Animal Husbandry Mimeograph
Series No. 55-10 October, 1955
THE UTILIZATION OF DIETHYLSTILBESTROL, AUREOMYCIN AND AN
AUREOMYCIN-DIETHYLSTILBESTROL COMBINATION IN STEER FATTENING RATIONS
J. F. Hentges, Jr., J. A. Black and T. J. Cunhal
The implantation of pellets containing 12 to 120 mg. of diethylstilbestrol,
a synthetic female sex hormone, has been shown by extensive experimentation
(1) (4) (5) to increase the rate of weight gain and efficiency of feed utili-
zation for fattening beef steers. Undesirable side effects were also observed.
High tailheads, depressed loins, abnormal teat development and hookiness was
observed in the steers given subcutaneous pellet implants in the ear or neck.
In addition, their carcass grades were low due to a higher water content.
Recent experimental work (2) (6) on the oral administration of diethyl-
stilbestrol in small daily allotments (10 to 20 mg.) has shown superior feed
lot performance without the undesirable side effects.
A summary of 17 feeding trials at eight experiment stations (3) showed
that diethylstilbestrol fed steers had 17% higher weight gains, 13% higher
feed efficiency and no difference in dressing percentage or Federal carcass
The oral administration of aureomycin to fattening steers has resulted
in faster rates of gain and more efficient feed utilization. The publications
on this field of research have been reviewed recently by C. A. Tucker, II. (7)
LHentges, Assistant Animal Husbandman; Black, Graduate Assistant; and Cunha,
Animal Husbandman and Head, Department of Animal Husbandry and Nutrition.
The technical assistance of D. W. Wakeman is gratefully acknowledged.
The experiment reported herein was conducted to determine the feeding
values of diethylstilbestrol, aureomycin and a combination of these treat-
ments administered orally in the rations of yearling fattening steers.
Twenty-four grade yearling steers were distributed equally into four
lots of six (6) each by weight and grade. The experiment was started
May 28, 1955, and was terminated on September 14, 1955. The initial weight
of the steers was taken after a 12 hour shrink. The final weight was de-
termined by deducting a 3% shrink from the live weight. The steers were
fed in dry lot on the rations shown in Table I.
Salt, bonemeal, and a trace mineral mixture supplying iron, copper,
cobalt, manganese, zinc and iodine was fed free choice. Criteria studied
were weight gains, feed consumption, efficiency of feed utilization, transit
shrink, carcass grades and endocrine gland weights. Comparative data on
transit shrink were obtained by trucking the steers forty miles to a slaughter
Results and Discussion
Results of the experiment are summarized in Table II. All steers on
diethylstilbestrol and aureomycin-diethylstilbestrol combination exhibited
faster gains, greater feed consumption and better efficiency of feed utili-
zation throughout the experiment. As shown in Figure I, the steers receiving
the aureomycin-diethylstilbestrol combination gained at the fastest rate
during the first 35 days of the trial but their rate of gain dropped below
the diethylstilbestrol fed steers after 49 days on the trial. The
diethylstilbestrol fed steers consistently gained at a faster rate than the
control steers throughout the study and had a 11% larger average final weight
gain. The aureomycin fed steers gained faster than the control steers for
28 days. After 77 days on the trial, both lots of steers receiving aureo-
mycin exhibited lower weight gains, less appetite, and were difficult to
keep on feed. A slight enlargement of the teats was observed but no other
visible differences were apparent in the hormone fed steers. No differences
in transit shrink were observed. Carcass grades of the diethylstilbestrol
fed steers were higher due to a greater amount of inside and external finish.
Larger seminal vesicles were observed in the diethylstilbestrol fed steers.
(Lot I) 10.8, (Lot II) 17.2, (Lot III) 10.4 and (Lot IV) 19.1 grams. No
differences were observed in weights of the pituitary, adrenal or thyroid
glands between lots.
Under the conditions of this experiment, the addition of diethyl-
stilbestrol and an aureomycin-dlethylstilbestrol combination to a basal
steer fattening ration resulted in faster weight gains, greater feed con-
sumption, more efficient feed utilization, higher carcass grade and no vis-
ible undesirable side effects.
Composition of Rations
I II III IV
Cracked corn 150 150 150 150
Corn, coarsely ground 150 150 150 150
Citrus pulp, dried 150 150 150 150
Cottonseed meal, 41% 100 100 100 100
Aurofac 2i1 x x
Stilbosol2 x x
550 lb. 550 lb. 550 lb.
