Group Title: WFES mimeo report - West Florida Experiment Station ; 68-3
Title: Low-level use of antibiotics in beef cattle rations
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Permanent Link: http://ufdc.ufl.edu/UF00053579/00001
 Material Information
Title: Low-level use of antibiotics in beef cattle rations
Series Title: WFES mimeo report
Physical Description: 5 leaves : ; 28 cm.
Language: English
Creator: Bertrand, J. E ( Joseph Ezel ), 1924-
West Florida Experiment Station
Publisher: West Florida Experiment Station
Place of Publication: Jay Fla
Publication Date: [1968]
 Subjects
Subject: Beef cattle -- Feeding and feeds -- Florida   ( lcsh )
Antibiotics in animal nutrition -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: J.E. Bertrand
General Note: Caption title.
General Note: "May, 1966."
 Record Information
Bibliographic ID: UF00053579
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 62310379

Full Text







WEST FLORIDA EXPERIMENT STATION
Jay, Florida
May, 1968


WFES Mimeo Report 68-3


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LOW-LEVEL USE OF ANTIBIOTICS IN BEEF CATTLE RATIONS -/


J. E. Bertrand 2./


Antibiotics, such as chlortetracycline (Aureomycin), oxytetracycline (Terra-
mycin), and zinc bacitracin (Baciferm), have been tested and used quite extensively
at low levels (mostly 70 mg. per head daily) in beef cattle rations to increase
gain and improve feed efficiency. The low-level use of antibiotics has also been
effective in reducing the number of abscessed livers in feedlot cattle.

Burroughs and coworkers (1) in 1959 summarized the results of 112 low-level
antibiotic trials at college experiment stations (Table 1). The antibiotics
(Aureomycin, Terramycin) included in this summary stimulated gain an average of 4%
with an average feed saving of 3%. The return per dollar invested in antibiotics
wan $3.00.

Table 1

Summary of Experimental Comparisons with Antibiotics in Beef Cattle
Rations at College Experiment Stations a)


No. of Gain
obser- stimu- Feed
vations lation saving
Antibiotics(b) 112 4% 3%
(a) Adapted from Burroughs et al. (1)
(b) Aureomycin and Terramycin


Return
per
animal


g


Est. cost
per
animal


$3.16 $1.05


The results of a more recent (1966) summary of all readily available data from
college and feedlot trials testing antibiotics (Aureomycin, Baciferm, and Terra-
mycin) at low levels in beef cattle finishing rations are presented in Table 2.
Note that for 146 observations, gain due to the inclusion of an antibiotic was
improved by 4.7%. The feed efficiency, in 124 observations, was improved an aver-
age of 4.2%. These improvements are slightly higher than the 4% and 3% for gain
stimulation and feed saving, respectively, reported by Burroughs et al. (1) in
Table 1.



-1/ Presented at the 1968 Beef Cattle Short Course, University of Florida,
Gainesville.
2/ Associate Animal Scientist


Return
per $
invested


$3.00


__


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E Hu Lr Ii !


MAY 7 1968


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-2-


Table 2

A Summary of College and Feedlot Low-Level Antibiotic
Beef Cattle Trials (Finishing Cattle) With and
Without Stilbestrol (a)(b)

Control Antibiotic(c) Improvement
Total head of cattle ----------- 8726 -----------------------------
Av. initial wt., lb. ----------- 705 ------------------------------
Av. days on feed ---------------- 135 -----------------------------
Av. daily gain, lb.
(146 observations) 2.32 2.43 +4.7%
Feed/gain, lb.
(124 observations) 10.06 9.64 +4.2%
(a) Compiled by the author from all data readily available.
(b) Where stilbestrol was used it was administered to both the con-
trol and antibiotic treatment groups.
(c) Antibiotics were fed at a continuous low level (mostly 70 mg.
per head daily).

The results from college trials summarized recently (1966) from all data
readily available testing antibiotics in growing-wintering rations for beef cattle
are presented in Table 3. Note that for 115 observations, the average improvement
in gain due to the addition of antibiotics was 8.9%. In 66 observations, feed
efficiency was improved 5.4% on the average due to antibiotic feeding.

Table 3

A Summary of College Low-Level Antibiotic Beef
Cattle Trials (Growing-Wintering Cattle) (a)
Control Antibiotic(b) Improvement
Total head of cattle ----------- 5352 ------------------------------
Av. initial wt., lb. ----------- 501 ------------------------------
Av. days on feed ---------------- 112 -----------------------------
Av. daily gains, lb.
(115 observations) 1.24 1.35 +8.9%
Feed/gain, lb.
(66 observations) 12.70 12.02 +5.4%
(a) Compiled by the author from all data readily available.
(b) Antibiotics were fed at a continuous low level (mostly 70 mg.
per head daily).

