Almost 400 head of Canadian cattle have been slaughtered for testing of Bovine Spongiform Encephalopathy since the discovery of one infected animal last week.  According to Canadian agriculture officials, all 192 animals that made up the entire herd of the infected cow have tested negative for BSE. In addition another 180 have been slaughtered for and genetic tracing to find where and when the infected cow was born.

All cattle killed for testing come from five of the 17 farms or feedlots quarantined in the investigation. Four of those farms are located in Alberta and another farm is in Saskatchewan, where the animal spent four years.

Cattle feed from animal sources contaminated with BSE is considered the most likely cause of the infection, and officials want to trace all sources of feed that the cow received throughout its life. Canada banned the use of ruminant animal-based feed for cattle in 1997, meaning the infected cow could have eaten infected food before the ban took effect.