• TABLE OF CONTENTS
HIDE
 Title Page
 Table of Contents
 Introduction
 Literature review
 Levels of aureomycin for steer...
 Diethylstilbestrol and aureomycin...
 Summary
 General recommendations on the...
 Acknowledgement
 Literature cited
 Back Cover














Group Title: Bulletin - University of Florida. Agricultural Experiment Stations ; no. 627
Title: Diethylstilbestrol and aureomycin for fattening beef cattle
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00027336/00001
 Material Information
Title: Diethylstilbestrol and aureomycin for fattening beef cattle
Series Title: Bulletin Agricultural Experiment Stations, University of Florida
Physical Description: 22 p. : ill. ; 23 cm.
Language: English
Creator: Hentges, J. F
Publisher: University of Florida, Agricultural Experiment Stations
Place of Publication: Gainesville Fla
Publication Date: 1960
 Subjects
Subject: Beef cattle   ( lcsh )
Diethylstilbestrol   ( lcsh )
Aureomycin   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 21-22.
Statement of Responsibility: J.F. Hentges, Jr. ... et al..
General Note: "September 1960."
Funding: Bulletin (University of Florida. Agricultural Experiment Station)
 Record Information
Bibliographic ID: UF00027336
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000881635
oclc - 14255424
notis - AEH9504

Table of Contents
    Title Page
        Page 1
    Table of Contents
        Page 2
    Introduction
        Page 3
    Literature review
        Page 3
    Levels of aureomycin for steer fattening
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
    Diethylstilbestrol and aureomycin used singly and in combination for fattening beef cattle
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
    Summary
        Page 16
        Page 17
        Page 18
    General recommendations on the use of antibiotics and hormones for fattening cattle
        Page 19
        Page 20
    Acknowledgement
        Page 21
    Literature cited
        Page 21
        Page 22
    Back Cover
        Back Cover
Full Text



September 1960


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATIONS
J. R. BECKENBACH, Director
GAINESVILLE, FLORIDA




Diethvlstilbestrol and Aureomycin

For Fattening Beef Cattle

J. F. HENTGES, JR., W. D. FLETCHER, J. A. BLACK,
C. A. TUCKER II and T. J. CUNHA


Fig. 1.-Implants of diethylstilbestrol pellets may be placed under
the skin on the ears of cattle to be fattened for slaughter.


Bulletin 627



















CONTENTS


Page


INTRODUCTION


LITERATURE REVIEW ....


PART I-LEVELS OF AUREOMYCIN FOR STEER FATTENING ......................---... 4


Experiment I



Experiment II


A Comparison of Two Levels of Aureomycin for
Fattening Steer Calves on High-Concentrate
Rations (Group-fed) .-.-....-...... --.. ..-.. ...- ...--- 4

A Comparison of Two Levels of Aureomycin for
Fattening Steer Calves on High-Concentrate
Rations (Individually-fed) ................-.... ..... ......... 7


PART II-DIETHYLSTILBESTROL AND AUREOMYCIN USED SINGLY AND IN
COMBINATION FOR FATTENING BEEF CATTLE .......................


Experiment III



Experiment IV


Diethylstilbestrol and Aureomycin Used Singly
and in Combination for Fattening Steers on
High-Concentrate Rations .....-.... -. ............

Diethylstilbestrol Implants and Aureomycin Used
Singly and in Combination for Fattening Heifers
on High-Roughage Rations .......... ..... .........


SUM M ARY ..... -......... ...- .......................- ....


GENERAL RECOMMENDATIONS ON THE USE OF ANTIBIOTICS AND
HORMONES FOR FATTENING CATTLE ............. .... -..


. 10



.13

S16



S19


ACKNOWLEDGMENTS

LITERATURE CITED.


. -......... 3


....... 3


.._







Diethylstilbestrol and Aureomycin

For Fattening Beef Cattle

J. F. HENTGES, JR., W. D. FLETCHER, J. A. BLACK,
C. A. TUCKER II and T. J. CUNHAi

INTRODUCTION
The development of highly efficient rations to produce beef
at less cost is being emphasized in beef cattle nutrition research.
Antibiotics and hormones are destined to play an important
role in the formulation of these highly efficient cattle rations.
Aureomycin, identified chemically as chlortetracycline, is a
broad spectrum antibiotic used extensively in commercial live-
stock feeds. Diethylstilbestrol is a synthetic female sex hor-
mone which is available in commercial feed premixes and in
pellets for implantation. Both of these chemical compounds
have been approved by the Federal Food and Drug Administra-
tion for inclusion in rations to fatten livestock for human con-
sumption.
The experiments discussed in this bulletin were designed to:
1. Compare levels of aureomycin in steer fattening rations.
2. Compare diethylstilbestrol and aureomycin singly and in
combination in steer fattening rations.
3. Compare diethylstilbestrol implants and aureomycin singly
and in combination in heifer fattening rations.

LITERATURE REVIEW
Aureomycin.-Literature reviews by Knodt (9), Lassiter
(10) and Reid et al (14) have reported the extensive and benefi-
cial use of aureomycin in rations for calves. A growth response
observed by the feeding of aureomycin to calves was attributed
to an increase in feed intake and the control of certain calfhood
infectious diseases, notably scours. Rusoff et al (15) reported
larger skeletons in aureomycin supplemented calves but Jacobson
et al (8) reported no increase in height at withers or depth of
chest in calves fed aureomycin. They conclude that increased
weight gains must be muscle and fat rather than skeletal. For
mature ruminants, Reid et al (14), in a review of literature,
state that in general, antibiotics have not been beneficial. They
indicate that the antibiotic supplementation of fattening rations
'Hentges: Associate Animal Husbandman; Fletcher, Black and Tucker:
Research Assistants; Cunha: Animal Husbandman and Head, Animal Hus-
bandry and Nutrition Department.







