The Tryptophan Requirement of Young Chickens as Influenced by Niacin

ALMQUIST and Mecchi (1941) reported that the l -tryptophan requirement for optimum growth of chicks was 0.5 percent of the diet. Results obtained by Grau and Almquist (1944) indicated that the l -tryptophan requirement was 0.25 percent of the ration, and that d -tryptophan was not utilized by the chick. Wilkening and associates (1947) fed purified diets to chicks in which the major sources of protein were 12 percent of oxidized casein and 10 percent of gelatin supplemented with cystine and methionine. Using this ration with graded levels of tryptophan, the l -tryptophan requirement was reported to be 0.18 percent of the diet. Wilkening and Schweigert (1947) observed 17 to 40 percent utilization of d -tryptophan by the chick. The tryptophan requirement for poults was reported by Bird (1950) to be 0.28 percent of the diet for optimum growth and feed efficiency to three weeks of age. It was concluded that the poults were able . . .