SUPPLEMENTAL IRON, COPPER, ZINC, ASCORBATE, CAFFEINE AND CHLORTETRACYCLINE DO NOT AFFECT RIBOFLAVIN UTILIZATION IN THE CHICK

Chick experiments were conducted to investigate dietary effects of exc ess supplemental Fe (420 mg/kg), Zn (448 mg/kg), Cu (245 mg/kg), L-asc orbate (1000 mg/kg), caffeine (200 mg/kg) and chlortetracycline (500 m g/kg) on riboflavin utilization. A dose-titration study indicated a li near increase in weight gain as riboflavin was supplemented up to 2.5 mg/kg in a soy isolate diet. Riboflavin utilization was evaluated at t wo deficient levels of dietary riboflavin (1.0 and 1.5 mg/kg) in the p resence of adequate and excess levels of Fe, Cu and Zn, and also in th e presence of zero and excess levels of L-ascorbate, caffeine and chlo rtetracycline. Growth rate was increased markedly in chicks fed the 1. 5 mg/kg compared with the 1.0 mg/kg riboflavin dose, and none of the p utative antagonizing factors influenced growth rate, food intake or ga in per unit of riboflavin intake at either riboflavin level. The resul ts suggest that excess levels of Fe, Cu, Zn, L-ascorbate, caffeine and chlortetracycline do not affect crystalline riboflavin utilization in the chick. Copyright (C) 1996 Elsevier Science Inc.