Diethylstilbestrol and Aureomycin

For Fattening Beef Cattle

J. F. HENTGES, JR., W. D. FLETCHER, J. A. BLACK,
C. A. TUCKER II and T. J. CUNHAi

INTRODUCTION
The development of highly efficient rations to produce beef
at less cost is being emphasized in beef cattle nutrition research.
Antibiotics and hormones are destined to play an important
role in the formulation of these highly efficient cattle rations.
Aureomycin, identified chemically as chlortetracycline, is a
broad spectrum antibiotic used extensively in commercial live-
stock feeds. Diethylstilbestrol is a synthetic female sex hor-
mone which is available in commercial feed premixes and in
pellets for implantation. Both of these chemical compounds
have been approved by the Federal Food and Drug Administra-
tion for inclusion in rations to fatten livestock for human con-
sumption.
The experiments discussed in this bulletin were designed to:
1. Compare levels of aureomycin in steer fattening rations.
2. Compare diethylstilbestrol and aureomycin singly and in
combination in steer fattening rations.
3. Compare diethylstilbestrol implants and aureomycin singly
and in combination in heifer fattening rations.

LITERATURE REVIEW
Aureomycin.-Literature reviews by Knodt (9), Lassiter
(10) and Reid et al (14) have reported the extensive and benefi-
cial use of aureomycin in rations for calves. A growth response
observed by the feeding of aureomycin to calves was attributed
to an increase in feed intake and the control of certain calfhood
infectious diseases, notably scours. Rusoff et al (15) reported
larger skeletons in aureomycin supplemented calves but Jacobson
et al (8) reported no increase in height at withers or depth of
chest in calves fed aureomycin. They conclude that increased
weight gains must be muscle and fat rather than skeletal. For
mature ruminants, Reid et al (14), in a review of literature,
state that in general, antibiotics have not been beneficial. They
indicate that the antibiotic supplementation of fattening rations
'Hentges: Associate Animal Husbandman; Fletcher, Black and Tucker:
Research Assistants; Cunha: Animal Husbandman and Head, Animal Hus-
bandry and Nutrition Department.






Florida Agricultural Experiment Stations


for beef cattle is without effect upon rate of gain. Perry et al
(13) reported similar findings with fattening steers on high
concentrate rations but noted faster gains and better feed effi-
ciency when aureomycin was fed to steers on high roughage
rations. Recently, aureomycin has been used as a therapeutic
agent in conditioning feeds and medicated starter feeds for
feeder cattle and calves.
Diethylstilbestrol Fed Orally.-A literature review by Cunha
(6) of diethylstilbestrol feeding experiments with fattening cat-
tle indicated that, in general, weight gains were increased by 18
percent and the amount of feed required for 100 pounds of gain
was reduced by 12 percent. Carcass grades apparently were not
affected by proper feeding of the recommended level of 10 mg.
diethylstilbestrol per head daily.
Subcutaneous Diethylstilbestrol Implants.-The implantation
of 12 to 36 milligrams of diethylstilbestrol in pellets under the
skin of fattening cattle has produced gains equal to those ob-
tained by orally fed diethylstilbestrol, according to Baker (2, 3).
A serious problem of vaginal and uterine prolapse has been re-
ported by Clegg et al (5), Andrews et al (1) and Walker et al
(16) when heifers were given 24, 36 and 60 mg. diethylstilbestrol
implants. On the other hand, no evidence of prolapse was ob-
served by Dinnusson et al (7), who used 42 mg. implants, or Par-
sons et al (12), who used 12 and 24 mg. implants.


PART 1.-LEVELS OF AUREOMYCIN
FOR STEER FATTENING

EXPERIMENT 1.-A COMPARISON OF TWO LEVELS OF
AUREOMYCIN FOR FATTENING STEER CALVES ON
HIGH-CONCENTRATE RATIONS (GROUP FED)
This experiment was conducted to evaluate aureomycin as
an ingredient in high-concentrate fattening rations by its effect
upon skeletal growth, endocrine gland weights, carcass meas-
urements and feed lot performance.
EXPERIMENTAL PROCEDURE
Twenty-one British-Brahman crossbred steer calves were di-
vided into 3 comparable lots and were group fed from November
8, 1953, to April 4, 1954, a period of 147 days. The high-con-
centrate basal ration shown in Table 1 was fed to all lots with







Diethylstilbestrol and Aureomycin for Beef Cattle 5

the daily allowances for each lot being regulated to that of the
lot consuming the least amount of feed. Table 1 shows a com-
parison of nutrients provided by the rations and the nutrient
requirements of fattening calves as stated by the National Re-
search Council and reveals that restriction of consumption did
not render the diet deficient for certain nutrients. Aureomycin
in the form of Aurofac 2A (3.6 grams aureomycin per pound)
was mechanically mixed with the cottonseed meal to insure daily
consumption of aureomycin at the following rates: Lot I, none;
Lot II, 10 mg. per 100 pounds live weight; and Lot III, 20 mg.
per 100 pounds live weight. Criteria studied were rate of gain,
efficiency of feed utilization, skeletal growth, blood hemoglobin
levels, endocrine gland weights and various carcass character-
istics.

TABLE 1.-BASAL RATION COMPONENTS AND AVERAGE DAILY CONCENTRATE,
ROUGHAGE AND NUTRIENT INTAKE OF STEERS.

Average Daily Intake, Lbs.
Basal Ration Components Estimated I Estimated Total
Air-dry Digestible Digestible
Matter Protein Nutrients

Concentrates:
Cottonseed meal (36%) 2.0 0.6 1.4
Ground snapped corn ..... 6.3 0.3 4.6
Citrus molasses ................. 1.6 0.0 0.8
Trace mineralized salt .... ad lib.
Steamed bonemeal ........... ad lib.
Roughage:
Alfalfa hay .............-......-.. --4.8 0.5 2.5

Total daily intake, Ibs....... 14.7 1.4 9.3
Daily requirements, lbs.*.. 12.0 1.0 8.0

Daily nutrient requirements for 400-pound fattening calves as set forth by the Na-
tional Research Council.
RESULTS
Results of this experiment are summarized in Table 2. There
were no statistically significant differences between treatments
for any of the above criteria; thus, the antibiotic treatments ap-
parently were of no benefit.








Florida Agricultural Experiment Stations


These results might be explained by the status of health of
these calves. Although the calves were born and reared under
average flatwoods commercial ranch conditions, they apparently
were not affected by disease level during this experiment. This
observation is supported by the blood hemoglobin values which
remained within the normal range during the experiment. The
rate of gain was similar in all lots, being 2.03, 2.07 and 2.08
for Lots I, II and III, respectively.

