Purdue University Agricultural Experiment Station Lafayette, Indiana
THE EFFECTS OF ADDING DIFFERENT AMOUNTS OF AN ANTIBIOTIC (AUREOMYCIN)
IN A PROTEIN SUPPLEMENT FOR SWINE
W. M. Beeson and J. H. Conrad
Department of Animal Husbandry
Antibiotics have been shown to be effective in stimulating rate of gain (10-20$) and improving feed efficiency (5-10$) in swine• Clear-cut evidence has been obtained showing '"just the presence** of an antibiotic in a feed does not always insure an improvement in growth rate or feed efficiency unless the antibiotic is fed in sufficient amounts (5»0 to 7°5 nigo per pound of total feed) to produce a biological response.,
A majority of the hogs are fed on a free choice basis (shelled corn, supplement and minerals) and therefore rely on the protein supplement as the source of antibiotico The ratio of corn to protein supplement consumed becomes wider as pigs mature; therefore, the amount of antibiotic furnished daily by a protein supplement fed free choice with corn will be considerably different than the amount supplied by feeding an antibiotic in a total finished ration.
Usually the amount of protein supplement consumed daily by hogs remains fairly constant for the entire feeding period but the quantity of corn eaten increases proportionally to the liveweighto In view of these facts, this experiment was designed to determine the optimum level of antibiotic required in the protein supplement for growing-fattening swine.
Experimental Procedure
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 oil meal, 20$ fishmeal, 20$ meat and bone scraps, 10$ cottonseed meal, and 10$ alfalfa meal) and minerals * The mineral mixture was composed of 40 percent steamed bonemeal, 40 percent limestone and 20 percent salt and loose salt was fed free choice in addition to the mineral mixture. The following levels of aureomycin were added to the protein supplement.
Lot	Levels of Aureomycin added
No.	to Supplement 5c
Summary
1.	A complete summary of the results are presented in Table I.
2.	These data indicate that a level of 25 milligrams of aureomycin per pound of supplement (50 grams per ton) produces the ma^cimum growth response for growing-fattening hogs.
Mimeo AH 92___________
September, 1952 (10M)