Purdue University Agricultural Experiment Station Lafayette, Indiana
MLmeo AS-280 April 22, I960
THE PRESENT STATUS OF THE USE OF HORMONES AND HORMONE-LIKE SUBSTANCES CURRENTLY APPROVED FOR USE IN BEEF CATTLE
F. N. Andrews, Department of Animal Science
The importance of natural hormones secreted within the animal body on growth, fattening, reproduction and milk production has been recognized for more than 25 years. The synthesis of diethylstilbestrol by the British chemists Dodds and Lawson in 1937 made it possible to undertake large-scale studies with farm animals. Diethylstilbestrol does not occur in nature but produces many of the effects of the natural female sex hormones which are secreted by the ovary. Diethylstilbestrol has the added advantage that it is effective in animals, whether administered in the ration, injected in solution or implanted as a solid pellet beneath the skin.
Since 1937 other substances rather similar to diethylstilbestrol, such as hexestrol, dienestrol and dienestrol diacetate, have been prepared in the laboratory, and a number of materials with hormonal activity have been recovered from certain legumes.
Experimental studies are being carried on with a large number of natural hormones and synthetic materials which have hormone-like properties. It is the purpose of this report to review the effects of those substances which are available for use in beef cattle under certain conditions specified by the Food and Drug Administration.
I. The Use of Diethylstilbestrol in the Feed
In 1954 research workers at the Iowa Experiment Station reported that the addition of 10 mg. of diethylstilbestrol to the daily ration of fattening steers increased rate of gain and improved feed efficiency. It was shown that residues of diethylstilbestrol did not remain in the edible tissues of cattle, and the Food and Drug Administration approved its use under rules and regulations which were then in effect.
The rate of growth of cattle and efficiency of feed utilization are, of course, affected by age, quality and sex of cattle, type of ration, length of feeding period, environmental conditions and many other factors. However, in general, the addition of 10 mg. of diethylstilbestrol to the daily rations of steers or heifers can be expected to increase rate of gain from 10 to 25 percent and feed efficiency by five to 15 percent.
IT. Thft ImnDantation of Diethylstilbestrol.
Purdue experiments with beef heifers in 1948 and 1949 and with beef steers in 1950 and 1951 showed that the implantation of pellets of diethylstilbestrol beneath the skin would increase rate of gain and improve feed efficiency. Subsequent research at Purdue and other experiment stations led to the acceptance of this technique for use by cattle feeders in 1955. In practice, steers weighing more than 400 pounds are usually implanted with 24 or 36 mg. of diethylstilbestrol near the base of the ear.