TABLE 2.-SUMMARY OF DATA ON THE FEEDING OF 2 LEVELS
OF AUREOMYCIN TO FATTENING STEERS.

Lot Number I II III
Aureomycin (Mg./live cwt.) None 10 Mg. 20 Mg.

Number of steers per lot ........................... ...... 7 7 7
Days on experiment .---.................. --................ 147 147 147
Av. initial weight, lbs. ............-......... ......... ...... 361 360 360
Av. final weight, Ibs. ...................................... 660 664 666
Av. total gain per steer, lbs .......................... 299 304 306
Av. daily gain, lbs. ...............-........................... 2.03 2.07 2.08

Total feed required per cwt. gain, lbs .-......... 724 712 707
Concentrates, lbs. ........-............ ............... 487 479 475
Roughages, lbs. ...............-- ... ................. 237 233 232

Av. dressing percent (warm)* ................---........ 59.0 58.0 58.1
Carcass grades, federal **
Choice ..................... ....... .. .... .- ...... 0 1 0
G ood ................... ....... ...............---...... 5 3 4
Com m ercial ..... ---..~ ............................ 1 2 3
Utility .................................------ ....---- .. 1 1 0
Av. numerical carcass score t ------...................-.. 8.7 8.6 9.1

Skeletal measurements
Av. increase of ht. at withers, in. .......... 5.8 4.3 5.3
Av. increase of heart girth, in. ...........- 11.9 13.4 12.0
Av. increase of cannon bone, in ................ 1.0 1.4 1.2

Initial blood hemoglobin, mg. % ...........-......... 13.4 11.7 13.6
Final blood hemoglobin, mg. % ....................... 13.5 12.8 13.3

Endocrine gland weights ...--..........................
Pituitary, non-standardized, gm......... ..... 1.4 1.2 1.4
Pituitary, standardized, gm. ...................... 2.1 2.1 1.9
Thyroid, non-standardized, gm. ............... 17.2 15.5 16.5
Thyroid, standardized, gm. .............-....... 25.9 23.9 25.1
Adrenals, non-standardized, gm. ................ 11.9 13.8 12.1
Adrenals, standardized, gm. -.............. ..-.. 17.9 21.1 19.3
Seminal vesicles, non-standardized, gm.. 7.4 6.8 5.3
Seminal vesicles, standardized, gm. .......... 11.3 10.6 8.2

warm carcass weight
Average dressing percentage = X 100
shrunk live weight
** Carcass grades based on 1953 U.S.D.A. standards. Grades were Prime, Choice, Good,
Commercial and TTtilitv.
t Numerical scores from 1 to 17 were placed upon thirds of grades as follows: High Good,
11; Averae Good, 10 and Low Good, 9.
t Shows actual weights and weights standardized to grams per 1000 pounds body weight.







Diethylstilbestrol and Aureomycin for Beef Cattle 7

One reason for limiting all lots to the same feed intake was
to determine whether the antibiotic would show a feed efficiency
response not complicated by differences in feed intake. No signifi-
cant feed efficiency response was observed. However, steers in
Lots II and III required slightly less feed per 100 pounds of
gain than the control steers. The steers in Lot I had 1 percent
higher dressing percentage than those in Lots II and III but
differences in carcass grade were too small to be significant.
The circumference of cannon bone and heart girth were
larger in the aureomycin-fed steers but these differences were
not statistically significant and cannot be viewed as support of
the postulate that antibiotics may stimulate growth by a direct
effect on metabolism. An increase in average weight of adrenal
glands and a decrease in average weight of the seminal vesicles
and thyroid gland was observed in the aureomycin-fed steers.
Considerable variation of weights within lots was observed be-
tween treatments. Therefore, it must be concluded that the
treatments had no significant effect on these parts of the en-
docrine system of steers.

EXPERIMENT II.-A COMPARISON OF 2 LEVELS OF
AUREOMYCIN FOR FATTENING STEERS ON HIGH-
CONCENTRATE RATIONS (INDIVIDUALLY FED)
Fattening steers were used in this experiment to further
study the effects of the 2 levels of aureomycin on criteria used
in Experiment I. However, this study differed in that each
steer was individually fed as much as he would consume in an
attempt to determine whether the antibiotic would have an
effect on daily feed intake and subsequent gain and feed effi-
ciency.
EXPERIMENTAL PROCEDURE
Eighteen grade Angus steers averaging 465 pounds in weight
were allotted on the basis of initial weight and slaughter grade
into 3 comparable lots. The trial was initiated February 19,
1955, and was terminated 140 days later. The steers were indi-
vidually fed twice daily and were allowed 90 minutes at each
feeding to consume their ration. Basal ration components and
average daily feed intake are shown in Table 3. Aureomycin
in the form of Aurofac 2A was hand mixed with each individual
ration at the following rates: Lot I, none; Lot II, 4.6 mg. per
pound of basal ration; and Lot III, 9.2 mg. per pound of basal
ration. These aureomycin treatments when converted to a







Florida Agricultural Experiment Stations


"mg. per 100 lb. body weight basis" were comparable at the
beginning of the experiment to those used in Experiment I.
All steers were slaughtered for the collection of carcass data.
Other criteria studied were the same as in Experiment I.
TABLE 3.-BASAL RATION COMPONENTS AND AVERAGE DAILY INTAKE
OF CONCENTRATES AND ROUGHAGES.

Basal Ration Components Average Daily Intake, Lbs. Air-dry Feed *
Lot I | Lot II Lot III
Concentrates:
Cottonseed meal (36%) ...... 3.7 3.7 3.7
Ground snapped corn .......... 7.5 7.5 7.5
Citrus molasses .-----....- 3.7 3.7 3.7
Trace mineralized salt ........ ad lib. ad lib. ad lib.
Steamed bonemeal .............. ad lib. ad lib. ad lib.
Roughage:
Pangolagrass hay ............. 4.6 4.9 4.1

Total daily intake, lbs ... 19.5 19.8 19.0

The average feed intake of each lot was adequate to fulfill the daily nutrient require-
ments set forth by the National Research Council for fattening 600 pound steers.

