Purdue University
Agricultural Experiment Station	Mimeo A.Ho 113
Lafayette, Indiana	September 1953
THE EFFECTS OF ADDING DIFFERENT LEVELS AND SOURCES OF ANTIBIOTICS TO A PROTEIN SUPPLEMENT FOR SWINE
Jo Ho Conrad and Wo Mo Beeson Animal Husbandry Department
Certain antibiotics, when fed at the recommended levels, usually produce a 10
10	20 per cent increase in growth rate and a 5 per cent increase in feed efficiency. Evidence has shown that an effective antibiotic needs to be included at a level of 5 to 7.5 mgo per pound of total ration to produce such a growth response0
The majority of hogs in the Midwest arc not fed a complete mixed ration, but arc fed a free choice ration of shelled corn, protein supplement and minerals. Therefore, the most logical way to add the antibiotic to a free choice ration would be to include it in the protein supplement.
Two experiments were conducted to study the effects of adding different levels and sources of antibiotics to a protein supplement fed free choice.
Experiment I - Summer, 1952
Six lots of 12 Duroc pigs each were started at an average weight of 40 pounds and fed free choice in dry lot on shelled corn, Purdue Supplement 5 (40$ soybean
011	meal, 20$ fishmeal, 2G$ meat and bone scraps, 10$ cottonseed meal, and 10$ alfalfa meal) and minerals (40$ limestone, 40$ bonemeal and 20$ salt),
Aureomycin from an antibiotic feed supplement was added to the protein supplement in the following amounts:	0, 10,	15, 20, 25 and 30 mg. per pound of supple-
ment.
The results are presented in Table I.