The trials included in Table 2 were separated into more specific classifi-
cations and summarized (Tables 4, 5, 6, and 7). College trials testing antibiotics
at low levels in beef cattle finishing rations, with stilbestrol in both treatment
groups, are summarized in Table 4. Note that the average improvement due to the
addition of antibiotics for 38 observations was 3.2% in gain, while the average
improvement in feed efficiency was 3.8% for 32 observations.












Table 4

A Summary of College Low-Level Antibiotic Beef Cattle
Trials (Finishing Cattle) With Stilbestrol (a)(b)
Control Antibiotic(c) Improvement
Total head of cattle ----------- 918 -------------------------------
Av. initial wt., lb. ----------- 714 -------------------------------
Av. days on feed ---------------- k38 -------------------------------
Av. daily gain, lb.
(38 observations) 2.51 2.59 +3.2%
Feed/gain, lb.
(32 observations) 8.90 8.56 +3.8%
(a) Compiled by the author from all data readily available.
(b) Stilbestrol was administered to both the control and antibiotic
treatment groups.
(c) Antibiotics were fed at a continuous low level (mostly 70 mg.
per head daily).

College trials testing antibiotics at low levels in beef cattle finishing
rations, without stilbestrol in either treatment groups, are summarized in Table 5.
Note that the average improvement in gain due to the addition of antibiotics in
70 oboervntions was 4.9%, while the average improvement in feed efficiency was
4.3% for 56 observations.

Table 5

A Summary of College Low-Level Antibiotic Beef Cattle
Trials (Finishing Cattle) Without Stilbestrol (a)
Control Antibiotic(b) Improvement
Total head of cattle ----------- 2447 ------------------------------
Av. initial wt., lb. ------------ 702 ---------------------------
Av. days on feed ---------------- 142 -----------------------------
Av. daily gain, lb.
(70 observations) 2.05 2.15 +4.9%
Feed/gain, lb.
(56 observations) 11.04 10.56 +4.3%
(a) Compiled by the author from all data readily available.
(b) Antibiotics were fed at a continuous low level (mostly 70 mg.
per head daily).

Feedlot trials testing antibiotics at low levels in beef cattle finishing
rations, with stilbestrol in both treatment groups, are summarized in Table 6. In
19 observations, gain was improved on the average by 3.7% in the antibiotic-fed
groups. The average improvement in feed efficiency was 4.2% for 18 observations.








-4-


Table 6

A Summary of Feedlot Low-Level Antibiotic Beef Cattle
Trials (Finishing Cattle) With Stilbestrol (a)(b)
Control Antibiotic(c) Improvement
Total head of cattle ----------- 3007-------------------
Av. initial wt., lb. ------------ 725 ------------- ------
Av. days on feed ---------------- 124 ------------------ -----
Av. daily gain, lb.
(19 observations) 2.73 2.83 +3.7%
Feed/gain, lb.
(18 observations) 9.33 8.94 +4.2%

(a) Compiled by the author from all data readily available.
(b) Stilbestrol was administered to both the control and antibiotic
treatment groups.
(c) Antibiotics were fed at a continuous low level (mostly 70 mg.
per head daily).

In 19 observations, beef cattle fed low-level antibiotics in feedlot finishing
rations, without stilbestrol in either treatment groups, gained 6.7% more on the
average than the control cattle (Table 7). The antibiotic-fed cattle were 4.9% on
Itho .rnrs voro efficient in converting feed to gain (18 observations).

Table 7

A Summary of Feedlot Low-Level Antibiotic Beef Cattle
Trials (Finishing Cattle) Without Stilbestrol (a)
Control Antibiotic(b) Improvement
Total head of cattle ----------- 2354 ------------------------
Av. initial wt., lb. ----------- 682 --------------------------
Av. days on feed ---------------- 117 -------------------------
Av. daily gain, lb.
(19 observations) 2.55 2.72 +6.7%
Feed/gain, lb.
(18 observations) 9.85 9.37 +4.9%
(a) Compiled by the author from all data readily available.
(b) Antibiotics were fed at a continuous low level (mostly 70 mg.
per head daily).

From this review of the low-level use of antibiotics in beef cattle rations,
the following conclusions seem justified:

1. The addition of a low-level antibiotic in growing-wintering rations for
beef cattle produces, percentage-wise, a greater improvement in gain than
in finishing rations. The improvement in gain in both types of rations
appears to be about 0.1 pound per head daily.









5 -


2. The addition of a low-level antibiotic in finishing rations produces,
percentage-wise, a greater improvement in gain and feed efficiency where
stilbestrol is not administered.

3. The addition of a low-level antibiotic in beef cattle finishing rations
produces a greater improvement in gain and feed efficiency under field
conditions. Stress periods are more numerous under field conditions than
under more closely controlled conditions.


REFERENCE

0). Burroughs, W., C. E. Summers, W. Woods, and W. Zmolek. 1959. Five-year
summary of more than 400 experimental comparisons of feed ndditives in
beef cattle rations at college enxplerTment Psttions. ASAF Ext. Section
Meeting. November.




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