1Aurofac 2A, supplied by Lederle Laboratories, Pearl River, New
York. (One pound contains 3,6 grams aureomycin) The rate of
feeding Aurofac 2A was adjusted bi-weekly to provide 10 mg,
aureomycin per hundred pounds live weight daily.
2Stilbosol, supplied by Eli Lilly and Co., Indianapolis, Indiana.
(Ten pounds was mixed with one ton of basal ration. Two pounds
of the Stilbosol-basal mix was fed per head daily to supply 10 mg.
Summary of Performance
Lot Number I I III Iv
Basal Plus Basal Plus Basal plus
Ration Compared Basal g. 10 g. aureo combination
Ra Cmpare Basal bestrol per mycin/cwt of Lots 2
head/day and 3
Number of steers per lot
Days on experiment
Av. initial weight, lb.
final weight, lb.
total gain per steer, lb.
daily gain, lb.
Av. daily concentrate, lb.
coarsely gr. corn meal
Av. daily hay consumption, lb.
Feed required per cwt gain, lb.
Feed cost per cwt gain, dollars
diethylstilbestrol/cwt gain, $
aureomycin per cwt gain, $
total feed cost per cwt gain
Initial cost per steer, $1
Feed cost per steer, $2
Total cost per steer, $
Returns per steer, $3
Profit per steer, $
4Initial cost per steer $14.50 per cwt.
2Feed cost $0.027 per pound of concentrate,
a pound for Aurofac 2A.
3Lot 1, $18.50 per cwt;
$20.00 per cwt. (based
Lot 2, $19.70 per c
on carcass values)
0.50 a pound for Stilbosol, and 0.49
,wt; Lot 3, $19.00 per cwt; and Lot 4
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Summary of Carcass Datal
I II III IV
Initial live grade, av. 6 5.8 5.8 6.5
Federal carcass grade, av. 9.7 11.0 10.6 11.2
conformation 11.8 12.0 11.3 11.8
outside finish 10.6 11.2 11.0 11.7
inside finish 8.8 10.0 9.0 10.6
quality 8.8 10.0 9.2 10.3
Dressing per cent, av. 58.1 57.8 58.0 57.7
Federal carcass grades
choice 2 1 2
good 5 3 5 4
commercial 1 1
Av. shrink in transit, lb2 30 35 34 33
1Numerical scores were placed upon thirds of grades as follows: Ave.
Prime, 16; Low Prime, 15; High Choice, 14; Ave. Choice, 13; Low Choice,
12; High Good, 11; Ave. Good, 10; Low Good, 9; High Commercial, 8;
Ave. Commercial, 7; Low Commercial, 6; Utility, 5.
2Steers were weighed, loaded and trucked forty (40) miles to packing
house and then weighed again.
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DIETHYLSTILBESTROL AND AUREOMYCIN IN
STEER FATTENING RATIONS
(Accumulative ave. daily gains)
c~- C -
- r,-_ II
1. Andrews, F. N., W, M. Beeson and F. D. Johnson. 1954.
Stilbestrol, Dienestrol, Testosterone and Progesterone
and Fattening of Beef Steers. J. Ani, Sci. 13, 99.
The Effect of
on the Growth
2. Burroughs, Wise, C. C. Culbertson, R. M. McWilliams, Joseph Kastelic,
and William Hale. 1953. Hormone Feeding (Diethylstilbestrol) to Fat.
tening Cattle. Iowa Agr. Exp. Sta. A. H. Leaflets 188 and 189,
3. Burroughs, Wise, C. C. Culbertson and Joseph Kastelic. 1955. Summary
of Stilbestrol Cattle Feeding Experiments Conducted at Nine Agricultural
Experiment Stations. Iowa Agr. Exp. Sta, A. H. Leaflet 201,
4. Clegg, M. T. and H. H. Cole.
Growth Response in Ruminants.
1954. The Action of Stilbestrol on the
J. Ani. Sci. 1, 108.
5. Dinusson, W. E., F. N. Andrews and W. MN Beeson. 1950. The
Stilbestrol, Testosterone, Thyroid Alteration and Spaying on
and Fattening of Beef Heifers. J. Ani. Scl. 2 321.
6. Perry, T. W., W. M. Beeson, G. N. Andrews and Martin Stob. 1955. The
Effect of Oral Administration of Hormones on Growth Rate and Deposition
in the Carcass of Fattening Steers. J. Ani. Sci. 14 329.
7. Tucker, Cecil A. 1954. M.S. Thesis. Aureomycin and Waste Beef Fat as
Components of Steer Fattening Rations. University of Florida.
A. H. Dept.