MAR 17 1955
Animal Husbandry Mimeograph January, 1955
Series No. 55-2
HIGH LEVEL AUREOMYCIN SUPPLEMENTATION
OF GROWING-FATTENING PIGS
H. D. Wallace and L, Gillespie1
Antibiotics have been widely accepted as valuable feed ingredients for
growing-fattening swine. Recommended levels of feeding presently range from
about 2,5 mg. to 10 mg. of antibiotic per pound of feed. These levels vary
some according to the antibiotic used and the class of swine being fed. The
higher levels are suggested for very young pigs and particularly for animals
reared on milk replacements.
This study was undertaken to determine the feasibility of supplementing
weanling pigs with levels of aureomycin higher than normally recommended.
Thirty two weanling Hampshire pigs (56 days old) were divided into four
experimental groups. Each experimental group consisted of two lots of four
animals. They were self-fed the experimental rations on concrete floored
pens which were washed daily.
The basal ration consisted of the following ingredients and contained
approximately 16 percent of crude protein,
Ground Yellow corn 77.0
Soybean Oilmeal 21.0
Ground Limestone 1.0
Steamed bonemeal 0.5
Salt-trace minerals 0,53
1Wallace, Associate Animal Husbandman, Agricultural Experiment Station,
Gillespie, Graduate Assistant, Department of Animal Husbandry and Nutrition.
The technical assistance of W. E. Collins, is gratefully acknowledged.
The salt-trace mineral mixture was composed of 50 pounds iodized salt;
921 gm, manganese sulfate; 398 gm. ferrous sulfate; 125 gm, copper sulfate;
and 10 gm. cobalt carbonate. The following levels of B-vitamins were added
to all rations per 100 lbs, of feed: 1 gm, thiamine, 230 mg, riboflavin,
2.33 gm. niacin, 1 gm, pantothenic acid,. 375 mg, pyridoxine, 19.4 gm. choline
chloride, 22,7 mgo folic acid and 1.0 mg, vitamin B12. The levels of aureo-
mycin supplementation studied are given in Table 1.
Results and Discussion
Results of the experiment are summarized in Table 1. At the end of eight
weeks Group I (Basal) had gained at an average rate of 1,30 lbs, per day, and
required 2,90 pounds feed per pound gain The addition of 5 mg. aureomycin
to each pound of basal ration (Group 2) resulted in only a slight improvement
in gains and feed efficiency, When the level of aureomycin supplementation
was increased to 25 mg, per pound (Group 3) gains were increased to 1,44 lbs.
per day and feed efficiency improved to 2.80, A further increase in the level
of antibiotic supplementation to 50 mg, per pound (Group 4), gave an additional
response in average daily gains. Average daily feed consumption during the
first eight weeks increased with the increase in level of aureomycin,
The experiment was terminated by individually weighing off the pigs as
they reached a weight of approximately 195 pounds. Final average daily gain
figures for the entire experiment showed the same trend which was apparent
during the first eight weeks, However, the magnitude of the differences was
less; indicating that the greatest effect from feeding aureomycin at high
levels was produced during the early growth period. Average daily gains and
feed efficiencies for 0, 5, 25, and 50 mg. levels of aureomycin supplementation
were respectively, 1,53, 3,09; 1,55, 3,21; 1,59, 3,02; and 1,66, 2,92, These
represent fairly good gains and the feed conversion values are exceptionally
TABLE 1, HIGH LEVEL AUREOMYCIN SUPPLEMENTATION OF GROWING-FATTENING PIGS
Basal f 5 mg,
per lb, of feed
Basal / 25 mg,
lb, of feed
Basal / 50 mg,
lb, of feed
Number of Pigs
Initial weight, lbs.
First Eight Weeks
AV, daily gain, lbs.
Feed per pound gain, lbs,
Av. Daily feed per pig, lbs.
Av. daily gain, lbs,
Feed per pound gain, lbs.
Av. Daily feed per pig, lbs.
Av. final wt., lbs.
Number days on experiment
Thirty two weanling pigs, divided into four similar groups, were fed a
well fortified corn-soybean oilmeal rationsupplemented with 0, 5, 25, and 50
mgs, of aureomycin per pound of feed,
At least a slight increase in gains was observed with each increase in
the level of aureomycin fed. The high level (50 mg,) resulted in only 8S
percent improvement in gains over the controls throughout the entire period,
However, the high level did produce a 14 percent increase in rate of gain
during the first 8 weeks of the trial,
Overall feed efficiency was not improved by the addition of 5 mgo of
aureomycin but was at the two higher levels of supplementation,
Daily feed intake was increased at all levels of supplementation.
This experiment indicates that presently recommended levels of antibiotic
feeding may not be stimulating the pig to maximum performance, However, the
present cost of high level feeding would make such a program economically un@
feasible in the case of thrifty, well fed and managed swine. The value of
high level antibiotic feeding for unthrifty pigs maintained under poor sani-
tary conditions needs to be investigated,