The Influence of Thiouracil and Stilbestrol on Broiler Quality

FOLLOWING 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), it was shown that thiouracil would increase fat deposition and improve market quality in the chicken (Kempster and Turner, 1945; Andrews and Schnetzler, 1946; and Andrews and Bohren, 1947). It has likewise been shown that the subcutaneous implantation of stilbestrol pellets or the feeding of certain estrogens, especially 3, 4-dianisylhexene-3, would increase fattening and improve carcass quality in poultry (Lorenz, 1943 and 1945; Jaap and Thayer, 1944; and Thayer et al., 1945). Schnetzler et al. (1945), observed that thiouracil and stilbestrol in combination increased the amount of fat in 18-month old cocks. Andrews and Bohren (1947) found that administration of thiouracil and stilbestrol in combination to young cockerels improved fleshing and market grade . . .