Effects of high environmental temperatures on cecal coccidiosis

Maintenance of broiler or White Leghorn cockerels in a high temperature (32 C.), high humidity (90%) environment for six days following artificial infection with Eimeria tenella significantly reduced coccidiosis severity as compared to birds similarly infected and maintained in an ambient environment averaging 24.5 C., and 62% humidity. Disease severity was determined by lesion scores, fecal scores, and hematocrit readings. The heavier broiler stock maintained body temperatures of 0.7-1.6 C. higher than those birds kept at ambient temperatures for the entire six days. Body temperatures of heat-treated Leghorn cockerels were 0.9 C. higher during the first 48 hours post-inoculation (P.I.), but similar to ambient temperature controls for the last four days. Elevated body temperatures during the first two days following inoculation impaired the survival and development of some parasites while shorter periods (24 hours) of heat treatment did not affect parasite survival.