Effect of Feeding Thyroactive Iodocasein on Growth, Feathering, and Weights of Glands of Young Chicks

MANY investigators during the past three decades have reported on the various effects of feeding fresh or desiccated thyroid to chickens. Results have been variable, dependent upon dosage level and potency of the material. Most of the work reported has concerned adult stock, and the data relative to chicks and young growing stock appears to be meager. Crew and Huxley (1923) fed dried thyroid to 12 chicks and found no significant difference in weight between the control and experimental group. It is known that thyroid given in excessive amount will retard the rate of growth or even cause a loss of body weight. However, some investigators have reported acceleration of the growth rate in dogs, rats, and mice when thyroid was fed in optimum amounts. Recently Koger and associates (1942 (1943) reported improvement of growth and appetite in mice receiving subcutaneous injections of crystalline thyroxine and the feeding of thyroactive . . .