Agriculture Secretary Mike Johanns (search) began his new job Monday caught in a dispute between meatpackers and some ranchers over reopening U.S. borders to cattle from Canada.

He also faced reluctance in Japan to resuming imports of U.S. cattle.

Johanns told reporters that in the aftermath of a new case of mad cow disease (search) discovered in Canada on Jan. 11, U.S. inspectors were traveling there Monday to investigate that country's compliance with its 1997 ban on putting cattle remains in feed. The brain-wasting disease is thought to spread through infected animal parts added to animal feed.

"It is my goal here to make sure that I look at everything that is available, that I look at what the team finds in Canada, that I make sure that my briefings are thorough, and that I've got all the information at my disposal," Johanns said on his first day at the Agriculture Department.

The newest Canadian animal to test positive for the disease was significant because, unlike in two earlier cases, it was born after the feed ban. Canadian officials said it probably had eaten feed manufactured before the ban. A cow in which the disease was confirmed Jan. 2 came from the same herd as six cows that were shipped to the United States.

Mad cow disease is formally known as bovine spongiform encephalopathy (search). The illness raised great concern when a form of it passed to humans in England in the 1980s and 1990s. It has killed more than 150 people, including a woman in the United States who died last June after being infected years earlier in England. The human form of BSE is known as variant Creutzfeldt-Jakob disease.

Imports of live cattle from Canada are scheduled to resume on March 7, and the Bush administration has indicated the border will reopen as planned unless investigators determine that it should stay closed.

The administration's announcement on Dec. 29 that it was reopening borders to Canadian cattle set off protests from cattlemen in the Plains states.

A cattlemen's group filed a lawsuit on Jan. 10 to stop the Agriculture Department from allowing the import of live cattle from Canada, saying both U.S. producers and consumers would be jeopardized.

The same group, Montana-based R-CALF United Stockgrowers of America (search), filed a lawsuit last year that prompted the Agriculture Department to halt imports of Canadian ground beef and other products until it completed a rule-making process to allow Canadian imports, which it did Dec. 29.

Senators from Plains states introduced legislation Monday to keep the border with Canada closed to live cattle imports until the United States implements country-of-origin labeling of food, which is to begin in 2006. Similar legislation is pending in the House.

Johanns couldn't say when Japan would resume buying U.S. beef despite agreeing last October to lift the ban it imposed after the discovery in December 2003 of the lone case of mad cow disease in the United States.

Resuming beef trade with Japan is "priority one," Johanns said. Japan, which had been the top customer of U.S. beef, agreed to reopen its market, but slow negotiations have kept that from happening.

The talks, delayed by conflict over how to determine the age of cattle, are delicate enough that Johanns is against naming a special envoy to Japan on the issue.

"You'll find that I don't put a lot of ego into this job; I'm thrilled to get whatever help I can, but quite honestly, I would worry that that might be viewed as an opportunity to pull back, reassess, re-examine, et cetera, and I just don't want that to happen," Johanns said. "I feel very, very strongly that we've had over a year here, and it's really time to ink the deal and move forward."