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Summary The inclusion of L-Val and L-Ile is progressively becoming an economically feasible strategy to reduce the dietary CP content of broiler diets. In the current experiment, the influence of supplementing the feed-grade branched chain amino acids (BCAA) Val and Ile was evaluated in corn and soybean meal–based (CSBM) diets, with or without the inclusion of either peanut meal (PM) or an animal protein blend (APB), on broiler growth performance (0–48 D), processing characteristics, and incidence of pododermatitis and litter characteristics. Supplementation of BCAA reduced analyzed CP by an average of 1.62 percentage units across 4 feeding phases. Overall (0–48 D), broiler body weight gain and FCR were unaffected when fed supplemental BCAA; however, feed intake was increased for those supplemented with BCAA. Overall growth performance was similar when including either PM or APB in CSBM diets. At processing, broilers fed BCAA diets had increased relative and absolute breast fillets and total white meat weights, as well as heavier fat pad weights. Nitrogen excretion was reduced when BCAA were supplemented, but no differences were observed for footpad dermatitis (FPD) lesion scores. Interestingly, APB supplementation did not impact litter moisture or nitrogen but improved FPD scores compared to birds fed CSBM, with PM-fed birds having intermediate FPD scores. In conclusion, these data indicate that BCAA inclusion can support CP reductions while maintaining growth performance, improving breast fillet yield, and reducing nitrogen excretion in broilers reared to market ages.

SUMMARY: Recent research within our laboratory has determined the optimal Ross 708 × Ross YP male broiler dIle:dLys ratio for the starter and grower phases to be 70 and 68%, respectively. Thus, the current objective was to continue to re-evaluate the optimal dIle:dLys ratio for this broiler, focusing on the finisher phase. On d of hatch, 2,400 chicks were equally allocated to 96 pens and fed a common starter (d 0–14; 70% dIle:dLys) and grower diet (d 14–28; 68% dIle:dLys). Pen weights were equalized at d 28 by block (12/treatment). Experimental finisher diets (d 28–42;18.0% crude protein, 3,200 kcal/kg, 0.97% dLys, 130% dLeu:dLys) were created from a common deficient (54% dIle:dLys) corn and soybean meal-based diet and contained animal protein. Half of the deficient was retained to create the summit (84% dIle:dLys). The remaining 5 diets were blended proportions of the deficient and summit diets (ranging from 59 to 79% dIle:dLys). A practical control diet (PRAC-CON; 69% dIle:dLys) was manufactured separately to verify the blended control diet (BLEND-CON). All dIle:dLys ratios were estimated using quadratic regression (QR; 95% of the asymptote), as well as linear and quadratic broken line models (LBL; QBL). Feeding equivalent to or slightly lower than current breeder dIle:dLys recommendations (69%) improved broiler performance from d 28 to 42. Based on the current data and multiple regression models, the estimated ratios ranged from 62 to 66% for BW and BWG and 63 to 66% for FCR. Further research should evaluate the optimal dIle:dLys ratio for this broiler throughout the remaining withdrawal phase.

1. Four experiments were conducted to determine the 4th limiting amino acid (AA) in maize-soybean meal-based diets. 2. Deletion assay methodology was used to quantify performance and carcase trait responses to potential deficiencies in essential and conditionally essential AA caused by reductions in dietary crude protein of maize-soybean meal-based diets from 202.9 to 186.5 g/kg. 3. The deletion of Val, Phe and Gly + Pro resulted in negative effects on live performance and carcase traits for male broilers, whereas AA deletion only affected wing weights for females with no response on live performance. 4. Further experimentation could not duplicate a response to Phe or Pro in male broilers. 5. Valine was identified as the potential 4th limiting AA in maize-soybean meal-based diets and was not found to be co-limiting with Ile.

SUMMARY Continuous genetic improvement of high yielding broiler strains necessitates reevaluation of amino acid requirements. The objective of this study was to evaluate the dIle requirement of Ross 708 x Ross YP male broilers from d 0 to 18. Experimental diets were created from a common deficient corn and soybean meal-based diet providing a dIle:dLys of 52%; after manufacturing, half was retained for the creation of the summit diet (82% dIle:dLys). The remaining 5 experimental diets ranged from 57 to 77% dIle:dLys and were blended proportions of deficient and summit dIle diets. A practical control diet (PRAC-CON; 67% dIle:dLys) was manufactured separately for verification of the blended control diet (50 deficient:50 summit blend; BLEND-CON; 67% dIle:dLys); all diets were subsequently pelleted/crumbled. On d of hatch, 2,400 male chicks were equally allocated to 96 pens (12 replications/treatment). All dIle:dLys ratios were estimated using quadratic regression (QR; 95% of the asymptote), as well as linear and quadratic broken line models (LBL; QBL). Performance data demonstrated that feeding higher than starter breed nutrient specifications, for broilers, at the time of this study (67% dIle:dLys) improved broiler performance from 0 to 18 d. After considering the estimated requirements produced by the multiple regression models for all measured variables (BW, BW gain, FCR, and CV of ending BW), these data suggest that the optimum starter dIle:dLys ratio for male Ross 708 × Ross YP broilers from 0 to 18 d, ranged from 63 to 74% dIle:dLys. Further research should evaluate dIle:dLys requirements of male Ross 708 × Ross YP broilers during the remaining grow-out phases.

