• TABLE OF CONTENTS
HIDE
 Copyright
 Front Cover
 Table of Contents
 Foreword
 Experimental procedure
 Orally administered stilbestro...
 Implanted stilbestrol
 Relative value of oral and implanted...
 Summary
 Literature cited
 Acknowledgement






Group Title: Bulletin - University of Florida. Agricultural Experiment Station - no. 666
Title: Oral and implanted stilbestrol for beef cattle fattened on pasture and in drylot
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00027250/00001
 Material Information
Title: Oral and implanted stilbestrol for beef cattle fattened on pasture and in drylot
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 16 p. : ; 23 cm.
Language: English
Creator: Chapman, H. L ( Herbert L. ), 1923-
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1964
 Subjects
Subject: Diethylstilbestrol   ( lcsh )
Beef cattle -- Weight   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 15.
Statement of Responsibility: H.L. Chapman, Jr. ... et al..
General Note: Cover title.
Funding: Bulletin (University of Florida. Agricultural Experiment Station) ;
 Record Information
Bibliographic ID: UF00027250
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: aleph - 000929049
oclc - 18353669
notis - AEN9814

Table of Contents
    Copyright
        Copyright
    Front Cover
        Page 1
    Table of Contents
        Page 2
    Foreword
        Page 3
    Experimental procedure
        Page 4
        Page 5
    Orally administered stilbestrol
        Page 6
    Implanted stilbestrol
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Relative value of oral and implanted stilbestrol
        Page 12
    Summary
        Page 12
        Page 13
        Page 14
    Literature cited
        Page 15
    Acknowledgement
        Page 15
        Page 16
Full Text





HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida




Y ~6~'


Oral and Implanted
Stilbestrol
for Beef Cattle
Fattened on Pasture
and in Drylot




H. L. Chapman, Jr., A. Z. Palmer, R. W. Kidder,
J. W. Carpenter, and C. E. Haines


Agricultural Experiment Stations
University of Florida, Gainesville
J. R. Beckenbach, Director


Bulletin 666
February 1964
























CONTENTS
Page


FOREW ORD ............... .-.. .. ......... ---.-----.. -- ---- -- -- ... ...--------- 3


EXPERIMENTAL PROCEDURE ...................... ....................... 4


ORALLY ADMINISTERED STILBESTROL ....................................---- 6


IMPLANTED STILBESTROL ........ ............ -.------------- --.-------- 6


RELATIVE VALUE OF ORAL AND IMPLANTED STILBESTROL ............- ...-.------- 12


SUMMARY ............ .-.-- ... ------------- 12


LITERATURE CITED ............. ....... .. .... ...................... ...-.... -.. 15


ACKNOWLEDGMENTS ...............- ...... .....----.-. -- ..- ....-... .. 15








ORAL AND IMPLANTED

STILBESTROL'

FOR BEEF CATTLE FATTENED ON

PASTURE AND IN DRYLOT

H. L. CHAPMAN, JR., A. Z. PALMER, R. W. KIDDER,
J. W. CARPENTER, AND C. E. HAINES 2

FOREWORD
The practice of feeding 10 milligrams of stilbestrol per ani-
mal daily has been widely accepted during the past 10 years for
use in rations for drylot-fed steers. In drylot it has consistently
increased the rate and efficiency of gain and generally has not
altered carcass characteristics. However, in south Florida many
cattle are sold directly from pasture, having received little or
no supplemental feed. Many steers are fed a limited intake of
concentrate feed, ranging from 4 to 8 pounds per animal daily,
immediately prior to being sold for slaughter. Such a practice
often limits the use of stilbestrol.
Information on the use of stilbestrol in pasture fattening
programs is limited. Fontenot et al. (4)8 reviewed the research
done with stilbestrol on pasture and reported that a 12-milligram
implant of stilbestrol per animal increased the rate of gain 20
percent and had no undesirable effect on carcass characteris-
tics. As the level of implantation was increased to 24, 36, and 48
milligrams per steer, there was no significant additional increase
in rate of gain, but carcass grade was lowered and there was a de-
crease in tenderness and fat deposition. Research in Florida (1, 2,
3) indicated that 24 milligrams of implanted stilbestrol increased
weight gain at a rate comparable to that from a daily intake
of 10 milligrams administered orally and did not alter carcass

1The term stilbestrol is a popular abbreviation for diethylstilbestrol, a
synthetic compound capable of producing effects of natural estrogenic
substances.
2 Chapman, Animal Nutritionist, Everglades Station
Palmer, Associate Meat Scientist, Main Station
Kidder, Animal Husbandman, Everglades Station
Carpenter, Assistant Meat Scientist, Main Station
Haines, Assistant Animal Husbandman, Everglades Station
SNumbers in parentheses refer to Literature Cited.







