  0.0128  0.0651  0.0589   P-value    Diet  0.013  <0.001  <0.001  0.029  0.059  <0.001  <0.001     Linear effect of diet  0.886  0.021  <0.001  0.398  0.847  <0.001  <0.001     Quadratic effect of diet  <0.01  <0.01  <0.01  0.012  0.018  0.044  0.065    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  0.199  0.033  0.305  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  0.039  0.898  0.876  <0.001  <0.001  <0.001  <0.001    Total tract DM  Total tract N  Total tract N  Energy  N-corrected energy        retention,  retention,  retention,  metabolizability,  metabolizability,  AME,  AMEn,  Item  g/g DM  g/g N  g/g DM intake  kcal/kcal  kcal/kcal  kcal/g  kcal/g  Dietary meat and bone meal (diet), g/kg1   0  0.724  0.715  0.029  0.759  0.706  3.443  3.203   40  0.712  0.691  0.030  0.751  0.698  3.457  3.210   80  0.725  0.701  0.032  0.762  0.705  3.538  3.273  Feeding age post hatching (age), d2   0 to 7  0.707  0.699  0.030  0.736  0.682  3.380  3.131   6 to 11  0.738  0.732  0.032  0.774  0.717  3.556  3.295   10 to 16  0.712  0.676  0.029  0.755  0.702  3.466  3.225   15 to 21  0.724  0.703  0.030  0.765  0.711  3.515  3.265  SD  0.0163  0.0210  0.0009  0.0142  0.0128  0.0651  0.0589   P-value    Diet  0.013  <0.001  <0.001  0.029  0.059  <0.001  <0.001     Linear effect of diet  0.886  0.021  <0.001  0.398  0.847  <0.001  <0.001     Quadratic effect of diet  <0.01  <0.01  <0.01  0.012  0.018  0.044  0.065    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  0.199  0.033  0.305  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  0.039  0.898  0.876  <0.001  <0.001  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 5. Total tract dry matter (DM), nitrogen (N), and energy utilization responses to dietary meat and bone meal and feeding age post hatching.   Total tract DM  Total tract N  Total tract N  Energy  N-corrected energy        retention,  retention,  retention,  metabolizability,  metabolizability,  AME,  AMEn,  Item  g/g DM  g/g N  g/g DM intake  kcal/kcal  kcal/kcal  kcal/g  kcal/g  Dietary meat and bone meal (diet), g/kg1   0  0.724  0.715  0.029  0.759  0.706  3.443  3.203   40  0.712  0.691  0.030  0.751  0.698  3.457  3.210   80  0.725  0.701  0.032  0.762  0.705  3.538  3.273  Feeding age post hatching (age), d2   0 to 7  0.707  0.699  0.030  0.736  0.682  3.380  3.131   6 to 11  0.738  0.732  0.032  0.774  0.717  3.556  3.295   10 to 16  0.712  0.676  0.029  0.755  0.702  3.466  3.225   15 to 21  0.724  0.703  0.030  0.765  0.711  3.515  3.265  SD  0.0163  0.0210  0.0009  0.0142  0.0128  0.0651  0.0589   P-value    Diet  0.013  <0.001  <0.001  0.029  0.059  <0.001  <0.001     Linear effect of diet  0.886  0.021  <0.001  0.398  0.847  <0.001  <0.001     Quadratic effect of diet  <0.01  <0.01  <0.01  0.012  0.018  0.044  0.065    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  0.199  0.033  0.305  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  0.039  0.898  0.876  <0.001  <0.001  <0.001  <0.001    Total tract DM  Total tract N  Total tract N  Energy  N-corrected energy        retention,  retention,  retention,  metabolizability,  metabolizability,  AME,  AMEn,  Item  g/g DM  g/g N  g/g DM intake  kcal/kcal  kcal/kcal  kcal/g  kcal/g  Dietary meat and bone meal (diet), g/kg1   0  0.724  0.715  0.029  0.759  0.706  3.443  3.203   40  0.712  0.691  0.030  0.751  0.698  3.457  3.210   80  0.725  0.701  0.032  0.762  0.705  3.538  3.273  Feeding age post hatching (age), d2   0 to 7  0.707  0.699  0.030  0.736  0.682  3.380  3.131   6 to 11  0.738  0.732  0.032  0.774  0.717  3.556  3.295   10 to 16  0.712  0.676  0.029  0.755  0.702  3.466  3.225   15 to 21  0.724  0.703  0.030  0.765  0.711  3.515  3.265  SD  0.0163  0.0210  0.0009  0.0142  0.0128  0.0651  0.0589   P-value    Diet  0.013  <0.001  <0.001  0.029  0.059  <0.001  <0.001     Linear effect of diet  0.886  0.021  <0.001  0.398  0.847  <0.001  <0.001     Quadratic effect of diet  <0.01  <0.01  <0.01  0.012  0.018  0.044  0.065    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  0.199  0.033  0.305  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  0.039  0.898  0.876  <0.001  <0.001  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 6. Efficiency of utilization of leal digestible nitrogen and retainable nitrogen intake for body weight gain.   Nitrogen  Ileal digestible  Retainable nitrogen  Weight gain/ileal digestible  Weight gain/retainable  Item  intake, g  nitrogen intake, g  intake, g  nitrogen intake, g/g  nitrogen intake, g/g  Dietary meat and bone meal (diet), g/kg1   0  11.77  9.70  8.37  28.91  33.58   40  12.18  9.80  8.38  29.49  34.58   80  13.18  10.57  9.23  29.29  33.88  Feeding age post hatching (age), d2   0 to 7  5.17  4.28  3.61  33.33  39.48   6 to 11  9.18  7.59  6.71  30.16  34.09   10 to 16  14.44  11.77  9.76  26.81  32.29   15 to 21  20.69  16.46  14.55  26.62  30.19  SD  0.751  0.616  0.678  1.383  1.586   P-value    Diet  <0.001  <0.001  <0.001  0.339  0.089     Linear effect of diet  <0.001  <0.001  <0.001  0.341  0.527     Quadratic effect of diet  0.122  0.033  <0.01  0.262  0.035    Age     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.01  0.071  <0.01  <0.001  <0.001    Nitrogen  Ileal digestible  Retainable nitrogen  Weight gain/ileal digestible  Weight gain/retainable  Item  intake, g  nitrogen intake, g  intake, g  nitrogen intake, g/g  nitrogen intake, g/g  Dietary meat and bone meal (diet), g/kg1   0  11.77  9.70  8.37  28.91  33.58   40  12.18  9.80  8.38  29.49  34.58   80  13.18  10.57  9.23  29.29  33.88  Feeding age post hatching (age), d2   0 to 7  5.17  4.28  3.61  33.33  39.48   6 to 11  9.18  7.59  6.71  30.16  34.09   10 to 16  14.44  11.77  9.76  26.81  32.29   15 to 21  20.69  16.46  14.55  26.62  30.19  SD  0.751  0.616  0.678  1.383  1.586   P-value    Diet  <0.001  <0.001  <0.001  0.339  0.089     Linear effect of diet  <0.001  <0.001  <0.001  0.341  0.527     Quadratic effect of diet  0.122  0.033  <0.01  0.262  0.035    Age     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.01  0.071  <0.01  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 6. Efficiency of utilization of leal digestible nitrogen and retainable nitrogen intake for body weight gain.   Nitrogen  Ileal digestible  Retainable nitrogen  Weight gain/ileal digestible  Weight gain/retainable  Item  intake, g  nitrogen intake, g  intake, g  nitrogen intake, g/g  nitrogen intake, g/g  Dietary meat and bone meal (diet), g/kg1   0  11.77  9.70  8.37  28.91  33.58   40  12.18  9.80  8.38  29.49  34.58   80  13.18  10.57  9.23  29.29  33.88  Feeding age post hatching (age), d2   0 to 7  5.17  4.28  3.61  33.33  39.48   6 to 11  9.18  7.59  6.71  30.16  34.09   10 to 16  14.44  11.77  9.76  26.81  32.29   15 to 21  20.69  16.46  14.55  26.62  30.19  SD  0.751  0.616  0.678  1.383  1.586   P-value    Diet  <0.001  <0.001  <0.001  0.339  0.089     Linear effect of diet  <0.001  <0.001  <0.001  0.341  0.527     Quadratic effect of diet  0.122  0.033  <0.01  0.262  0.035    Age     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.01  0.071  <0.01  <0.001  <0.001    Nitrogen  Ileal digestible  Retainable nitrogen  Weight gain/ileal digestible  Weight gain/retainable  Item  intake, g  nitrogen intake, g  intake, g  nitrogen intake, g/g  nitrogen intake, g/g  Dietary meat and bone meal (diet), g/kg1   0  11.77  9.70  8.37  28.91  33.58   40  12.18  9.80  8.38  29.49  34.58   80  13.18  10.57  9.23  29.29  33.88  Feeding age post hatching (age), d2   0 to 7  5.17  4.28  3.61  33.33  39.48   6 to 11  9.18  7.59  6.71  30.16  34.09   10 to 16  14.44  11.77  9.76  26.81  32.29   15 to 21  20.69  16.46  14.55  26.62  30.19  SD  0.751  0.616  0.678  1.383  1.586   P-value    Diet  <0.001  <0.001  <0.001  0.339  0.089     Linear effect of diet  <0.001  <0.001  <0.001  0.341  0.527     Quadratic effect of diet  0.122  0.033  <0.01  0.262  0.035    Age     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.01  0.071  <0.01  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 7. Efficiency of utilization of leal digestible energy and metabolizable energy intake for body weight gain.   Gross energy  Ileal digestible  AME  AMEn  Weight gain/ileal  Weight  Weight    intake,  energy intake,  intake  intake,  digestible energy  gain/AME intake,  gain/AMEn intake,  Item  kcal  kcal  kcal  kcal  intake, g/kcal  g/kcal  g/kcal  Dietary meat and bone meal (diet) g/kg1   0  1,310  961  997  928  0.294  0.285  0.306   40  1,290  931  973  905  0.312  0.301  0.324   80  1,331  974  1,020  944  0.320  0.309  0.334  Feeding age post hatching (age), d2   0 to 7  548  401  403  374  0.356  0.354  0.382   6 to 11  973  715  753  697  0.320  0.304  0.328   10 to 16  1,529  1,123  1,154  1,073  0.281  0.273  0.293   15 to 21  2,191  1,583  1,678  1,558  0.277  0.262  0.282  SD  71.3  58.1  64.4  59.3  0.0153  0.0129  0.0139   P-value    Diet  0.154  0.039  0.050  0.073  <0.001  <0.001  <0.001     Linear effect of diet  0.311  0.459  0.214  0.339  <0.001  <0.001  <0.001     Quadratic effect of diet  0.098  0.015  0.034  0.037  0.230  0.250  0.294    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.001  0.026  <0.01  <0.01  <0.001  <0.001  <0.001    Gross energy  Ileal digestible  AME  AMEn  Weight gain/ileal  Weight  Weight    intake,  energy intake,  intake  intake,  digestible energy  gain/AME intake,  gain/AMEn intake,  Item  kcal  kcal  kcal  kcal  intake, g/kcal  g/kcal  g/kcal  Dietary meat and bone meal (diet) g/kg1   0  1,310  961  997  928  0.294  0.285  0.306   40  1,290  931  973  905  0.312  0.301  0.324   80  1,331  974  1,020  944  0.320  0.309  0.334  Feeding age post hatching (age), d2   0 to 7  548  401  403  374  0.356  0.354  0.382   6 to 11  973  715  753  697  0.320  0.304  0.328   10 to 16  1,529  1,123  1,154  1,073  0.281  0.273  0.293   15 to 21  2,191  1,583  1,678  1,558  0.277  0.262  0.282  SD  71.3  58.1  64.4  59.3  0.0153  0.0129  0.0139   P-value    Diet  0.154  0.039  0.050  0.073  <0.001  <0.001  <0.001     Linear effect of diet  0.311  0.459  0.214  0.339  <0.001  <0.001  <0.001     Quadratic effect of diet  0.098  0.015  0.034  0.037  0.230  0.250  0.294    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.001  0.026  <0.01  <0.01  <0.001  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 7. Efficiency of utilization of leal digestible energy and metabolizable energy intake for body weight gain.   