Feeder Lamb Response to Chlortetracycline-Sulfamethazine Supplementation

Three feeding experiments were conducted to evaluate the effects of adding a combination of chlortetracycline and sulfamethazine to finishing lamb rations. In the first experiment, two levels of chlortetracycline-sulfamethazine supplementation (55 mg of each/ kg ration and 110 mg of each/kg ration) resulted in improvement (P<.01) in average daily gain, while chlortetracycline alone (55 mg/kg ration) did not affect lamb performance. In experiment 2, supplementing with chlortetracycline-sulfamethazine (110 mg of each/kg ration) significantly increased gains (P<.01). In a third experiment, chlortetracycline-sulfamethazine (55 mg of each/kg ration) resulted in a 7% increase in average daily gain. This difference was nonsignificant (P>.05). Out of a total of 240 lambs in three experiments, only three lambs died from enterotoxemia, and these were receiving the control ration.