Florida Agricultural Experiment Stations


grade. Thirty-six and 48 milligrams slightly lowered carcass
grade when implanted and did not increase rate of gain above
that obtained with the 24-milligram level. The data reported
in this publication were collected from a series of experiments
conducted to compare the effect of stilbestrol administered orally
and implanted on growth and carcass characteristics and see if
its effect was the same on Roselawn St. Augustinegrass pastures
and in drylot and with two different levels of concentrate feed
intake.
EXPERIMENTAL PROCEDURE4
Except for minor variations, similar experimental procedures
were used in all of the experiments. Within each experiment the
steers were divided into equal groups on the basis of weight,
grade, and breed. These groups were randomly allotted to ex-
perimental treatment. Prior to being allotted to an experiment
each steer was treated at 21-day intervals with 6 ounces each
of phenothiazine and hexachloroethane for gastro-intestinal
worms and liver flukes. Roselawn St. Augustinegrass pastures
were stocked at a rate of two steers per acre. Full-fed and
limited-fed concentrated mixtures were similar within each ex-
periment except for an adjustment in mineral percentage that
was counter-balanced with an adjustment in ground snapped
corn. The limited-fed concentrate mixture was fed at the rate
of 6 pounds per animal daily and the other fed free-choice. The
ingredient composition of the feeds for the five experiments is
presented in Table 1. The mineral mixture contained 20.0 per-
cent steamed bonemeal, 20.0 percent defluorinated phosphate,
32.0 percent common salt, 5.5 percent dried citrus pulp, 2.5
percent cupric sulfate, 2.0 percent aluminum sulfate, 1.2 percent
cupric oxide, 5.0 percent red iron oxide, 0.8 percent Numanese
(manganese oxide), and 11 percent of mill-run blackstrap
molassses. It also contained 20 ounces of cobalt carbonate per
ton of mixture.
Carcass data obtained in each experiment included initial
slaughter grade, carcass grade, intransit shrink, dressing per-

SIn experiments number 1 and 5 a four-inch section of longissimus dorsi
muscle (the rib-eye) was taken from the left side of each carcass to include
the thirteenth rib. The section was evaluated for degree of marbling and
tenderness. Tenderness was determined both by a four-member taste panel
and by measuring the amount of pressure required to shear a one-half inch
core of meat, using the Warner-Bratzler shear apparatus. There were no
significant variations in these measurements that were attributable to stil-
bestrol administration, and these data have not been included in this bul-
letin.







Oral and Implanted Stilbestrol


cent, and 48-hour cooler shrink. A committee of three or more
graders placed an initial slaughter grade on each animal. The
final carcass grade was determined by a federal beef grader.
The grades were coded as follows:

Slaughter grade Low Medium High
Choice 12 13 14
Good 9 10 11
Standard 6 7 8
Utility 3 4 5


The increase in slaughter grade is presented in the sum-
mary tables in units of one-third of a grade. For example, an
increase of three indicates the animal improved one complete
grade while on experiment.

TABLE 1.-INGREDIENT COMPOSITION OF CONCENTRATE FEED USED IN THE
FIVE EXPERIMENTS (LBS.).

Experiment .................... 1* 2**t$ 3**t 4tf 5*t$
Rate of feed intake ..... F L F L F L F F L

Ground snapped corn .... 1136 1108 884 800 974 807 884 884 800
Dried citrus pulp ............. 600 600 800 800 800 800 800 800 800
Cottonseed meal (41%) .. 200 200 300 400 200 360 200 200
Urea- 262 ......................... 10 10 16 16 16 16
Mineral mixture ................ 14 42 10 33
Premix .............................. 40 40 100 100 400

F, feed provided free-choice; L, feed provided at 6 lbs. per animal daily.
Stilbestrol provided by Eli Lilly and Company, Indianapolis, Indiana. Premix was
composed of cottonseed meal plus stilbestrol to furnish 10 miligrams per animal daily.
Where no feed additive was given the premix was plain cottonseed meal.
** Cottonseed meal (36%)
t Stilbestrol implants were furnished by Charles Pfizer & Company, Terre Haute,
Indiana.
$ Mineral mixed in concentrate feed at rate of 0.1 pound animal daily, in the feed.

