Effect of selenium on peripheral blood leucocytes of chickens infected with Eimeria.

Experiments were conducted to study the effects of dietary selenium (Se) on peripheral blood leucocytes of chickens infected with coccidia. Primary coccidial infection significantly increased blood leucocyte number at 6 days postinfection (PI) in three of four experiments when chicks were fed a corn-soy diet, and in all four experiments at 11 days PI. When chickens were fed a semipurified (SP) diet, coccidial infection did not affect the blood leucocytes number at 6 days PI but significantly increased blood leucocyte number at 11 days PI. In the primary infection, Se significantly decreased blood leucocyte number in four of six experiments at 6 days PI and significantly increased the blood leucocyte number in three of five experiments at 11 days PI. In the secondary infection, chickens had significantly more blood leucocytes than chickens given a primary infection at 8 or 24 hr after challenge. Selenium significantly increased blood leucocyte number at 8 hr after challenge in one experiment and produced numerically higher leucocyte number in three other experiments. The results of these studies indicate that dietary Se supplementation modifies the number of peripheral blood leucocytes in chickens infected with coccidia.