MEXICO CITY (Reuters) - Mexico's agriculture ministry said on Tuesday it had no plans to stop beef trade with the United States after U.S. authorities confirmed a case of bovine spongiform encephalopathy, or mad cow disease, in California.

The ministry said it would maintain the same regimen of inspections for trade across the border and that there had been no imports of beef into Mexico from where the U.S. Agriculture Department (USDA) had detected the disease.

The United States usually exports more beef to Mexico than any other country, sending 500 million lbs (227 million kgs) in 2010 worth some $670 million, according to the USDA.

The detection in a California dairy cow was the fourth such U.S. case since the first domestic discovery of the disease in 2003.

Rumors before the USDA announcement pushed live cattle futures on the Chicago Mercantile Exchange down by as much as the 3-cent-per-lb daily limit. Prices pared some losses after the USDA said no meat from the infected animal had entered the food chain.

The carcass of the cow, which the USDA said was infected by an "atypical" form of the disease, would be destroyed.

Mexico, which also exports cattle for slaughter in the United States, said there would be no change to existing sanitary protocols but it would continue to monitor the situation with U.S. officials.

"Cases of atypical bovine spongiform encephalopathy (BSE) occur occasionally," Mexico's agriculture ministry said in a statement. "These cases have appeared in different places around the world and don't affect trade between countries."

Mad cow is believed to cause the deadly brain disease Creutzfeldt-Jakob in humans who eat infected animal parts.

Beef exports plunged nearly 75 percent in 2004 in the wake of the first U.S. incident, with the USDA reporting net cancellations of beef sales in five of the first six weeks following the news.

(Reporting by Adriana Barrera; Writing by Mica Rosenberg; Editing by Dale Hudson)