Everglades Station Mimeo Report 59-32
The Effects of Limited Concentrate and Antibiotic
Supplementation to Yearling Steers Wintered on Pasture
C. E. Haines, H. L. Chapman, Jr. and R. W. Kidder2
The practice of wintering yearling steers on pasture alone in the Everglades
area usually results in minute gains made by these animals during this period.
The results of a five year study by Allen (1) shoved that gains made by young
steers on pasture were the lowest between November and March. KLdder (2) re-
ported that steers receiving small amounts of concentrate feed atbvarious inter-
vals, during the year, while on pasture, made greater gains than those not sup-
plemented. The additional costs of providing the concentrate during the winter
period and the subsequent market value of the steers was not ascertained.
Although the value of antibiotic supplementation to beef cattle has not been
consistently favorable, a summary by Riggs (3) of 32 antibiotic studies indicated
that both gains and feed efficiency were frequently improved by the use of
antibiotics. As suggested by Beeson (4), it is very probable that new antibiotics
will prove of value for further stimulating the growth of beef cattle. In fact,
the use of a new antibiotic, called oleandomycin, as a growth promoter for steers
has recently been reported by Reynolds et al (5).
To determine the merits of providing a limited quantity of concentrate with
antibiotics to wintering steers on pasture, the following study was conducted.
One hundred and eight yearling steers were available for the study which was
initiated during the first part of December, 1958. Eighty-seven of the animals
were obtained, during the previous summer, from north Florida and 21 animals
originated from the Experiment Station herd. The steers were" predominately
Hereford, Angus and Shorthorn crossbreds. Each steer was devormed with 4
oz. of phenothiazine just prior to the initiation of this study.
The steers were divided into three groups of 36 animals each on the basis
of origin, breeding and weight and placed on Para and St. Augustine grass
pastures. In order to minimize pasture or forage differences, groups were
rotated among the three pasture lots at two-week intervals. Each lot was
approximately 20 acres in size.
One group was maintained on pasture only while a second group
was hand fed five pounds of a concentrate mixture per head daily. The third
group received the same amount of the concentrate mixture to which had been added
a combination lof-o-antibiotics,-terramycin and oleandomycin. A combination of
1The antibiotic material consisted of a oxytetracycline-oleandomycin mixture sup-
plied through the courtesy of the Chas. Pfizer Co. Inc., Terra Haute, Indiana.
Haines, Assistant Animal Husbandman; Chapman, Associatet a$ k ~4 nist;
and Kidder, Animal Husbandman, Everglades Experiment S on, Belle e,
Florida. 1/ i..
June 1, 1959
these two antibiotics was included in the feed at a level ot provide 80 milli-
grams (60 terramycin and 20 oleandomycin) of antibiotic for each steer daily.
hb eofcBtatefte consisted ofa cu= snap ed coan, eitrus pip, An dacottcmteed
meal and cost $0.13 for five pounds of the mixture for each steer daily. Trace
mineralized salt was provided free choice to each group.
The trial was conducted for 98 days after a preliminary period of 15 days.
The cost of the concentrate for this period was $12.74 per steer. Individual
market grades were assigned at both the initiation and termination of the trial.
The performance of the groups on the three wintering treatments were compared
by the weight gains realized during the study and changes in market grades.
Differences in mineral mixture consumption were also noted.
The steer groups each averaged between a high utility and low standard market
grade at the beginning of the test. The two seer groups receiving five pounds
of concentrate per head daily maintained almost the same average grades through-
out the trial. However, the average market grade of the steers receiving no
concentrate fell to low utility by the end of the study. This difference in
final market grade between the non-supplemented and supplemented groups was
The smallest gains were tade by the group receiving to suplpUmettary feed.
