Animal Husbandry & Nutrition Florida Agricultural
Mimeograph Series No. 58-5 Experiment Station
MYCOSTATIN AND CHLORTETRACYCLINE AS
ANTIBIOTIC FEED SUPPLEMENTS FOR GROWING PIGS/1
H. D. Wallace, C. E. Haines and G. E. Combs, Jr. /
Mycostatin (Squibb Nystatin) is an antifungal antibiotic derived from cultures
of Streptomyces noursel. It is known to be antagonistic toward many species of
yeasts and molds but to have very limited effects against bacteria, protozoans,
and the filterable viruses. The usefulness of this antibiotic for swine feeding
purposes has not been determined. Its possible value in this connection might be
to suppress intestinal fungi and the infections arising therefrom. These fungal
infections may become more troublesome following the administration of antibiotics
predominantly active against bacteria. Thus, in this experiment chlortetracycline,
an antibiotic effective against certain intestinal bacteria, was also employed.
The object was to determine the effect of the two antibiotics fed singly and
in combination on the rate of gain and feeding efficiency of growing pigs fed in
Eighty weanling pigs of mixed breeding were divided into eight lots of ten
pigs each according to breed,litter, weight and previous treatment. Two replicated
lots were fed for a period of 77 days on each of the following dietary treatments.
Lots I and IA Basal
Lots 2 and 2A Basal f 40 gm. chlortetracycline
per ton of feed.
Lots 3 and 3A Basal + 40 gm. mycostatin
per ton of feed.
Lots 4 and 4A Basal + 40 gm. chlortetracycline and
40 gm. mycostatin per ton of feed.
The antibiotics used were both of pharmaceutical grade. The experiment was
initiated April 13, and was terminated June 29, 1957. Feeding was accomplished by
the use of self-feeders and automatic watering devices supplied fresh water at
I/This study was supported in part by grant-in-aids from The Squibb Institute
for Medical Research, New Brunswick, N. J. and American Cyanamid Co., Pear ver,
N. Y. XP
2/Wallace, Haines and Combs: Assoc. Animal Husbandman, Researc sst. and As _
Animal Husbandman respectively, Department of Animal Husbandry and p ?on
University of Florida, Gainesville. The authors wish to acknowled We h 4ite n4
Dr. W. R. Carroll, Bacteriology Department, University of Florida assistng
with the fecal yeast cultures.
Composition of Basal Ration
Weaning to 125 Ibs.
125 Ibs. to end of test
Ground yellow corn 77.0 84.3
Soybean oil meal 20.3 13.0
Ground limestone !.0 1.0
Steamed bone meal 1.0 1.0
Iodized salt 0.5 0.5
Trace minerals / 0.1 0.1
Lederle Fortafeed 2-49C 0.1 0.1
-/By Calcium Carbonate Co. + 5.4 Ibs. ZnSO4*H20 per 100 Ibs.
On June 6, approximately 7 weeks after the experiment started, fresh fecal
samples were collected from seven representative pigs in each lot to determine if the
antibiotic supplements were affecting the growth of certain yeasts and molds.
Composite samples were made of the fecal samples from each lot and dilutions were
set up at the rate of 1/10, 1/100 and 1/1000 in sterile water. Cultures were made
on acidified Mycophil media (Icc. of 5% tartaric and 50% dextrose per 8cc. of
medium). Cultures were incubated at room temperatures and counts, including all
yeast and mold colonies, were made four days later. Individual cultures were picked
off the plates after 4 days of incubation and transferred to a Pagano-Levin media
supplied by the Squibb institute of Notrition. These cultures were then returned
to Squibb for further s+udy and differentiation.
Results and Discussion
A summary of the performance of the pigs is presented in Table I. A statis-
tical analysis of the values for average daily gain showed no significant differences
between treatments. It is interesting to point out that a significant difference in
gains between replicates occurred. In replicate I, Lots I, 2 and 3 gained at appro-
ximately the same rate whereas Lot 4 (combination of the two antibiotics) made some-
what poorer gains. In replicate II all lots out performed the control lot and the
pigs getting the combination of antibiotics made the fastest gains. There is no
apparent explanation for this reversal In performance. All of the feeding lots were
quite muddy during much of the experiment due to heavy precipitation. However, the
four lots in replicate I were worse in this regard than the four lots of replicate II.