Gross energy  Ileal digestible  AME  AMEn  Weight gain/ileal  Weight  Weight    intake,  energy intake,  intake  intake,  digestible energy  gain/AME intake,  gain/AMEn intake,  Item  kcal  kcal  kcal  kcal  intake, g/kcal  g/kcal  g/kcal  Dietary meat and bone meal (diet) g/kg1   0  1,310  961  997  928  0.294  0.285  0.306   40  1,290  931  973  905  0.312  0.301  0.324   80  1,331  974  1,020  944  0.320  0.309  0.334  Feeding age post hatching (age), d2   0 to 7  548  401  403  374  0.356  0.354  0.382   6 to 11  973  715  753  697  0.320  0.304  0.328   10 to 16  1,529  1,123  1,154  1,073  0.281  0.273  0.293   15 to 21  2,191  1,583  1,678  1,558  0.277  0.262  0.282  SD  71.3  58.1  64.4  59.3  0.0153  0.0129  0.0139   P-value    Diet  0.154  0.039  0.050  0.073  <0.001  <0.001  <0.001     Linear effect of diet  0.311  0.459  0.214  0.339  <0.001  <0.001  <0.001     Quadratic effect of diet  0.098  0.015  0.034  0.037  0.230  0.250  0.294    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.001  0.026  <0.01  <0.01  <0.001  <0.001  <0.001    Gross energy  Ileal digestible  AME  AMEn  Weight gain/ileal  Weight  Weight    intake,  energy intake,  intake  intake,  digestible energy  gain/AME intake,  gain/AMEn intake,  Item  kcal  kcal  kcal  kcal  intake, g/kcal  g/kcal  g/kcal  Dietary meat and bone meal (diet) g/kg1   0  1,310  961  997  928  0.294  0.285  0.306   40  1,290  931  973  905  0.312  0.301  0.324   80  1,331  974  1,020  944  0.320  0.309  0.334  Feeding age post hatching (age), d2   0 to 7  548  401  403  374  0.356  0.354  0.382   6 to 11  973  715  753  697  0.320  0.304  0.328   10 to 16  1,529  1,123  1,154  1,073  0.281  0.273  0.293   15 to 21  2,191  1,583  1,678  1,558  0.277  0.262  0.282  SD  71.3  58.1  64.4  59.3  0.0153  0.0129  0.0139   P-value    Diet  0.154  0.039  0.050  0.073  <0.001  <0.001  <0.001     Linear effect of diet  0.311  0.459  0.214  0.339  <0.001  <0.001  <0.001     Quadratic effect of diet  0.098  0.015  0.034  0.037  0.230  0.250  0.294    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.001  0.026  <0.01  <0.01  <0.001  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Feeding age post hatching affected ileal digestibility of energy (Table 4) as well as both metabolizability of energy and N-corrected metabolizability of energy (Table 5). Age-related regression-derived IDE, ME, and MEn values of MBM for broiler chickens from day 0 to 7, 6 to 11, 10 to 16, and 15 to 21 post hatching are shown in Table 8. There were quadratic effects (P < 0.01) of feeding age post hatching on IDE, ME, and MEn in which the day 0 to 7 energy values were lower than subsequent feeding ages, and these are depicted in Figure 1. Studies have shown that ME value of a diet is lowest between day 4 and 7 post hatching in broiler chicks followed by an increase with post hatching age (Zelenka, 1968). Furthermore, Sulistiyanto et al. (1999) reported that utilization of energy-yielding feedstuffs was age-dependent and suggested that by 14 d of age, broiler chicks are able to efficiently utilize the energy in the diet. The requirements of broiler chickens for nutrients and energy are not commonly based on post hatching age and only 1 ME value and 1 AA digestibility value are given for each feed ingredient. In the current study, IDE, ME, and MEn values increased with post hatching age of broiler chickens. The current results and earlier reports emphasize the importance of age-related differences in energy digestibility, which should be taken into consideration during diet formulation. Figure 1. View largeDownload slide Quadratic relationship between regression-derived ileal digestible energy (solid circle and dash line), metabolizable energy (solid diamond and solid line), and nitrogen-corrected metabolizable energy (solid triangle and dotted line) values of meat and bone meal for broiler chickens and feeding age post hatching from day 0 to 7, 6 to 11, 10 to 16, or 15 to 21. Ileal digestible energy, metabolizable energy, and nitrogen-corrected metabolizable energy of meat and bone meal in broiler chickens increased (P < 0.05) with feeding age post hatching. Figure 1. View largeDownload slide Quadratic relationship between regression-derived ileal digestible energy (solid circle and dash line), metabolizable energy (solid diamond and solid line), and nitrogen-corrected metabolizable energy (solid triangle and dotted line) values of meat and bone meal for broiler chickens and feeding age post hatching from day 0 to 7, 6 to 11, 10 to 16, or 15 to 21. Ileal digestible energy, metabolizable energy, and nitrogen-corrected metabolizable energy of meat and bone meal in broiler chickens increased (P < 0.05) with feeding age post hatching. Table 8. Age-related regression-derived ileal digestible energy (IDE), metabolizable energy (ME), and nitrogen-corrected metabolizable energy (MEn) values of meat and bone meal for broiler chickens from day 0 to 7, 6 to 11, 10 to 16, and 15 to 21 post hatching.1   IDE,  ME,  MEn,  Item  kcal/g DM  kcal/g DM  kcal/g DM  Feeding age post hatching (age), d1   0 to 7  2.852  2.909  2.687   6 to 11  2.962  3.125  2.887   10 to 16  2.927  3.083  2.839   15 to 21  2.959  3.075  2.845  SD  0.0598  0.1168  0.1082  P-value  <0.01  <0.01  <0.01    IDE,  ME,  MEn,  Item  kcal/g DM  kcal/g DM  kcal/g DM  Feeding age post hatching (age), d1   0 to 7  2.852  2.909  2.687   6 to 11  2.962  3.125  2.887   10 to 16  2.927  3.083  2.839   15 to 21  2.959  3.075  2.845  SD  0.0598  0.1168  0.1082  P-value  <0.01  <0.01  <0.01  1 Data are means of 6 slopes derived from regressions for 3 cages of 0, 40, or 80 g MBM/kg diet in each of 6 blocks. View Large Table 8. Age-related regression-derived ileal digestible energy (IDE), metabolizable energy (ME), and nitrogen-corrected metabolizable energy (MEn) values of meat and bone meal for broiler chickens from day 0 to 7, 6 to 11, 10 to 16, and 15 to 21 post hatching.1   IDE,  ME,  MEn,  Item  kcal/g DM  kcal/g DM  kcal/g DM  Feeding age post hatching (age), d1   0 to 7  2.852  2.909  2.687   6 to 11  2.962  3.125  2.887   10 to 16  2.927  3.083  2.839   15 to 21  2.959  3.075  2.845  SD  0.0598  0.1168  0.1082  P-value  <0.01  <0.01  <0.01    IDE,  ME,  MEn,  Item  kcal/g DM  kcal/g DM  kcal/g DM  Feeding age post hatching (age), d1   0 to 7  2.852  2.909  2.687   6 to 11  2.962  3.125  2.887   10 to 16  2.927  3.083  2.839   15 to 21  2.959  3.075  2.845  SD  0.0598  0.1168  0.1082  P-value  <0.01  <0.01  <0.01  1 Data are means of 6 slopes derived from regressions for 3 cages of 0, 40, or 80 g MBM/kg diet in each of 6 blocks. View Large Olukosi et al. (2007), and more recently Stefanello et al. (2016), reported age-related decreases in the total tract retention of DM, N, and energy as well as dietary and ingredient ME from day 7 to 21 post hatching. This is perhaps related to the development of digestive and absorptive capacities of the intestine, as has been demonstrated for pigs (Adeola and King, 2006), because digestive enzyme production and absorptive capacity increase with age; most probably, the ability of animals to extract nutrient from feeds increases with age. Birds undergo metabolic adaptations from embryonic yolk dependence to utilizing nutrients from exogenous feed (Noy and Sklan, 2001). Earlier, Nitsan et al. (1991) and Sell and Angel (1990) opined that the increased endogenous enzyme secretions and nutrient absorption from first to third week of age is part of the reason for the improved digestion that occurs with age. In summary, IDE of MBM were 2.852, 2.962, 2.927, or 2.959 kcal/g DM during the day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 feeding age post hatching, respectively. Corresponding ME of MBM were 2.909, 3.125, 3.083, or 3.075 kcal/g DM and those of MEn were 2.687, 2.887, 2.839, or 2.845 kcal/g DM. These results show that energy values of MBM increase with age post hatching and emphasize the importance of age-related differences in utilization of energy in feed ingredients, which should be taken into consideration when formulating diets. Acknowledgements The authors gratefully acknowledge F. Zaefarian, C. Naftel, E. James, and S. de Malmanche for their contribution to this study. REFERENCES Adedokun S. A., Adeola O.. 2005a. Metabolizable energy value of meat and bone meal for pigs. J. Anim. Sci . 83: 2519– 2526. Google Scholar CrossRef Search ADS   Adedokun S. A., Adeola O.. 2005b. Apparent metabolizable energy value of meat and bone meal for white pekin ducks. Poult. Sci . 84: 1539– 1546. 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Age-related energy values of meat and bone meal for broiler chickens

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© 2018 Poultry Science Association Inc.
