Acquired resistance in turkey poults to Pasteurella multocida (P-1059 strain) during aflatoxin consumption

The potential for impairment by aflatoxin of the development of acquired immunity to fowl cholera in 8 week old turkey poults from a commercial flock was investigated by challenge of vaccinated poults at 10, 12, and 16 weeks of age. Sixty poults were allotted to 4 groups: A) aflatoxin fed, nonvaccinated; B) aflatoxin fed, vaccinated; C) control fed, nonvaccinated; and D) control fed, vaccinated. Aflatoxin B-1 (.5 ppm) was added to the control ration of groups A and B from 49 to 70 days of age. The avirulent CU (Clemson University) strain of Pasteurella multocida drinking water vaccine was given for one day to groups B and C. Challenge (5 poults from each group) was by administration of the virulent (P-1059) strain of P. multocida in the drinking water for 4 consecutive days. The presence of aflatoxin B-1 (.5 ppm) in the feed during oral vaccination with the avirulent strain of P. multocida did not impair the development of acquired resistance to later challenge with the virulent strain. Results indicate that age of poults and method of vaccination may be important factors in the development of acquired resistance to fowl cholera when aflatoxin is present in the diet.