The tryptophan requirement of broiler chicks

1. The “available” tryptophan requirements of male and female broiler chicks were determined at 7‐d intervals from 0 to 56 d, using a diet‐dilution technique. Availability of tryptophan in the diets was estimated by growth assay with chicks.

2. The tryptophan requirements were 2.4 (males) and 2.2 g/kg of diet (females) from 0–7 d, and 1.7 g/kg (males and females) from 7–35 and 35–56 d. The absolute requirement of the chick for tryptophan increased with age and was significantly different for male and female birds.

3. A highly significant predictive equation relating tryptophan requirement to mean body weight and weight gain was established.