Among the hardest hit were the Cargill plant in High River, Alta., which shut down for two weeks before reopening at reduced capacity. The JBS Canada plant in Brooks, Alta., operated with just a single shift each day for a full month.

The restaurant chain, which prides itself on using only Canadian beef, says in a statement that its change in policy is due to limited processing capacity at Canadian suppliers.

Alone, the Cargill plant processes some 4,500 head of cattle daily or more than one-third of the country's total beef-processing capacity.