U.S. Agriculture secretary Michael Johanns opened the border to Canadian cattle hours after a federal appeals court dismissed arguments that imports could spread Mad Cow Disease.

American officials were already in contact with the Canadian Food Inspection Agency to prepare to certify cattle for shipment, Johanns said.

"Because the (court) ruling is effective immediately, we are immediately taking steps to resume the importation of cattle under 30 months of age from Canada."

Manitoba Agriculture minister Rosann Wowchuk said there are still likely a few details to work out.

"I don't expect the trucks will start to roll tomorrow," she said. "But this is very good news for Canadian producers."

Devastated by the ban on cattle that began after Canada's first Mad Cow case in May 2003, Canadians were jubilant.

However, they tempered their reaction by warning that there is another legal hurdle to cross on the long-term fate of the border later this month.

The unanimous decision by a three-judge panel of the 9th U.S. Circuit Court of Appeals was released after a one-day hearing in Seattle.

The court overturned a March ruling by Montana judge Richard Cebull, who sided with the protectionist ranchers' group R-CALF and temporarily blocked the border from reopening as expected.

Cebull is holding his own hearing on the issue July 27 in the Billings district court, where R-CALF will argue vigorously for a permanent ban on Canadian cattle and beef products.

"It was what we were hoping for and what we anticipated," Saskatchewan Agriculture minister Mark Wartman said of the appeal court's decision.

"It's a piece of good news, and it will be interesting to see how that affects the court ruling on the 27th."

Wartman said he expects "cattle should be moving quickly."

Canadian Cattlemen's Association president Stan Eby said the group is "very pleased and very excited. This is wonderful news that has been long awaited. We are not out of the woods completely on the legal front, but we feel this is a strong message from the Court of Appeal to the court in Montana."

Canada Beef Export Federation president Ted Haney called the decision "very encouraging."

"This is very positive and takes us one step closer to resuming at least restricted trade in live cattle to the United States."

The ruling applies to younger cattle thought to be at lowest risk of contracting Mad Cow.

Most cattle sales take place in late summer and early fall, said B.C. Agriculture minister Pat Bell, "so we are ideally positioned to take advantage of this opening. I think it just spells great news for our ranchers. They can really look forward to having a positive year this year."

At the appeal hearing, R-CALF argued that dropping a ban on cattle "would subject the entire U.S. beef industry to potentially catastrophic damages."

The group also argued that Canadian imports present a "genuine risk of death for U.S. consumers" and the U.S. Agriculture Department erred in trying to reopen the border.

However, U.S. government lawyer Mark Stern slammed R-CALF for using questionable scientific reasoning to justify a continued ban.

"Their risk assessment assumes everything goes wrong," said Stern, and does not take into account all the safety improvements America has made. Like Canada, the U.S. restricts animal tissues from cattle feed, thought to be the primary way that Mad Cow, or bovine spongiform encephalopathy, is spread.

The judges said they would issue another ruling soon explaining their rationale

"We are disappointed," R-CALF head Bill Bullard said. "The (appeal court) gave no reasons for their action, so there isn't much we can do until we see those reasons. R-CALF is confident that when we have a full hearing on the merits of the case, we will demonstrate to (Cebull) that USDA's actions are premature and unjustified."

Canadian ranchers estimate they have lost C $7 billion ($5.8 billion) in the trade tangle, while U.S. meatpackers are going out of business and have lost some 8,000 jobs without a steady supply of cows.

Patrick Boyle, head of the American Meat Institute, said his group is "grateful that the court has ruled on the side of science."

"The legal stonewalling that R-CALF has engaged in has done real harm, but today's ruling will help the industry rebuild. It's a great -- and long overdue -- day for the beef industry and for consumers."