Effects of Vitamin B 12 and Penicillin on Thiouracil Action in Chicks ∗

Abstract

Summary

1. White Leghorn male and Rhode Island Red chicks of both sexes were fed a vit. B₁₂-dencient ration which was supplemented with 0.1% thiouracil and/or 0.5 to 4.0μ% vit. B₁₂ or 2 mg procaine penicillin G per lb of food. After a preliminary depletion period of one and 2 weeks, respectively, on the vit. B₁₂-dencient diet, the chicks were fed the above supplements for an additional 4 or 3 week period. 2. Thiouracil markedly reduced body weight gains and food intake in both breeds of chicks, and increased the grams of food required for each gram of gain in body weight. Vit. B₁₂ and penicillin partially or completely counteracted this growth depression and increased appetite. The larger doses of vit. B₁₂ were more effective in these respects than the smaller doses, 3. The large increase in thyroid weight and severe inhibition of comb growth induced by thiouracil were not influenced by the vitamin or antibiotic. 4. In general, these results corroborate previous data on the effects of vit. B₁₂ and antibiotics on rats fed thiouracil or following parathyroidectomy.