The use of the hormones, diethylstilboestrol, hexoestrol and testosterone propionate, as growth stimulants in beef cattle has been studied. The subcutaneous implantation of 60 mg. stilboestrol into steers fattening in yards produced a highly significant increase in rate of gain (65%) and little difference in the yield and quality of the carcass. The implantation of 24 nig. or 36 mg. of diethylstilboestrol or 30 mg. hexoestrol into Friesian bullocks fattening on pasture produced highly significant increases in rates of gain (29%, 48% and 33% respectively). No significant difference was found in the rates of gain produced by these three treatments.
The oral administration of 10 mg. diethylstilboestrol per head per day for 168 days or the oral administration of 20 mg. rising to 40 mg. testosterone propionate per head per day for 154 days to dizygotic twin steers on equal feed intake significantly increased rate of gain by 15% and 21% respectively Feed efficiency as measured by the pounds of feed required to produce a pound of gain was significantly improved by both treatments. Carcass yield and carcass quality were not significantly affected by either treatment. No significant differences were found between the two treatments.
THE EFFECT OF TESTOSTERONE, TESTOSTERONE PROPIONATE AND DEHYDROANDROSTERONE ON THE SECRETION OF THE GONADOTROPIC COMPLEX AS EVIDENCED IN PARABIOTIC RATS