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0032-5791
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Abstract

Abstract Six hundred and eighty-four male Ross 308 broiler chicks were used to test the null hypothesis that post hatching age between day 0 and 21 does not affect utilization of energy in meat and bone meal (MBM). There were 6 replicate cages in each of 12 treatments consisting of 3 test diets (0, 40, or 80 g MBM/kg diets) at 4 feeding ages post hatching (day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 post hatching) for a total of 72 cages in a randomized complete block design. Birds were assigned to the 12 treatments on day 0, fed a standard starter diet until they were switched to the test diets on day 0, 6, 10, or 15, and the number of birds per cage for day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 were 12, 10, 8, or 8, respectively. Excreta were collected during the last 3 days of each feeding age post hatching and ileal digesta on the last day of each age. There was no interaction between dietary MBM level and feeding age post hatching for any of the response criteria. Weight gain and gain-to-feed ratio improved linearly (P < 0.001) with increasing dietary MBM and, expectedly, there was an increase (P < 0.001) in weight gain and a reduction (P < 0.001) in gain-to-feed ratio with bird feeding age post hatching. Ileal digestible energy (IDE), apparent metabolizable energy (AME), and nitrogen-corrected AME (AMEn) of the diet linearly increased (P < 0.001) with increasing dietary MBM. There were linear increases in dietary IDE (P < 0.05), AME (P < 0.001), and AMEn (P < 0.001) with bird feeding age post hatching. The IDE, ME, and MEn of MBM were determined by the regression procedure. During day 0 to 7, 6 to 11, 10 to 16, or 15 to 21, energy values increased (P < 0.05) with age and the respective IDE of MBM were 2.852, 2.962, 2.927, or 2.959 kcal/g DM. Corresponding ME of MBM were 2.909, 3.125, 3.083, or 3.075 kcal/g DM and those of MEn were 2.687, 2.887, 2.839, or 2.845 kcal/g DM. These results show that energy values of MBM increase with age post hatching and suggest the same energy value of MBM should not be used in formulating diets of broiler chickens during the first 3 weeks post hatching. INTRODUCTION Growth in early life period in animals is a critical time during which the animal must regulate nutrient supply to support growth and other metabolic functions. This regulation of nutrient supply involves both digestion and absorption of nutrients across the enterocyte brush border membrane. From hatching through the first week of life, the gut represents a small portion of the total body mass. When compared with the following 2 weeks, the first week of life is the time for maximal body growth along with corresponding demand for energy and amino acids (Obst and Diamond, 1992). During this time, the ability of the animal to extract nutrients may be limited and thus present a constraint to development. Because digestive enzyme production and absorptive capacity increase with age, the ability of animals to extract nutrients from feeds most likely increases with age and such age-related increases could be substrate-associated and therefore dependent on feed ingredient. From day 7 to 21 post hatching, there were effects of age on the total tract retention of dry matter, nitrogen, and energy, as well as dietary and ingredient ME (Olukosi et al. 2007; Stefanello et al., 2016), which are probably related to the development of digestive and absorptive capacities of the intestine, as has been demonstrated for pigs (Adeola and King, 2006). Birds undergo metabolic adaptations from embryonic yolk dependence to utilizing nutrients from exogenous feed (Noy and Sklan, 2001). The rendering of trimmings, bones, blood, heads, lean tissues, viscera, hooves, hide, feathers, and fat together with the differences in processing methods and conditions result in variations in the nutrient profile of meat and bone meal (MBM). In experiments with broiler chickens from day 14 to 21 post hatching, Bolarinwa et al. (2012) reported ME between 2.512 and 2.711 kcal/g and MEn between 2.127 and 2.345 kcal/g for MBM. Guirguis (1975) reported ME of 2.5 kcal/g MBM in older birds, whereas Oluyemi et al. (1976) reported ME of 2.14 kcal/g MBM for 9-day-old chicks. Factors such as the fat removal technique as observed by Dolz and De Blas (1992), cooking duration and temperature, and the ratio of bones to soft tissue in the MBM may also affect nutritional value. Increasing bone content has been reported by Dale (1997) and Wang and Parsons (1998) to have a negative effect on protein and energy concentration. The streamlining and standardization of processing methods and tissues processed for MBM could conceivably improve nutritional value. Because the effect of broiler chicken age during the first 21 d of life on energy value of MBM is not known, the current study was conducted to test the null hypothesis that post hatching age between day 0 and 21 does not affect utilization of energy in MBM. The objective was to determine the effect of post hatching age between day 0 and 21 on ileal digestible energy (IDE), metabolizable energy (ME), and nitrogen-corrected ME (MEn) values for broiler chickens using the regression procedure. MATERIALS AND METHODS Animals, Experimental Periods, and Test Diets Experimental procedures were in accordance with the Massey University Animal Ethics Committee guidelines. Male Ross 308 broiler chicks were purchased from a commercial hatchery, tagged, weighed individually, sorted, and assigned to day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 post hatching age on day 0 in a randomized complete block design using initial weight as a blocking factor. Birds were offered a standard starter diet (Table 1) that was formulated to contain 230 g CP and 3100 kcal ME/kg until day 0, 6, 10, or 15, when they were switched to the test diets (Table 1). There were 6 replicate cages in each of 12 treatments in a 3 × 4 factorial arrangement consisting of 3 test diets (0, 40, or 80 g MBM/kg diet, Table 1) at each of 4 different feeding ages post hatching (day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 post hatching) for a total of 72 cages. The number of birds per cage for day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 post hatching were 12, 10, 8, or 8, respectively, for a total of 684 birds. Table 1. Ingredient composition of starter diet and experimental diets formulated with meat and bone meal.     Meat and bone meal, g/kg  Item  Starter diet  0  40  80  Ingredients, g/kg   Corn  545.9  518.7  505.1  491.4   Soybean meal  360  360  350.8  341.7   Soy oil  50  50  48.7  47.5   Monocalcium phosphate  15  18.2  9  0   Limestone  15  14  7.3  0.3   Salt  4  4  4  4   DL-Methionine  3.8  3.8  3.8  3.8   L-Lysine HCl  2.9  2.9  2.9  2.9   L-Threonine  1.1  1.1  1.1  1.1   Vitamin premix1  0.8  0.8  0.8  0.8   Mineral premix2  1.5  1.5  1.5  1.5   Titanium dioxide premix3  0  25  25  25   Meat and bone meal  0  0  40  80   Total  1,000  1,000  1,000  1,000  Calculated nutrient composition, g/kg   ME, kcal/kg  3,127  3,103  3,110  3,118   CP  226  225  239  254   Ca  8.3  8.3  9.1  9.8   Total P  6.1  6.6  7.2  7.8   Non-phytate P  3.6  4.0  4.7  5.4   Phytate P  2.5  2.5  2.5  2.4   Ca:P ratio  1.4  1.3  1.3  1.3   Crude fiber  24.8  24.7  24.0  23.4   NDF  79.3  78.6  89.6  100.6   ADF  34.7  34.5  35.7  36.8   Total amino acids    Arg  14.6  14.6  15.6  16.6    His  5.9  5.8  6.1  6.3    Ile  9.2  9.2  9.5  9.8    Leu  18.9  18.9  19.6  20.3    Lys  14.3  14.3  15.1  15.8    Met  7.2  7.2  7.4  7.6    Met + Cys  10.8  10.7  11.1  11.4    Phe  10.5  10.5  10.9  11.3    Phe + Tyr  19.2  19.1  19.7  20.4    Thr  9.4  9.4  9.8  10.2    Trp  3.0  3.0  3.0  3.1    Val  10.2  10.1  10.8  11.4      Meat and bone meal, g/kg  Item  Starter diet  0  40  80  Ingredients, g/kg   Corn  545.9  518.7  505.1  491.4   Soybean meal  360  360  350.8  341.7   Soy oil  50  50  48.7  47.5   Monocalcium phosphate  15  18.2  9  0   Limestone  15  14  7.3  0.3   Salt  4  4  4  4   DL-Methionine  3.8  3.8  3.8  3.8   L-Lysine HCl  2.9  2.9  2.9  2.9   L-Threonine  1.1  1.1  1.1  1.1   Vitamin premix1  0.8  0.8  0.8  0.8   Mineral premix2  1.5  1.5  1.5  1.5   Titanium dioxide premix3  0  25  25  25   Meat and bone meal  0  0  40  80   Total  1,000  1,000  1,000  1,000  Calculated nutrient composition, g/kg   ME, kcal/kg  3,127  3,103  3,110  3,118   CP  226  225  239  254   Ca  8.3  8.3  9.1  9.8   Total P  6.1  6.6  7.2  7.8   Non-phytate P  3.6  4.0  4.7  5.4   Phytate P  2.5  2.5  2.5  2.4   Ca:P ratio  1.4  1.3  1.3  1.3   Crude fiber  24.8  24.7  24.0  23.4   NDF  79.3  78.6  89.6  100.6   ADF  34.7  34.5  35.7  36.8   Total amino acids    Arg  14.6  14.6  15.6  16.6    His  5.9  5.8  6.1  6.3    Ile  9.2  9.2  9.5  9.8    Leu  18.9  18.9  19.6  20.3    Lys  14.3  14.3  15.1  15.8    Met  7.2  7.2  7.4  7.6    Met + Cys  10.8  10.7  11.1  11.4    Phe  10.5  10.5  10.9  11.3    Phe + Tyr  19.2  19.1  19.7  20.4    Thr  9.4  9.4  9.8  10.2    Trp  3.0  3.0  3.0  3.1    Val  10.2  10.1  10.8  11.4  1 Supplied the following per kilogram of diet: vitamin A (vitamin A acetate), 12,000 IU; vitamin D3 (cholcalciferol), 4,000 IU; vitamin E (DL-α-tocopherol), 80 IU; biotin, 0.25 mg; pantothenic acid (calcium-D-pantothenate), 15 mg; cyanocobalamin, 0.02 mg; folic acid, 3.0 mg; vitamin K3 (menadione nicotinamide bisulphite), 4.0 mg; niacin (nicotinic acid), 60 mg; pyridoxine (pyridoxine hydrochloride), 10 mg; riboflavin, 9.0 mg; thiamine (thiamine mononitrate), 3.0 mg; ethoxyquin, 100 mg. 2 Supplied the following per kilogram of diet: choline (choline chloride 60%), 360 mg; Co (cobalt sulfate), 0.15 mg; Cu (copper sulfate), 6.0 mg; organic Cu (B-TRAXIM 2C G/Cu), 3.0 mg; Fe (iron sulfate), 36 mg; I (calcium iodate), 0.93 mg; Mn (manganese oxide), 60 mg; Mo (sodium molybdate), 0.15 mg; Se (sodium selenite), 0.26 mg; organic Se (enriched yeast), 0.14 mg; Zn (zinc sulfate), 48 mg; organic Zn (B-TRAXIM 2C G/Zn), 24 mg. 3 Prepared as 1 g of titanium dioxide added to 4 g of corn. View Large Table 1. Ingredient composition of starter diet and experimental diets formulated with meat and bone meal.     