ÜBER DEN ZUSAMMENHANG ZWISCHEN SCHILDDRÜSENAKTIVITÄT UND INTENSITÄT DES STOFFWECHSELS BEI HÄHNEN

Abstract

Eleven White Leghorn cockerels were given a standard diet (1.94% N) and 9 others the same diet + 50 mg. methylthiouracil daily. O2 consumption, N excretion and CO2 excretion were detd. by open circuit spirometric technic for gases and Li2CO3 extraction of feces for N. At the end of the expt. the birds were killed, the thyroids sectioned, and the ratio of follicle diam.: number of cells in the follicle wall estimated. This ratio falls as thyroid activity increases, since the latter is associated with smaller follicles with more and taller cells. Methylthiouracil failed to alter the metabolic rate, RQ or diam./cellularity ratio. When the diet was fortified with 50% casein, the metabolism fell; RQ fell; and follicle diam./cellularity ratio also fell after methylthiouracil. A relationship was shown between depression of metabolic rate and decrease of diam./cellularity ratio. N excretion was increased while on methylthiouracil and high-protein diet. Since methylthiouracil is effective only in the presence of a high-protein diet, the author concludes that the effect of thyroid hormone is on amino acid metabolism.