Evaluation of the isoleucine requirement of the commercial layer in a corn-soybean meal diet

An experiment was conducted with Hy-Line W36 hens to evaluate their Ile req uirement in a corn-soybean meal diet. Fi ve experimental diets were fed wit h Ile levels of 0.61, 0.58, 0.55, 0.52, and 0.49%. Supplemental amino acids (AA) were added to ensure that Ile was the first-limiting AA. Two diets wi th 0.55 and 0.52% Ile were also fed with higher levels of supplemental AA. A positive control (0.67% Ile) with only Met supplementation was fed, which had previously been shown to support maximum performance. All levels of Il e addition significantly increased egg production (EP), egg weight (EW), an d egg contents (EC). Broken-Line regression indicated a daily Ile requirement of 589.2, 601.2, a nd 601.4 mg per day for EP, EW, and EC, respectively, which indicated a req uirement of 12.6 mg Ile per gram of EC.