In each experiment the intransit shrink was determined as
the difference in weight when loaded on the truck at the Ex-
periment Station and when unloaded at the packinghouse. All
of the cattle in these experiments were sold on the basis of
carcass weight and grade. The carcass weight was determined
by the warm carcass weight minus 21/2 percent shrink. Dressing
percent was determined by dividing the live weight at the pack-
inghouse into the warm carcass weight shrunk 21/2 percent.
Cooler shrink was the difference between warm carcass weight
and the carcass weight after being in the cooler for 48 hours.






Florida Agricultural Experiment Stations


ORALLY ADMINISTERED STILBESTROL
Experiment 1.-This experiment was conducted to evaluate
the use of orally administered stilbestrol in rations for steers
being fattened on pasture and in drylot and to see whether this
effect was altered by the level of concentrate feed intake.
Sixty-four two-year-old steers having an initial low standard
slaughter grade were divided into eight groups of eight steers
each on the basis of weight, grade, and breed and randomly
allotted to the experimental treatments presented in Table 2.
The length of the feeding period was 142 days. Animals in
drylot received silage made from Roselawn St. Augustinegrass
to minimize differences attributable to the source of roughage.
The ingredient compositions of the experimental rations are
shown in Table 1.
Weight gain and shipping and carcass data are summarized
in Table 2. The gain of drylot steers was increased slightly by
including stilbestrol in the full-fed ration. However, steers re-
ceiving a full-feed on pasture and a limited feed in drylot had
less gain when stilbestrol was given. The effect was not statis-
tically significant. Stilbestrol did not significantly affect carcass
grade, intransit shrink, cooler shrink, or dressing percent.
The effect of stilbestrol upon rate of gain was more erratic
during this experiment than any other study conducted at the
Everglades Station. However, results emphasize that the proper
use of the compound will not alter carcass characteristics.

IMPLANTED STILBESTROL
Two experiments (Experiments 2 and 3) were conducted to
evaluate 24 milligrams of stilbestrol implanted in the ear of
steers both in drylot and on pasture and to determine whether
the level of concentrate feed intake altered the effect. Another
experiment (Experiment 4) was conducted to determine the
value of the implants for steers receiving no supplemental feed
and also to compare 24 and 36 milligram levels of implantation.
Experiment 2.-Ninety-six two-year-old steers of mixed
breeding and having an initial high utility slaughter grade were
divided into eight groups of 12 steers each, and the groups were
randomly allotted to the experimental treatments shown in
Table 3. The steers were fed for 112 days. The forage for
drylot steers was sorghum silage comprised of a mixture of






Florida Agricultural Experiment Stations


ORALLY ADMINISTERED STILBESTROL
Experiment 1.-This experiment was conducted to evaluate
the use of orally administered stilbestrol in rations for steers
being fattened on pasture and in drylot and to see whether this
effect was altered by the level of concentrate feed intake.
Sixty-four two-year-old steers having an initial low standard
slaughter grade were divided into eight groups of eight steers
each on the basis of weight, grade, and breed and randomly
allotted to the experimental treatments presented in Table 2.
The length of the feeding period was 142 days. Animals in
drylot received silage made from Roselawn St. Augustinegrass
to minimize differences attributable to the source of roughage.
The ingredient compositions of the experimental rations are
shown in Table 1.
Weight gain and shipping and carcass data are summarized
in Table 2. The gain of drylot steers was increased slightly by
including stilbestrol in the full-fed ration. However, steers re-
ceiving a full-feed on pasture and a limited feed in drylot had
less gain when stilbestrol was given. The effect was not statis-
tically significant. Stilbestrol did not significantly affect carcass
grade, intransit shrink, cooler shrink, or dressing percent.
The effect of stilbestrol upon rate of gain was more erratic
during this experiment than any other study conducted at the
Everglades Station. However, results emphasize that the proper
use of the compound will not alter carcass characteristics.