RESULTS
A summary of results is shown in Table 4. Although Lot II
on the 4.6 mg. aureomycin level had the highest rate of gain
and required the least feed per pound of gain, no statistically
significant differences between lots were noted. To test the
hypothesis that aureomycin supplementation would increase feed
intake, each steer was individually fed all he would consume.
No significant differences in feed intake were observed. The
feed intake data in Table 3 show that the average consumption
by steers in all lots exceeded 3 percent of their body weight,
which is accepted as a full-feed intake. Although these steers
were born and raised to weaning age on an average commercial
ranch, no digestive, respiratory or other disturbances, except
occasional pinkeye infections, were observed. These apparently
had no effect on steer performance. Both aureomycin-fed lots
exhibited a reduced appetite during the first week of the trial,
thereby confirming similar observations by other workers, Perry
et al (13) and Neumann et al (11).








Diethylstilbestrol and Aureomycin for Beef Cattle 9

TABLE 4.-SUMMARY OF DATA ON THE FEEDING OF TWO LEVELS OF
AUREOMYCIN TO FATTENING STEERS.

Lot Number I II III
Aureomycin (mg./lb. ration) None 4.6 Mg. 9.2 Mg.

Number of steers per lot .................. ....... 6 6 6
Days on experiment ........--.... .. 140 140 140
Av. initial weight, lbs .................................. 470 462 465
Av. final weight, lbs. ............... ................. 770 772 750
Av. total gain per steer, lbs ........................ 300 310 285
Av. daily gain, lbs ................................... 2.1 2.2 2.0
Total feed required per cwt. gain, lbs. 915 898 932
Concentrates, lbs. ......... ........ ........ 698 678 732
Roughages, lbs ...................................... 217 220 200

Av. dressing percent (warm)* ..................... 60.5 60.9 61.5
Carcass grades, federal **
Choice .. .......- .................. ....- 2 2 2
Good ...................... ................ ...... 4 4 4
Av. numerical carcass score f ...................... 11.2 11.0 11.0
Skeletal measurements
Av. increase of ht. at withers, in ........ 3.7 3.5 3.4
Av. increase of heart girth, in. .........- 12.9 13.3 12.7
Av. increase of cannon bone, in ........ 0.9 1.0 1.0

warm carcass weight
*Average dressing percentage = ---- X 100
shrunk live weight
** Carcass grades based on 1954 U.S.D.A. standards. Grades were Prime, Choice, Good,
Commercial and Utility.
t Numerical scores were placed upon thirds of carcass grades as shown in footnote on
Table 1.

During the last 4 weeks of the experiment, the steers in lot
III on the high level of aureomycin intake exhibited a reduced
appetite with a subsequent reduction of their daily weight gains
below those of the control lot. This might be explained by the
high continual level of aureomycin intake which exceeded 140
mg. per day for some steers. As was observed in Experiment I,
the largest increase in height at withers was seen in the control
lot while the largest increase in heart girth occurred in Lot II.
These differences, like the small differences in carcass measure-
ments, were not statistically significant.
Thus, aureomycin supplementation of high concentrate ra-
tions had no significant beneficial effects in these 2 experiments
with fattening steer calves previously handled under commercial
ranch conditions. These results are plausible in the light of
more recent research showing that the beneficial effect of anti-
biotics is most apparent in the control of digestive and respira-
tory diseases, none of which were evidenced in the calves of
either experiment.







Florida Agricultural Experiment Stations


PART II.-DIETHYLSTILBESTROL AND
AUREOMYCIN USED SINGLY AND IN
COMBINATION FOR FATTENING
BEEF CATTLE

EXPERIMENT III.-DIETHYLSTILBESTROL AND AUREO-
MYCIN USED SINGLY AND IN COMBINATION FOR
FATTENING STEERS ON HIGH-CONCENTRATE
RATIONS
This experiment was conducted to evaluate the synthetic
hormone diethylstilbestrol and the antibiotic aureomycin, used
singly and in combination as ingredients in a steer fattening
ration. To gain an insight to the mechanism of action of these
drugs, skeletal, gland and organ measurements were studied.

TABLE 5.-BASAL RATION COMPONENTS AND AVERAGE
DAILY INTAKE OF CONCENTRATES AND ROUGHAGES.

Basal Ration Components j Average Daily Intake, Lbs. Air-dry Feed *
Lot I Lot II Lot III Lot IV
Aureomycin, mg./live cwt. .... None None 10 mg. 10 mg.
Diethylstilbestrol, mg./day -- None 10 mg. None 10 mg.
Concentrates:
Cracked corn ........... .. 4.2 4.5 4.1 4.3
Corn m eal ........- ................. 4.2 4.5 4.1 4.3
Dried citrus pulp --... .......... 4.2 4.5 4.1 4.3
Cottonseed meal, 41% ...... 2.9 3.2 2.8 3.0
Citrus molasses .................. 2.0 2.0 2.0 1.9
Steamed bonemeal .............. ad lib. ad lib. ad lib. ad lib.
Trace mineralized salt ........ ad lib. ad lib. ad lib. ad lib.
Roughage:
Alfalfa hay .--..-.-...-... ... 5.3 5.9 5.0 4.9

Total daily intake, lbs ...... 22.8 24.6 22.1 22.7

*The average feed intake of each lot was adequate to fulfill the daily nutrient require-
ments set forth by the National Research Council for fattening 700 pound yearling steers.







Diethylstilbestrol and Aureomycin for Beef Cattle 11

EXPERIMENTAL PROCEDURE
Twenty-four yearling steers were distributed equally by
weight, grade and breed into 4 lots of 6 each. The experiment
was started May 28, 1955, and terminated 109 days later. The
initial weight of the steers was taken after a 12-hour shrink.
The final weight was determined by deducting a 3 percent shrink
from the live weight. The steers were fed in drylot.
Table 5 shows the basal ration components and the average
daily feed intake. Aurofac 2A was used as the source of aureo-
mycin. The rate of feeding Aurofac 2A was adjusted bi-weekly
to provide 10 mg. aureomycin per 100 pounds live weight daily.
Ten pounds of Stilbosol, the source of diethylstilbestrol, were
mixed with 1 ton of basal ration. Two pounds of the Stilbosol-
basal mix were fed per head daily to supply 10 mg. of diethyl-
stilbestrol. Criteria studied were weight gains, feed consump-
tion, efficiency of feed utilization, transit shrink, carcass grades
and endocrine gland weights. Comparative data on transit shrink
were obtained by trucking the steers 40 miles to a slaughter
plant.
RESULTS

