Older Canadian cattle will once again be allowed into the American market, the U.S. government has announced, saying the risk of mad-cow disease from Canada is negligible.

The imports will be allowed across the border beginning Nov. 19.

The ruling on the issue relates to cows born on or after March 1, 1999, as well as meat products from them.

The U.S. Agriculture Department's chief veterinarian, John Clifford, said Friday that the rule is scientifically based and that the risk from mad cow disease is "negligible."

Since July 2005, the U.S. has only been importing Canadian cattle under the age of 30 months.

After Canada's first mad-cow case in May 2003, U.S. officials shut the border to all Canadian cattle and beef products.

Trade resumed in 2005 for cows younger than 30 months of age, thought to be at less risk for contracting the disease.

"This rule is firmly based in science and ensures that we continue to protect the U.S. against BSE," said Bruce Knight, undersecretary for marketing and regulatory programs, in a release. "It also is consistent with our commitment to promote fair trade practices and further normalizes trade with countries that institute the appropriate safeguards to prevent the spread of BSE."

With files from the Canadian Press