April 26, 2012
Many importers, such as the EU and Mexico, said that the discovery in California of a cow with the disease, known officials as, would have no impact on purchases of US beef.
John Clifford, the USDA's chief veterinary officer, said that the infected cow was "never presented for slaughter for consumption, so at no time presented a risk to the food supply chain or human health".
"This detection should not affect US trade."
However, Taiwan said it was closely monitoring the situation, and would tighten security checks on US beef imports to ensure correct documentation.
Russia, the biggest beef importer, said it had yet to make any decision on a response.
And two South Korean retailers, Lotte Mart and Home Plus, suspended sales of US beef.
Home Plus is controlled by the UK's Tesco chain, which has yet return Agrimoney.com's repeated requests for further information on the decision.
The South Korean government, which last year tackled a domestic outbreak of foot-and-mouth disease, said it would continue to permit US beef imports, but would strengthen quarantine inspections.
The country earlier this year lifted a nine-year-old ban on beef from Canada, which has suffered the majority of North America's BSE cases.
Indeed, BSE outbreaks can have long-lasting effects.
While Japan, the second-ranked beef importer after Russia, said there would be no change to its policies on US beef imports, these still include curbs introduced after America's first BSE case, in 2003.
The US has now suffered four cases of BSE, two in beef cattle, in Alabama and Texas, with Tuesday's case the second in a California dairy cow.
"Milk does not transmit BSE," Mr Clifford said.
The US itself prides itself on the measures it has taken to prevent mad cow disease, linked to brain-wasting Creutzfeldt-Jakob Disease (CJD) in humans, entering the country.
America has not imported beef from Britain, where BSE was discovered in the 1980s, since 1985, and restricts blood donations from UK donors.
On the Chicago futures market, feeder cattle, animals ready for fattening, recovered 0.5% to reach 148.550 cents a pound for the May contract, which fell the daily limit of 3.0 cents in the last session.
Live cattle, those ready for slaughter, rebounded 0.7% to 112.350 cents a pound for the July lot, which also fell limit down on Tuesday.