就麻烦了。这个牛蛋白，在一定外界条件下会变成海绵状（spongiform），牛的精神就不正常了。
Bovine spongiform encephalopathy (BSE)
Transmissible spongiform encephalopathies (TSEs) are a family of diseases of humans and animals characterized by spongy degeneration of the brain with severe and fatal neurological signs and symptoms.
In animals, scrapie is a common disease in sheep and goats. Mink and North American mule deer and elk can contract TSEs. Bovine spongiform encephalopathy (BSE) is also a TSE, affecting a number of species (cattle, human, cats, some types of animals in 300 settings).
BSE is a transmissible, neuro-degenerative fatal brain disease of cattle. The disease has a long incubation period of 4-5 years and it is fatal for cattle within weeks to months of its onset. The nature of the BSE agent is still being debated.
Strong evidence currently available supports the theory that the agent is composed largely, if not entirely, of a self-replicating protein, referred to as a prion. It is transmitted through the consumption of BSE-contaminated meat and bone meal supplements in cattle feed.
