WINNIPEG, Man. — Shortly after announcing increased feed ban restrictions to further lower mad cow disease rates, two such cases herded the attention of the Canadian Food Inspection Agency (CFIA) at the National Reference Laboratory in Winnipeg.

Last week the lab confirmed a suspected case of bovine spongiform encephalopathy (BSE) in a mature cross-bred beef cow from Manitoba. This week the lab is currently analyzing samples from a 50-month old dairy cow from Alberta, as preliminary tests were not able to rule out BSE.

CFIA officials have stated that the detections are consistent with a low level of disease and do not indicate an increased risk of BSE in Canada.

Both cases were identified through the national BSE surveillance program. Canada’s surveillance program, which targets cattle most likely to be affected by BSE, has tested more than 115,000 animals since Canada’s first BSE case in 2003.

In the Manitoba case, the animal was purchased as part of an assembled group of cattle in 1992. Being at least 15 years of age, the cow would have been born well before the 1997 introduction of Canada’s feed ban. As a priority, investigators are attempting to locate the birth farm, which will provide the basis needed to identify the animal’s herdmates and feed to which it may have been exposed at a young age.

Given the animal’s age, investigative efforts may be constrained by few surviving animals and limited sources of information, such as detailed records. A calf born to the affected animal in 2004 is also being traced.

In Alberta, the animal under investigation is reported to be a 50-month-old dairy cow and born after the 1997 feed ban. Officials suspect the animal was exposed to the BSE agent during its first year of life.

An investigation to examine possible routes of infection has begun on the farm. In addition, the CFIA will identify other animals of equivalent risk, namely cattle born on the same farm within 12 months before and after the affected animal.

In both cases the CFIA has stated that no part of the cows entered the human food or animal feed systems.

In late-June the CFIA unveiled new measures to strengthen Canada’s feed controls. Cattle tissues capable of transmitting BSE will be banned under the new controls from all animal feeds, pet foods and fertilizers.

The enhancement will not go into effect until July 2007, but according to CFIA officials, the move will significantly accelerate Canada’s progress toward eradicating the disease by preventing more than 99% of any potential BSE infectivity from entering the Canadian feed system.

The banned tissues, which are known as specified risk material (SRM), have been shown in infected cattle to contain concentrated levels of the BSE agent. This measure is internationally recognized as the most effective way to protect the safety of food from BSE.

“This ban tightens already strong, internationally recognized feed controls and shortens the path we must follow to move beyond BSE,” stated Chuck Strahl, Minister of Agriculture and Agri-Food and Minister for the Canadian Wheat Board. “Preventing all these materials from entering the animal feed chain minimizes risks and demonstrates the commitment of Canada’s new government to take necessary, science-based actions to address BSE.”

Canada’s current feed ban has prohibited the use of SRM in feed for cattle and other ruminant animals since 1997. Extending SRM controls to all animal feeds attempts to address potential contamination that could occur during feed production, transportation, storage and use.