Digestible tryptophan requirements for broilers from 22 to 42 days old

The objective of this experiment was to establish different criteria to evaluate the requirements of digestible tryptophan for broilers from 22 to 42 d of age, using different regression models (quadratic, exponential and Linear Response Plateau) and in case of statistical significance the comparison of means by Duncan test at 5% probability was also adopted. A total of 1,920 Cobb 500 male broilers were distributed in a completely randomized experimental design, with 6 treatments (6 digestible tryptophan levels: 0.1395, 0.1610, 0.1825, 0.2040, 0.2255 and 0.2470%) and 8 replications containing 40 broilers each. Performance and carcass characteristics were evaluated. The level of 0.2255% of digestible tryptophan numerically improves feed conversion, and the 0.1919% estimated by the quadratic equation significantly improves carcass yield.