Results of this experiment are summarized in Table 6. The
steers fed diethylstilbestrol and the aureomycin-diethylstilbestrol
combination made faster gains and had larger daily feed intakes
and a higher efficiency of feed utilization than the other lots.
The lot fed 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 in
Lot II after 49 days on the experiment. The aureomycin-fed
steers in Lot III gained faster than the control lot during the
first 28 days but lost this advantage later. During the last 30
days of the experiment, both lots fed aureomycin were difficult
to keep on full feed. This had been observed earlier in Experi-
ment II.
It is interesting to note that the excellent feed lot perform-
ance, especially weight gains and feed conversion, by all lots in
the experiment was obtained during the supposedly less favorable
cattle fattening months of high summer temperatures, June,
July and August.
The diethylstilbestrol-fed steers had the highest carcass
grades and this was due primarily to their higher rating on out-
side finish, inside finish and quality. No significant effect on
carcass conformation was attributed to the feeding of diethyl-







Florida Agricultural Experiment Stations


TABLE 6.-SUMMARY OF DATA ON THE FEEDING OF DIETHYLSTILBESTROL
AND AUREOMYCIN SINGLY AND IN COMBINATION TO FATTENING STEERS.

Lot Number I II III IV
Aureomycin (mg./live cwt.) None None 10 Mg. 10 Mg.
Diethylstilbestrol (mg./day) None 10 Mg. None 10 Mg.

Number of steers per lot ......... 6 6 6 6
Days on experiment ............. 109 109 109 109
Av. initial weight, lbs.............. 536 536 540 539
Av. final weight, lbs. ............... 839 873 819 846
Av. total gain per steer, Ibs. .... 303 337 279 307
Av. daily gain, lbs. .---.. ..... ...... 2.7 3.1 2.6 2.8

Total feed required per
cwt. gain, lbs. --------......... 818 796 857 808

Concentrates, lbs .................... 628 606 663 633

Roughages, lbs .--------.......-..... 190 190 194 175

Basal feed cost per cwt.
gain, dollars .--........ .......... 22.09 21.51 23.14 21.78
Diethylstilbestrol/cwt.
gain, dollars ............- ...... 0.16 0.18
Aureomycin per cwt.
gain, dollars -----....- .... --.... .... 0.34 0.33
Total feed cost per cwt. gain .... 22.09 21.67 23.48 22.29

Av. initial estimated
slaughter grade ................ 6.0 5.8 5.8 6.5
Av. federal carcass grade* ...... 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
Av. dressing percent .............. 58.1 57.8 58.0 57.7
Av. shrink in transit, lbs.* ..... 30.0 35.0 34.0 33.0

Initial cost per steer, dollars t .. 77.72 77.72 78.30 78.16
Feed cost per steer, dollars --. 66.92 73.03 65.51 68.43
Total cost per steer, dollars ...... 144.64 150.75 143.81 146.59
Returns per steer, dollars ..... 155.22 171.98 155.61 169.20
Profit per steer, dollars ............. 10.58 21.23 11.80 22.61

Numerical scores were placed upon thirds of carcass grades as shown in footnote under
Table 1.
** Steers were weighed, loaded and trucked forty (40) miles to packing house and then
weighed again.
t Initial cost per steer $14.50 per cwt.
$ Feed cost $0.027 per pound of concentrate, $0.05 per pound for Stilbosol, and $0.49
per pound for Aurofac 2A.
Lot 1, $18.50 per cwt: Lot 2, $19.70 per cwt; Lot 3, $19.00 per cwt; and Lot 4, $20.00
per ewt. (Based on carcass grade and weight).

stilbestrol. Likewise, no differences between treatments were
apparent for transit shrink or dressing percentage. Although
the diethylstilbestrol-fed steers in Lot II were superior in all
the criteria measured, combination-fed steers in Lot IV sold for
the highest price per 100 pounds live weight when marketed on







Diethylstilbestrol and Aureomycin for Beef Cattle 13

a carcass grade and weight basis at a large packing firm. This
resulted in Lot IV returning the largest profit, $22.61 per steer,
which was only $1.38 more profit per head than was obtained
on Lot II steers.
In Table 7, an effect of diethylstilbestrol feeding is observed
by increased teat size and seminal vesicle weights. As observed
in Experiment I, thyroid gland weights were slightly smaller in
the aureomycin-fed animals in this trial. However, too much
variation exists within treatments to draw conclusions on the
effects of aureomycin or diethylstilbestrol on the endocrine sys-
tem of cattle. Statistically, significance (5 percent level) was
shown by steers fed diethylstilbestrol as compared to those not
fed diethylstilbestrol for increased carcass grade, carcass quality
and seminal vesicle weights. Differences in average daily gains
were highly significant (1 percent level) between these groups.

TABLE 7.-ENDOCRINE GLAND WEIGHTS AND ORGAN MEASUREMENTS.

Organ or Gland Lot I Lot II Lot III Lot IV

Pituitary, grams ..................... 2.0 2.2 2.0 2.2
Adrenal, grams ..................... 14.7 16.5 16.4 14.2
Thyroid, grams ':' ..................... 15.0 15.3 13.1 12.8
Seminal vesicles, grams '* ....... 10.8 17.2 10.4 19.1
Penis diameter, cm. .................. 17.2 17.5 17.5 18.5
Teat size, visual ...................... Small Large Small Large

*Actual fresh weight of whole gland.