Meat and bone meal, g/kg  Item  Starter diet  0  40  80  Ingredients, g/kg   Corn  545.9  518.7  505.1  491.4   Soybean meal  360  360  350.8  341.7   Soy oil  50  50  48.7  47.5   Monocalcium phosphate  15  18.2  9  0   Limestone  15  14  7.3  0.3   Salt  4  4  4  4   DL-Methionine  3.8  3.8  3.8  3.8   L-Lysine HCl  2.9  2.9  2.9  2.9   L-Threonine  1.1  1.1  1.1  1.1   Vitamin premix1  0.8  0.8  0.8  0.8   Mineral premix2  1.5  1.5  1.5  1.5   Titanium dioxide premix3  0  25  25  25   Meat and bone meal  0  0  40  80   Total  1,000  1,000  1,000  1,000  Calculated nutrient composition, g/kg   ME, kcal/kg  3,127  3,103  3,110  3,118   CP  226  225  239  254   Ca  8.3  8.3  9.1  9.8   Total P  6.1  6.6  7.2  7.8   Non-phytate P  3.6  4.0  4.7  5.4   Phytate P  2.5  2.5  2.5  2.4   Ca:P ratio  1.4  1.3  1.3  1.3   Crude fiber  24.8  24.7  24.0  23.4   NDF  79.3  78.6  89.6  100.6   ADF  34.7  34.5  35.7  36.8   Total amino acids    Arg  14.6  14.6  15.6  16.6    His  5.9  5.8  6.1  6.3    Ile  9.2  9.2  9.5  9.8    Leu  18.9  18.9  19.6  20.3    Lys  14.3  14.3  15.1  15.8    Met  7.2  7.2  7.4  7.6    Met + Cys  10.8  10.7  11.1  11.4    Phe  10.5  10.5  10.9  11.3    Phe + Tyr  19.2  19.1  19.7  20.4    Thr  9.4  9.4  9.8  10.2    Trp  3.0  3.0  3.0  3.1    Val  10.2  10.1  10.8  11.4      Meat and bone meal, g/kg  Item  Starter diet  0  40  80  Ingredients, g/kg   Corn  545.9  518.7  505.1  491.4   Soybean meal  360  360  350.8  341.7   Soy oil  50  50  48.7  47.5   Monocalcium phosphate  15  18.2  9  0   Limestone  15  14  7.3  0.3   Salt  4  4  4  4   DL-Methionine  3.8  3.8  3.8  3.8   L-Lysine HCl  2.9  2.9  2.9  2.9   L-Threonine  1.1  1.1  1.1  1.1   Vitamin premix1  0.8  0.8  0.8  0.8   Mineral premix2  1.5  1.5  1.5  1.5   Titanium dioxide premix3  0  25  25  25   Meat and bone meal  0  0  40  80   Total  1,000  1,000  1,000  1,000  Calculated nutrient composition, g/kg   ME, kcal/kg  3,127  3,103  3,110  3,118   CP  226  225  239  254   Ca  8.3  8.3  9.1  9.8   Total P  6.1  6.6  7.2  7.8   Non-phytate P  3.6  4.0  4.7  5.4   Phytate P  2.5  2.5  2.5  2.4   Ca:P ratio  1.4  1.3  1.3  1.3   Crude fiber  24.8  24.7  24.0  23.4   NDF  79.3  78.6  89.6  100.6   ADF  34.7  34.5  35.7  36.8   Total amino acids    Arg  14.6  14.6  15.6  16.6    His  5.9  5.8  6.1  6.3    Ile  9.2  9.2  9.5  9.8    Leu  18.9  18.9  19.6  20.3    Lys  14.3  14.3  15.1  15.8    Met  7.2  7.2  7.4  7.6    Met + Cys  10.8  10.7  11.1  11.4    Phe  10.5  10.5  10.9  11.3    Phe + Tyr  19.2  19.1  19.7  20.4    Thr  9.4  9.4  9.8  10.2    Trp  3.0  3.0  3.0  3.1    Val  10.2  10.1  10.8  11.4  1 Supplied the following per kilogram of diet: vitamin A (vitamin A acetate), 12,000 IU; vitamin D3 (cholcalciferol), 4,000 IU; vitamin E (DL-α-tocopherol), 80 IU; biotin, 0.25 mg; pantothenic acid (calcium-D-pantothenate), 15 mg; cyanocobalamin, 0.02 mg; folic acid, 3.0 mg; vitamin K3 (menadione nicotinamide bisulphite), 4.0 mg; niacin (nicotinic acid), 60 mg; pyridoxine (pyridoxine hydrochloride), 10 mg; riboflavin, 9.0 mg; thiamine (thiamine mononitrate), 3.0 mg; ethoxyquin, 100 mg. 2 Supplied the following per kilogram of diet: choline (choline chloride 60%), 360 mg; Co (cobalt sulfate), 0.15 mg; Cu (copper sulfate), 6.0 mg; organic Cu (B-TRAXIM 2C G/Cu), 3.0 mg; Fe (iron sulfate), 36 mg; I (calcium iodate), 0.93 mg; Mn (manganese oxide), 60 mg; Mo (sodium molybdate), 0.15 mg; Se (sodium selenite), 0.26 mg; organic Se (enriched yeast), 0.14 mg; Zn (zinc sulfate), 48 mg; organic Zn (B-TRAXIM 2C G/Zn), 24 mg. 3 Prepared as 1 g of titanium dioxide added to 4 g of corn. View Large Test diets were based on corn-soybean meal in which corn, soybean meal, and soy oil were used as the sources of energy and MBM was added at 0, 40, or 80 g/kg diet to partly replace corn, soybean meal, and soy oil in a manner that maintained the same ratio of corn, soybean meal, and soy oil across the test diets (Table 1), which is important for the analysis (Zhang and Adeola, 2017a,b). These ratios were 1.4, 7.2, and 10.4 for corn: soybean meal, soybean meal:soy oil, and corn:soy oil, respectively. Because of the contribution of Ca and P from MBM, dietary levels of monocalcium phosphate and limestone were adjusted to maintain a total Ca:total P ratio of 1.3:1 across the 3 test diets (Table 1). Titanium dioxide was incorporated into the test diets as an indigestible marker at 5 g/kg on an as-fed basis. Sampling Procedures and Processing During day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 feeding ages post hatching, excreta collection trays underneath the cages were lined with waxed paper on day 4, 8, 13, or 18, respectively. Fresh excreta samples were collected twice daily during the subsequent 3 days, pooled by cage, and stored at –20°C until freeze-dried and ground. On day 7, 11, 16, or 21 post hatching, birds assigned to day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 feeding ages post hatching, respectively, were euthanized by intravenous injection of sodium pentobarbitone (Provet NZ Pty. Ltd., Auckland, New Zealand) at 0.5 mL/kg BW. Ileal digesta in the distal two-thirds from the Meckel's diverticulum to approximately 2 cm cranial to the ileo-cecal junction from all birds in each cage were flushed with distilled water into plastic bags, pooled by cage, and stored at –20°C until freeze-dried and ground. Pooled excreta and ileal digesta were freeze-dried (Model 0610, Cuddon Engineering, Blenheim, New Zealand), and the diet, excreta, and ileal digesta were subsequently ground to a homogenous mixture through a 0.50-mm screen and stored at 4°C until laboratory analysis. Analyses Samples of ground diets, excreta, and ileal digesta were analyzed for dry matter (DM), titanium (Ti), gross energy, and N. Ground MBM sample was analyzed for DM, Ti, gross energy, and N, crude fat, Ca, P, amino acids, and particle size. All analyses were conducted in an ISO17025 accredited laboratory (Nutrition Laboratory, Massey University). Dry matter content was determined using standard procedures (methods 930.15 and 925.10; AOAC International, 2005). Gross energy was determined using an adiabatic bomb calorimeter (Gallenkamp Autobomb, London, UK) standardized with benzoic acid. Nitrogen content was determined by the combustion method using a CNS-2000 carbon, nitrogen and sulfur analyzer (LECO Corporation, St. Joseph, MI). Fat content was determined using the Soxhlet extraction procedure (method 991.36; AOAC International, 2005). Samples were assayed for Ti on a UV spectrophotometer following the method of Short et al. (1996). Amino acids were determined as described by Ravindran et al. (2009). Briefly, the samples were hydrolyzed with 6 N HCl (containing phenol) for 24 h at 110 ± 2°C in glass tubes sealed under vacuum. Amino acids were detected on a Waters ion-exchange HPLC system, and the chromatograms were integrated using dedicated software (Millennium, Version 3.05.01, Waters, Millipore, Milford, MA) with the AA identified and quantified using a standard AA mixture (Product no. A2908, Sigma, St. Louis, MO). The HPLC system consisted of an ion-exchange column, two 510 pumps, Waters 715 ultra-WISP sample processor, a column heater, a post column reaction coil heater, a ninhydrin pump, and a dual wavelength detector. Amino acids were eluted by a gradient of pH 3.3 sodium citrate eluent to pH 9.8 sodium borate eluent at a flow rate of 0.4 mL/min and a column temperature of 60°C. Cysteine and methionine were analyzed as cysteic acid and methionine sulfone, respectively, by oxidation with performic acid for 16 h at 0°C and neutralization with hydrobromic acid prior to hydrolysis. For mineral analysis, the samples were wet acid digested with nitric and perchloric acid mixture, and concentrations of P and Ca were determined by Inductively Coupled Plasma-Optical Emission Spectroscopy using a Thermo Jarrell Ash IRIS instrument (Thermo Jarrell Ash Corporation, Franklin, MA). The dry sieving method was used to determine the particle size distribution of MBM sample using the method described by Baker and Herrman (2002). Calculations and Statistical Analysis The ileal digestibility and total tract metabolizability coefficients (C) of nutrients and energy were determined (McCormick et al., 2017; Zhang and Adeola, 2017) and calculated as C = 1 − [(Cd/Co) × (Eo/Ed)], where Cd is the concentration of Ti in the diet; Co is the concentration of Ti in the ileal digesta or excreta output; Eo is the concentration of nutrient or energy in the ileal digesta or excreta output; and Ed is the concentration of nutrient or energy in the diet. The IDE (kcal/kg) or AME (kcal/g) of the diets were calculated as the product of C and the gross energy concentration (kcal/g) of the diet. Because catabolic compounds in excreted N can contribute to energy loss, ME was corrected to zero N retention using a factor of 8.22 kcal/g (Hill and Anderson, 1958) as MEn = ME − (8.22 × Nret), where Nret is N retention in g/g of DM intake. The Nret was calculated as Nret = Ni – (No × Cd/Co), where Ni and No are the N concentrations (g/g of DM) in the diet and excreta, respectively. The C of IDE, ME, or MEn for reference diet (0 g MBM/kg), test diets (40 or 80 g MBM/kg), and MBM are Crd, Ctd, and Cmbm, respectively. The definition that the test diet energy consists of energy from reference diet (0 g MBM/kg) and the energy from MBM make the sum of proportional contribution of