Evaluation of tryptophan requirement of the commercial layer by using a corn-soybean meal basal diet

An experiment was conduced with Hy-Line W36(R) hens to evaluate the require ment for Trp in a corn-soybean meal diet. Seven experimental diets were fed with Trp levels of 0.12, 0.13, 0.14, 0.15, 0.16, 0.17 and 0.18%. Supplemen tal amino acids (AA) were added to all diets to ensure that Trp was the fir st-limiting AA. A positive control diet (0.20% Trp) with Met supplementatio n was fed that had previously been shown to support maximum performance. Eg g production (EP), egg weight (EW), and egg content (EC) were significantly increased by the addition of Trp to the basal diet. Broken-line regression indicated the Trp requirement for EP and EC was 139.8 and 149.0 mg per hen /d, respectively, for EP and EC when hens had a daily EC of 45.4 g per hen/ d.