Effect of Chlortetracycline, Sulfamethazine and Procaine Penicillin on the Performance of Starting Pigs

Abstract

Approximately 730 pigs were used in a series of experiments under laboratory and farm conditions to investigate the effects of combinations of chlortetracycline, sulfamethazine and penicillin in pig starter rations on rate of gain, feed efficiency and disease prevention. The safety of the combination was also studied. The addition of chlortetracycline, sulfamethazine and penicillin to the rations of pigs weaned at 3 weeks of age and maintained on experiment for 6 weeks resulted in increased average daily gain of statistically significant magnitude. Feed required per pound of gain was reduced and average daily feed increased. Exposure of pigs to a mild S. choleraesuis infection reduced their performance rates as measured by average daily gains and feed efficiency. Performance under this condition was improved markedly by the addition of an antibacterial combination of 100 gm. chlortetracycline, 100 gm. sulfamethazine and 50 gm. procaine penicillin per ton of feed. Exposure of pigs to a severe S. choleraesuis infection resulted in mortality, slow gains, very poor feed efficiency and slow recovery. Medication of rations with the three antibacterial agents resulted in rapid recovery of the pigs from the infection. By the end of 7 days post-infection, the medicated pigs were performing equally as well as the non-infected controls. The data presented indicate that this combination of antibacterial agents may have practical benefits as an additive for pig starter rations and may be used safely since examination of the blood, urine and tissues showed no abnormalities as a result of treatment.