I can't speak about the ulcers as I have no experience with them, however I have read articles that suggest alfalfa can help with ulcers due to the higher calcium content.
I guess I just wanted to say that alfalfa also helps put weight on them. We feed lots of alfalfa out west and the horses are all slick and shiny. So the alfalfa should help with both the ulcers and weight gain.
I think the person who suggested turn-out is right on track too.