Purdue University Mimeo A.H. 166 Agricultural Experiment Station April 27 1956 Lafayette, Indiana
The Effect of Feeding A Female Hormore and an Antibiotic Alone and in Combination to Fattening Steers
W. M. Beeson, T. W. Perry, Martin Mohler,
F. N. Andrews and Martin Stob
Department of Animal Husbandry
Within the past few years two types of substances have been shown to increase the gains of cattle under certain feeding conditions. These two types of substances are the female hormore-like materials, such as diethylstilbestrol, hexestrol and dienestrol; and the antibiotics, such as Aureomycin and Terramycin.
Although a large number of trials has shown that both the female hormones and the antibiotics do stimulate gaining ability, no real clue as to how each functions in bringing about increased gains has been found.
The trial reported in this mimeograph was designed to show the effect of feeding a female hormore (hexestrol) and an antibiotic (aureomycin) separately and in combination to cattle being fed a fattening ration in drylot. In other words, the design of this experiment was such that the results should show whether the effect of a female hormone and of an antibiotic was similar or different, and whether their respective effects were additive in increasing the gains of beef cattle.
Experimental
Forty-two-year old Hereford steers averaging 925 pounds were divided into four lots of ten steers each on the basis of liveweight and previous gain. The basal ration consisted of a full-feed of ground shelled corn; Purdue Supplement A, 2 lb.; legume silage, ad lib; and minerals, ad lib. (Formula for Supplement A, 1000 lb. mix; soybean meal, 650 lb.; dehydrated alfalfa meal, 140 lb.; molasses, 140 lb.; salt with cobalt, 17 lb.; vitamin A and D concentrate, 0.5 lb. (contains 4,540,000 U.S.P. units A and 567,500 U.S.P. units D per lb.). Lot I served as the control and received the basal ration listed above. The three treated lots received, in addition to the basal ration, the following: Lot II, 12 mg. hexestrol per animal, daily; Lot III, 100 mg. aureomycin (chlorotetracycline) per animal daily; Lot IV 12 mg. hexestrol and 100 mg. aureomycin per animal daily.
At the completion of the fattening trial, the four lots of cattle were followed through the marketing phase for obtaining comparative data on shrink-in-transit, dressing percent and U0S. Federal grades.
The twelfth rib was removed from one side of each carcass for individual chemical analyses of the attached meat.
Summary of Results
The feeding of 12 milligrams of hexestrol per animal daily to two-year old fattening steers in drylot resulted in a 24 percent increase in growth rate (2.03 vs. 2.50 lb. per day).
The feeding of 100 milligrams of aureomycin resulted in a 10 percent increase in growth rate. When hexestrol and aureomycin were fed in combination the growth stimulatory effect (37 percent increase in growth rate) was almost exactly equal to the sum of effects of the two when fed separ-ately, indicating the growth stimulatory effects of these two substances are exerted independently and are additive.