Purdue University Agricultural Experiment Station Lafayette, Indiana
EFFECTS OF FEED ADDITIVES ON GROWING-FINISHING SWINE*
J. H. Conrad, D. M. Nelson and W. M. Beeson Department of Animal Science
A recent report (Mimeo AS-238) has clearly indicated that the seven feed additives or combinations of feed additives tested (including two arsenicals) had no significant effect on carcass quality as measured by backfat thickness, lean cut yield, loin eye area, carcass length or dressing percentage. However, four treatments significantly increased daily gains, and the maximum improvement is feed efficiency was 7.8 percent. Therefore, two important criteria for evaluating presently available feed additives are daily gain and feed efficiency.
In general, the most pronounced response due to feed additives is brought about because of their effect on the intestinal microorganisms of the host animal. Environmental changes and continuous use of antibiotics and feed additives undoubtedly change the kinds and numbers of certain intestinal microorganisms. Continuous research, therefore, is necessary to evaluate the response of the various feed additives that are presently used, as well as to compare them with certain new feed additives which appear promising.
The objective of this experiment was to determine the effect of certain antibiotics, combinations of antibiotics and an arsenical on rate of gain, feed efficiency and backfat thickness of growing-finishing swine.
Mimeo AS-263 November, 1959 Final Report
Experimental Plan
Ninety-six Duroc weanling pigs averaging 35 pounds were divided into eight lots of twelve pigs each on the basis of sex, weight, litter and general appearance. All pigs were self-fed a complete mixed ration on concrete-paved lots and were wormed with piperazine phosphate in the feed at the rate of 12 pounds per ton when they averaged 100 pounds.
The experimental treatments were as follows:
Lot 1 - Control
Lot 2 - Control plus 20 grams antibiotic combination per ton (5 grams aureomycin, 2.5 grams procaine penicillin, 5 grams terramycin and 7*5 grams zinc, bacitracin).
Lot 3 - Control plus arsanilic acid, 90 grams per ton.
Lot k - Control plus erythromycin thiocyanate, 10 grams per ton.
* The authors wish to acknowledge the following companies for the products which they supplied that were used in this experiment. Arsanilic acid and erythromycin thiocyanate were furnished by Abbotts Laboratories, North Chicago, Illinois; Aureomycin by American Cyanamid Co., Pearl River, New York; Oleandomycin and terramycin hy Chas. Pfizer and Co., Terre Haute, Indiana; Penicillin, streptomycin and sulfa-Quinoxaline by Merck and Co., Rahway, New Jersey; Spiramycin by Rhodia, Inc., New York, New York; Zinc bacitracin-penicillin by Commercial Solvents Corp., Terre Haute, Indiana.