EDMONTON, Alberta (AP)

Canada has confirmed its ninth case of mad cow disease since 2003, in an Alberta bull that died on a farm last week.

A mature bull tested positive for mad cow, or bovine spongiform encephalopathy, the Canadian Food Inspection Agency said Wednesday.

The animal's death caused it to be identified as an 'animal of interest' at the farm level as part of a national surveillance programme, said Dr. George Luterbach, the agency's senior veterinarian for Western Canada.

No human deaths

Eating meat products contaminated with BSE has been linked to more than 150 human deaths, mostly in Britain, from variant Creutzfeldt-Jakob Disease, a rare and fatal nerve disease. No human deaths as a result of mad cow have been reported in Canada.

An investigation is under way to find other animals born within a year of the bull that may have been exposed to the same feed source, Luterbach said. He would not say where in the province the animal was when it died.

"These animals are removed, destroyed, tested and disposed of in a manner that they do not enter into the feed system," he said, adding that officials are certain the bull also did not enter that system.

Eight previous cases of BSE have been detected in Canadian cattle since May 2003, when the discovery of an Alberta cow with the disease caused the United States to slam the border shut to cattle exports entirely.

The border reopened for Canadian beef from younger cattle within months of the original ban. But live cattle have only been allowed to move across the border since July 2005.

New rules proposed by the U.S. Department of Agriculture would allow exports of older live Canadian cattle to resume. They are up for public review until March 12.

Almost one-third of the Canadian beef herd and one-quarter of the total herd is estimated to have been born before 1998.