Influence of Thiouracil and Stilbestrol on Growth, Fattening, and Feed Efficiency in Broilers

THE discovery that a large number of substances related to thiourea inhibit thyroid hormone secretion and decrease basal metabolic rate in the rat (Richter and Clisby, 1942, Astwood and co-workers, 1943, and MacKenzie and MacKenzie, 1943) was followed by several experiments on the effects of one of these compounds, thiouracil, on growth and fattening in the domestic fowl. Kempster and Turner (1945) found that the addition of thiouracil to a broiler ration at a level of 0.2% improved market quality. Andrews and Schnetzler (1946) reported that although 0.2% thiouracil in a standard broiler ration reduced growth rate somewhat, market quality and fat deposition were significantly increased and that there was a tendency for the efficiency of feed utilization to be increased. Glazener and Jull (1946) however, reported that thiouracil decreased both growth rate and feed consumption of broilers and did not improve finished appearance. Mixner et al. (1946) found that . . .