IMPLANTED STILBESTROL
Two experiments (Experiments 2 and 3) were conducted to
evaluate 24 milligrams of stilbestrol implanted in the ear of
steers both in drylot and on pasture and to determine whether
the level of concentrate feed intake altered the effect. Another
experiment (Experiment 4) was conducted to determine the
value of the implants for steers receiving no supplemental feed
and also to compare 24 and 36 milligram levels of implantation.
Experiment 2.-Ninety-six two-year-old steers of mixed
breeding and having an initial high utility slaughter grade were
divided into eight groups of 12 steers each, and the groups were
randomly allotted to the experimental treatments shown in
Table 3. The steers were fed for 112 days. The forage for
drylot steers was sorghum silage comprised of a mixture of







Oral and Implanted Stilbestrol


medium dwarf Sumac, Sumac 6550, and Martin sorghum. The
ration ingredient composition is shown in Table 1. Stilbestrol
was implanted at the rate of 24 milligrams per animal at the
beginning of the experiment. Carcass data and the initial and
final slaughter grades were obtained in the same manner as dur-
ing the first experiment. Two animals died while on experiment,
and data from these were not included.
The average weight changes and carcass data are summarized
in Table 3. Gains on pasture were higher than during Experi-
ment 1 because of better quality pasture forage. During Ex-
periment 2 stilbestrol stimulated the rate of gain both in dry-
lot and on pasture and at both levels of feed intake. Stilbestrol
did not significantly affect intransit shrink, 48-hour cooler shrink,
dressing percent, or change in slaughter grade. The rate of
gain increase was more variable with a limited concentrate in-
take as compared to full feed.
Experiment 3.-Sixty-four coming-two-year-old steers having
an average initial low standard slaughter grade were divided into
eight lots of eight steers each and fed for 132 days. The groups
were randomly allotted to the eight treatments shown in Table 4.
All experimental details were similar to Experiment 2 except
that the roughage for the drylot fed steers in this study was
Roselawn St. Augustinegrass silage and there were minor dif-
ferences in the experimental concentrate mixture (Table 1).
Stilbestrol was implanted at the rate of 24 milligrams per ani-
mal at the beginning of the experiment.
Experimental data are summarized in Table 4. The rate of
gain was significantly increased when stilbestrol was used. The
increase was greatest among steers in drylot with full feed, next
on pasture with full feed, and the least on pasture with limited
feed. Considerable variation in carcass measurements occurred
during this experiment. The steers that received the implants
had a greater cooler shrink than those that did not. The in-
crease in grade for drylot, full-fed cattle was greater with the
implants. Otherwise, stilbestrol treated cattle increased in grade
less than untreated ones. Stilbestrol had no significant effect on
dressing percent or intransit shrink.
These results re-emphasize the variation that might be ex-
pected when stilbestrol is used in pasture feeding programs. The
most consistent benefit from the compound was in drylot with
a full intake of concentrate feed.












TABLE 2.-AVERAGE WEIGHT CHANGES, SHIPPING, CARCASS AND
EXPERIMENT 1.


FEED CONSUMPTION DATA, PER STEER,


Drylot Pasture
Level of concentrate intake Limited Limited Full Full Limited Limited Full Full
Stilbestrol-oral ........................ No Yes No Yes No Yes No Yes

Number of steers .....-.........-...... 8 8 8 8 8 8 8 8
Final weight (lbs.) ....----......... 944 902 1039 1048 988 984 1089 1057
Initial weight (Ibs.) ................ 766 764 768 767 765 766 766 764
Total gain (lbs.) ...................-.. 178 138 271 281 223 218 323 293
Daily gain (lbs.) ........................ 1.25 0.97 1.91 1.98 1.57 1.54 2.27 2.06
Intransit shrink (%)* .............. 3.18 3.10 2.41 2.38 4.86 3.66 3.49 2.65
48-hour cooler shrink (%) ...... 1.53 1.59 1.29 1.09 1.46 1.28 1.22 1.25
Dressing percent .................-...... 55.7 56.2 60.4 61.2 56.9 56.2 61.0 60.4
Carcass grade ............................ 8 8 10 10 7 8 10 10
Initial slaughter grade .----........ 6 6 6 6 6 6 6 6
Increase ........................................ 2 2 4 4 1 2 4 4
Daily feed intake (Ibs.)
Concentrate ........................ 6.0 6.0 21.3 19.8 6.0 6.0 21.8 20.9
Roughage ............................ 46.0 41.3 17.7 19.7

Cattle were slaughtered in Miami, an intransit distance of 80 miles.











TABLE 3.-AVERAGE WEIGHT


CHANGES, SHIPPING, CARCASS AND
EXPERIMENT 2.


FEED CONSUMPTION DATA PER STEER,


Level of concentrate intake Limited
Stilbestrol-implant .........----- No

Number of steers .......... --......... 12
Final weight (lbs.) .......----- 691
Initial weight (lbs.) ................ 615
Total gain (lbs.)* ................... 76
Daily gain (lbs.) ...................... 0.68


Intransit shrink (%)** ..-........
48-hour cooler shrink (%) .....-
Dressing percent ...-.............-.....
Carcass grade ............................
Initial slaughter grade ..........
Increase .................. ..........


