How many acres per horse in Montana?

You will need more acres per horse in the southern part of Alberta than the north. Average is around 4 acres per horse, and up to 1.5 acre per horse in the northern parts. Though that's on Excellent quality pasture: stocking rates may be a bit less on less-quality pasture. Not to mention that horses need room to run, unlike cattle, so you will need to add on a couple extra acres in addition to the amount that they will graze.