Published literature elucidating dietary valine (Val) requirements for female broilers is limited and lacks data for the finisher phase. Three experiments (Exp) were conducted to determine the Val requirement for Cobb MX × 500 females during the grower (Exp 1; 14–28 days), finisher (Exp 2; 28–42 days), and withdraw periods (Exp 3; 42–56 days). Two additional Exp were conducted to determine the Val requirement for Cobb MV × 500 male (Exp 4) and female (Exp 5) broilers from 14–35 days. Corn-soybean meal diets were fed in the experimental period of all Exp to create Val dose response titration diets. Dietary titration levels of digestible Val to digestible Lys (Val/Lys) ratios were: 64–82 in Exp 1; 65–83 in Exp 2 and 3; and 57–92 in Exp 4 and 5. Body weight (BW) gain, feed intake, and feed conversion ratio were determined for each experimental period. At the conclusion of Exp 2 through 5, broilers were processed to determine carcass traits. Requirements were determined using regression analysis, considering the requirement to be 95 % of the quadratic response. No significant linear or quadratic responses were determined for Exp 1 through 3. In Exp 4 and 5, significant responses were observed for feed conversion ratio, but not processing yields. The lack of responsiveness in Exp 1 through 3 are likely due to an inadequate reduction in dietary Val to observe female quadratic responses. Valine requirements were determined to be 78 and 77 Val/Lys for males and females, respectively, based on feed conversion responses.

An experiment was conducted to evaluate the digestible tryptophan (Trp) requirement of laying hens from 22 to 34 wk of age. A total of 252 Hy-line W-36 laying hens were selected at 16 wk of age and allocated by weight (P = 0.90) to 7 dietary treatments resulting in 12 replicate cages of 3 birds for each treatment. A Trp-deficient basal diet was formulated using corn, corn gluten meal, and soybean meal for each of the 3 dietary phases and supplemented with synthetic L-Trp to provide 105, 119, 133, 147, 162, 176, and 190 mg digestible Trp on a daily basis over the experimental period. To adapt the hens to experimental diets, pullets were fed complete diets that contained increasing amounts of corn gluten meal. Hens received a controlled amount of feed daily based on feed intake expected under commercial conditions. Linear and quadratic brokenline, and quadratic polynomial models were used to estimate digestible Trp requirements based on hen-housed egg production (HHEP), egg mass (EM), and feed efficiency (FE). FE was calculated using EM and feed intake. Digestible Trp requirements were estimated to be 137, 183, and 192 mg/d for HHEP; 133, 180, and 183 for EM and 133, 177, and 173 for FE using linear brokenline, quadratic broken-line, and quadratic polynomial analysis, respectively. The quadratic broken line model in this experiment resulted in the best fit (R-2) for all parameters measured. Linear broken line estimates resulted in lower estimates that the other models, and HHEP resulted in higher estimated digestible Trp requirement than EM and FE. CJ America Inc, USA This experiment was financially supported by CJ America Inc, USA. Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by Virginia Tech, and does not imply approval to the exclusion of other products that may be suitable. Special thanks to Hy-Line international for providing the chicks, Elanco for SE vaccine, CJ for amino acids (lysine, methionine, tryptophan, isoleucine, and threonine) . The authors gratefully acknowledge the assistance of Dale Shumate, Kolby Foltz, Alicia Arne-son, Becky Tran, Alyssa Lyons, Siobhan Boothe (Virginia Tech, Blacksburg VA) for animal care and feed mixing assistance.

Data pertaining to the branched-chain amino acids (BCAA) are of particular importance due to the positioning of valine (Val) and isoleucine (Ile) as limiting amino acids (AA) in conventional diets. Similarly, current research evaluating their potential interaction is sparse. Therefore, two experiments were conducted using Box-Behnken design (BBD) to determine performance and carcass responses to BCAA and glycine (Gly) supplementation in male broilers from 15–34 days (Experiment 1) and 15–35 days (Experiment 2). In Experiment 1, 13 experimental diets were formulated to contain various levels of digestible BCAA supplementation based on BBD. Inclusion levels for the BCAA were based on ratios to digestible lysine (Lys) and included: 65, 75, and 85 for digestible Val; 58, 66, and 74 for digestible Ile; and 110, 130, and 150 for digestible leucine (Leu). Diets for Experiment 2 were formulated in a similar manner and design, but total glycine + serine (Gly + Ser) inclusions were substituted for Leu. Inclusion levels were the same for Val and Ile as in Experiment 1 and ratios to digestible Lys of 131, 151, and 171 for total Gly + Ser. Fifteen-hundred and sixty male broilers were distributed across 78 pens and randomly assigned to 13 experimental diets in each Experiment. Body weight (BW) gain, feed intake, and feed conversion ratio (FCR) were determined for the experimental grower period in both Experiments. On day 35 (Experiment 1) or 36 (Experiment 2), six birds per pen were processed for the evaluation of carcass traits. Data were analyzed for linear, quadratic, and interactive effects. In Experiment 1, increased Leu inclusion linearly increased (P