(Reuters) - The U.S. Agriculture Department confirmed on Tuesday that it found a case of bovine spongiform encephalopathy (BSE), or mad cow disease, the nation's fourth, in a dairy cow in central California.

The USDA has begun to notify the World Organization for Animal Health (OIE) as well as its trading partners, but the finding should not affect U.S. beef exports, said John Clifford, the USDA's chief veterinary officer.

COMMENTS:

RICH NELSON, DIRECTOR OF RESEARCH FOR ALLENDALE INC:

"Keep in mind the majority of our beef exports go to countries with limitations for U.S. product anyway (beef from cattle aged under 30 months). Japan has the more restrictive 20 months and under standard. World health standards suggest beef from cattle under 30 months is safe because the majority of cases don't appear until after 30 months of age (though Japan had cases down to 20 - 22 months of age).

"With these limitations our foreign buyers have already been prepared for more cases in the U.S.. This is not a 2003 situation. There will not be any new bans because of these limitations. Exports may dip temporarily but not in a meaningful way."

DENNIS SMITH, AN ANALYST WITH ARCHER FINANCIAL:

"The key is what the export customers' reaction is to all of this. My feeling is there won't be a big reaction and if they do they'll go with an age restriction like the Japanese do.

"Japan tightened import regulations on imports of U.S. beef after the first case in 2003 and currently only allows imports of beef from cattle aged 20 months or younger.

"The restriction, along with import curbs from other countries, caused U.S. beef exports to plunge, but sales have gradually recovered over the years."

SHAWN MCCAMBRIDGE, GRAINS ANALYST FOR JEFFERIES BACHE:

"The concern is that importing nations might ban imports from the affected area. Meat exports have been very brisk, so anything like this is bearish for meats and grains too, especially corn and meal. In the past, they've banned imports so it now depends on what our overseas customers do."

(Editing by Marguerita Choy and Jim Marshall)