The average total gains for these 36 steers was 53.6 pounds for the 98 day
period. Groups receiving the five pounds of concentrate per head daily without
and with the antibiotic averaged total gains of 94.3 and 124.7 pounds, respect-
ively. Differences between the gains made by group 1 and group 2 as well as
those between group 2 and group 3 were each highly significant. A summary of the
gains made by each group and a monetary value for the additional gains made by
the supplemented groups is shown in Table 1.
Table 1. Average Weights and Gains of Yearling Steers, on Pasture, Under Three
Wintering Treatments for 98 Days (lbs.)
Steer Group 1 2 3
Supplied Concentrate No Yes Yes
With Antibiotics No No Yes
Number of Animals 36 36 36
Initial Weight 421 426 420
Final Weight 474 521 545
Daily Gain 0.55 0.96 1.27
Increased Daily Gain1 .. 0.41 0.72
Daily Cost of Cone/Steer $0.13 $0.13
Cost/lb of Extra Gain -- $0.32 $0.18
1. Values indicate positive differences between control and and supplemented
2. Cost rf feed ingredients, excluding antibiotics, were corn $2.50/cwt,, citrus
pulp = $2.38/cwt., and cottonseed meal : $3.42/cwt.
At present market prices, the cost of adding extra weight to steers by the
use of concentrates may not appear economically sound. However, it is important
to keep in mind that the steers receiving the concentrate attained higher market
grades and thus could demand a higher price on the market for short term feeding
purposes. The fact that the terramycin-oleandomycin antibiotic combination re-
sulted in an additional increase of 0.3 pounds daily in gains indicates that
antibiotics can be of value to yearling steers. Since oleandomycin is a relat-
ively new antibiotic, in the field of beef cattle feeding investigations, its
growth promoting potential needs to be further evaluated.
An interesting aspect of this study was that the groups receiving the con-
centrate with antibiotics included (group 3) consumed considerably more of the
salt-mineral mixture than either of the other two test groups. This group
consumed a total of 301 pounds of the salt-mineral mixture in 98 days compared
to 221 pounds by group 1 (control) and 206 pounds for the group receiving the
concentrate mixture without antibiotics (group 2). It is possible that the
intake of antibiotics may have stimulated the desire for additional mineral
A total of 108 yearling steers were divided into three groups and placed on
pasture to determine the value of concentrate and antibiotic supplementation during
the winter period. Groups received either 0 or 5 pounds of a corn, citrus pulp,
and cottonseed meal mixture per steer daily with and without antibiotics. The
antibiotics were a combination of terramycin and oleandomycin calculated to
supply a total of 80 mg. of antibiotics per head daily. The trial was conducted
for 98 days.
Steers on pasture alone averaged a total gain of 53.6 pounds in 98 days com-
pared to 94.3 and 124.7 pounds for those receiving the concentrate and the con-
centrate plus antibiotics,1 respectively. Steers fed the antibiotic combination
in the concentrate consumed approximately 1/3 more of a salt-mineral mixture,
fed free choice, than either of the other two steer groups.
The inclusion of antibiotics did not affect market grades as the two steer
groups receiving concentrates maintained approximately the same grade through-
out the trial. Steers not supplemented during the winter, terminated the trial
with lower market grades than at the beginning of the study. Therefore, the
concentrate was of value on the basis of market grade differences, also.
1. Allen, R. J., Jr. 1957. Summarization of Grazing Trial Experiments.
Everglades Station Mimeo Report 57-11.
2. Kidder, R. W. 1957. Feeding Steers from Weaning to Feed Lot. Everglades
Station Mimeo Report 57-9.
3. Riggs, J. K. 1958. Fifty Years of Progress in Beef Cattle Nutrition.
Jour. An. Sci. 17:4.
4, Beeson, W. M. 1958 The Next Fifty Years of Animal Science. Jour. An.
5. Reynolds, W. M.,-W. H. Hale, W. C. Sherman, H. G. Luther. 1958. Studies
of Oleandomycin at Nutritional Levels in Lamb and Steer Rations. (Abs.)
Jour. An. Sci. 17:4.