Lots of info out there; google 'botulism baleage'...
Seems like baling/wrapping at the appropriate moisture level is a big deal.
Here's one article:
http://hayandforage.com/article-135-wet ... -risk.html
And an excerpt from another:
Should I be concerned with Botulism?
Clostridium botulinum is a bacterium that produces one of the most potent classes of toxins
known to man. The spores of these bacteria are widespread in the environment (soils in
particular) but are dormant. Under anaerobic conditions and with the right nutrients, the spores
can germinate and grow, releasing toxins.
To minimize the risk of botulinum toxicosis from baleage, wrap bales at the correct moisture
content (50-60%) and store them in areas that will reduce damage to the plastic from the
environment or from critters. Type C botulism toxicity is usually associated with decomposing
carcasses. This can be a problem if a dead animal is accidentally baled in the baleage or dry
haymaking process.
Botulism toxicity on dairy, beef, and other livestock farms occurs via ingestion of the toxin. The
potent neurotoxin impairs transmission of electrical impulses from nerve to muscle. Tongue
weakness is a commonly associated symptom of botulism toxicosis. In most cattle, the tongue
will retract into the mouth if it is pulled out to the side. In affected cattle, the tongue may lie limp
after being pulled or only slowly retract. Jaw movement and muscle tone is also severely
compromised. Cattle with botulism will also drool as a result of having a difficult time
swallowing. Botulism toxicity is often first diagnosed as an animal with "downer cow
syndrome." When an outbreak occurs, it often affects multiple animals and at any stage of
lactation. Animals also usually do not show signs of nervousness or apprehension, which
eliminates diagnosis for listeriosis or milk fever. Death in cattle is often due to respiratory
failure, dehydration, or complications of being down for prolonged periods of time. Cattle can
recover from moderate exposures to botulinum toxin within 5 to 10 days.
Adapted from Botulism in Cattle by Dr. Limin Kung, Jr., Dept. of Animal & Food Sciences,
University of Delaware, Newark