This experiment was carried out to evaluate the tryptophan (Trp) requirements and the recovery performance pattern of laying hens fed Trp-deficient diets. One hundred sixty Hisex White commercial laying hens were randomly distributed in five Trp levels in the diets (0.13, 0.15, 0.17, 0.19 and 0.21% ) with eight replicates of four birds. The laying hens remained for two weeks in adaptation (51 to 52 weeks), for six weeks for evaluation of Trp requirements (53 to 58 weeks) and for four weeks for the determination of the recovery performance pattern (59 to 62 weeks). Egg production and egg mass were impaired when laying hens were fed diets containing 0.13% of Trp, however, the performance was recovered after one week of feeding under a diet containing 0.21% of this amino acid. Internal egg quality was not influenced by the Trp levels studied (intake among 137.1 to 228.0 of Trp mg/day). Tryptophan requirements ranged from 161 to 188 mg/ay, depending on the characteristics evaluated (egg production or egg mass) and the regression model applied (polynomial, exponential or broken line).
amino acids; birds; eggs; hens; nutritional requirements
