The Effect of Thiouracil on Efficiency of Gains and Carcass Quality in Swine

The effect of thiouracil fed as .1 percent of the ration on economy of gains and carcass quality was studied with Chester White, Yorkshire and cross-bred market pigs. Compared with the controls, five Chester White barrows averaging 162 pounds and fed ad libitum for 41 days on a ration containing thiouracil made .16 pound less daily gain, but required 13.8 percent less feed per unit of gain. Five Yorkshire pigs given thiouracil for the same period averaged .09 pound less daily gain and required 18.8 percent less feed per unit of gain. Nine crossbred pigs fed thiouracil at a different season made .35 pound less daily gain and required 8.4 percent less feed per unit of gain than their controls. All of the pigs in the experimental groups became lazy toward the end of the second week and became increasingly sluggish as the trial progressed. The greater increase in the economy of gain in the Yorkshires as compared to the Chester Whites is believed to be due to a higher natural thyroid secretion rate in the former and consequently a greater reduction in rate of metabolism under the influence of thiouracil. There were no significant differences in the carcasses attributable to the thiouracil treatment.