3.64
1.48
51.6
6
5
1


Drylot
Limited Full Full
Yes No Yes


11
738
611
127
1.13
3.54
1.50
51.9


Daily feed intake (lbs.)
Concentrate ...................... 6.0
Roughage ............................ 33.5


12
888
608
280
2.50
3.61
1.32
57.5
10
5
5

23.1
11.2


12
944
617
327
2.92
2.74
1.33
58.3
10
5
5

23.1
11.2


Pasture
Limited Limited Full


No Yes


12
796
624
172
1.54
4.17
1.49
54.7
7
5
2


12
841
626
215
1.92
4.11
1.48
55.0
7
5
2


No

11
913
632
281
2.51
3.12
1.37
58.5
9
5
4


6.0 6.0 23.1


SEffect of stilbestrol significant at P < .01
** Steers were slaughtered in Miami, an intransit distance of 80 miles.


Full O
Yes

12
956
630
326
2.91 S
3.04
1.51 4
58.0
9
5
4

23.1


~












TABLE 4.-AVERAGE WEIGHT CHANGES, SHIPPING, CARCASS, AND
EXPERIMENT 3.


Level of concentrate intake


Drylot
Limited


Full


FEED CONSUMPTION DATA PER STEER,



Pasture
Limited Full


Stilbestrol-implant


....... N o


Number of steers ..................... 8
Final weight (lbs.) .............. 972
Initial weight (lbs.) ............... 742
Total gain (lbs.)* ...--............. 230
Daily gain (lbs.) .......-......... 1.74
Intransit shrink (%)** .......... 7.82
48-hour cooler shrink (%)* .... 1.91
Dressing percent ..................... 56.9
Carcass grade ............................ 7
Initial slaughter grade .......... 6
Increase ...................-- .......--- 1
Daily feed intake (lbs.)
Concentrate ................... 6.0
Roughage ...................... 51.4


Yes No


8
996
741
255
1.93
7.83
1.75
54.7
6
6
0

6.0
54.2


8
1071
730
341
2.58
6.72
1.43
61.2
8
6
2

22.2
19.2


Yes No


8
1177
750
427
3.23
6.37
1.74
60.9
10
6
4

25.1
18.3


8
949
751
198
1.50
5.16
1.75
55.8
6
6
0


8
953
752
201
1.52
6.82
1.97
55.8
5
6
-1


6.0 6.0 23.6


* Effect of stilbestrol significant at P < .01
** Cattle were slaughtered in Tampa, an intransit distance of 185 miles.


8
1081
761
320
2.42
5.09
1.58
60.3
9
6
3


Yes


8
1122
741
381
2.89
4.81
1.68 'S
59.8
8
6
2

25.3
--







Oral and Implanted Stilbestrol


Experiment 4.-The purposes of this experiment were to de-
termine whether 24 milligrams of implanted stilbestrol would
stimulate gain when no supplemental feed was provided to steers
on pasture and to determine whether 36 milligrams of stilbestrol
implant would produce undesirable effects in cattle on pasture
receiving concentrate feed free-choice. Forty two-year-old steers
were divided into five groups of eight animals each, and the
groups were randomly allotted to the experimental treatments
shown in Table 5. The cattle were fed for 131 days. Composi-
tion of the experimental concentrate mixture is shown in Table 1.
The complete mineral mixture was fed free-choice to the cattle
not receiving concentrate feed.

TABLE 5.-AVERAGE GAIN, SHIPPING, CARCASS, AND FEED
CONSUMPTION DATA, EXPERIMENT 4.


Level of concentrate intake None Full feed
Stilbestrol implant ............. 0 24 0 24 36

Number of animals ............ 8 8 8 8 8
Final weight (lbs.) .............. 807 811 1018 1073 1084
Initial weight (lbs.) ............ 759 754 741 771 747
Total gain (lbs.)* ................ 48 57 277 302 337
Daily gain (lbs.) .................. 0.37 0.44 2.12 2.31 2.57
Intransit shrink (%)** ...... 3.96 3.04 4.48 3.80 3.24
Dressing percent* ................ 50.8 51.5 61.8 61.2 61.3
Cooler shrink (%) .............. 4.12 3.71 2.88 2.84 2.85
Carcass grade ...................... 4 4 8 8 8
Initial slaughter grade ...... 5 5 6 6 6
Increase .............................. 1 1 2 2 2
Concentrate feed intake
per day (lbs.) ............ 0 0 20.7 22.6 23.2

Treatment effect significant at P < .01
** Cattle were slaughtered in Miami, an intransit distance of 80 miles.

