Japanese scientists believe they may have successfully infected cattle with mad cow disease as part of an experiment aimed at early detection of the fatal bovine illness, a laboratory official said Thursday.
The Hokkaido Animal Research Center injected prions from infected cows into the brains of 14 Holstein calves in 2004 -- six in February, three in July and five in September -- and some in the first group have developed what seems to be early symptoms of mad cow disease, said Tsutomu Ogi, director of the institute's livestock engineering section. Prions are proteins thought to cause the disease.
Several of the calves became groggy when walking -- changes considered typical of early symptoms of bovine spongiform encephalopathy, or BSE, Ogi said.
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