Improved performance of Cobb 500 birds fed increased amino acid density in Wheat or Maizebased diets D. PARKER 1 *, R. SHIRLEY 1, M. VAZQUEZ-AÑÓN 1, C. KNIGHT 1, L. AZEVEDO 1 and A. MARANGOS 2 1 Novus International Inc., St Louis, Mo, USA, 2 Nutrition Solutions, Winchester, UK, *Corresponding author: david.parker@novusint.com The objective of this experiment was to evaluate the impact of increasing amino acid density of commercial broiler diets that are based on either Wheat or Maize. There were three dietary regimes: Diet 1 was formulated to be similar to the Cobb Broiler Nutrition Guide (2004) for minimum feed cost (); Diet 2 was based on the Cobb guidelines for maximizing white meat yield (WM) and Diet 3 was similar to WM but had the addition of higher amino acid levels (AA). Diets were fed in three phases and ME levels for the Starter (2968 kcal/kg), Grower (3053 kcal/kg) and Finisher (3154 kcal/kg) were calculated to be the same across all treatments. The six diets were pelleted and the starters fed crumbled. Eight replicates of 24, 1-day old Cobb 500 chicks were randomly allocated to 96 floor pens and grown until 36 days of age. Since there were no significant interactions between gender and diet, gender and level, or diet and level for any of the production parameters only the main effects are presented. As expected male birds outperformed female birds in most parameters across diet type and amino acid supplementation level. Body weight gain (BWG) and feed consumption were significantly influenced by amino acid density. Broilers consuming the diet had the lowest BWG and poorest feed conversion, while broilers consuming the AA diet had the greatest BWG (p=0.0315) and best feed conversion (p<0.0001). Despite the latter differences feed intake was not affected by amino acid density. On a dietary basis birds fed the Wheat-based diets tended to have lower gains (p<0.0285) and lower feed consumption (p<0.0041), resulting in no net change in feed conversion when compared to birds fed Maize-based diets. Carcass analysis showed a significant reduction (p<0.0006) in fat pad weight and a significant increase (p<0.0086) in breast meat yield at the highest level of amino acid inclusion. Economic analysis of the trial also illustrated an improved return over feed costs when Cobb 500 broilers were fed a high amino acid diet. Keywords: broilers; amino acids; Cobb 500; nutrient density Introduction Poultry nutritionists often formulate broiler rations on a least-cost basis, with the result that rations are formulated with a lower nutrient density and broilers are unable to reach their maximum genetic potential. Previous studies of Kidd et al. (2004) and Kidd et al. (2005a, b) demonstrated that increasing the dietary amino acid (AA) density above that of average industry levels can result in greater performance that fully compensates for higher feed costs. The latter results indicate that the broiler industry may be limiting their potential to not only maximize broiler genetics, but also increase profitability. Using European Union (EU) or Asian poultry feeding and management conditions, such as antibiotic-free, all vegetable protein diets, the objective of this trial was to compare the performance of male and female Cobb 500 birds under three nutritional programs that varied in AA density.
