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).


Experimental Procedure

 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