Persistence of Clostridium botulinum type B on a cattle farm after an outbreak of botulism.

On farms involved in botulism outbreaks, cycles of Clostridium botulinum have occurred. The cycles were initiated by feeding brewers' grains contaminated with proteolytic C. botulinum type B to the cows. Spreading of manure containing feces of these cows increased the contamination of the pastures. In grass silages prepared with wilted grass from these pastures the number of C. botulinum type B organisms increased, and toxin type B was produced. Feeding cows with the contaminated silage fodder completed the cycle. Besides contamination of human foodstuffs (milk and meat), further contamination of the environment occurred. It was demonstrated that fowl may be important vectors in spreading C. botulinum.