The nutritional requirement of the protein-depleted chicken

Summary

The requirements of normal and of variously depleted birds of equal body weight were compared for tryptophan, arginine, methionine and lysine. Marked differences in requirement were noted between control and depleted birds as well as among the differently depleted groups. Birds depleted by starvation had a higher tryptophan requirement and a lower requirement for methionine and lysine than either controls or birds depleted on a N-free or a gelatin-containing diet. Those depleted on a N-free diet gained less well on a hydrolyzed casein diet than controls or previously starved birds. This difference in weight gain could be overcome by supplementing the hydrolyzed casein with small amounts of leucine, phenylalanine, and threonine. The birds depleted on a gelatin diet had a significantly lower arginine requirement than any of the other groups. We conclude that in birds of similar body weight the state of depletion influences not only the quantitative needs for protein and amino acids but, perhaps more importantly, the amino acid pattern necessary for optimal repletion.