The Influence of Thiouracil, Propylthiouracil and Thyroprotein on the Growth and Fattening of Lambs

THE effectiveness of thiouracil and related compounds in inhibiting the action of the thyroid gland has been established in the human and in many other species. The possible use of these compounds to alter the growth rate, fattening efficiency and market quality of animals because of thyroid alteration has been investigated with several species. Much of the early work with these materials was done with the rat. The administration of thiouracil to growing rats has been shown to retard growth by numerous workers: Hughes 1944; Gordon, Goldsmith and Charipper (1946), and Williams, Weinglass, Bissell and Peters (1944).Astwood, Bissell and Hughes (I944) reported that 0.5 percent thiouracil in the ration of young chicks greatly retarded growth and development although o.I percent thiouracil in the ration did not impair growth. Kempster and Turner (1945) reported that thiouracil fed to ten week old New Hampshire broilers for a 16 day period did not retard growth.