Lysine needs of rapidly growing turkeys from 12-22 weeks of age

Two experiments were conducted with Large White male turkeys to investigate the lysine requirement from 12 to 22 weeks of age. Six pens of 20 turkeys were fed each of the experimental diets. In experiment 1, a basal diet containing wheat, meat meal, cottonseed meal and distillers dried grains with solubles was supplemented with four levels of L-lysine. Lysine at 4.27% of protein and 2.31 g./mcal. of metabolizable energy from 16 to 20 weeks of age, and 1.83 g. from 20 to 22 weeks of age was inadequate for optimum growth and feed efficiency (16-22 weeks). Supplementing the diet with lysine from soybean meal gave performance equivalent to synthetic lysine, indicating that it was fully available. Performance of turkeys fed a diet containing 88% triticale from 16 to 20 weeks of age, and 72% from 20 to 22 weeks of age was equivalent to that of turkeys fed a more complex ration with an equivalent level of lysine. In experiment 2, Large White male turkeys were fed a basal diet composed largely of triticale and soybean meal from 12 to 20 weeks of age with different levels of added lysine. From 12 to 16 weeks of age, 3.11 g. lysine/mcal. of M.E. (4.9% of protein) was adequate for optimum growth and feed efficiency. From 16-20 weeks of age 2.36 g. lysine/mcal. of M.E. (4.3% of protein) was adequate for optimum performance. Although the estimated requirement from 16 to 20 weeks of age based on the two experiments differs (perhaps because of differences in lysine availability), the results suggest that the current N.R.C. recommendation may be higher than necessary.