EXPERIMENT IV.-DIETHYLSTILBESTROL IMPLANTS
AND AUREOMYCIN USED SINGLY AND IN COM-
BINATION FOR FATTENING HEIFERS ON
HIGH ROUGHAGE RATIONS

In the southeastern Gulf Coast States, thousands of beef
calves weighing 200 to 250 pounds are sold through auction mar-
kets during the late fall months. These calves are the result of
late summer calving. The majority are suffering from respira-
tory diseases, are infested with internal parasites and, in gen-
eral, are in a very unthrifty condition. Because of the flooding
of the market at this time, the calves bring exceptionally low







Florida Agricultural Experiment Stations


prices. It seems logical that more beef would be produced and a
reasonable profit realized if these calves were fed through the
winter months on a balanced economical ration and sold as feeder
or slaughter calves in the spring when the market is stronger.
The purposes of this investigation were (1) to determine the
effect of a high-roughage fattening ration on winter weight gains
and slaughter grade of heifer calves; (2) to determine what
effect aureomycin used alone and in combination with diethyl-
stilbestrol implants might have in heifer calf rations under typi-
cal Florida conditions; (3) to determine which level of aureomy-
cin in a high-roughage ration might produce the highest rate
of gain; and (4) to study the effect of aureomycin and diethyl-
stilbestrol on the development of side effects in heifers.

EXPERIMENTAL PROCEDURE
Thirty-three registered Angus, Brahman and Hereford heif-
ers were allotted by weight and breed into 3 comparable pastures.
The heifers were 12 to 14 months of age and weighed an aver-
age of 545 pounds when the experiment was initiated February

TABLE 8.-BASAL RATION COMPONENTS AND AVERAGE DAILY CONCENTRATE,
ROUGHAGE AND NUTRIENT INTAKE BY HEIFERS.

Average Daily Intake, Pounds
Basal Ration Components Estimated Estimated total
Air-dry digestible digestible
matter protein nutrients
Concentrates:
Cottonseed meal (41%) .. 1.5 0.51 1.0
Grade "C" raw sugar ..... 1.0 0.00 0.9
Dehydrated alfalfa meal 0.5 0.08 0.3
Steamed bonemeal ........ ad lib.
Trace mineralized salt .... ad lib.
Roughage:
Pearl millet silage ........ ad lib.* 0.34 5.0

Total daily intake, lbs. .. 13.0 0.93 7.2
Daily requirements, lbs.** 16.0 0.9 8.5

Ad libitum daily intake averaged 28.5 pounds fresh or 10 pounds air-dry silage in
each lot.
** Daily nutrient requirements for 600 Ib..heifers for normal growth as set forth by the
National Research Council.







Dieth.,l.tillo, !rol and Aufreon.,I, for Beef Cattle 15

2, 1957. After a 63-day winter feeding period the heifers were
continued on the same pastures without supplementation in order
to observe treatment effects upon the frequency of estrus periods.
These observations were made visually and were confirmed by
periodic rectal palpation. The high-roughage basal wintering
ration is shown in Table 8.
The silage was fed ad libituiw in sheltered bunks every eve-
ning and the silage supplement was spread evenly over the re-
maining silage the following morning. All lots were fed in 4-
acre pastures and had access to frosted winter forage consisting
of pangolagrass, bermudagrass and some White Dutch clover.
Aurofac 10 was mixed with the silage supplement to provide for
a daily consumption of aureomycin at the following rates per
head: Lot I, none; Lot II, 25 mg.; and Lot III, 75 mg. On the
first day of the trial 4 heifers in each lot were given a 24-milli-
gram diethylstilbestrol pellet implant. Criteria studied were
rate of gain, increase in estimated slaughter grade, frequency
of estrus, teat size and general appearance.

RESULTS
Data on feed consumption, rates of gain and estimated
slaughter grades are summarized in Table 9. Diethylstilbestrol
implants produced a significant increase in rate of gain in all
lots. The combination treatment, 75 milligrams aureomycin fed
daily to heifers which had received a 24-milligram diethylstil-
bestrol implant, resulted in the highest average daily gain of 2.0
pounds. Twenty-five milligrams aureomycin fed daily to heifers
which had been given a 24-milligram diethylstilbestrol implant
produced an average daily gain of 1.7 pounds, which was equal
to that of diethylstilbestrol implants alone. Twenty-five milli-
grams aureomycin fed daily without diethylstilbestrol produced
a slight increase in rate of gain over the control ration, while the
75-milligram level apparently slightly suppressed rate of gain.
The majority of implanted heifers exhibited increased teat and
udder development (see Figure 3) ; slight relaxation of the loin
(see Figure 2) ; and excessive mucus secretions from the vulva
midway between heat periods. These observations indicate that
the 24-milligram implant of diethylstilbestrol may have been
larger than is desired. No indications of vaginal prolapse were
observed, however. Subsequent ovary palpations and visual ob-
servations revealed no gross harmful effects from the diethyl-
stilbestrol feeding.







Florida Agricultural Experiment Stations


TABLE 9.-SUMMARY OF DATA ON DIETHYLSTILBESTROL IMPLANTS AND
AUREOMYCIN USED SINGLY AND IN COMBINATION FOR FATTENING HEIFERS.

A m dy Lot I Lot II Lot III
Aureomycin, daily ---
Diethystilbestrol None 25 mg. 75 mg.
implants None 24 mg. None 24 mg. None 24 mg.

Number of heifers ...... 7 4 7 4 7 4
Av. initial weight, lb. 562 514 561 512 560 517
Av. final weight, lb. 657 623 661 622 647 645
Av. total gain, lb....... 94 109 100 107 87 128
Av. daily gain, lb. ..... 1.5 1.7 1.6 1.7 1.4 2.0
Av. initial grade* .... 9 9 9 9 8 9
Av. final grade* -......... 8 8 8 9 8 8

Numerical scores were placed upon thirds of each slaughter grade as shown in footnote
under Table 1.

SUMMARY
Diethylstilbestrol significantly increased weight gains when
10 milligrams per day were fed to steers on a high-concentrate
ration and when a 24-milligram implant was placed in the ears
of heifers fed a high-roughage ration.
Aureomycin, fed alone, at the various levels studied in high-
concentrate and high-roughage rations did not significantly in-
crease rates of gain, feed efficiency or profits.
In 1 experiment with growing and fattening heifers fed a
high roughage ration, a combination of 75 milligrams aureo-
mycin fed daily plus implantation with 24 milligrams diethyl-
stilbestrol produced faster gains than the 24-milligram diethyl-
stilbestrol implant alone. In another experiment with fattening
steers on a high-concentrate ration, a combination of diethylstil-
bestrol and aureomycin, both given in the feed, produced faster
gains than diethylstilbestrol alone during the first 35 days of
the trial.
No significant differences among aureomycin and diethylstil-
bestrol treatments were detected for the following criteria: en-
docrine gland weights, internal organ weights, skeletal growth
and carcass measurements.







