EFFECT OF DIETARY SELENIUM ON THE RESPONSE OF STRESSED AND UNSTRESSEDCHICKENS TO ESCHERICHIA-COLI CHALLENGE AND ANTIGEN

Selenium was added to the feed of White Leghorn type chickens 1 day pr ior to challenge with either Escherichia coli or sheep erythrocyte ant igen. The incidence of death or lesions was reduced from 86% to 21% at the optimal dose of selenium (0.4 mg/kg resulting in feed concentrati on of 0.45 mg/kg). After the chickens were stressed by chilling, selen ium was ineffective against E. coli. Dietary additions of selenium bet ween 0.1 and 0.8 mg/kg resulted in an antibody titer increase from 2.2 to 3.9 to the log(2) against sheep erythrocytes (SRBC). Following chi lling, antibody titer response was reduced from 4.9 to 2.4 to the log( 2). This titer reduction could be prevented with dietary additions of selenium between 0.1 and 1.2 mg/kg. The effects of a nitrofuran and se lenium were additive against E. coli challenge infection.