Effects of selenium and vitamin E on the development of immunity to coccidiosis in chickens. Poult. Sci

ABSTRACT Six experiments were conducted using broiler chickens to study the effect of selenium (Se) or vitamin E supplementation of a corn-soybean meal diet on the immune response to coccidiosis. Immunized chickens fed diets supplemented with.25 ppm Se or 100 IU vitamin F./kg of diet had increased body weight gain and feed intake and a tendency for lower feed con-version ratio than chickens fed unsupplemented diet after a challenge with 150,000 oocysts of Eimeria tenella. In two experiments, chickens fed.25 and.50 ppm of Se and immunized against E. tenella had higher body weight gain and a tendency for higher feed intake and lower feed conversion ratio than unsupplemented chickens when challenged with 150,000 oocysts of E. tenella. Except for a reduction on cecal lesion scores and blood packed cell volume in Experiments 1 and 4, respectively, no dietary effect was observed on cecal lesion score or blood packed cell volume of immunized chickens. Dietary supplementation with selenium or vitamin E reduced mortality and increased body weight gain of nonimmunized chickens infected with E. tenella in three of four experiments. These studies suggest that immunization of chickens against cocci-diosis is enhanced by Se or vitamin E supplementation