energy of the reference diet and the test ingredient equal to 1: Prd + Pmbm = 1, where Prd and Pmbm represent the proportion of energy contribution from reference diet and MBM, respectively. The assumption of additivity in diet formulation gives: Ctd = (Crd × Prd) + (Cmbm × Pmbm); solving for Cmbm gives: Cmbm = [Ctd − (Crd × Prd)]/Pmbm; substituting 1− Pmbm for Prd gives: Cmbm = [Crd + (Ctd − Crd)/Pmbm]. The product of Cmbm at each level of MBM substitution rate (0, 40, or 80 g/kg), grams of dry MBM intake (product of 0, 0.04, or 0.08 and dry feed intake), and the gross energy of test ingredient are the MBM-associated IDE, ME, or MEn in kilocalories (Bolarinwa and Adeola, 2012). The data were analyzed as a 3 × 4 factorial arrangement in a randomized complete block design using the GLM of SAS (SAS Inst. Inc., Cary, NC). The model included two main effects of dietary MBM level (0, 40, or 80 g/kg) with 2 degrees of freedom (df), feeding age post hatching (day 0 to 7, 6 to 11, 10 to 16, or 15 to 21) with 3 df, and the interaction effects with 6 df as fixed effects, and block with 5 df as a random effect. Cage served as the experimental unit for all statistical analyses. Where there was no interaction between dietary MBM level and feeding age post hatching in the initial analyses, interaction term was pooled into the error term. Main effect means were separated using linear and quadratic contrasts. Regression of the MBM-associated IDE, ME, or MEn intake in kilocalories against grams of MBM intake for cage of birds was conducted. The SLOPE and INTERCEPT functions of Microsoft Office Excel 2010 (Microsoft Corp., Redmond, WA) were used to generate the respective slopes and intercepts from 3 cages of 0, 40, or 80 g MBM/kg diet in each of 6 blocks. One-way ANOVA was then performed to determine the differences in slopes among the 4 feeding ages post hatching of day 0 to 7, 6 to 11, 10 to 16, or 15 to 21 using the PROC GLM of SAS. Feeding age post hatching was considered an independent variable, whereas the slope was used as dependent variable (Adeola and Kong, 2014). Statistical significance was determined at a probability level of 0.05. RESULTS AND DISCUSSION Birds remained healthy throughout the experiment and 6 of the 684 birds that were started on the study died from causes unrelated to the experimental treatments. Table 2 provides the analyzed nutritional characteristics of the corn, soybean meal, limestone, and monocalcium phosphate used in starter and experimental diets as well as those of the meat and bone meal. The analyzed gross energy of corn (3.9 Mcal/kg) and the analyzed N of soybean meal (74 g/kg) are similar to the average values previously reported (NRC, 2012), but the N in corn at 1.95 g/kg and energy in soybean meal at 4.1 Mcal/kg are higher and lower, respectively, than the previously reported (NRC, 2012) average values. Analyzed Ca in limestone is consistent, but Ca and P in monocalcium phosphate are lower than expected. Nutritional characteristics, including N, amino acids, crude fat, Ca, and P of MBM presented in Table 2, are similar to the average values reported in NRC (2012) for MBM containing more than 4% P. Furthermore, the N, Ca, and P are in the range of values in Anwar et al. (2015, 2016). The gross energy of the MBM sample at 3.7 Mcal/kg, assessed for energy value in the current broiler chicken study, is in the range of values previously reported for a variety of MBM samples (Adedokun and Adeola, 2005a,b; Olukosi and Adeola, 2009; Kerr et al., 2017). Geometric mean diameter of the MBM sample was 533 μm with SD of 1.9 based on 3 observations (Table 2). For the particle size distribution, approximately 75% of the MBM sample used was between 250 and 1,000 μm with more than 29% in the particle size bracket of 500 and 1,000 μm and the geometric mean diameter between 250 and 500 μm accounted for slightly more than 45%. The geometric mean diameter of 533 μm for the MBM sample used in the current study is smaller than and the particle size distribution is different from those reported by Anwar et al. (2015, 2016) for 7 MBM samples, but both the geometric mean diameter and particle size distribution are similar to those reported for 1 of the 3 MBM samples in Mutucumarana et al. (2015). Table 2. Nutritional characteristics of the test ingredient—meat and bone meal, corn, soybean meal, limestone and monocalcium phosphate used in starter and experimental diets on an as-is basis. Item, g/kg  Meat and bone meal  Corn  Soybean meal  Limestone  Monocalcium phosphate  DM  925.1  885.4  892.4  999  943.6  Gross energy (kcal/kg)  3,678  3,873  4,113      N  78.8  15.3  74.1      Crude fat  114.5          Calcium  107.7      370.9  113.1  Phosphorus  53.1      0.3  154.5  Indispensable AA   Arg  34.2           His  8.8           Ile  12.9           Leu  29.6           Lys  26.1           Met  7.8           Phe  16.9           Thr  16.0           Val  21.9          Dispensable AA             Ala  35.5           Asp  36.2           Cys  4.9           Glu  55.8           Gly  70.3           Pro  42.4           Ser  19.8           Tyr  10.9          Particle size             Geometric mean diameter (GMD), μm  533           GMD standard deviation, μm  1.9          Particle size distribution, %             >2,000 μm  3.71           1,000 to 2,000 μm  16.2           500 to 1,000 μm  28.66           250 to 500 μm  45.71           125 to 250 μm  5.4           75 to 125 μm  0.12           <75 μm  0.02          Item, g/kg  Meat and bone meal  Corn  Soybean meal  Limestone  Monocalcium phosphate  DM  925.1  885.4  892.4  999  943.6  Gross energy (kcal/kg)  3,678  3,873  4,113      N  78.8  15.3  74.1      Crude fat  114.5          Calcium  107.7      370.9  113.1  Phosphorus  53.1      0.3  154.5  Indispensable AA   Arg  34.2           His  8.8           Ile  12.9           Leu  29.6           Lys  26.1           Met  7.8           Phe  16.9           Thr  16.0           Val  21.9          Dispensable AA             Ala  35.5           Asp  36.2           Cys  4.9           Glu  55.8           Gly  70.3           Pro  42.4           Ser  19.8           Tyr  10.9          Particle size             Geometric mean diameter (GMD), μm  533           GMD standard deviation, μm  1.9          Particle size distribution, %             >2,000 μm  3.71           1,000 to 2,000 μm  16.2           500 to 1,000 μm  28.66           250 to 500 μm  45.71           125 to 250 μm  5.4           75 to 125 μm  0.12           <75 μm  0.02          View Large Table 2. Nutritional characteristics of the test ingredient—meat and bone meal, corn, soybean meal, limestone and monocalcium phosphate used in starter and experimental diets on an as-is basis. Item, g/kg  Meat and bone meal  Corn  Soybean meal  Limestone  Monocalcium phosphate  DM  925.1  885.4  892.4  999  943.6  Gross energy (kcal/kg)  3,678  3,873  4,113      N  78.8  15.3  74.1      Crude fat  114.5          Calcium  107.7      370.9  113.1  Phosphorus  53.1      0.3  154.5  Indispensable AA   Arg  34.2           His  8.8           Ile  12.9           Leu  29.6           Lys  26.1           Met  7.8           Phe  16.9           Thr  16.0           Val  21.9          Dispensable AA             Ala  35.5           Asp  36.2           Cys  4.9           Glu  55.8           Gly  70.3           Pro  42.4           Ser  19.8           Tyr  10.9          Particle size             Geometric mean diameter (GMD), μm  533           GMD standard deviation, μm  1.9          Particle size distribution, %             >2,000 μm  3.71           1,000 to 2,000 μm  16.2           500 to 1,000 μm  28.66           250 to 500 μm  45.71           125 to 250 μm  5.4           75 to 125 μm  0.12           <75 μm  0.02          Item, g/kg  Meat and bone meal  Corn  Soybean meal  Limestone  Monocalcium phosphate  DM  925.1  885.4  892.4  999  943.6  Gross energy (kcal/kg)  3,678  3,873  4,113      N  78.8  15.3  74.1      Crude fat  114.5          Calcium  107.7      370.9  113.1  Phosphorus  53.1      0.3  154.5  Indispensable AA   Arg  34.2           His  8.8           Ile  12.9           Leu  29.6           Lys  26.1           Met  7.8           Phe  16.9           Thr  16.0           Val  21.9          Dispensable AA             Ala  35.5           Asp  36.2           Cys  4.9           Glu  55.8           Gly  70.3           Pro  42.4           Ser  19.8           Tyr  10.9          Particle size             Geometric mean diameter (GMD), μm  533           GMD standard deviation, μm  1.9          Particle size distribution, %             >2,000 μm  3.71           1,000 to 2,000 μm  16.2           500 to 1,000 μm  28.66           250 to 500 μm  45.71           125 to 250 μm  5.4           75 to 125 μm  0.12           <75 μm  0.02          View Large Initial statistical analysis of the growth performance data revealed the absence of interaction between dietary MBM concentration and feeding age post hatching. Therefore, the df and sums of squares of the interaction term were pooled into the error term. Thus, the body weight (BW) gain, feed intake, and gain-to-feed ratio data presented in Table 3 are the main effects of dietary MBM concentration and feeding age post hatching. Proportional substitution of corn, soybean meal, and soy oil, which are the energy-contributing ingredients in the reference diet, with 0, 40, or 80 g MBM/kg diet linearly improved (P < 0.001) weight gain and gain-to-feed ratio (Table 3). Dietary protein and amino acids increased with increasing addition of MBM. In addition, both dietary non-phytate P and Ca increased with increasing supplementation of MBM. It is not known whether the improvement in weight gain and gain-to-feed ratio in the current study resulted from one of or a combination of the increase in dietary amino acids, P, and Ca. Feeding a 216 g CP/kg corn-soybean meal-based diet, Drewyor and Waldroup (2000) reported that substitution of 75 g high-ash MBM/kg diet improved BW by 8%, which was attributed to an increase in dietary non-phytate P from 4.5 to 5.5 g/kg. There were the expected and predictable increases (P < 0.001) in weight gain, feed intake, and gain-to-feed ratio with increasing feeding age post hatching (Table 3). Except for the feeding age post hatching between day 0 and 7, where weight gain, feed intake, and gain-to-feed ratio were approximately 97.5% of the Aviagen (2014) Ross 308 broiler performance objectives, subsequent growth performance for day 6 to 11, 10 to 16, or 15 to 21 feeding ages post hatching data were numerically superior to Aviagen (2014) Ross 308 broiler performance objectives. Table 3. Growth performance response to the main effect of dietary meat and bone meal and feeding age post hatching.   