Safer mad cow rating could boost U.S. beef exports WASHINGTON (Reuters) - The World Organization for Animal Health (OIE) has upgraded the United States' risk classification for mad cow disease to its safest level, which could increase U.S. beef exports, the U.S. Agriculture Department said on Wednesday. The decision to rank the United States' risk as "negligible" instead of "controlled" came at the OIE's annual meeting in Paris. Its scientific arm earlier recommended the upgrade after reviewing U.S. safeguards. The ranking puts the United States among countries said to have the lowest risk for the fatal, brain-wasting disease formally known as bovine spongiform encephalopathy. The new risk category was a "strong foundation" for increasing U.S. beef and beef product exports, USDA Secretary Tom Vilsack said in a statement. Vilsack said the United States would press its trading partners "to base their decisions on science, consistent with international standards." The U.S. Cattlemen's Association, a trade group, has said the safer designation would be "a big step toward enhancing our export opportunities." Four cases of BSE have been reported in the United States since 2003. The most recent was in April 2012. U.S. safeguards include a ban on using ruminant parts in cattle feed and keeping spinal cords, brains and nervous tissue, the items most at risk of infection, out of the food supply. USDA tests about 40,000 head a year for the disease. Reporting by Ros Krasny; Editing by Richard Chang