The results of the experiment are summarized in Table 5.
The rate of gain increased approximately 20 percent when stil-
bestrol was implanted in steers receiving no supplemental feed.
Also, intransit and cooler shrink decreased, dressing percent in-
creased slightly, and increase in carcass grade was the same as
compared to steers receiving no implants. When steers received
a full feed of concentrate on pasture, the major effect of stil-
bestrol was on the rate of gain and intransit shrink. Rate of







Florida Agricultural Experiment Stations


gain increased and intransit shrink decreased as stilbestrol treat-
ment increased. Other carcass measurements were similar for
all full-fed cattle. Neither level or implant caused any undesir-
able effects upon the carcasses.

RELATIVE VALUE OF ORAL AND IMPLANTED
STILBESTROL
Experiment 5.-The purpose of this experiment was to com-
pare oral and implanted stilbestrol and to determine whether the
value was the same on pasture and in drylot with two different
levels of concentrate feed intake. Ninety-six two-year-old steers
having an initial average utility slaughter grade were divided
into 12 groups of eight animals each. The groups were allotted
to the experimental treatment presented in Tables 6 and 7 and
fed for 131 days. The ingredient compositions of experimental
rations are presented in Table 1. The roughage was Roselawn
St. Augustinegrass silage. Orally administered stilbestrol was
given at the rate of 10 milligrams per head daily. Implanted
stilbestrol was administered only at the beginning of the experi-
ment at a rate of 24 milligrams per animal.
The results obtained during this experiment are summarized
in Tables 6 and 7. The only measurement for which variations
attributable to stilbestrol were significant was weight gain. In
every case, whether orally or implanted, stilbestrol stimulated
rate of gain. The orally administered stilbestrol stimulated gain
more than the implanted material among steers on pasture. The
highest rate of gain in drylot full-fed steers was for the implanted
steers. There were slight variations in average intransit shrink,
cooler shrink, dressing percent, and change in slaughter grades
among the 12 lots of steers, but there was no significant effect
of stilbestrol on any of these measurements.

SUMMARY
A series of five experiments was conducted to determine the
value of stilbestrol in steer-feeding programs to (1) compare
the effect obtained on Roselawn St. Augustinegrass pasture with
that in drylot, (2) determine the effect of different levels of
concentrate feed intake on response to stilbestrol, and (3) com-
pare orally administered and implanted stilbestrol in steer fat-
tening programs. Stilbestrol significantly stimulated rate of gain







Florida Agricultural Experiment Stations


gain increased and intransit shrink decreased as stilbestrol treat-
ment increased. Other carcass measurements were similar for
all full-fed cattle. Neither level or implant caused any undesir-
able effects upon the carcasses.

RELATIVE VALUE OF ORAL AND IMPLANTED
STILBESTROL
Experiment 5.-The purpose of this experiment was to com-
pare oral and implanted stilbestrol and to determine whether the
value was the same on pasture and in drylot with two different
levels of concentrate feed intake. Ninety-six two-year-old steers
having an initial average utility slaughter grade were divided
into 12 groups of eight animals each. The groups were allotted
to the experimental treatment presented in Tables 6 and 7 and
fed for 131 days. The ingredient compositions of experimental
rations are presented in Table 1. The roughage was Roselawn
St. Augustinegrass silage. Orally administered stilbestrol was
given at the rate of 10 milligrams per head daily. Implanted
stilbestrol was administered only at the beginning of the experi-
ment at a rate of 24 milligrams per animal.
The results obtained during this experiment are summarized
in Tables 6 and 7. The only measurement for which variations
attributable to stilbestrol were significant was weight gain. In
every case, whether orally or implanted, stilbestrol stimulated
rate of gain. The orally administered stilbestrol stimulated gain
more than the implanted material among steers on pasture. The
highest rate of gain in drylot full-fed steers was for the implanted
steers. There were slight variations in average intransit shrink,
cooler shrink, dressing percent, and change in slaughter grades
among the 12 lots of steers, but there was no significant effect
of stilbestrol on any of these measurements.

