Efficacy of a lysine-tryptophan blend for growth of chicks

Two chick experiments were conducted to compare the growth-promoting efficacy as well as the toxicity of a new source of L-tryptophan and L-lysine, Tryptosine (16.1% tryptophan, 56.3% lysine). A corn-feather meal-soybean meal basal diet was made singly deficient in either lysine or tryptophan, and graded doses of lysine or tryptophan from either Tryptosine or feed-grade sources of lysine and tryptophan were supplemented. Linear (P < .01) weight gain responses occurred, and responses to lysine or tryptophan in Tryptosine were similar to those obtained with equal doses of lysine or tryptophan provided by feed-grade sources of L-lysine.HCI or L-tryptophan. The toxicity trial involved additions of 1, 2, or 4% lysine with .29, .58, or 1.16% tryptophan to a lysine- and tryptophan-adequate corn-soybean meal diet. Both amino acids were provided as either Tryptosine or as feed-grade sources of lysine and tryptophan. Weight gain and feed intake were reduced in a linear fashion (P < .01) as levels of the two excess amino acids increased. The decreases caused by Tryptosine were similar to those caused by equivalent levels of excess feed-grade lysine and tryptophan.