Materials and methods The study was conducted in a floor pen setting using d-old Cobb 500 male and female birds. Each treatment was replicated eight times, and each of the 96 pens contained 24, 1-day old Cobb 500 chicks (2,304 total chicks). The birds were fed three nutritional programs using Wheat or Maize-based diets from d-old until 36 d of age in three phases (starter 1-10d, grower 11-25d, and finisher 26-36d). Dietary programs consisted of a nutrient density representing the feed cost () and modified white meat (WM) diets of the Cobb Broiler Nutrition Supplement (2004), and a high AA supplemented diet (HAA; approximately 8% higher than the WM diet). All diets were commercial-based, formulated on a digestible AA basis, and were fed pelleted except for the starter diets, which were offered in crumbles (Tables 1 and 2). Performance was measured at the end of each phase. Feed was withdrawn about 12 hrs before slaughter on d 37, and carcass quality was quantified on d 38 from 6 randomly selected birds per pen (3 males and 3 females). On d 38 the birds were individually weighed, terminated by rapid decapitation, bled, scalded and plucked. After plucking, the feet were removed at the tibia-shank joint; and the head and neck were removed to leave approximately 5-7 cm of the neck with the carcass. The carcass was eviscerated including the lungs but not the kidneys or gonads; and the abdominal fat pad was also removed for quantification. Hot carcass weight and fat pad weight were subsequently recorded. The carcasses were placed in rinse water and then drained and placed in refrigerated chill tubs overnight. On day 39, after the chill period, both leg quarters and the right skinless pectoralis major and pectoralis minor cuts were removed; and all pieces were weighed together to obtain a cold carcass weight. Yield for each cut of meat was determined by dividing the weight of the specific cut by that of the live weight, and multiplying that ratio by 100. Data were analyzed in a factorial 2 x 2 x 3 design using SAS (1999). Duncan s procedure was used to establish differences among treatments and main effect means at a p = 0.05. Results and discussion There were no significant interactions between gender and diet, gender and level, diet and level, or diet and level and gender for any production (three-way interaction not shown) or carcass parameters. The 36 d performance data illustrates the benefits of feeding a higher level of AA in both a Wheat and Maize-based diet. Broilers fed the HAA diet had significantly higher body weight gain and feed conversion (P < 0.0315) when compared to broilers that consumed either the or WM diets (Table 3). While broilers consuming the diets gained 1.871 kg/bird and had a feed conversion of 1.682, broilers consuming the HAA diets gained 1.927 kg/bird and had a feed conversion of 1.636. Broilers consuming the WM diets had a body weight gain of 1.879 kg/bird and a feed conversion of 1.669; these values were similar to that of broilers consuming the diets. There was very little difference in feed intake as the level of dietary AA s increased (P = 0.9341). These results are very similar to the observations of Kidd et al. (2004), Kidd et al. (2005a) and Kidd et al. (2005b), despite the fact that Kidd s group used either Ross 508 or Ross 708 broilers. Mortality across all treatments was low until day 31, when environmental temperatures exceeded 35 O C (Figure 1). This increase in temperature resulted in a spike in mortality across all treatments within the house (128 birds), but especially in the row of pens that received the greatest amount of sunlight. This area included several pens of birds that were consuming Wheat diets, resulting in the observed higher mortality for