Weight gain,  Feed intake,  Gain/feed,  Item  g  g  g/kg  Dietary meat and bone meal (diet), g/kg1   0  269  318  890   40  277  314  927   80  297  320  976  Feeding age post hatching (age), d2   0 to 7  143  133  1,076   6 to 11  229  236  972   10 to 16  314  370  851   15 to 21  438  531  826  SD  17.1  17.3  39.4   P-value    Diet  <0.001  0.421  <0.001     Linear effect of diet  <0.001  0.560  <0.001     Quadratic effect of diet  0.136  0.240  0.516    Age  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001     Quadratic effect of age  0.019  <0.001  <0.001    Weight gain,  Feed intake,  Gain/feed,  Item  g  g  g/kg  Dietary meat and bone meal (diet), g/kg1   0  269  318  890   40  277  314  927   80  297  320  976  Feeding age post hatching (age), d2   0 to 7  143  133  1,076   6 to 11  229  236  972   10 to 16  314  370  851   15 to 21  438  531  826  SD  17.1  17.3  39.4   P-value    Diet  <0.001  0.421  <0.001     Linear effect of diet  <0.001  0.560  <0.001     Quadratic effect of diet  0.136  0.240  0.516    Age  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001     Quadratic effect of age  0.019  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 3. Growth performance response to the main effect of dietary meat and bone meal and feeding age post hatching.   Weight gain,  Feed intake,  Gain/feed,  Item  g  g  g/kg  Dietary meat and bone meal (diet), g/kg1   0  269  318  890   40  277  314  927   80  297  320  976  Feeding age post hatching (age), d2   0 to 7  143  133  1,076   6 to 11  229  236  972   10 to 16  314  370  851   15 to 21  438  531  826  SD  17.1  17.3  39.4   P-value    Diet  <0.001  0.421  <0.001     Linear effect of diet  <0.001  0.560  <0.001     Quadratic effect of diet  0.136  0.240  0.516    Age  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001     Quadratic effect of age  0.019  <0.001  <0.001    Weight gain,  Feed intake,  Gain/feed,  Item  g  g  g/kg  Dietary meat and bone meal (diet), g/kg1   0  269  318  890   40  277  314  927   80  297  320  976  Feeding age post hatching (age), d2   0 to 7  143  133  1,076   6 to 11  229  236  972   10 to 16  314  370  851   15 to 21  438  531  826  SD  17.1  17.3  39.4   P-value    Diet  <0.001  0.421  <0.001     Linear effect of diet  <0.001  0.560  <0.001     Quadratic effect of diet  0.136  0.240  0.516    Age  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001     Quadratic effect of age  0.019  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 4 shows the main effects of dietary MBM concentration and feeding age post hatching on ileal DM, N, and energy digestibility as there were no interactions between dietary MBM concentration and feeding age post hatching for those response criteria. When 0, 40, or 80 g MBM/kg diet were proportionally substituted with corn, soybean meal, and soy oil, there were responses (P < 0.01) in ileal digestibility of DM, N, and energy as well as IDE. Furthermore, responses to dietary substitution were quadratic (P < 0.01), whereas only the responses in ileal digestibility of N and IDE were linear (P < 0.01). There were both linear and quadratic decreases (P < 0.05) in ileal digestibility of N, and energy as well as IDE with advancing age, but only a linear (P < 0.05) response in ileal digestibility of DM to age (Table 4). Corn, soybean meal, and MBM supply N in the experimental diets with MBM proportionally replacing corn and soybean meal. Comparative ileal digestibility of N in studies (Bolarinwa et al., 2012; Adedokun et el., 2014) has shown lower N digestibility in MBM than soybean meal, and thus the reduction in ileal N digestibility with proportional substitution of 0, 40, or 80 g MBM/kg into the diets. As with growth performance and ileal DM, N, and energy utilization, there was no interaction between dietary MBM concentration and feeding age post hatching. Thus, the main effects of dietary MBM concentration and feeding age post hatching on total tract DM, N, and energy utilization responses are presented in Table 5. Proportionally substituting 0, 40, or 80 g MBM/kg into the diets resulted in linear effects (P < 0.01) of diet on AME, AMEn, and total tract retention of N. Total tract retention of N was linearly increased (P < 0.05) with feeding age post hatching. In addition, there were quadratic increases (P < 0.001) in metabolizability of energy, AME, and AMEn with increase in feeding age post hatching. There are no studies reported in the literature on age-related energy utilization responses of broiler chickens to MBM supplementation. For diets and bakery meal, age-related increases in energy utilization that are similar to observations in the current study have been reported (Sulistiyanto et al., 1999; Olukosi et al. 2007; Stefanello et al., 2016). Efficiency with which nitrogen and energy are utilized for BW gain is presented in Tables 6 and 7, respectively. Although there were predictable effects of diet on nitrogen intake (due to dietary nitrogen concentration), proportional substitution of corn, soybean meal, and soy oil with 0, 40, or 80 g MBM/kg diet did not affect the efficiency of ileal digestible N intake for BW gain. Increase in N intake as total, digestible, or retainable did not affect the efficiency of utilization for BW gain, which concurs with previous reports (Xue et al., 2016; Adedokun and Adeola, 2017). Efficiency of IDE, AME, and AMEn utilization for BW gain were linearly (P < 0.001) improved with the addition of 0, 40, or 80 g MBM/kg diet (Table 7). There were both linear and quadratic reductions (P < 0.001) in the efficiency of utilization of intakes of ileal digestible nitrogen, retainable nitrogen, IDE, and AME for BW gain with feeding age post hatching. Table 4. Ileal dry matter (DM), nitrogen (N), and energy digestibility responses to dietary meat and bone meal and feeding age post hatching.   Ileal DM  Ileal  Ileal energy  Ileal digestible    digestibility,  N digestibility,  digestibility,  energy,  Item  g/g DM  g/g N  kcal/kcal  kcal/g DM  Dietary meat and bone meal, (diet) g/kg1   0  0.709  0.831  0.735  3.337   40  0.694  0.809  0.724  3.329   80  0.706  0.809  0.734  3.405  Feeding age post hatching (age), d2   0 to 7  0.708  0.828  0.732  3.361   6 to 11  0.703  0.827  0.735  3.376   10 to 16  0.707  0.815  0.734  3.374   15 to 21  0.692  0.796  0.722  3.372  SD  0.0134  0.0145  0.0134  0.0613   P-value    Diet  <0.001  <0.001  <0.01  <0.01     Linear effect of diet  0.391  <0.001  0.618  <0.01     Quadratic effect of diet  <0.001  <0.01  <0.01  <0.01    Age  <0.01  <0.001  0.019  0.018     Linear effect of age  <0.01  <0.001  0.034  0.034     Quadratic effect of age  0.116  0.025  0.019  0.018    Ileal DM  Ileal  Ileal energy  Ileal digestible    digestibility,  N digestibility,  digestibility,  energy,  Item  g/g DM  g/g N  kcal/kcal  kcal/g DM  Dietary meat and bone meal, (diet) g/kg1   0  0.709  0.831  0.735  3.337   40  0.694  0.809  0.724  3.329   80  0.706  0.809  0.734  3.405  Feeding age post hatching (age), d2   0 to 7  0.708  0.828  0.732  3.361   6 to 11  0.703  0.827  0.735  3.376   10 to 16  0.707  0.815  0.734  3.374   15 to 21  0.692  0.796  0.722  3.372  SD  0.0134  0.0145  0.0134  0.0613   P-value    Diet  <0.001  <0.001  <0.01  <0.01     Linear effect of diet  0.391  <0.001  0.618  <0.01     Quadratic effect of diet  <0.001  <0.01  <0.01  <0.01    Age  <0.01  <0.001  0.019  0.018     Linear effect of age  <0.01  <0.001  0.034  0.034     Quadratic effect of age  0.116  0.025  0.019  0.018  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 4. Ileal dry matter (DM), nitrogen (N), and energy digestibility responses to dietary meat and bone meal and feeding age post hatching.   Ileal DM  Ileal  Ileal energy  Ileal digestible    digestibility,  N digestibility,  digestibility,  energy,  Item  g/g DM  g/g N  kcal/kcal  kcal/g DM  Dietary meat and bone meal, (diet) g/kg1   0  0.709  0.831  0.735  3.337   40  0.694  0.809  0.724  3.329   80  0.706  0.809  0.734  3.405  Feeding age post hatching (age), d2   0 to 7  0.708  0.828  0.732  3.361   6 to 11  0.703  0.827  0.735  3.376   10 to 16  0.707  0.815  0.734  3.374   15 to 21  0.692  0.796  0.722  3.372  SD  0.0134  0.0145  0.0134  0.0613   P-value    Diet  <0.001  <0.001  <0.01  <0.01     Linear effect of diet  0.391  <0.001  0.618  <0.01     Quadratic effect of diet  <0.001  <0.01  <0.01  <0.01    Age  <0.01  <0.001  0.019  0.018     Linear effect of age  <0.01  <0.001  0.034  0.034     Quadratic effect of age  0.116  0.025  0.019  0.018    Ileal DM  Ileal  Ileal energy  Ileal digestible    digestibility,  N digestibility,  digestibility,  energy,  Item  g/g DM  g/g N  kcal/kcal  kcal/g DM  Dietary meat and bone meal, (diet) g/kg1   0  0.709  0.831  0.735  3.337   40  0.694  0.809  0.724  3.329   80  0.706  0.809  0.734  3.405  Feeding age post hatching (age), d2   0 to 7  0.708  0.828  0.732  3.361   6 to 11  0.703  0.827  0.735  3.376   10 to 16  0.707  0.815  0.734  3.374   15 to 21  0.692  0.796  0.722  3.372  SD  0.0134  0.0145  0.0134  0.0613   P-value    Diet  <0.001  <0.001  <0.01  <0.01     Linear effect of diet  0.391  <0.001  0.618  <0.01     Quadratic effect of diet  <0.001  <0.01  <0.01  <0.01    Age  <0.01  <0.001  0.019  0.018     Linear effect of age  <0.01  <0.001  0.034  0.034     Quadratic effect of age  0.116  0.025  0.019  0.018  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 5. Total tract dry matter (DM), nitrogen (N), and energy utilization responses to dietary meat and bone meal and feeding age post hatching.   