The Canadian Food Inspection Agency (CFIA) this week confirmed BSE had been found in an old cross-bred beef cow in Manitoba.
The US cattle industry is now under-producing for the domestic market, falling short by three billion pounds - the beef equivalent of 3.9 million cattle.
The loss of US export markets due to BSE partially explains the reduced production and falling prices for beef in the domestic market. Increased imports from cheaper producers overseas has also hurt the domestic cattle market.
While Canada says the testing proves its beef supply is safe, cattle producers on the other side of the border claim it shows the problem is worse than thought before.
The infected cow was at least 15 years of age and was born before Canada implemented restrictions on potentially dangerous feed in 1997, said Dr. George Luterbach, a senior veterinarian with the Canadian Food Inspection Agency.
R-CALF United Stockgrowers of America, a producers association, this week called on the US Department of Agriculture (USDA) to drop plans to make it easier for more Canadian cattle to be sold into the US.
"It is clear that Canada's BSE problem is making it more difficult for US beef to get back into the markets of South Korea and Japan," said R-CALF USA president Chuck Kiker. "We need to be able to differentiate high-quality US beef from Canadian beef to gain full resumption of US exports. "
South Korea recently informed the US that it was delaying the resumption of imports of US beef because it was concerned that the country was commingling its beef with that sourced from Canada, the association claimed.
Kiker said that because USDA policies allow Canadian beef to be commingled with U.S. beef, and remain indistinguishable to consumers, the US cattle industry is unnecessarily tying its reputation to the Canadian cattle herd.
"USDA must take immediate action to protect the integrity and viability of the US cattle industry," he said.
The association wants the USDA to postpone indefinitely the agency's plans to further liberalize US import restrictions by allowing Canadian cattle and beef over 30 months of age into the country.
The association wants more stringent BSE import standards. This would include a requirement that high-risk tissues be removed from Canadian cattle at 12 months of age and a restriction on the scope of imported products, such as only boneless beef from cattle less than 30 months of age.
It wants the USDA to reverse its policy of granting access for imports before the US regains market access in foreign countries. It wants a country-of-origin labelling system to distinguish US beef from imported beef.
One of the seven Canadian-origin BSE cases was detected in the US in December 2003. The remaining six cases were detected in Canada from a test sample size of about 115,000 total cattle tested since the disease was first detected in Canada's native cattle herd in May 2003.
There has been three positive cases detected within a test sample size of 55,346 cattle tested during the past 12 months.
Canada increased its surveillance testing program in 2004. It has tested about 31,500 cattle in the first six months of 2006. Other measures, such as removal of specified risk materials from all cattle slaughtered are in place.
On June 29, agriculture secretary Mike Johanns announced that the US would now allow Canada to resume trade beef from animals over 30 months of age and all classes of US cattle, including those for breeding purposes born after 1999.