"U.S. officials have balked at blanket testing of all cattle, saying it's too expensive and unnecessary. In addition, they say the tests are reliable only on cattle 30 months old or older.
Japan, however, has reported finding BSE in two younger animals - one 21 months old and the other 23 months old.
Most U.S. fed cattle are slaughtered before they reach 21 months, according to industry officials. They acknowledge that for exports to Japan to resume, the two governments would have to agree on measures to assure that beef bound for Japan is from cattle no older than 20 months.
The Agriculture Department's beef grading system is focused on meat quality, not age, said William Sessions, deputy administrator of the department's Agricultural Marketing Service."