Total tract DM  Total tract N  Total tract N  Energy  N-corrected energy        retention,  retention,  retention,  metabolizability,  metabolizability,  AME,  AMEn,  Item  g/g DM  g/g N  g/g DM intake  kcal/kcal  kcal/kcal  kcal/g  kcal/g  Dietary meat and bone meal (diet), g/kg1   0  0.724  0.715  0.029  0.759  0.706  3.443  3.203   40  0.712  0.691  0.030  0.751  0.698  3.457  3.210   80  0.725  0.701  0.032  0.762  0.705  3.538  3.273  Feeding age post hatching (age), d2   0 to 7  0.707  0.699  0.030  0.736  0.682  3.380  3.131   6 to 11  0.738  0.732  0.032  0.774  0.717  3.556  3.295   10 to 16  0.712  0.676  0.029  0.755  0.702  3.466  3.225   15 to 21  0.724  0.703  0.030  0.765  0.711  3.515  3.265  SD  0.0163  0.0210  0.0009  0.0142  0.0128  0.0651  0.0589   P-value    Diet  0.013  <0.001  <0.001  0.029  0.059  <0.001  <0.001     Linear effect of diet  0.886  0.021  <0.001  0.398  0.847  <0.001  <0.001     Quadratic effect of diet  <0.01  <0.01  <0.01  0.012  0.018  0.044  0.065    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  0.199  0.033  0.305  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  0.039  0.898  0.876  <0.001  <0.001  <0.001  <0.001    Total tract DM  Total tract N  Total tract N  Energy  N-corrected energy        retention,  retention,  retention,  metabolizability,  metabolizability,  AME,  AMEn,  Item  g/g DM  g/g N  g/g DM intake  kcal/kcal  kcal/kcal  kcal/g  kcal/g  Dietary meat and bone meal (diet), g/kg1   0  0.724  0.715  0.029  0.759  0.706  3.443  3.203   40  0.712  0.691  0.030  0.751  0.698  3.457  3.210   80  0.725  0.701  0.032  0.762  0.705  3.538  3.273  Feeding age post hatching (age), d2   0 to 7  0.707  0.699  0.030  0.736  0.682  3.380  3.131   6 to 11  0.738  0.732  0.032  0.774  0.717  3.556  3.295   10 to 16  0.712  0.676  0.029  0.755  0.702  3.466  3.225   15 to 21  0.724  0.703  0.030  0.765  0.711  3.515  3.265  SD  0.0163  0.0210  0.0009  0.0142  0.0128  0.0651  0.0589   P-value    Diet  0.013  <0.001  <0.001  0.029  0.059  <0.001  <0.001     Linear effect of diet  0.886  0.021  <0.001  0.398  0.847  <0.001  <0.001     Quadratic effect of diet  <0.01  <0.01  <0.01  0.012  0.018  0.044  0.065    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  0.199  0.033  0.305  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  0.039  0.898  0.876  <0.001  <0.001  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 5. Total tract dry matter (DM), nitrogen (N), and energy utilization responses to dietary meat and bone meal and feeding age post hatching.   Total tract DM  Total tract N  Total tract N  Energy  N-corrected energy        retention,  retention,  retention,  metabolizability,  metabolizability,  AME,  AMEn,  Item  g/g DM  g/g N  g/g DM intake  kcal/kcal  kcal/kcal  kcal/g  kcal/g  Dietary meat and bone meal (diet), g/kg1   0  0.724  0.715  0.029  0.759  0.706  3.443  3.203   40  0.712  0.691  0.030  0.751  0.698  3.457  3.210   80  0.725  0.701  0.032  0.762  0.705  3.538  3.273  Feeding age post hatching (age), d2   0 to 7  0.707  0.699  0.030  0.736  0.682  3.380  3.131   6 to 11  0.738  0.732  0.032  0.774  0.717  3.556  3.295   10 to 16  0.712  0.676  0.029  0.755  0.702  3.466  3.225   15 to 21  0.724  0.703  0.030  0.765  0.711  3.515  3.265  SD  0.0163  0.0210  0.0009  0.0142  0.0128  0.0651  0.0589   P-value    Diet  0.013  <0.001  <0.001  0.029  0.059  <0.001  <0.001     Linear effect of diet  0.886  0.021  <0.001  0.398  0.847  <0.001  <0.001     Quadratic effect of diet  <0.01  <0.01  <0.01  0.012  0.018  0.044  0.065    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  0.199  0.033  0.305  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  0.039  0.898  0.876  <0.001  <0.001  <0.001  <0.001    Total tract DM  Total tract N  Total tract N  Energy  N-corrected energy        retention,  retention,  retention,  metabolizability,  metabolizability,  AME,  AMEn,  Item  g/g DM  g/g N  g/g DM intake  kcal/kcal  kcal/kcal  kcal/g  kcal/g  Dietary meat and bone meal (diet), g/kg1   0  0.724  0.715  0.029  0.759  0.706  3.443  3.203   40  0.712  0.691  0.030  0.751  0.698  3.457  3.210   80  0.725  0.701  0.032  0.762  0.705  3.538  3.273  Feeding age post hatching (age), d2   0 to 7  0.707  0.699  0.030  0.736  0.682  3.380  3.131   6 to 11  0.738  0.732  0.032  0.774  0.717  3.556  3.295   10 to 16  0.712  0.676  0.029  0.755  0.702  3.466  3.225   15 to 21  0.724  0.703  0.030  0.765  0.711  3.515  3.265  SD  0.0163  0.0210  0.0009  0.0142  0.0128  0.0651  0.0589   P-value    Diet  0.013  <0.001  <0.001  0.029  0.059  <0.001  <0.001     Linear effect of diet  0.886  0.021  <0.001  0.398  0.847  <0.001  <0.001     Quadratic effect of diet  <0.01  <0.01  <0.01  0.012  0.018  0.044  0.065    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  0.199  0.033  0.305  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  0.039  0.898  0.876  <0.001  <0.001  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 6. Efficiency of utilization of leal digestible nitrogen and retainable nitrogen intake for body weight gain.   Nitrogen  Ileal digestible  Retainable nitrogen  Weight gain/ileal digestible  Weight gain/retainable  Item  intake, g  nitrogen intake, g  intake, g  nitrogen intake, g/g  nitrogen intake, g/g  Dietary meat and bone meal (diet), g/kg1   0  11.77  9.70  8.37  28.91  33.58   40  12.18  9.80  8.38  29.49  34.58   80  13.18  10.57  9.23  29.29  33.88  Feeding age post hatching (age), d2   0 to 7  5.17  4.28  3.61  33.33  39.48   6 to 11  9.18  7.59  6.71  30.16  34.09   10 to 16  14.44  11.77  9.76  26.81  32.29   15 to 21  20.69  16.46  14.55  26.62  30.19  SD  0.751  0.616  0.678  1.383  1.586   P-value    Diet  <0.001  <0.001  <0.001  0.339  0.089     Linear effect of diet  <0.001  <0.001  <0.001  0.341  0.527     Quadratic effect of diet  0.122  0.033  <0.01  0.262  0.035    Age     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.01  0.071  <0.01  <0.001  <0.001    Nitrogen  Ileal digestible  Retainable nitrogen  Weight gain/ileal digestible  Weight gain/retainable  Item  intake, g  nitrogen intake, g  intake, g  nitrogen intake, g/g  nitrogen intake, g/g  Dietary meat and bone meal (diet), g/kg1   0  11.77  9.70  8.37  28.91  33.58   40  12.18  9.80  8.38  29.49  34.58   80  13.18  10.57  9.23  29.29  33.88  Feeding age post hatching (age), d2   0 to 7  5.17  4.28  3.61  33.33  39.48   6 to 11  9.18  7.59  6.71  30.16  34.09   10 to 16  14.44  11.77  9.76  26.81  32.29   15 to 21  20.69  16.46  14.55  26.62  30.19  SD  0.751  0.616  0.678  1.383  1.586   P-value    Diet  <0.001  <0.001  <0.001  0.339  0.089     Linear effect of diet  <0.001  <0.001  <0.001  0.341  0.527     Quadratic effect of diet  0.122  0.033  <0.01  0.262  0.035    Age     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.01  0.071  <0.01  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 6. Efficiency of utilization of leal digestible nitrogen and retainable nitrogen intake for body weight gain.   Nitrogen  Ileal digestible  Retainable nitrogen  Weight gain/ileal digestible  Weight gain/retainable  Item  intake, g  nitrogen intake, g  intake, g  nitrogen intake, g/g  nitrogen intake, g/g  Dietary meat and bone meal (diet), g/kg1   0  11.77  9.70  8.37  28.91  33.58   40  12.18  9.80  8.38  29.49  34.58   80  13.18  10.57  9.23  29.29  33.88  Feeding age post hatching (age), d2   0 to 7  5.17  4.28  3.61  33.33  39.48   6 to 11  9.18  7.59  6.71  30.16  34.09   10 to 16  14.44  11.77  9.76  26.81  32.29   15 to 21  20.69  16.46  14.55  26.62  30.19  SD  0.751  0.616  0.678  1.383  1.586   P-value    Diet  <0.001  <0.001  <0.001  0.339  0.089     Linear effect of diet  <0.001  <0.001  <0.001  0.341  0.527     Quadratic effect of diet  0.122  0.033  <0.01  0.262  0.035    Age     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.01  0.071  <0.01  <0.001  <0.001    Nitrogen  Ileal digestible  Retainable nitrogen  Weight gain/ileal digestible  Weight gain/retainable  Item  intake, g  nitrogen intake, g  intake, g  nitrogen intake, g/g  nitrogen intake, g/g  Dietary meat and bone meal (diet), g/kg1   0  11.77  9.70  8.37  28.91  33.58   40  12.18  9.80  8.38  29.49  34.58   80  13.18  10.57  9.23  29.29  33.88  Feeding age post hatching (age), d2   0 to 7  5.17  4.28  3.61  33.33  39.48   6 to 11  9.18  7.59  6.71  30.16  34.09   10 to 16  14.44  11.77  9.76  26.81  32.29   15 to 21  20.69  16.46  14.55  26.62  30.19  SD  0.751  0.616  0.678  1.383  1.586   P-value    Diet  <0.001  <0.001  <0.001  0.339  0.089     Linear effect of diet  <0.001  <0.001  <0.001  0.341  0.527     Quadratic effect of diet  0.122  0.033  <0.01  0.262  0.035    Age     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.01  0.071  <0.01  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 7. Efficiency of utilization of leal digestible energy and metabolizable energy intake for body weight gain.   