Diethylstilbestrol and Aureomycin for Beef Cattle


Fig. 2.-Upper: Depression of loin area and raised tailhead are often
observed in yearling heifers given 1 24-milligram diethylstilbestrol implant.
Lower: An untreated heifer.







Florida Agricultural Experiment Stations


Fig. 3.-Upper: Enlargement of teat and udder size observed in young
heifers given a 24-milligram diethylstilbestrol implant. Lower: Udder
area of an untreated heifer.







Diethylstilbestrol and Aureomycin for Beef Cattle 19

GENERAL RECOMMENDATIONS ON THE USE OF
ANTIBIOTICS AND HORMONES FOR
FATTENING CATTLE
1. The effect of feeding the broad spectrum antibiotics,
chlortetracycline (aureomycin) and oxytetracycline (terramy-
cin), to fattening cattle may not be visibly apparent in the ap-
pearance or performance of all lots or individuals, since the ma-
jor known effect of antibiotics is primarily to combat certain
digestive and respiratory diseases, some of which may be sub-
clinical or not visibly detectable. Elimination of these diseases,
as well as protection against these diseases during periods of
stress, may indirectly affect weight gains and efficiency of feed
utilization. The general recommendation on amount of chlor-
tetracycline or oxytetracycline to feed cattle weighing over 700
pounds is 10 milligrams per 100 pounds body weight per day
during the first part of the feeding period while the animals are
recovering from shipment and becoming adjusted to a different
environment and feeding program. A minimum of 70 milligrams
per head daily is recommended for feeder cattle and calves weigh-
ing less than 700 pounds. Under stress conditions, a daily in-
take of 350 or more milligrams per head is recommended for a
limited time. Follow the recommendations listed on the package
when feeding large quantities to cattle under stress. Continued
feeding of the antibiotic may or may not be advisable, depending
on the disease level, prevalent or potential, in the individual feed-
lot operation. Each feed lot operator must determine whether
he needs to continuously feed antibiotics by conducting experi-
ments with a lot of steers given antibiotics and a comparable lot
fed without antibiotics to act as a control for comparison of per-
formance. By keeping at least 1 test lot of steers on antibiotics
year after year, the operator will be able to determine the disease
level of his feed lot and will be able to make sound decisions on
antibiotic feeding.
2. For dry-lot feeding, diethylstilbestrol, administered either
in the feed or as an implant of pellets under the skin of the ear,
has been shown to increase weight gains and decrease the amount
of feed required per 100 pounds of gain. When mixed in the
feed, 10 milligrams per head daily is recommended. When im-
plants are preferred, the pellets should be inserted under the
skin on the rear side of the ear at the beginning of the dry-lot
feeding period. If the feeder cattle had been given stilbestrol







Florida Agricultural Experiment Stations


previously, delay the implantation to allow an approximate 150-
day interval before giving additional stilbestrol. Amounts to
implant vary with age, sex and ration. Desired performance,
without harmful side effects, is reported when heifer feeder
calves under 500 pounds in weight are given 12 milligrams and
when yearling or older female feeders are given 24-milligram
implants. For steers, the recommended implants are 12 milli-
grams for calves under 500 pounds, 24 milligrams for yearling
steers weighing 500 to 700 pounds and 36 milligrams for long
yearling and 2-year steers weighing over 700 pounds. Diethyl-
stilbestrol should not be administered to animals to be kept for
breeding purposes.
3. Combinations of the broad spectrum antibiotics in the
feed with stilbestrol either implanted or in the feed often gives
gains superior to either alone, especially during the first half of
the feeding period.
4. Caution must be practiced in feeding hormones to cattle
to prevent undesirable side effects, namely: excessive mounting,
high tail head with depressed loin area (see Fig. 2), persistent
"heat" or nymphomania in females and vaginal or uterine pro-
lapse in females. When stilbestrol is fed, these disorders are
easily avoided by thorough feed mixing and proper supervision
of feeding to insure that each animal consumes the recommended
dosage. Errors are easy to make when implanting pellets. Many
attempts to speed up the job of implanting have resulted in ex-
pensive loss of time later because side effects occurred. Use an
implanter which permits accurate counting of the number of
pellets used and which has a thumb-operated plunger (see Fig.
1). Automatic implanting guns frequently crumble the pellets
in the implanting process, causing side effects apparently due
to faster absorption of the crumbled pellet. Another possible
cause for side effects is administration of stilbestrol to pur-
chased feeder cattle without checking whether they had been
given an implant within approximately 150 days prior to pur-
chase for the feedlot.
5. The feeding of diethylstilbestrol does not shorten the time
required in the feed lot to deposit the degree of fat needed in
the carcass for a specific federal carcass grade. This fact is
often overlooked by feeders who market their cattle at a spe-
cific weight or by their visual appearance. Stilbestrol-fed cattle
gain faster; hence they reach any given weight faster and may
appear to have a higher slaughter grade than proves to be the








Diethylstilbestrol and Aureomycin for Beef Cattle 21

case when they are given a federal carcass grade on the rail.
To reach any given carcass grade, stilbestrol-fed or implanted
cattle should remain on feed the same number of days as cattle
not given stilbestrol.
6. Diethylstilbestrol must be removed from the ration of
slaughter animals at least 48 hours before their slaughter.

ACKNOWLEDGMENTS

The authors are indebted to: Ralph Elliott and the American Cyana-
mid Company, Pearl River, New York, for providing a grant-in-aid and
the Aurofac products; Dr. R. M. Keck, Lilly Research Laboratories, In-
dianapolis, Indiana, for supplying the Stilbosol; Wick and Fry, Inc., Cum-
berland, Indiana, who supplied the diethylstilbestrol pellets for implanta-
tion; Dr. Marvin Koger, who assisted with statistical analyses; and to
Dr. A. C. Warnick, who assisted with gland and organ weights.

