The US Agriculture Department has quarantined a second herd in Washington state as part of its investigation into the nation's first case of mad cow disease.
Ron DeHaven, the USDA's chief veterinarian, told reporters that officials quarantined a cattle feeder herd in Sunnyside, Washington, that contains a young bull calf recently born to the infected Holstein cow.
The USDA earlier this week quarantined a 4,000-animal herd at another farm where the infected cow lived before it was slaughtered on Dec. 9.