The Effects of Oral Estrogens and Androgens Singly and in Combination on Yearling Steers

Abstract

The feeding of 10 mg diethyl-stilbestrol or a combination of 5 mg diethylstilbestrol and 50 mg of methyl testosterone to fattening yearling steers resulted in a 12% increase in growth rate over a 179-day trial. The increase in growth in stilbestrol-fed steers occurred during the first 98 days. Steers fed no hormone dressed significantly higher than steers fed stilbestrol (P0.05), whereas steers fed a combination of stilbestrol and testosterone dressed significantly higher than the steers fed stilbestrol (P 0.05) or steers fed with either testosterone alone or no hormone (P 0.05). The carcasses from the hormone-fed steers were slightly inferior, according to Federal Grading Standards, to carcasses from steers which had not received hormones. Twelfth rib samples from carcasses of steers which had not been fed hormone contained significantly more fat and less moisture and protein than those from steers which had been fed either diethylstilbestrol or methyl testosterone.