FRESNO, Calif. — Officials have lifted quarantines on two Central California dairies linked to a case of mad cow disease, after investigators found the illness didn't come from cattle feed.
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Tests performed by the World Organization for Animal Health confirmed what U.S. labs had found: The diseased cow had a form of the illness involving a spontaneous mutation of a protein gene that hasn't caused illness in humans.
The cases of mad cow reported across Great Britain in the 1990s were caused by cattle being fed protein supplements made from the spinal columns and brains of diseased cows. That practice has since been banned.
The case in Tulare County was discovered through random testing.
Officials have not released the names of the affected dairies, which had been shuttered since April 24.
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