Amino acid requirements of broiler breeders at peak production for egg mass, body weight, and fertility.

Two trials were conducted to determine the amino acid and protein requirements of broiler breeders at peak production. In trial 1, 32-wk-old Cobb 500 broiler breeders with similar BW were selected to determine the digestible amino acid requirement for daily product output (g of egg mass + g of BW gain/b/d) and feed conversion (g of feed/g of product) for Met, Phe, Arg, Ile, Lys, and CP in a 42-d production study. In trial 2, 30-wk-old Cobb 500 broiler breeders were selected to determine the digestible requirement for Met, Lys, Ile, Arg, Cys, Val, Trp, and Thr in a 70-d production study. Breeders were given a corn-soy basal diet plus crystalline amino acids with 8 graded levels of amino acids (10 birds per level), representing 40 to 130% of the highest suggested requirements reported in the literature. All other amino acids were maintained at 100% of their suggested requirement level. All breeders were inseminated weekly and fertility was determined. A third trial consisted of 41-wk-old colostomized hens randomly assigned to 1 of 2 diets differing only in the amount of Ile. Urine was collected after a 6-wk feeding period. The average digestible requirements per breeder per day for both product and feed/product ratio from trials 1 and 2 for Met, Cys, TSAA, Phe, Phe + Tyr, Trp, Arg, Ile, Lys, Val, Thr, and CP were 424, 477, 901, 689, 997, 252, 1,026, 830, 916, 799, 613 mg/d, and 20.0 g/d, respectively. The ideal profile for digestible Met, Cys, TSAA, Phe, Phe + Tyr, Trp, Arg, Ile, Lys, Val, and Thr was 46, 52, 98, 76, 108, 28, 112.0, 91, 100.0, 87, and 67%, respectively. A significant decrease in fertility was noted with increasing levels of Ile and Lys. Urine pH was significantly more alkaline in hens fed the higher level of Ile. It is suggested that adequate dietary Lys and Ile should be provided for maximum hatching egg production but an excess may affect fertility.