Our hay does not have any alfalfa in it, so I feed alfalfa , but I don't really feed too much, and I only start feeding them in late October.
I actually prefer the alfalfa cubes, but I'd never give them to my horses as they come out of the bad. Most of the cubes are too big and too hard. So, I first put the dried beet pulp in my bucket, and then I count out only two or three of the big cubes per horse. I have 16 horses, so I usually put anywhere from 40 to 50 cubes into the bucket. Then I bring the bucket into the house in the morning after chores, fill it with water, and set it next to the wood stove.
Sometime in the late afternoon all the beet pulp and alfalfa cubes are soaked, and the cubes have fallen apart, so I give it all a good stir. When I'm ready to go to the barn in the evening I quickly drain off the excess water, and then each horse gets about three really heaping cups of this mixture; less for weanlings. It goes right on top of their grain, as I don't like them eating grain unless they've got something else in their stomachs, because of the way the grain metabolizes on somewhat empty stomachs.
They also get their feeders filled with hay, but I've found that giving them this beet pulp/alfalfa mixture and their grain makes their hay last much longer into the night. That way they will be sure to have something to nibble if they aren't sleeping or if it's really cold, and it's always really cold here this time of year!
Towards the end of March I start cutting down the alfalfa, so that by the time they are getting onto pasture for a short time every day in April, they are off the alfalfa, but they get the beet pulp all year round.