Response of Growing-Fattening Pigs to Bacitracin, Aureomycin and Other Supplements

Abstract

The addition of 5 mg. aureomycin hydrochloride per pound of a 20 percent crude protein “corn-solvent soybean oil meal” ration fortified with minerals, vitamins A and D and riboflavin, pantothenic acid, niacin, choline and a vitamin B¹² feed supplement fed to growing-fattening pigs in drylot from weaning to 100 pounds liveweight resulted in a 27 percent increase in rate of gain (highly significant). The addition of 5 mg. bacitracin to the same ration promoted a 16 percent increase in rate of gain (significant). The response from pharmaceutical grade bacitracin and from bacitracin feed supplement when each furnished 5 mg. bacitracin per pound of ration was essentially the same. The deletion of the vitamin B₁₂ feed supplement which furnished approximately 7.5 mcg. vitamin B₁₂ per pound of ration from the above ration caused pigs to gain 15 percent slower, but the difference in gains was not statistically significant. The substitution of 3-percent condensed menhaden fish solubles for the vitamin B₁₂ feed supplement in the basal ration plus an antibiotic (bacitracin) feed supplement did not significantly alter daily gains. In a second phase of the investigation (100 lb. to 200 lb., drylot) pigs which had received no antibiotic supplementation from weaning to 100 pounds were subdivided into two groups; one group continued on the basal ration and the other group received 5 mg. bacitracin per pound of ration. Pigs which had previously received bacitracin from weaning to 100 pounds were subdivided in like manner, one group continuing to receive bacitracin and the other group being fed the basal ration. Under the conditions of this experiment best results were obtained when bacitracin was included in the ration for the entire period from weaning to 200 pounds liveweight. Pigs which received bacitracin in the ration throughout the entire feeding period gained significantly faster than pigs receiving no bacitracin supplementation throughout. Copyright © . .