SUMMARY
A series of five experiments was conducted to determine the
value of stilbestrol in steer-feeding programs to (1) compare
the effect obtained on Roselawn St. Augustinegrass pasture with
that in drylot, (2) determine the effect of different levels of
concentrate feed intake on response to stilbestrol, and (3) com-
pare orally administered and implanted stilbestrol in steer fat-
tening programs. Stilbestrol significantly stimulated rate of gain











TABLE 6.-AVERAGE WEIGHT CHANGES, SHIPPING, CARCASS, AND FEED CONSUMPTION DATA, PER STEER
IN DRYLOT, EXPERIMENT 5.


Level of concentrate intake ............................. Limited Full
Stilbestrol treatment -........-----.................... 0 Oral Implant 0 Oral Implant

Number of steers ............................... ... 8 7 8 8 8 8
Final weight (lbs.) ................. ...... .. .. 911 988 934 1057 1104 1161
Initial weight (lbs.) -..-............................-- 734 768 746 744 750 754
Total gain (lbs.)* .... ...................... ..... --- 177 220 188 313 354 407
Daily gain (lbs.) .....- ....... ..........-- 1.35 1.68 1.44 2.39 2.70 3.11 m
Intransit shrink (%)** ..... ...................... 5.01 4.67 5.72 4.78 4.68 4.77
48-hour cooler shrink (%) .. ........................... 3.68 3.32 3.11 2.96 2.87 3.45
Dressing percent ...................-......... ......... 55.2 55.2 55.5 61.6 59.5 60.8
Carcass grade .................. -----.......- 6 6 6 10 9 9
Initial slaughter grade ...............................- 6 6 6 6 5 5
Increase ....................... ..... -- 0 0 0 4 4 4
Daily feed intake (lbs.)
Concentrate ..............................- ---- 6.0 6.0 6.0 22.8 21.1 22.9
Roughage ............-... --- ..............47.6 50.0 50.9 17.6 18.0 20.1

Effect of stilbestrol significant at P < .01
** Steers were slaughtered in Miami, an intransit distance of 80 miles.














TABLE 7.-AVERAGE WEIGHT CHANGES, SHIPPING, CARCASS, AND FEED CONSUMPTION DATA PER STEER
FOR PASTURE-FED STEERS, EXPERIMENT 5.


Level of concentrate intake ...................... .......
Stilbestrol treatment .......................-----------....---- 0

Number of steers ........--..... ...................... ..... 8
Final weight (lbs.) ..... -----............-........ ..-- .. 870
Initial weight (Ibs.) ..------....................-----.. .. 741
Total gain (lbs.)* .....----.--...........---.. ------.. 129
Daily gain (lbs.) .......................-..-.... ..... ....... 0.98
Intransit shrink (%)** .............--.......---.. ..... .... 4.27
48-hour cooler shrink (%) ...--..............----........... 3.27
Dressing percent .....................-------.....-.......-.--- 55.2
Carcass grade ... .......................-------... 5
Initial slaughter grade ....................................--- 5
Increase ..............-- -------......... ------.... 0
Concentrate feed intake/day (lb.) .........---.............. 5.9

Effect of stilbestrol significant at P < .01
** Steers were slaughtered in Miami, an intransit distance of 80 miles.


Limited
Oral Implant


8
948
764
184
1.40
3.73
3.57
55.4
5
5
0


8
948
789
159
1.21
3.86
3.35
53.5
5
5
0


6.0 6.0


Full
0 Oral In


8
1018
741
277
2.12
4.48
2.88
61.8
8
6
2
20.7


8
1071
756
315
2.40
3.97
2.82
62.9
8
6
2
23.2


1I


-t



plant
3.
8
073
771
302
2.31
3.80
2.84
61.1
8
6
2
22.6
c--
-







Oral and Implanted Stilbestrol


except in one experiment. Oral and implanted stilbestrol
each significantly increase rate of gain but had no significant
effect on intransit shrink, dressing percent, cooler shrink, or
slaughter grade increase, except in one experiment where varia-
tions occurred in cooler shrink. Implanted stilbestrol increased
the rate of gain of steers that received no supplemental feed on
pasture. When 36 milligrams were implanted, the rate of gain
was further increased, with no harmful carcass effects.
When the feed nutrient supply was adequate to fatten cattle,
the proper use of stilbestrol resulted in faster gains but little
apparent carcass changes. The most consistent benefit from stil-
bestrol was among steers provided a full-feed in drylot. The
response to stilbestrol was more variable on pasture. However,
in most cases gains were increased in pasture-fed steers. Either
orally administered (10 milligrams per animal daily) or im-
planted (24 milligrams per animal) stilbestrol should be used
in steer fattening programs. Thirty-six milligrams implanted
in steers on pasture may occasionally cause a lowering of carcass
grade (1, 2, 3). Therefore, no more than 24 milligrams of stil-
bestrol should be used for pasture-fed steers.