Wheat diets compared to Maize diets. Diet type and the level of AA supplementation had a significant influence on carcass parameters (Table 4). While increasing the AA density of the diet (WM) had a minimal effect on all carcass parameters, increasing the AA density by 8% (HAA) significantly improved live weight by 3.67%, hot carcass weight by 4.11%, leg quarter weight by 4.43%, breast weight by 5.59%, and lowered fat pad weight by 9.40% and fat pad yield by 13.19% (p < 0.0160). Broilers fed the Wheatbased diets had a significantly higher breast yield (p = 0.0123). Carcass weight and yield was also affected by gender. Males had significantly (p < 0.0004) higher live weight
Table 1 Experimental Wheat-based diets composition. Cobb Feed Cost (WC) Cobb White meat (WCWM) High amino acids (WHAA) Ingredients Starter Grower Finisher Starter Grower Finisher Starter Grower Finisher Wheat % 42.50 45.00 42.00 36.00 39.60 40.57 33.00 38.00 31.01 Soybean meal % 29.78 26.81 24.65 35.17 27.94 25.90 37.68 31.93 30.27 Maize % 20.96 20.76 25.00 20.43 25.00 25.00 20.66 22.09 30.00 Canola oil % 1.14 3.04 4.17 2.99 2.99 4.30 3.12 3.53 4.60 Dicalcium P % 2.10 2.01 1.87 2.04 2.02 1.87 2.03 1.99 1.86 Limestone % 1.07 1.04 0.98 0.94 1.03 0.98 0.93 1.02 0.96 Common salt % 0.31 0.26 0.26 0.31 0.26 0.26 0.31 0.27 0.27 NaH 2 CO 3 % 0.14 0.10 0.10 0.18 0.10 0.10 0.18 0.10 0.10 Alimet % 0.25 0.22 0.23 0.29 0.26 0.26 0.36 0.28 0.27 L-Lysine % 0.17 0.18 0.19 0.12 0.22 0.20 0.17 0.19 0.13 L-Threonine % 0.06 0.06 0.08 0.02 0.08 0.09 0.05 0.07 0.07 Other 1 % 1.52 0.52 0.47 1.52 0.52 0.47 1.52 0.52 0.47 Nutrients ME (Kcal/kg) 2,968 3,053 3,154 2,968 3,053 3,154 2,968 3,053 3,154 Crude protein % 21.0 19.0 18.0 23.0 19.4 18.0 24.0 21.0 19.9 Calcium % 1.00 0.96 0.90 1.00 0.96 0.90 1.0 0.96 0.90 Available P % 0.50 0.48 0.45 0.50 0.48 0.45 0.5 0.48 0.45 Sodium % 0.20 0.17 0.17 0.20 0.17 0.17 0.20 0.17 0.17 Dig. Lysine % 1.08 1.01 0.96 1.18 1.07 1.00 1.28 1.14 1.05 Dig. TTSA % 0.80 0.78 0.77 0.87 0.82 0.80 0.95 0.88 0.84 Dig. Threonine % 0.69 0.65 0.64 0.76 0.68 0.66 0.82 0.73 0.70 1 Soybean oil (1.00% in Starter, 0% in Grower and Finisher), Santoquin (0.01%), Tox Guard (0.1%), Avizyme 1502 (0.01%), Sacox (0.05% in Starter and Grower and 0% in Finisher), and Novus Vitamin/Mineral Mix (0.35%). Table 2 Experimental Maize-based diets composition. Cobb Feed Cost (MC) Cobb White meat (MCWM) High amino acids (MHAA) Ingredients Starter Grower Finisher Starter Grower Finisher Starter Grower Finisher Soybean meal % 33.78 29.88 27.54 38.85 28.95 28.05 41.08 34.63 30.89 Maize % 60.65 63.82 65.03 54.83 64.70 64.38 52.15 58.27 61.13 Soybean oil % 1.11 1.93 3.24 1.93 1.75 3.31 2.26 2.68 3.77 Dicalcium P % 2.14 2.09 1.94 2.11 2.09 1.94 2.09 2.06 1.92 Limestone % 0.98 1.01 0.95 0.95 1.01 0.94 0.94 0.99 0.94 Common salt % 0.31 0.29 0.29 0.31 0.29 0.29 0.31 0.29 0.29 NaH 2 CO 3 % 0.19 0.10 0.10 0.19 0.10 0.10 0.19 0.10 0.10 Alimet % 0.24 0.23 0.25 0.27 0.29 0.28 0.34 0.29 0.29 L-Lysine % 0.08 0.11 0.13 0.04 0.22 0.16 0.10 0.13 0.14 L-Threonine % 0.00 0.03 0.06 0.00 0.08 0.08 0.01 0.05 0.07 Other 1 % 0.51 0.51 0.46 0.51 0.51 0.46 0.51 0.51 0.46 Nutrients ME (Kcal/kg) 2,968 3,053 3,154 2,968 3,053 3,154 2,968 3,053 3,154 Crude protein % 21.0 19.0 18.0 23.0 18.8 18.2 24.0 20.9 19.4 Calcium % 1.00 0.96 0.90 1.00 0.96 0.90 1.00 0.96 0.90 Available P % 0.50 0.48 0.45 0.50 0.48 0.45 0.50 0.48 0.45 Sodium % 0.20 0.17 0.17 0.20 0.17 0.17 0.20 0.17 0.17 Dig. Lysine % 1.08 1.01 0.96 1.18 1.07 1.00 1.28 1.14 1.05 Dig. TTSA % 0.80 0.78 0.79 0.87 0.82 0.80 0.95 0.88 0.84 Dig. Threonine % 0.69 0.65 0.64 0.77 0.68 0.66 0.82 0.73 0.70 1 Santoquin (0.01%), Tox Guard (0.1%), Sacox (0.05% in Starter and Grower and 0% in Finisher), and Novus Vitamin/Mineral Mix (0.35%).
