A Comparison of Three Antibiotics for Weanling Beef Calves i/
C. E. Haines and R. W. Kidder
One of the most critical times in the life of beef calves is the post-
weaning period. The effects of weaning and adjusting to an all forage type
ration usually results in poor growth and also lowers the resistance of calves
to respiratory infections. This period of stress persists for only a few
months after the weaning of beef calves.
Although there is extensive information on the value of antibiotics to
dairy calves on milk replacer diets and beef cattle on fattening rations,
their value to newly weaned beef calves has not been studied as frequently.
A majority of the antibiotic studies reported, involving beef cattle, in-
clude aureomycin and terramycin. Johnson (1), Diutsman and Kessler (2) and
Perry et al (3) all reported that aureomycin often improved the rate of gain
and general condition of beef calves. Haines et al (4) found that the res-
ponse of beef calves to aureomycin was dependent upon the season or condition
of the calves at weaning time while Strothers and Stringam (5) reported that
aureomycin did not improve gains in feeder calves. Rates of antibiotic sup-
plementation and the age of the beef calves varied in these studies. The
feeding of terramycin to fattening heifers were reported by Kolari and Harvey
(6) and to weaner calves by Hubbert et al (7). As suggested by Beeson (8),
it is probable that new antibiotics will prove of value in further stimulating
growth in beef cattle. Recently, the value of oleandomycin to calves and
lambs has been reported by Reynolds et al (9).
In order to compare the response of weanling beef calves to three anti-
biotics a study was conducted with weaned calves at the Everglades Experiment
Station. Aureomycin, terramycin and oleandomycin were supplied to beef calves
during post-weaning periods in two consecutive years (1959-1960).
One hundred weanling calves were divided at weaning time into four equal
groups on the basis of weaning weights, sex and breeding in each year. The
calves were weaned during a three day period in July 1959 and June 1960.
Calves were steer and heifer progeny of Angus, Brahman, Devon and Hereford
breeding and crosses of these breeds. At weaning time, the calves
from 175 to 300 days of age. Following a ten day adjustment peri
the calves were confined to small pastures and supplied a conce e feed
mixture, each trial was initiated. Experimental procedures and eatmentq (O
were exactly the same for each year of the study. V'!
1. This study was supported in part by a grant from Chas. Pfiz Co., In"
Terre Haute, Ind. Antibiotic materials were supplied by Cha er
Co., Inc., Terre Haute, Ind. and American Cyanamid Co., Prince -
2. Assistant Animal Husbandman and Animal Husbandman respectively, Everglades
Experiment Station, Belle Glade, Fla.
Ev. Sta. Mimeo Rpt. 61>-7
January 30, 1961
Groups were placed in separate four acre pastures of Roselawn St. August-
inegrass and fed four pounds of a concentrate mixture per head daily for 98
day test periods. Pastures appeared to be equal in amount and quality of
forage present and abundant forage was available throughout the trials. The
concentrate mixture consisted of two parts of ground snapped corn, two parts
of citrus pulp, 6ne part of cottonseed meal and a salt-mineral mixture. Threc
of the groups received either, aureomycin, terramycin or oleandomycin in the
concentrate mixture while the fourth group was not supplemented with an anti-
biotic. The antibiotics were incorporated in the mixture at rates to provide
an average of 75 mg. of aureomycin, 75 mg. of terramycin and 25 mg. of olean-
domycin per calf daily in the respective groups.
Calves were individually weighed at 28 day intervals but the major crit-
erion for evaluating differences between antibiotic treatments was the gains
for the entire test period. The statistical significance of difference in
gains among the treatment groups and sexes were determined by an analysis of
variance. Market grades given to the calves at the beginning and termination
of the trial were also compared.
Results and Discussion
One male calf died during the 1st trial (1959) from unknown causes and
three calves were removed during the conduct of the second trial (1960). The
largest gains by each group, in both years, occurred during the first 28 days
of the experiments. This might be expected as calves recover the weight lost
during the immediate post-weaning period rather quickly. Poorest gains were
recorded during the last 14 days of the test periods by every group in each
year. This was probably caused by the heavy rainfall which occurred during
the final part of these test periods. Losses in weight actually occurred in
the second trial during this period when the rainfall was excessive. In-
dividual gains, during the 98 day test periods, ranged from 25 to 140 pounds.
In the first trial, calves receiving aureomycin made the best gains and
those being supplemented with oleandomycin the poorest gains. However, olean-
domycin caused the highest gains in the second trial. Gains of the control
and terramycin supplemented groups in the first study were almost identical.
The same situation resulted for the control, aureomycin and terramycin sup-
plemented groups in the second study.
The steer calves gained slightly better than heifer calves, in each trial,
and in most cases within each antibiotic treatment. These differences were
usually rather small. The average gain for all steer calves in the first and
second trial was the same but heifer calves in the first trial gained better
than heifer calves in the second trial. The combined data by years showed
that the average gain of all calves in the first trial was almost 0.9 pounds
a day compared to slightly over 0.8 pound for all calves in the second trial.
Since one pound of gain per day is considered satisfactory during the post-
weaning period for calves not being fattened, the gains of these calves may
be considered sufficient. The average daily gains by treatment, sex and year
are illustrated in Table 1.
Table 1. Average Daily Gains of Weanling Beef Calves Receiving Three Anti-
biotics by Sex and Year of Study (Ibs.).