LITERATURE CITED

1. Baker, F. S., Jr. Stilbestrol implants vs. stilbestrol in feed for fatten-
ing steers. North Florida Experiment Station Mimeo 57-5. 1956.
2. Stilbestrol in feed, stilbestrol implants and proges-
terone-estradiol implants for fattening steers. North Florida Experiment
Station Mimeo 57-10. 1957.
3. Stilbestrol implants for steers on pasture and in
feed lot. North Florida Experiment Station Mimeo 60-5. 1960.
4. Fontenot, J. P., R. F. Kelly, and J. A. Gaines. The influence of im-
planting graded levels of stilbestrol in grazing beef steers. Virginia
Agricultural Experiment Station Bulletin 522. 1961.

ACKNOWLEDGMENTS

These studies could not have been conducted without the as-
sistance of a number of people. The authors wish to acknowledge
the assistance provided by the K-Bar Ranch, Zephyrhills; Cross-7
Ranch, Fort Pierce; W. T. Stitt, Clewiston; U. S. Sugar Corpora-
tion, Clewiston; Montgomery Ranch, Arcadia; M & M Ranch,
Loxahatchee; and Dewey Hawkins, Fort Lauderdale, in provid-
ing some of the animals used in these experiments. Also, ap-
preciation is extended to L. V. Morris, J. R. Crockett, J. V.







Oral and Implanted Stilbestrol


except in one experiment. Oral and implanted stilbestrol
each significantly increase rate of gain but had no significant
effect on intransit shrink, dressing percent, cooler shrink, or
slaughter grade increase, except in one experiment where varia-
tions occurred in cooler shrink. Implanted stilbestrol increased
the rate of gain of steers that received no supplemental feed on
pasture. When 36 milligrams were implanted, the rate of gain
was further increased, with no harmful carcass effects.
When the feed nutrient supply was adequate to fatten cattle,
the proper use of stilbestrol resulted in faster gains but little
apparent carcass changes. The most consistent benefit from stil-
bestrol was among steers provided a full-feed in drylot. The
response to stilbestrol was more variable on pasture. However,
in most cases gains were increased in pasture-fed steers. Either
orally administered (10 milligrams per animal daily) or im-
planted (24 milligrams per animal) stilbestrol should be used
in steer fattening programs. Thirty-six milligrams implanted
in steers on pasture may occasionally cause a lowering of carcass
grade (1, 2, 3). Therefore, no more than 24 milligrams of stil-
bestrol should be used for pasture-fed steers.

LITERATURE CITED

1. Baker, F. S., Jr. Stilbestrol implants vs. stilbestrol in feed for fatten-
ing steers. North Florida Experiment Station Mimeo 57-5. 1956.
2. Stilbestrol in feed, stilbestrol implants and proges-
terone-estradiol implants for fattening steers. North Florida Experiment
Station Mimeo 57-10. 1957.
3. Stilbestrol implants for steers on pasture and in
feed lot. North Florida Experiment Station Mimeo 60-5. 1960.
4. Fontenot, J. P., R. F. Kelly, and J. A. Gaines. The influence of im-
planting graded levels of stilbestrol in grazing beef steers. Virginia
Agricultural Experiment Station Bulletin 522. 1961.

ACKNOWLEDGMENTS

These studies could not have been conducted without the as-
sistance of a number of people. The authors wish to acknowledge
the assistance provided by the K-Bar Ranch, Zephyrhills; Cross-7
Ranch, Fort Pierce; W. T. Stitt, Clewiston; U. S. Sugar Corpora-
tion, Clewiston; Montgomery Ranch, Arcadia; M & M Ranch,
Loxahatchee; and Dewey Hawkins, Fort Lauderdale, in provid-
ing some of the animals used in these experiments. Also, ap-
preciation is extended to L. V. Morris, J. R. Crockett, J. V.






16 Florida Agricultural Experiment Stations

McLeod, R. H. Alsmeyer, and others who assisted in conducting
the feeding studies, carcass studies, or data processing. AS-
sistance with the statistical analyses was provided by E. D.
Harris.




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