Table 3 Broiler performance (1-36d of age). Gender Diet Weight Gain Intake Conversion Mortality 1 Body Weight Feed Feed - kg/bird % Male WC 2.018 b 1.977 b 3.288 b 1.664 bcd 10.94 Male WCWM 2.070 ab 2.028 ab 3.334 ab 1.644 cde 9.52 Male WHAA 2.083 ab 2.041 ab 3.283 b 1.609 e 8.85 Male MC 2.121 a 2.080 a 3.416 a 1.643 cde 2.38 Male MCWM 2.047 ab 2.007 ab 3.353 ab 1.671 bc d 8.86 Male MHAA 2.078 ab 2.038 ab 3.317 ab 1.627 de 4.17 Female WC 1.744 d 1.703 d 2.928 d 1.720 a 7.81 Female WCWM 1.778 d 1.737 d 2.914 d 1.679 abc 10.94 Female WHAA 1.821 cd 1.780 cd 2.923 d 1.643 cde 6.77 Female MC 1.792 d 1.752 d 2.973 cd 1.698 ab 5.73 Female MCWM 1.803 cd 1.762 cd 2.960 cd 1.681 abc 5.21 Female MHAA 1.878 c 1.836 c 3.060 c 1.669 bcd 9.52 CV 3.79 3.89 3.48 2.39 97.94 RMSE 0.0733 0.0736 0.1094 0.0398 7.4158 Wheat 1.916 b 1.875 b 3.107 b 1.660 9.13 a Maize 1.951 a 1.910 a 3.177 a 1.665 5.98 b 1.912 b 1.871 b 3.143 1.682 a 6.86 WM 1.920 b 1.879 b 3.134 1.669 a 8.60 HAA 1.968 a 1.927 a 3.148 1.636 b 7.26 Male 2.068 a 2.027 a 3.330 a 1.643 b 7.52 Female 1.801 b 1.760 b 2.958 b 1.682 a 7.62 WC 1.881 1.840 3.108 1.692 a 9.38 ab WCWM 1.914 1.873 3.110 1.663 ab 10.28 a WCAA 1.952 1.911 3.103 1.626 c 7.81 ab MC 1.946 1.905 3.180 1.672 ab 4.17 b MCWM 1.925 1.884 3.156 1.676 ab 7.03 ab MCAA 1.985 1.944 3.197 1.647 bc 6.67 ab ANOVA 1 P-values Treatment < 0.0001 < 0.0001 < 0.0001 < 0.0001 0.5514 Diet 0.0279 0.0285 0.0041 0.5656 0.0400 Level 0.0314 0.0315 0.9341 0.0001 0.5668 Gender < 0.0001 < 0.0001 < 0.0001 < 0.0001 0.9388 Diet x Level 0.1440 0.1496 0.5595 0.0807 0.5374 Level x Gender 0.1904 0.1992 0.1601 0.2587 0.7576 Diet x Gender 0.5505 0.5737 0.7210 0.7191 0.3409 1 Wheat Cobb Feed Cost (WC), Wheat Cobb White Meat (WCWM), Wheat High Amino Acids (WHAA), Maize Cobb Feed Cost (MC), Maize Cobb White Meat (MCWM), Maize High Amino Acids (MHAA). 2 Diet refers to Wheat vs. Maize; Level refers to vs. HAA. (15.30%), hot carcass weight (15.72%), leg quarter weight (17.87%), breast weight (13.64%), and leg quarter yield (2.03%); but also had a significantly (p < 0.0318) lower fat pad yield (13.51%) and breast yield (1.55%).
