Department of Animal Science Florida Agricultural
Mimeograph Series No. 63-5 Experiment Station
July, 1962 Gainesville, Florida
ANTIBIOTICS IN PIG STARTER RATIONS
G. E. Combs and H. D. Wallace /
Supplementation of swine rations with antibiotics has for several years
been recognized as a beneficial practice. With this widespread usage the
question often arises as to which antibiotic, combination of antibiotics or
other growth-promoting feed additives are most efficient.
The purpose of this study was to compare the growth-promoting ability
of mycostatin, an antifungal*antibiotic, with chlortetracycline and a combi-
nation of other antibiotics.
Sixty pigs weaned at 2 weeks of age were.allotted on the basis.of weight
and litter into fifteen lots of 4 pigs each. All lots were self fed ad
libitum in concrete-floor pens for 42 days.
The experimental treatments were as follows:
Treatment I Basal
Treatment 2 Basal + 80 gm. mycostatin per ton
Treatment 3 Basal + 80 gm. chlortetracycline per ton
Treatment 4 Basal + 80 gm. mycostatin + 80 gm. chlortetracycline per
Treatment 5 Basal + 25 gm. chlortetracycline + 25 gm. oxytetracycline
+ 15 gm. penicillin + 15 gm. streptomycin per ton
The composition of the basal rations is presented in Table i. Basal
ration I was fed for the first 4 weeks; then all lots were given basal ration
II for the remainder of the experiment. E,
The average performance is summarized In Table 2. The ave naeSg lY lin
I/ Combs and Wallace, Associate Animal Nutritionist and Animal Nu t
respectively, Florida Agricultural Experiment Station. The assis
of W. E. Collins and L. S. Taylor, Swine Herdsmen, is gratefully acknowl-
The study was partially supported by funds supplied by the Squibb Institute
for Medical Research, New Brunswick, New Jersey and American Cyanamid Co.,
Pearl River, New York.
of the groups which received the basal, mycostatin, chlortetracycline and
the combination of mycostatin and chlortetracycline treatments were similar.
Pigs which received the combination of four antibiotics (treatment 5)
gained significantly faster than the other treatment groups. This treat-
ment group also consumed more feed than the other groups.
The feed efficiency figures also demonstrate the superiority of the
combination of four antibiotics (treatment 5) relative to the remaining
groups. Statistically, treatment 5 is different only from treatments I, 2
and 4 (p = .05) but the magnitude of the difference between treatments 5
and 4 was quite large.
These results would indicate that the antifungal antibiotic mycostatin
fed singly or in combination with chlortetracycline was not an effective
Sixty early weaned pigs were used to study the effects of supplementing
starter rations with various antibiotics.
Pigs that received a combination of chlortetracycline, oxytetracycline,
penicillin and streptomycin gained significantly faster than pigs which
received mycostatin, chlortetracycline or a combination of mycostatin and
chlortetracycline. More efficient gains were also obtained with the group
which received the combination of four antibiotics.
Table I. COMPOSITION OF BASAL RATIONS
Ingredient Basal I Basal II
Ground yellow corn 18.32 74.40
Sugar 18.54 ---
Dried skim milk 40.00 --
Soybean meal 8.74 17.00
Tankage --- 4.00
Rolled oats 5.00 ---
Dried whey 2.50 ---
Beet pulp 1.00 --
Lard 2.00 ---
Salt .50 .50
Trace minerals .10 .10
Bone meal 1.00 1.00
Limestone --- .70
Vitamin supplement .20 .20
Vitamin B12 supplement .10 .10
Vitamin A and D premix 2.00 2.00
I/ Contained 2,000 mg. riboflavin; 4,000 mg. pantothenic acid; 9,000 mg.
niacin; and 10,000 mg. choline chloride per pound.
2/ Contained 9 mg. vitamin 812 per pound.
3/ Contained 14 gm. vitamin A (10,000 I.U./gm.), 2 gm. vitamin D (9,000
I.U./gm.) and 892 gm. yellow corn.
Table 2. RESPONSE OF EARLY WEANED
PIGS TO VARIOUS ANTIBIOTICS
Chlortetra- cycline +
+ Penicillin +
C+ rr. t 4 in
-- %UY -
No. of pigs 12 12 12 12 12
Av. initial weight, lb. 5.9 6.0 6.0 6.2 5.9
Av. final weight, lb. 24.1 24.1 28.5 26.1 31.8
Av. daily gain, lb. .43 .44 ".52 .47 .62a
Av. daily feed, Ib. .98 1.03 1.14 1.10 1.22
Feed/lb. gain, Ib. 2.26 2.34 2.21 2.31 1.99b
Treatments 1, 2 and
b. Treatment 5 significantly different (P = .05) from Treatments I, 2 and 4.
a. Treatment 5 significantly different (P = .01) from
4; different (P = .05) from Treatment 3.