The immunization of broiler chickens against type C botulism.

Broiler chickens were inoculated with different amounts of a Clostridium botulinum type C toxoid at 1 or 14 or both 1 and 14 days of age. Immunity was assessed following challenge with type C botulism toxin at 3, 6, and 8 weeks of age. Protection induced by toxoid injection was affected more by time and number of inoculations than by the amount of toxoid administered. Single toxoid injections at one day of age furnished poor protection, whereas groups injected at 14 days of age were well protected at 6 and 8 weeks of age but not at 3 weeks of age. Variable results were observed in groups inoculated at both 1 and 14 days of age: immunity was evident in some groups following 3-, 6-, and 8-week toxin challenges.