Table 4 Carcass performance (1-36d of age). Hot Carcass Weight Leg Quarter Weight Leg Quarter Yield Gender Diet Weight Fat Pad Weight 2 Yield Yield 1 Live Breast Fat Pad Breast --- g/bird -- - % Male WC 1899 a 1366 a 462 a 31.7 abc 173 ab 24.40 abcd 1.66 bc 9.13 abc Male WCWM 1888 a 1368 a 472 a 31.4 abc 174 ab 24.91 a 1.65 bc 9.18 abc Male WHAA 1957 a 1407 a 479 a 27.8 c 180 a 24.48 abcd 1.42 d 9.15 abc Male MC 1937 a 1374 a 471 a 32.1 ab 174 ab 24.29 abcd 1.65 bc 8.98 bc Male MCWM 1946 a 1386 a 481 a 33.1 a 172 ab 24.69 abc 1.70 bc 8.83 c Male MHAA 1950 a 1402 a 484 a 29.2 abc 176 ab 24.79 ab 1.50 cd 9.00 bc Female WC 1609 c 1156 c 388 c 31.8 ab 148 d 24.20 abcd 1.97 a 9.20 abc Female WCWM 1661 bc 1188 bc 400 bc 32.3 ab 153 cd 24.04 bcd 1.96 a 9.18 abc Female WHAA 1689 bc 1203 bc 403 bc 29.7 abc 159 cd 23.86 d 1.74 b 9.40 a Female MC 1642 c 1166 c 394 c 32.2 ab 147 d 24.03 cd 1.97 a 8.90 c Female MCWM 1687 bc 1205 bc 410 bc 30.5 abc 155 cd 24.30 abcd 1.81 ab 9.17 abc Female MHAA 1752 b 1255 b 425 b 28.8 bc 164 bc 24.20 abcd 1.66 bc 9.32 ab CV 4.99 5.36 5.57 11.15 7.05 2.66 10.73 3.66 RMSE 89.86 69.16 24.43 3.44 11.60 0.647 0.185 0.333 Wheat 1784 1281 434 30.8 165 24.32 1.73 9.21 a Maize 1819 1298 444 31.0 165 24.38 1.72 9.03 b 1772 b 1265 b 429 b 31.9 a 161 b 24.23 1.82 a 9.06 WM 1795 ab 1287 ab 441 ab 31.8 a 164 b 24.49 1.78 a 9.09 HAA 1837 a 1317 a 448 a 28.9 b 170 a 24.33 1.58 b 9.22 Male 1929 a 1384 a 475 a 30.9 175 a 24.59 a 1.60 b 9.05 b Female 1673 b 1196 b 403 b 30.9 154 b 24.10 b 1.85 a 9.19 a WC 1754 1261 425 31.7 a 160 24.30 1.82 a 9.17 ab WCWM 1774 1278 436 31.9 a 164 24.48 1.81 a 9.18 ab WCAA 1823 1305 441 28.7 b 169 24.17 1.58 b 9.28 a MC 1789 1270 432 32.1 a 161 24.16 1.81 a 8.94 b MCWM 1816 1295 445 31.8 a 163 24.49 1.75 a 9.00 b MCAA 1851 1328 455 29.0 b 170 24.50 1.58 b 9.16 ab ANOVA 3 P-values Treatment < 0.0001 < 0.0001 < 0.0001 0.0581 < 0.0001 0.0408 < 0.0001 0.0425 Diet 0.0588 0.2438 0.0515 0.7921 0.9739 0.6080 0.6452 0.0123 Level 0.0160 0.0149 0.0092 0.0006 0.0086 0.2827 < 0.0001 0.1335 Gender < 0.0001 < 0.0001 < 0.0001 0.9870 < 0.0001 0.0004 < 0.0001 0.0318 Diet x Level 0.9533 0.9273 0.8698 0.9627 0.9825 0.3490 0.8328 0.8109 Level x Gender 0.3658 0.5743 0.7987 0.6462 0.1942 0.3760 0.4494 0.2211 Diet x Gender 0.7731 0.4898 0.5651 0.1726 0.4690 0.5843 0.1277 0.5023 Level x Gender x Diet 0.5028 0.6355 0.6835 0.5756 0.6642 0.6713 0.5042 0.3365 1 Wheat Cobb Feed Cost (WC), Wheat Cobb White meat (WCWM), Wheat High amino acids (WHAA), Maize Cobb Feed Cost (MC), Maize Cobb White meat (MCWM), Maize High amino acids (MHAA). 2 Weight and yield are calculated from only the right half of the pectoralis major and pectoralis major. 3 Diet refers to Wheat vs. Maize; Level refers to vs. HAA. Gross revenue was calculated for each of the dietary regimes using a hot carcass value of 1.07/kg, a breast value of 3.89/kg, and a set of EU ingredient costs. A change in revenue between the diet and either the WM or HAA diets was also calculated for the Wheat and Maize-based diets. The composition of the diets was such that the dietary cost was influenced by the relative inclusion rate of Maize and fat (Table 1 and 2). A priori, the assumption is that any increase in performance is
