Reduction of Clostridium perfringens by feed additive antibiotics in the ceca of chickens infected with Eimeria tenella.

Abstract

Two experiments were performed ot investigate the effect of feed additive antibiotics on Clostridium perfringens and Enterobacteriaceae in the ceca of chickens infected with Eimeria tenella. In the first experiment, chickens were continuously fed rations containing thiopeptin, 2 mg./kg.; bacitracin, 20 mg./kg.; penicillin, 12 mg./kg.; or chlortetracycline, 22 mg./kg. One day after antibiotic feed was given, each bird received an oral inoculation of 30,000 E. tenella oocysts. The growth of C. perfringens was stimulated by the infection in unmedicated chickens. Dietary thiopeptin, bacitracin, penicillin, or chlortetracycline suppressed the number of C. perfringens recovered 5 and 7 days after infection. Enterobacteriaceae were increased by the infection, but dietary antibiotics did not reduce the increase. In the second experiment, chickens were given feed containing amprolium plus ethopabate, 125 plus 8 mg./kg., and a combination of the coccidiostat and one of 4 antibiotics: thiopeptin, bacitracin, penicillin, or chlortetracycline. Birds were each given an oral inoculation of 30,000 coccidiostat-resistant E. tenella oocysts. Infection resulted in an increase of C. perfringens in the unmedicated control and the coccidiostat-treated groups. Dietary thiopeptin, bacitracin, penicillin, or chlortetracycline reduced the number of C. perfringens found 5 and 7 days after infection. Counts of Enterobacteriaceae were increased by the infection, but dietary antibiotics did not suppress the increased counts. In both experiments, dietary administration of antibiotics did not reduce gross cecal lesions.