We could certainly pull some numbers together with that, but there's not really a one-size-fits-all answer to it. I would say it's more often categorized across the amount of gross revenue they're generating on an annual basis.
Evidence of meeting #116 for Agriculture and Agri-Food in the 44th Parliament, 1st session. (The original version is on Parliament’s site, as are the minutes.) The winning word was farm.
A recording is available from Parliament.