I remember reading somewhere one time that if you give horses alfalfa that are already on pasture all day with rich grass it can cause them to founder. My question is this. My horses are on pasture all day. We order hay and it gets delivered. The batch of hay we just got is supposed to me O&A, but it looks like straight Alfalfa. This worries me because my horse Abby is a little over weight and I don't want her to founder or my mom's horse Charlie, or any of the horses out there for that matter. So can Alfalfa along with being on pasture with good grass cause a horse to founder?