I don't know about feeding alfalfa pellets. We don't let our chickens free range either. They are in a movable chicken tractor, but they clean up the grass long before I get around to moving it again. I try to pick some clover and grass for them each day. I plan on adding a portable chicken tunnel connection to the chicken tractor using some 5 ft. high welded wire fencing bent into an arch and held that way by some pieces of PVC pipe with the ends notched and zip tied to the wire..I added some alfalfa to their feed when they were chicks. So I don't think you have to wait that long. Are the pellets huge? If so just break them up and add a little water. You can add it to the ferment or not. I think they'll like it either way.