I recommend harder/longer workouts to lose weight and SupperSport by Purina to build muscle. It also helps with the lactic acid build up in the muscles during workouts with its amino acid support!
We use Lucerne hay or pressed because of the protein
We have a very good product to help your horse to build muscle.
It's EQUISTRO MYO POWER.
Find more information here : http://www.equistro.com/products/equistro-myo-power