Thank you for the suggestions! I thought about alfalfa but have not switched because my two horses eat together and my other old guy should be on grass hay only. I might try hay cubes for the hard keeper, though, because they eat their grain separately...

I love the idea of three meals but unfortunately I'm gone from 7:30 AM until 6:00PM so that's not an option. I do give them hay 3x in the winter (they get a late snack). Maybe I'll add beet pulp or hay cubes if I don't see an improvement.

He's not so thin around his barrel - the worse part is actually below his hip. He looks like a rescue case! Once he puts on a few more pounds I might start riding him again (I was riding him and ponying the other on easy two mile trail rides last summer) to build up some muscle. They are turned out 24/7 on about 3 acres so moving around all day isn't really an issue for them.