Experimental botulism in chickens: the cecum as the site of production and absorption of botulinum toxin.

Highly purified preparations of Clostridium botulinum toxins were administered to chickens by various routes. Chickens were highly susceptible to type A toxin, but relatively resistant to toxins of other types. Type C toxin (12S) at a dose of 1 X 10(7) mouse ip LD50 failed to kill the chicken by the oral route. Oral administration of 10 or more of type A, C, or D spores killed normal chickens, whereas cecoligated chickens were insusceptible to oral administration of 10(6) spores. These results show that the site of production and absorption of botulinum toxin in chickens is the cecum. Peroral administration of spores of a type C strain cured of its prophages and producing the C2 factor only also killed normal chickens. Chickens appeared to the more susceptible to the C2 factor than to the C1 toxin. The C2 factor, therefore, may play more important role in chicken deaths from toxico-infection with type C organisms. The optimum temperature for growth of C. botulinum types C and D was found to be 40-42 C. Type C and D toxins were significantly more stable than type A toxin in the cecum contents with pH above 7. These characteristics and the high density of distribution of type C spores in the environment may explain prevailing cases of type C botulism among broiler chickens.