Differences in average daily feed consumed and feed required per pound of gain were
not significant between treatments or replicates.
A summary of the yeast and mold counts made on fecal samples is shown in
Table 2. In terms of total colonies per gram of feces it appears that the control
pigs were somewhat more heavily contaminated. Mycostatin tended to reduce the total
count of smooth yeasts but not the rough yeast-like molds. It was also noted that
the pigs in replicate I showed higher total counts in all cases than those of
replicate II. This may have been a reflection of the wetter conditions prevalent
in the lots of replicate I.
TABLE I. INFLUENCE OF MYCOSTATIN AND CHLORTETRACYCLINE ON THE PERFORMANCE OF GROWING PIGS
Treatment Replicate I Replicate II
Treatment B C & M B C M C & M
Lot Number I 2 3 4 IA 2A 3A 4A
Number of pigs 10 10 10 10 10 10 92/ 10
Av. Initial wt., Ibs. 54.0 54.0 53.7 54.2 54.2 54.0 54,1 54.1
Av. wt. after 6 wks., Ibs. 122.1 123.3 124.0 119.0 118.6 121.1 121.2 125.2
Av. Final wt., Ibs. 193.0 190.6 194.3 186.0 181.1 187.3 186.4 191.9
Av. daily gain (Ist 6 wks.) Ibs. 1.62 1.65 1.67 1.55 1.53 1.60 1.59 1.69
Av. daily gain (entire period) Ibs. 1.81 1.77 1.83 1.71 1.65 1.73 1.72 1.79
Av. daily feed (Ist 6 wks.) Ibs. 5.00 5.24 5.23 4.94 4.72 4.99 4.91 5.30
Av. daily feed (entire period) Ibs. 6.27 6.24 6.27 6.19 5.82 5.91 5.97 6.20
Feed/lb. gain (lst 6 wks.) Ibs. 3.09 3.!8 3,i3 3.19 3.08 3.12 3.09 3.14
Feed/lb. gain (entire period) Ibs. 3.47 3.52 3.44 3.62 3.53 3.41 3.48 3.47
Total days on test 77 77 77 77 77 77 77 77
= Basal + Chlortetracycline
= Basal + Mycostatin
= Basal + Chlortetracycline and Mycostatin
/One pig removed from experiment after 10 days due to anal prolapse.
TABLE 2. YEAST AND MOLD COLONY COUNTS MADE ON
_. FECES SAMPLES FROM THE EXPERIMENTAL PIGS
Experimental Lot Smooth Yeast-Like Total Colonies
Treatment No. Yeasts Molds per/gm. Feces
Control I 150 110 260,000
Control IA 144 10 154,000
Chlortetracycline 2 77 90 167,000
Chlortetracycline 2A 99 35 130,000
Mycostatin 3 30 133 163,000
Mycostatin 3A 22 118 140,000
Chlortetracycline & Mycostatin 4 84 59 143,000
Chlortetracycline & Mycostatin 4A 12 66 78,000
The cultures sent to Squibb were studied in particular for the presence
of Candida albicans, a toxic strain of fungi. The results were negative for all
samples, indicating that this type of Candida commonly found in humans is not
present in swine, or at least was not present in the swine of this experiment.
A study involving 80 weanling pigs has been conducted to determine the sup-
plemental feeding value of mycostatin, an antifungal antibiotic, and chlorte-
tracycline. Results obtained showed no significant effect of the antibiotic
treatments on gains, feed intake, or feed required per pound gain.
Cultures made on fecal samples for yeasts and molds indicated some possible
treatment differences but in general were not conclusive. The presence of Candida
albicans, a toxic strain of fungi, was not confirmed in these pigs. Numerous
other types of Candida were cultured in all samples.