Lysine and sulfur amino acid requirements of broiler chicks over short time periods within the starter phase

Six experiments were conducted to validate the hypothesis that Lys and SAA requirements decrease within the starter phase using 3-d periods from 2 to 11 d of age. In the first 3 experiments, 7 diets were generated by adding L-Lys to a lysine-deficient basal diet in 0.10% increments, ranging from 0.85 to 1.45% digestible Lys. In experiments 4 to 6, and 7 diets were generated by adding 0.07% increments of DL-methionine to a SAA-deficient diet to produce diets ranging from 0.63 to 1.04% DSAA. The linear broken line estimate for digestible Lys was 1.22, 1.17, and 1.16% for BWG and 1.31, 1.21, and 1.14% for FCR in experiments 1, 2, and 3, respectively. The linear broken line estimate for DSAA was 0.82, 0.81, and 0.94% for BWG and 0.82, 0.80, and 0.90 for FCR in experiments 4, 5, and 6, respectively. These results indicated that Lys requirements decreased linearly as hypothesized, however, the SAA requirements did not follow same pattern.