The Effects of Stilbestrol, Dienestrol, Testosterone and Progesterone on the Growth and Fattening of Beef Steers

Abstract

Three experiments involving a total of 120 beef steers were conducted. Rate of gain was significantly increased by the subcutaneous administration of 60, 108 or 120 mg. of stilbestrol pellets, 60 mg. of stilbestrol pellets in combination with 200 mg. of progesterone pellets, or 80 mg. of dienestrol pellets. Feed efficiency was consistently improved by all levels of stilbestrol or dienestrol pellets. However, the increased efficiency was not statistically significant at the 60 mg. level of stilbestrol. The administration of 255 mg. of testosterone pellets or dienestrol and progesterone in combination in a semi-solid injectable base did not improve rate of gain or feed efficiency. In experiments I, II and III stilbestrol, dienestrol and testosterone had no effect on dressing percentage. There was a reduction in carcass grade of some of the stilbestrol-treated steers. Among the undesirable side effects of stilbestrol treatment are the elevation of the tail head and the resulting unevenness of the topline. The onset, degree of change and duration vary with individual animal and time. In steers fed in dry lot undesirable mammary changes were not encountered. Copyright © . .