WASHINGTON – The United States tightened country-of-origin labeling provisions to specify where animals are born, raised and slaughtered after the World Trade Organization backed complaints from Canada and Mexico that challenged the policy.

The rule also bans the mingling of meat cuts of commodities from different nations, according to U.S. Department of Agriculture regulation to be published in Friday's Federal Register. The measures and adjustment expenses will cost meatpackers as much as $192 million, according to the USDA. Canada may challenge the U.S. again at the WTO, Agriculture Minister Gerry Ritz said.

The labeling provision has led many U.S. meatpackers to stop buying animals born in Canada, costing that nation's livestock industry millions of dollars, according to Canadian farmer and rancher groups. Canada and Mexico told the WTO the label program is unfair to their products.

"USDA remains confident that these changes will improve the overall operation of the program," Agriculture Secretary Tom Vilsack said Thursday. The revised rule will bring the labeling program "into compliance with U.S. international trade obligations," he said.

Under U.S. law in force since 2009, food processors must identify the nations where cattle, hogs and some fresh produce originate. The legislation was introduced in response to the discovery of bovine spongiform encephalopathy, or mad cow disease, in a Canadian-bred animal in 2003.

Canada and Mexico said the label requirement impose unjust costs on their exports. WTO judges agreed last year that beef and pork from Canada and Mexico were treated less favorably than the same U.S. products.

Canada's Ritz said he's disappointed with the U.S. move because both Canadian and U.S. processors and retailers oppose the labeling provision.

"It's a solution that no one is looking for," Ritz said. "Even customers aren't demanding this."

The National Farmers Union, a U.S. group that has supported the labeling, in a statement welcomed the move to tighten rather than scrap the rule, an approach the Mexican and Canadian governments have criticized.