"At this point I've had no indication that any cohorts have been exported ... The record trace will indicate that," Darcy Undseth, a veterinary specialist with the CFIA, said of the cows, which were born on the same farm as the diseased animal. The on-going investigation was spurred after the CFIA confirmed Canada's fourth home-grown case of bovine spongiform encephalopathy, also known as BSE or mad cow disease, on a western Canadian farm earlier this week.

It is possible that some of the "birth cohort" animals, which were born within 12 months before or after the infected cow, entered the food supply, Undseth said. Health risks from any of the animals that may have been slaughtered for human or animal consumption are minimal since specified risk material, nervous system tissue that may transmit BSE, has been removed since 2003, he said.

Prior to then, most slaughtered animals were too young to be at risk of having infectious doses of BSE, Undseth said. The current whereabouts of the birth cohorts are still being traced through previous owners' records, but those found alive will be destroyed and tested.

One of the 67 animals has already tested negative for BSE. "There's very little risk of a cohort being infected," Undseth said. The birth cohorts from Canada's three other native BSE findings have all tested negative, he said. The cow's 2004 calf has not yet been located and cohort numbers could change as the investigation continues, the CFIA said.

The infected cow's 2005 calf was destroyed earlier this week, along with the other 24 cattle on the farm. All 25 tested negative for BSE. The infected cow was six years old and born after the 1997 feed ban that prohibited protein from cows and other ruminants such as goats and sheep in cattle feed, following Britain's mad cow outbreak. The ban is believed to stop the spread of BSE but not all of the old feed had been disposed of by 1997.

The infected animal did not enter the food supply, the CFIA has stated. The CFIA is investigating the feed from the infected farm.

This fourth finding came after BSE-related trade bans had started to ease. International borders slammed shut to Canadian beef and cattle after the first native case of mad cow disease was confirmed in May 2003. Canada was listed as a minimal BSE risk country and trade gradually resumed with restrictions.

Source: Reuters - 30th January 2006