The Effect of Thyroprotein and Thiouracil on the Growth and Fattening of Swine

Abstract

A thiouracil intake of 0.1 percent of the ration resulted in highly significantly reduced growth rate, reduced food intake, and caused severe myxedema in weanling pigs. When thiouracil was fed at the level of 0.1 percent of the ration to pigs which averaged 150 pounds live weight and which previously had received thyroprotein at the level of 0.0088 percent of the ration, growth was almost stopped and it was not until after two weeks that the animals began to grow at about the same rate as the animals in the control groups. Significantly increased growth rate was obtained by the feeding of thyroprotein at the level of 0.0088 percent of the ration in Trial I, at the level of 0.0132 percent of the ration in Trial II, and at the level of 0.0176 percent of the ration in Trial III. The feeding of thyroprotein at all levels caused an increased growth rate. Less feed per unit of gain was required by animals receiving thyroprotein in Trials I and III. In Trial II, animals receiving thyroprotein required no more feed per unit of gain than the control animals. When carcass comparisons were made on animals that were of approximately the same weight at the time of slaughter, (Trial III) carcasses from animals which received thyroprotein at the level of 0.0176 percent had highly significantly greater chest depth (lean only) than the control group.