Canada’s food safety watchdog says a small amount of leftover contaminated feed was the most plausible cause of mad cow disease discovered last February on a farm near Edmonton.

The Canadian Food Inspection Agency released a report Monday that says no part of the Black Angus beef cow entered the human food or animal feed systems.

The report says no significant events could be linked to the discovery of bovine spongiform encephalopathy (BSE) near Edmonton and no other sick animals were found.

The February case — the 19th in Canada — prompted a few countries to place temporary restrictions on Canadian beef imports.

An investigation report says the cow was born at a nearby farm almost two years after Canada brought in more strict controls on animal feed to prevent BSE. A previous case was diagnosed on the same birth farm in an animal born in 2004.

“No significant events could be linked with this case but the potential for the carry-over of a small amount of residual contaminated feed could not be discounted,” says the report.