unlikely to be profitable as feed cost increases; however, the composition of feed and the amount of feed consumed in this study had an impact on how broilers performed (Table 3), and thus the amount of revenue generated from meat yield (Tables 4 and 5). Comparing the differences in revenue for hot carcass and breast weight between the three levels of AA, feeding the HAA diet not only led to greater performance, but to higher gross revenue when compared to the diet for either the Wheat or Maizebased diets. Additionally, the HAA Wheat diet yielded more revenue for breast meat than the HAA Maize diet. This is an artifact of higher Maize cost and thus overall feed cost for the HAA Maizebased diet, as breast meat weight was essentially identical between the two diet types. Regardless, increasing AA levels improved performance and profitability, despite an increase in feed cost. Table 5 Return over feed cost calculations. Temp, deg C Temp, deg C Mortality, # 36 70 35 60 34 50 33 40 32 30 31 20 30 10 29 0 25 27 29 31 33 35 Day of Study Figure 1 Incidence of mortality 25 to 36 days. Mortality, # Hot Carcass Wheat Diets vs. AA Maize Diets vs. AA Breast Meat Wheat Diets vs. AA Maize Diets vs. AA Value ( /bird) 1.349 1.367 1.396 1.359 1.386 1.421 1.249 1.272 1.319 1.249 1.272 1.323 Feed Cost ( /bird) 0.554 0.574 0.585 0.608 0.610 0.634 0.554 0.574 0.585 0.608 0.610 0.634 Gross Revenue ( /bird) 0.795 0.794 0.811 0.751 0.776 0.787 0.694 0.698 0.734 0.640 0.662 0.688 Estimated Revenue ( /M birds) -1,000 16,000 25,000 36,000 4,000 40,000 22,000 48,000 Conclusions Increasing the amino acid density of the diet beyond levels recommended by the Cobb Broiler Nutrition Supplement (2004) can improve gain and feed conversion of Cobb 500 birds raised up to 36 d of age when fed Wheat or Maize-based diets. Feeding high amino acid diets increased carcass leanness and breast and carcass weight. Revenue analysis suggests that although feeding a higher AA diet costs more, the amount of revenue generated is superior to least-cost formulated diets that just meet the currently published nutrient requirements for Cobb 500 broilers. References Cobb Broiler Nutrition Supplement (2004) Cobb-Vantress Inc., Siloam Springs, Arkansas. Kidd, M.T., Corzo, A., Hoehler D., Miller E.R., and Dozier, W.A. 3 rd. (2005a) Broiler responsiveness (Ross x 708) to diets varying in amino acid density. Poult Sci. 84:1389-1396. Kidd, M.T., Virden, W.S., Corzo, A., Dozier, W.A. 3 rd, and Burnham, D.J. (2005b) Amino acid density and L-threonine responses in Ross broilers. Int J Poult Sci. 4:258-262. Kidd, M.T., McDaniel, C.D., Branton, S.L., Miller E.R., Boren, B.B., and Fancher, B.I. (2004) Increasing amino acid density improves live performance and carcass yields of commercial broilers. J Appl Poult Res. 13:593-604. SAS Institute. (1999) SAS/STAT User s Guide Version 8.0. SAS Institute Inc., Cary, NC.