The final test on a 20-month-old steer in Japan to determine its bovine-spongiform-encephalopathy status proved negative. The first round of tests raised BSE suspicions. If the following tests had confirmed the disease, it would have opened up new concerns about the prospect of "younger" animals (those younger than 30 months old) contracting BSE.

Previously, only one animal as young as the steer has ever been identified with the disease, Japanese officials had suggested that if the steer in question had been confirmed infected, import rules on U.S. beef would need to be revisited.

At the same time, Japanese authorities announced that another suspected BSE case surfaced, this one involving a 6-year-old dairy cow. Confirmatory test results are underway. The animal was on its way to slaughter when diagnosed.