THE EFFECT OF PROTEIN LEVEL AND AMINO ACID BALANCE UPON THYROID ACTIVITY IN THE CHICK

Abstract

Chicks fed diets containing 26% of protein had larger thyroid glands than did chicks fed diets containing 17.5% of protein. Thyroidal uptake of I131per chick was also greater in the chicks fed the higher level of protein. The basal diets were deficient in methionine. Supplementation of the diets with lysine, which would aggravate the amino acid imbalance, significantly depressed thyroidal uptake of I131per chick. It is concluded that the amino acid composition of dietary protein, as well as the protein level in the diet, affects thyroid activity in the chick.