Im about to bring my new horse home and will be boarding her. She will be a pasture horse and will be feed hay, but does she need more than just hay and grass? She's a 12 year old tennessee walker, she needs to loose some weight, and ill most likely be riding her for pleasure and trail 3-4 times a week. Will she be find on just hay and grass? The days I will be able to go out are random and I could feed her grain those days but I wasn't sure if that would cause her to get sick from the random days feeding grains. Thanks!