WASHINGTON (AP) - Canadian cattle over 30 months of age will be allowed into the U.S. market starting Nov. 19, the Agriculture Department said Friday in expanding its policy on mad cow disease.

In May 2003, the discovery of an Alberta cow with mad cow disease caused the United States to slam the border shut to cattle imports from Canada.

The border between the world's largest trade partners reopened for Canadian beef from younger cattle within months of the original ban. Live cattle under the age of 30 months have been allowed to move across the border since July 2005.

North Dakota Agriculture Commissioner Roger Johnson said cattle producers should be "deeply disappointed" by the decision.

"Until Canada can prove that they are strictly enforcing the proper safeguards, it is risky to allow these higher-risk animals into the U.S," Johnson said in a statement. "Infected Canadian animals have already been responsible for millions of dollars in lost U.S. exports."

"USDA should take all steps to immediately and fully implement mandatory, country-of-origin labeling to avoid weakening our standards on Canadian beef imports," he said.