I feed my horse grain once a day, only because she is still growing. Personally I think that a lot of people feed way to much grain, but I do agree that if you are going to feed grain, unless you stop working the horse for a week or more at a time, that you should not stop feeding grain for a day or two and then feed it again. Most horses should be getting all the nutrients they need out of the hay they get, generally a mix of alfalfa and grass, or something like that, and don't need all the extra grain. The obvious exceptions being horses that are still growing and often pregnant mares, horses that are in heavy work/competition, and horses that are thin, or hard keepers. I don't have my hay tested, though it is a good idea if you are able, but as long as it isn't obviously poor quality, I believe that between that and the mineral and salt blocks my horse has, that she gets enough nutrients to keep going in a moderate amount of work if she weren't still growing. She gets 2 1/2 lbs of Omelene 300 for right now, but once she's done growing, no more grain until she starts doing heavy work, and competing regularly. I read a good book Understanding Equine Nutrition, by Karen Briggs. Great book, and maybe that would help both you and your dad. Sorry for such a long post.