Table 2. Comparison of Average Slaughter Grade Changes by Year and Treatment.

 1959 1960
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.


 Summary

 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.


 Literature Cited

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.