Government officials are now tracing six cows shipped into the U.S. from the same Canadian herd as an animal with mad cow disease, according to a Dow Jones report.

The infected dairy cow was born within one year of the others. U.S. Agriculture Department spokesman Ed Loyd said Wednesday that the agency is tracking their movements.

Two cases of the brain-wasting disease have turned up in Canada since the Bush Administration said it would lift a ban on Canadian cattle. An earlier case in 2003 prompted the ban.

The Agriculture Department is sending nine inspectors to Canada next week in response to the newest case, Loyd said. Unlike the other cases, that animal was born after Canada banned the use of cattle remains in feed, which is how the brain-wasting disease is thought to spread.

Outgoing U.S. Agriculture Secretary Ann Veneman reiterated Wednesday that the decision to lift the ban is on track. Veneman said there is no reason to change the decision, unless further investigation reveals the justification was flawed.