Effect of graded biotin levels in the diet on liver pyruvate carboxylase of chicks fed ad libitum and after starvation.

Decreasing levels of biotin in the diet from 200 mug/kg to 0 mug/kg reduced the pyruvate carboxylase activity per g liver and in the whole liver of chicks to 17% of the normal activity. Oral supplementation with 3 mg biotin per chick increased the enzyme activity within 24 hours back to normal. In animals well supplemented with biotin (200 mug/kg diet) 24 hours of starvation increased the per g liver pyruvate carboxylase activity. When the pyruvate carboxylase activities were related to the whole liver, no effect of starvation was found.