She needs turnout time, lots of it, and as much hay as she can eat, preferably grass hay or alfalfa/grass mixed hay. Some Alfalfa is fine, but it shouldn't be the sole source of forage in her diet. I don't like feeding more than 7 lbs of Alfalfa a day (about 1 heavy flake or 3 two qt feed scoops of Alfalfa pellets).
Cut out the grain completely. I would feed her a vitamin supplement or a ration balancer (pelleted feed that only need to be fed at the rate of 1-3 lbs TOTAL per day) mixed with beet pulp (that has NO molasses), 1-2 lbs of stabilized rice bran, and a probiotic (digestive aid, like Probios Powder, Fastrack, or Source Focus WT).