I'm assuming you mean free choice loose minerals as opposed to the blocks. Animals get the amount they need much easier and more often from the loose. However are you meaning something other than the generic, found at every feed store, loose mineral? I can assure you pretty much any Canadian that raises cattle offers them free choice mineral unless they're in a feedlot or other intensive management setting where a set amount is given in their feed daily.
 
 If you mean premixes, any mill - Hi pro, Master Feeds, etc. or farm/ranch store - UFA, Peavy Mart, Co - Op, will have these in varying amounts. Most common are Breeding mineral, Dry cow mineral and lactating mineral although there are other options, each offering differing balances of minerals. (UFA won't be in Ontario and I'm not sure about Peavy Mart. I don't know the Ontario equivelants, sorry!)
 
 If you mean something like the ABC mineral program where you offer free amounts of each mineral individually then no, I don't know of any retailers who supply this sort of thing in Canada. However you can order from the 
ABC website  directly.
 
 Hope this helps!