Quantitative DL-Tryptophan Requirement of the Weanling Pig

Purified diets containing zein and gelatin, plus amino acid supplements, have been used to determine the level of DL-tryptophan required by weanling Duroc pigs. In the presence of adequate nicotinic acid maximum growth was obtained when DL-tryptophan constituted 0.2%, or more, of the diet. Pigs receiving 0.1% DL-tryptophan consumed approximately one-half as much feed, and gained at about one-third the rate of the pigs receiving 0.2% DL-tryptophan. The feed efficiency of the pigs receiving the lower level of DL-tryptophan was reduced.