Purdue University	Mimeo A.H. 194
Agricultural Experiment Station	February 1, 1957
Lafayette, Indiana
THE COMPARATIVE EFFECT OF ORAL AND SUBCUTANEOUS IMPLANTATION OF STILBESTROL FOR FATTENING STEERS ON PASTURE
W. M. Beeson, T. W. Perry, W. H. Smith,
F. N. Andrews and Martin Stob
Department of Animal Husbandry
Recent research at Purdue University (Mimeo A.H. 165) has shown that implanting steers with 36 milligrams (3 pellets) of stilbestrol at the base of the ear is equally effective from the standpoint of gain, feed efficiency and carcass quality as feeding 10 milligrams of stilbestrol daily when steers are being fattened in dry lot. In this research, side effects were the same regardless of whether steers were implanted or fed stilbestrol.
Several experiments have indicated that the response of cattle to stilbestrol feeding on pasture is not consistent and varies with the amount of grain being fed and the type of pasture. It has been demonstrated in this laboratory that pasture grasses have varying amounts of estrongenic activity, and this probably has some influence on the response of cattle to the oral feeding of stilbestrol. Most studies reported to date have indicated that implanting steers with stilbestrol at low levels (24 milligrams) will significantly increase the daily gain when grazing on pasture without grain.
In view of these facts, this experiment was designed with the following objectives;
1= To compare the daily feeding of 10 milligrams of stilbestrol with the subcutaneous administration of stilbestrol pellets (implanted under the skin at the base of the ear) in pasture-fed steers.
2. To compare the response of steers fed on pasture, to 24 vs. 36 milligrams of implanted stilbestrol.
Experimental Procedure
Sixty yearling Hereford steers, averaging approximately 693 pounds, were divided into 4 lots of 15 steers each and were fed ground ear corn. Supplement A (Table I), and minerals free choice on alfalfa-ladino brome and timothy pasture from May 29 to October 1, 1956.
The 4 lots of steers were grazed on 40 acres of pasture (10 acres per lot) and we re rotated every week from May 29 to August 28 in order to reduce to a minimum the variability in response due to the composition of the pasture. From August 28 until October 1, the steers were rotated every 2 weeks.
During the first 56 days, all lots were fed 6 pounds of ground ear corn, 1 pound of Purdue Cattle Supplement A and minerals free choice (2 parts of bonemeal and 1 part of salt plus salt free choice). For the remainder of the feeding period, the cattle were full-fed ground ear corn, 2 pounds of Supplement A and minerals free choice.