Effects of Low Level Implantations of Stilbestrol in Steers Fattened on Dry Lot Rations1

Abstract

Two experiments were conducted on the effects of low level implantation of stilbestrol in steers. Each experiment involved 50 steers. In the first experiment of 105 days duration, 36 mg. of stilbestrol implanted in the ear resulted in a highly significant increase in rate of gain for the treated steers when compared to controls. An additional 36 mg. implanted at 42 days failed to give an additional growth stimulus. The seminal vesicle weights were increased in steers treated with stilbestrol. However, there were no significant differences between the treated and control groups in either carcass grade or dressing percentage. In Experiment II the daily rate of gain of steers treated with 36 mg. of stilbestrol was significantly higher than for the control steers over the first 8 weeks, but 12 mg. of stilbestrol had no significant effect. During the second 8-week period an additional 24 mg. following the initial 12 mg. resulted in increased daily gains over the controls. The difference was highly significant. The final results of Experiment II over the 140 days showed a highly significant difference in rate of gain between steers treated with 36 mg. of stilbestrol and controls but no significant difference between the 12 plus 24 mg. treated steers and controls. The treated steers showed a depression of the loin at 85 days and 65 days for Experiments I and II, respectively.