Gross energy  Ileal digestible  AME  AMEn  Weight gain/ileal  Weight  Weight    intake,  energy intake,  intake  intake,  digestible energy  gain/AME intake,  gain/AMEn intake,  Item  kcal  kcal  kcal  kcal  intake, g/kcal  g/kcal  g/kcal  Dietary meat and bone meal (diet) g/kg1   0  1,310  961  997  928  0.294  0.285  0.306   40  1,290  931  973  905  0.312  0.301  0.324   80  1,331  974  1,020  944  0.320  0.309  0.334  Feeding age post hatching (age), d2   0 to 7  548  401  403  374  0.356  0.354  0.382   6 to 11  973  715  753  697  0.320  0.304  0.328   10 to 16  1,529  1,123  1,154  1,073  0.281  0.273  0.293   15 to 21  2,191  1,583  1,678  1,558  0.277  0.262  0.282  SD  71.3  58.1  64.4  59.3  0.0153  0.0129  0.0139   P-value    Diet  0.154  0.039  0.050  0.073  <0.001  <0.001  <0.001     Linear effect of diet  0.311  0.459  0.214  0.339  <0.001  <0.001  <0.001     Quadratic effect of diet  0.098  0.015  0.034  0.037  0.230  0.250  0.294    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.001  0.026  <0.01  <0.01  <0.001  <0.001  <0.001    Gross energy  Ileal digestible  AME  AMEn  Weight gain/ileal  Weight  Weight    intake,  energy intake,  intake  intake,  digestible energy  gain/AME intake,  gain/AMEn intake,  Item  kcal  kcal  kcal  kcal  intake, g/kcal  g/kcal  g/kcal  Dietary meat and bone meal (diet) g/kg1   0  1,310  961  997  928  0.294  0.285  0.306   40  1,290  931  973  905  0.312  0.301  0.324   80  1,331  974  1,020  944  0.320  0.309  0.334  Feeding age post hatching (age), d2   0 to 7  548  401  403  374  0.356  0.354  0.382   6 to 11  973  715  753  697  0.320  0.304  0.328   10 to 16  1,529  1,123  1,154  1,073  0.281  0.273  0.293   15 to 21  2,191  1,583  1,678  1,558  0.277  0.262  0.282  SD  71.3  58.1  64.4  59.3  0.0153  0.0129  0.0139   P-value    Diet  0.154  0.039  0.050  0.073  <0.001  <0.001  <0.001     Linear effect of diet  0.311  0.459  0.214  0.339  <0.001  <0.001  <0.001     Quadratic effect of diet  0.098  0.015  0.034  0.037  0.230  0.250  0.294    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.001  0.026  <0.01  <0.01  <0.001  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Table 7. Efficiency of utilization of leal digestible energy and metabolizable energy intake for body weight gain.   Gross energy  Ileal digestible  AME  AMEn  Weight gain/ileal  Weight  Weight    intake,  energy intake,  intake  intake,  digestible energy  gain/AME intake,  gain/AMEn intake,  Item  kcal  kcal  kcal  kcal  intake, g/kcal  g/kcal  g/kcal  Dietary meat and bone meal (diet) g/kg1   0  1,310  961  997  928  0.294  0.285  0.306   40  1,290  931  973  905  0.312  0.301  0.324   80  1,331  974  1,020  944  0.320  0.309  0.334  Feeding age post hatching (age), d2   0 to 7  548  401  403  374  0.356  0.354  0.382   6 to 11  973  715  753  697  0.320  0.304  0.328   10 to 16  1,529  1,123  1,154  1,073  0.281  0.273  0.293   15 to 21  2,191  1,583  1,678  1,558  0.277  0.262  0.282  SD  71.3  58.1  64.4  59.3  0.0153  0.0129  0.0139   P-value    Diet  0.154  0.039  0.050  0.073  <0.001  <0.001  <0.001     Linear effect of diet  0.311  0.459  0.214  0.339  <0.001  <0.001  <0.001     Quadratic effect of diet  0.098  0.015  0.034  0.037  0.230  0.250  0.294    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.001  0.026  <0.01  <0.01  <0.001  <0.001  <0.001    Gross energy  Ileal digestible  AME  AMEn  Weight gain/ileal  Weight  Weight    intake,  energy intake,  intake  intake,  digestible energy  gain/AME intake,  gain/AMEn intake,  Item  kcal  kcal  kcal  kcal  intake, g/kcal  g/kcal  g/kcal  Dietary meat and bone meal (diet) g/kg1   0  1,310  961  997  928  0.294  0.285  0.306   40  1,290  931  973  905  0.312  0.301  0.324   80  1,331  974  1,020  944  0.320  0.309  0.334  Feeding age post hatching (age), d2   0 to 7  548  401  403  374  0.356  0.354  0.382   6 to 11  973  715  753  697  0.320  0.304  0.328   10 to 16  1,529  1,123  1,154  1,073  0.281  0.273  0.293   15 to 21  2,191  1,583  1,678  1,558  0.277  0.262  0.282  SD  71.3  58.1  64.4  59.3  0.0153  0.0129  0.0139   P-value    Diet  0.154  0.039  0.050  0.073  <0.001  <0.001  <0.001     Linear effect of diet  0.311  0.459  0.214  0.339  <0.001  <0.001  <0.001     Quadratic effect of diet  0.098  0.015  0.034  0.037  0.230  0.250  0.294    Age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Linear effect of age  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001  <0.001     Quadratic effect of age  <0.001  0.026  <0.01  <0.01  <0.001  <0.001  <0.001  1 Data are main effect means of 24 replicate cages. 2 Data are main effect means of 18 replicate cages. View Large Feeding age post hatching affected ileal digestibility of energy (Table 4) as well as both metabolizability of energy and N-corrected metabolizability of energy (Table 5). Age-related regression-derived IDE, ME, and MEn values of MBM for broiler chickens from day 0 to 7, 6 to 11, 10 to 16, and 15 to 21 post hatching are shown in Table 8. There were quadratic effects (P < 0.01) of feeding age post hatching on IDE, ME, and MEn in which the day 0 to 7 energy values were lower than subsequent feeding ages, and these are depicted in Figure 1. Studies have shown that ME value of a diet is lowest between day 4 and 7 post hatching in broiler chicks followed by an increase with post hatching age (Zelenka, 1968). Furthermore, Sulistiyanto et al. (1999) reported that utilization of energy-yielding feedstuffs was age-dependent and suggested that by 14 d of age, broiler chicks are able to efficiently utilize the energy in the diet. The requirements of broiler chickens for nutrients and energy are not commonly based on post hatching age and only 1 ME value and 1 AA digestibility value are given for each feed ingredient. In the current study, IDE, ME, and MEn values increased with post hatching age of broiler chickens. The current results and earlier reports emphasize the importance of age-related differences in energy digestibility, which should be taken into consideration during diet formulation. Figure 1. View largeDownload slide Quadratic relationship between regression-derived ileal digestible energy (solid circle and dash line), metabolizable energy (solid diamond and solid line), and nitrogen-corrected metabolizable energy (solid triangle and dotted line) values of meat and bone meal for broiler chickens and feeding age post hatching from day 0 to 7, 6 to 11, 10 to 16, or 15 to 21. Ileal digestible energy, metabolizable energy, and nitrogen-corrected metabolizable energy of meat and bone meal in broiler chickens increased (P < 0.05) with feeding age post hatching. Figure 1. View largeDownload slide Quadratic relationship between regression-derived ileal digestible energy (solid circle and dash line), metabolizable energy (solid diamond and solid line), and nitrogen-corrected metabolizable energy (solid triangle and dotted line) values of meat and bone meal for broiler chickens and feeding age post hatching from day 0 to 7, 6 to 11, 10 to 16, or 15 to 21. Ileal digestible energy, metabolizable energy, and nitrogen-corrected metabolizable energy of meat and bone meal in broiler chickens increased (P < 0.05) with feeding age post hatching. Table 8. Age-related regression-derived ileal digestible energy (IDE), metabolizable energy (ME), and nitrogen-corrected metabolizable energy (MEn) values of meat and bone meal for broiler chickens from day 0 to 7, 6 to 11, 10 to 16, and 15 to 21 post hatching.1   IDE,  ME,  MEn,  Item  kcal/g DM  kcal/g DM  kcal/g DM  Feeding age post hatching (age), d1   0 to 7  2.852  2.909  2.687   6 to 11  2.962  3.125  2.887   10 to 16  2.927  3.083  2.839   15 to 21  2.959  3.075  2.845  SD  0.0598  0.1168  0.1082  P-value  <0.01  <0.01  <0.01    IDE,  ME,  MEn,  Item  kcal/g DM  kcal/g DM  kcal/g DM  Feeding age post hatching (age), d1   0 to 7  2.852  2.909  2.687   6 to 11  2.962  3.125  2.887   10 to 16  2.927  3.083  2.839   15 to 21  2.959  3.075  2.845  SD  0.0598  0.1168  0.1082  P-value  <0.01  <0.01  <0.01  1 Data are means of 6 slopes derived from regressions for 3 cages of 0, 40, or 80 g MBM/kg diet in each of 6 blocks. View Large Table 8. Age-related regression-derived ileal digestible energy (IDE), metabolizable energy (ME), and nitrogen-corrected metabolizable energy (MEn) values of meat and bone meal for broiler chickens from day 0 to 7, 6 to 11, 10 to 16, and 15 to 21 post hatching.1   IDE,  ME,  MEn,  Item  kcal/g DM  kcal/g DM  kcal/g DM  Feeding age post hatching (age), d1   0 to 7  2.852  2.909  2.687   6 to 11  2.962  3.125  2.887   10 to 16  2.927  3.083  2.839   15 to 21  2.959  3.075  2.845  SD  0.0598  0.1168  0.1082  P-value  <0.01  <0.01  <0.01    IDE,  ME,  MEn,  Item  kcal/g DM  kcal/g DM  kcal/g DM  Feeding age post hatching (age), d1   0 to 7  2.852  2.909  2.687   6 to 11  2.962  3.125  2.887   10 to 16  2.927  3.083  2.839   15 to 21  2.959  3.075  2.845  SD  0.0598  0.1168  0.1082  P-value  <0.01  <0.01  <0.01  1 Data are means of 6 slopes derived from regressions for 3 cages of 0, 40, or 80 g MBM/kg diet in each of 6 blocks. View Large Olukosi et al. (2007), and more recently Stefanello et al. (2016), reported age-related decreases in the total tract retention of DM, N, and energy as well as dietary and ingredient ME from day 7 to 21 post hatching. This is perhaps related to the development of digestive and absorptive capacities of the intestine, as has been demonstrated for pigs (Adeola and King, 2006), because digestive enzyme production and absorptive capacity increase with age; most probably, the ability of animals to extract nutrient from feeds increases with age. Birds undergo metabolic adaptations from embryonic yolk dependence to utilizing nutrients from exogenous feed (Noy and Sklan, 2001). Earlier, Nitsan et al. (1991) and Sell and Angel (1990) opined that the increased endogenous enzyme secretions and nutrient absorption from first to third week of age is part of the reason for the improved digestion that occurs with age. 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Poultry ScienceOxford University Press

Published: Apr 17, 2018

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