Canadians confirmed an eighth case of BSE in that country last Wednesday, this one in a mature cow they believe was either born just before the ban on feeding mammalian protein or during the program's early stages.

A day later, the Canadian Food Inspection Agency (CFIA) completed its investigation into the seventh BSE case there -- confirmed July 13 -- in a cow born after the ban. As to the completed investigation, CFIA officials say: "A particular incident was documented in one commercial feed facility that may have permitted the contamination of a single batch of cattle feed with prohibited material. The entire batch of feed was shipped to the BSE-positive animal's farm. While the investigation looked at all possible routes of exposure, this particular batch of feed is the most probable source of infection. The CFIA has launched an enforcement investigation."

As for the effectiveness of Canada's feed ban, CIFA reports, "Investigators observed good levels of compliance with the feed ban at the farm, retail and manufacturing levels... In 2005, Canadian and American officials reviewed and confirmed the effectiveness of Canada's feed ban. In addition, the surveillance program continues to indicate the feed ban has prevented the level of infectivity in Canada from increasing. Nonetheless, the extremely small infective dose of BSE means even very limited opportunities for contamination may permit periodic cases."

You'll recall that, following discovery of the seventh case, USDA delayed final rulemaking to expand Canadian imports to include cattle over 30 months of age and the beef from them. There's no telling how the completed investigation and the more recent discovery will impact the proposed rule.

According to USDA officials on Friday, "USDA participated in the investigation and we're now reviewing the report to determine whether it impacts the Department's proposed minimal risk rule."