Performance of Chicks Fed Graded Levels of Niacin and Tryptophan

The effect of excess dietary niacin on the performance of chicks was investigated in a factorial experiment in which niacin and tryptophan were studied simultaneously in terms of interdependence. Weight gain of chicks was increased with increasing levels of dietary tryptophan. Dietary supplementation of niacin enhanced feed consumption, thus resulting in significant weight gain but excess dietary niacin appeared to depress feed consumption and hence retard chick growth. Tryptophan was observed to partially spare dietary niacin but could not compensate entirely for a niacin deficiency. It is concluded that the maximum dietary requirement of niacin is no higher than 30 mg/kg of feed at any level of tryptophan, and that any additional input of the vitamin may negatively affect feed consumption and weight gain of the chicks.