LITERATURE CITED

1. Andrews, F. N., W. H. Smith, T. W. Perry, Martin Stob and W. M.
Beeson. Feeding stilbestrol vs. implanting stilbestrol or hexestrol for
fattening heifers. Purdue Univ. Agr. Exp. Sta. Mimeo. A. H. 203.
1957.
2. Baker, F. S., Jr. Stilbestrol implants versus stilbestrol in feed for
fattening steers. No. Fla. Agr. Exp. Sta. Mimeo. Rpt. 57-5. 1956.
3. Baker, F. S., Jr. Stilbestrol in feed, stilbestrol implants and pro-
gesterone-estradiol implants for fattening steers. No. Fla. Agr. Exp.
Sta. Mimeo. Rpt. 57-10. 1957.
4. Beeson, W. M., M. T. Mohler and T. W. Perry. Effect of antibiotics
on cattle fattened on corn silage or grass silage. Purdue Univ. Agr.
Exp. Sta. Mimeo. A. H. 142. 1955.
5. Clegg, M. T., and H. H. Cole. The action of stilbestrol on the growth
response in ruminants. J. Animal Sci. 13: 108. 1954.
6. Cunha, T. J. Recent developments in swine and beef cattle nutrition.
Proc. Fla. Vet. Med. Assn. 1957.
7. Dinusson, W. E., F. N. Andrews and W. M. Beeson. The effects of
stilbestrol, testosterone, thyroid alteration and spaying on the growth
and fattening of beef heifers. J. Animal Sci. 9: 321. 1950.
8. Jacobson, N. L., J. G. Kaffetzakis and P. G. Homeyer. The effect of
aureomycin feeding on changes in weight and in body measurements
of dairy calves. J. Dairy Sci. 35: 1094. 1952.
9. Knodt, C. B. Antibiotics in the growth of ruminant animals: A re-
view. Antibiotics and Chemotherapy 3: 442. 1953.
10. Lassiter, C. A. Antibiotics as growth stimulants for dairy cattle. A
review. J. Dairy Sci. 38: 1102. 1955.
11. Neumann, A. L., R. R. Snapp and L. S. Gall. The longtime effect of
feeding aureomycin to fattening beef cattle with bacteriological data.
J. Animal Sci. 10: 1058. 1951.








Diethylstilbestrol and Aureomycin for Beef Cattle 21

case when they are given a federal carcass grade on the rail.
To reach any given carcass grade, stilbestrol-fed or implanted
cattle should remain on feed the same number of days as cattle
not given stilbestrol.
6. Diethylstilbestrol must be removed from the ration of
slaughter animals at least 48 hours before their slaughter.

ACKNOWLEDGMENTS

The authors are indebted to: Ralph Elliott and the American Cyana-
mid Company, Pearl River, New York, for providing a grant-in-aid and
the Aurofac products; Dr. R. M. Keck, Lilly Research Laboratories, In-
dianapolis, Indiana, for supplying the Stilbosol; Wick and Fry, Inc., Cum-
berland, Indiana, who supplied the diethylstilbestrol pellets for implanta-
tion; Dr. Marvin Koger, who assisted with statistical analyses; and to
Dr. A. C. Warnick, who assisted with gland and organ weights.

LITERATURE CITED

1. Andrews, F. N., W. H. Smith, T. W. Perry, Martin Stob and W. M.
Beeson. Feeding stilbestrol vs. implanting stilbestrol or hexestrol for
fattening heifers. Purdue Univ. Agr. Exp. Sta. Mimeo. A. H. 203.
1957.
2. Baker, F. S., Jr. Stilbestrol implants versus stilbestrol in feed for
fattening steers. No. Fla. Agr. Exp. Sta. Mimeo. Rpt. 57-5. 1956.
3. Baker, F. S., Jr. Stilbestrol in feed, stilbestrol implants and pro-
gesterone-estradiol implants for fattening steers. No. Fla. Agr. Exp.
Sta. Mimeo. Rpt. 57-10. 1957.
4. Beeson, W. M., M. T. Mohler and T. W. Perry. Effect of antibiotics
on cattle fattened on corn silage or grass silage. Purdue Univ. Agr.
Exp. Sta. Mimeo. A. H. 142. 1955.
5. Clegg, M. T., and H. H. Cole. The action of stilbestrol on the growth
response in ruminants. J. Animal Sci. 13: 108. 1954.
6. Cunha, T. J. Recent developments in swine and beef cattle nutrition.
Proc. Fla. Vet. Med. Assn. 1957.
7. Dinusson, W. E., F. N. Andrews and W. M. Beeson. The effects of
stilbestrol, testosterone, thyroid alteration and spaying on the growth
and fattening of beef heifers. J. Animal Sci. 9: 321. 1950.
8. Jacobson, N. L., J. G. Kaffetzakis and P. G. Homeyer. The effect of
aureomycin feeding on changes in weight and in body measurements
of dairy calves. J. Dairy Sci. 35: 1094. 1952.
9. Knodt, C. B. Antibiotics in the growth of ruminant animals: A re-
view. Antibiotics and Chemotherapy 3: 442. 1953.
10. Lassiter, C. A. Antibiotics as growth stimulants for dairy cattle. A
review. J. Dairy Sci. 38: 1102. 1955.
11. Neumann, A. L., R. R. Snapp and L. S. Gall. The longtime effect of
feeding aureomycin to fattening beef cattle with bacteriological data.
J. Animal Sci. 10: 1058. 1951.







22 Florida Agricultural Experiment Stations


12. Parsons, A. R., and W. P. Garrigus. The value of implanting stilbes-
trol for fattening heifers. Ky. Agr. Exp. Sta. Prog. Rpts. for 1956-57.
13. Perry, T. W., W. M. Beeson, E. C. Hornback and M. T. Mohler. Au-
reomycin for growing and fattening beef animals. J. Animal Sci.
13: 3. 1954.
14. Reid, J. T., R. G. Warner and J. K. Loosli. Antibiotics in the nutri-
tion of ruminants. J. Agr. and Food Chem. 2: 186. 1954.
15. Rusoff, L. L., J. M. Fussell, C. E. Hyde and R. M. Crown. Oral sup-
plementation versus intramuscular injection of aureomycin to young
calves. J. Dairy Sci. 36: 593. 1953.
16. Walker, G. L., E. F. Smith, B. A. Koch and R. F. Cox. The value of
stilbestrol implants for beef cattle. Kansas Agr. Exp. Sta. Cir. 349.
1957.





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