Sex of Calves Male Female Combined
Treatment Year 1 Year 2 Year 1 Year 2 Year 1 Year 2
Control 0.86 0.84 0.93 0.76 0.90 0.80
Aureonycin 1.01 0.87 0.93 0.69 0.97 0.79
Terramycin 0.92 0.85 0.82 0.72 0.87 0.79
Oleandomycin 0.80 1.02 0.77 0.76 0.78 0.90
Combined 0.90 0.90 0.86 0.73 0.88 0.82
The data was combined from each of the two trials by antibiotic treat-
ment groups. Sexes were exactly equal in number in each antibiotic group
when years were combined as there were 12 steer and 13 heifer calves per
treatment group in the first year and 13 steer and 12 heifer calves in the
second year. This is 25 calves, of each sex, for each treatment group. On
an overall basis, the average daily gains for calves in the control group
was 0.85 pound compared to 0.88, 0.83 and 0.84 pounds for the calves re-
.* giving aureomycin, terranycin and oleandomycin, respectively. Thus gains
among the antibiotic treatments were similar.
The analysis of variance showed that differences in gain between year
and rations were not statistically significant; However differences in gains
between steer and heifer calves were significant at the 1% level of signifi-
cance. Interactions between year, treatment and sex were all statistically
significant because the largest gains were not produced by the same antibiotic
treatment in each of the two years. Furthermore, differences between the
two sexes were not significant in the first year but were highly significant
for the second year, when analysed on an within year basis.
The average initial market slaughter grade for all calves (both years)
was a medium standard and the average grades dropped to a low standard at
the end of the trial. In the first trial, the greatest decrease in grade
occurred in the control and oleandomycin supplemented groups while the calves
in the aureomycin group of the second trial showed the greatest decrease in
market grades (Table 2). None of the experimental groups showed average de-
creases of more than two thirds of a market grade. This decline in slaughter
grade appears to be a normal reaction during the life of a beef calf when it
is changing from veal to beef. The full-feeding of concentrates would tend
to diminish this decline in grade. The antibiotics apparently did not in-
fluence the slaughter grade changes occurring in this study. (Slaughter
grade was used as a measurement because it is dependent upon the condition
and degree of fleshing, hence it is an indicator of the health and thrifti-
ness of an animal). Therefore, the antibiotics did not improve the health
of the calves.
Table 2. Comparison of Average Slaughter Grade Changes by Year and Treatment.
Treatment Initial Final Initial Final
Control 7.4 5.8 7.1 6.1
Aureomycin 7.1 6.5 7.3 5.8
Terramycin 7.3 6.2 7.3 6.0
Oleandomycin 7.1 5.8 7.4 6.6
* 6, 7 and 8 = Low, Medium and High standard grades, respectively.
One hundred weanling beef calves were used to compare no antibiotic
with the value of aureomycin, terramycin and oleandomycin during 98 day
post-weaning periods in each of two consecutive years. Antibiotics were
fed at the rate to provide either 75 mg. of aureomycin, 75 mg. of terra-
mycin or 25 mg. of oleandomycin per calf daily in four pounds of concen-
trate mixture. A control group received no antibiotic. Calves were kept
on Roselawn St. Augustinegrass pasture.
The average daily gains for the control, aureomycin, terramycin and
oleandomycin supplemented groups were 0.85, 0.88, 0.83, and 0.84 pounds
respectively for both years combined. Aureomycin supplementation caused
the highest gains the first year and oleandomycin in the second year.
Treatment and year differences were not statistically significant but
difference between steers and heifer calves were significant. Antibiotic
treatments did not appear to affect market grades as each group averaged
approximately 1/3 of a slaughter grade lower at the termination of the
trial. Therefore, these results indicate that the weanling calves res-
ponded equally well on pasture to a limited amount of a concentrate ration
with or without any of these three antibiotics.
1. Johnson, W. P. 1957. Feeding Antibiotics to Ruminants. Cyanamid Vet.
Bul. 16: 18.
2. Duitsman, W. W. and F. B. Kessler. 1953. Beef cattle Feeding and
Breeding Investigations. Kansas Agr. Exp. Sta. Cir. No. 298.
3. Perry, T. W., W. M. Beeson, E. C. Hornback and M. T. Mohler. 1954.
Aureomycin for Growing and Fattening Beef Animals. Jour. An. Sci. 13: 3.
4. Haines, C. E., H. L. Chapman, Jr. and J. R. Crockett. 1959. Effects
of Four Levels of Chlortetracycline Intake on Beef Calves After Weaning.
Jour. An. Sci. 18: 1516.
5. Strothers, S. C. and E. W. Stringam. 1956.
Diethylstilbestrol in Combination on Feeder
Jour. An. Sci. 15: 1293.
Effect of Chlortetracycline-
Calves Fed a Finishing Ration.
6. Kolari. O. E. and A. L. Harvey. 1957. Terramycin, Stilbestrol, Soybean
Oil Meal and Linseed Oil Meal for Fattening Heifers in Drylot. Minn.
Agr. Exp. Sta. Eul. B-116.
7. Hubbert, F. Jr., J. D. Wallace,
Oxytetracycline and High Levels
of Beef Cattle. Jour. An. Sci.
W. P. Skelton and W. A. Sawyer. 1959.
of Phosphorus in the Wintering Rations
8. Beeson, W. M. 1958. The Next Fifty Years of Animal Science. Jour. An.
Sci. 17: 4.
9. Reynolds, W. M., W. H. Hale, W. C. Sherman and H. G. Luther. 1958.
Studies of Oleandomycin at Nutritional Levels in Lamb and Steer
Rations. Jour. An. Sci. 17: 4.
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