Responses of Broiler Breeder Hens to Dietary Digestible Lysine, Methionine+Cystine, and Threonine

To evaluate the response of broiler breeder hens submitted to different amino acid intakes of methionine+cystine, lysine, and threonine, and to determine the coefficients for egg output and body weight for maintenance. Three studies were performed using 160 broiler breeder hens housed individually in metabolic cages. A summit diet and a nitrogen-free diet were formulated. The levels ranged from 1.79 to 7.13, 2.49 to 8.3, and 2.04 to 6.79 g/kg of methionine+cystine, lysine, and threonine, respectively. The variables measured were feed intake, amino acid intake, rate of lay, egg weight, and egg output. The broken line model was used to evaluate the responses. It was verified that higher values of the rate of lay, egg weight, and egg output were observed for the higher concentrations of amino acids studied. A significant difference was observed for the variables rate of lay, egg weight, egg output, and body weight (p < 0.05) for the three amino acids evaluated. The amount of each amino acid required to produce one gram per egg was estimated at 12.4 mg, 14.5 mg, and 11.2 mg for methionine+cystine, lysine, and threonine, respectively. The values estimated by coefficient b that represent the amino acid for maintenance requirement were methionine+cystine, lysine, and threonine of 30.2, 32.2, and 42.4 mg/kg BW, respectively. The coefficients may be used to design additional models to study requirements nutrition in broiler breeders, allowing a better understanding of how these birds respond to different dietary amino acids.