Your local or state extension agent can help you evaluate hay quality. Ideally, a horse should be fed two or even three times a day. Grain should be considered as a supplement to the fiber part of the diet. Grains should be used when additional energy is necessary or to balance the fiber portion of the diet. There are many commercial feed mixtures available and you should choose the proper one, depending on the intended use and amount of activity your horse will have.
Most feeds come in either textured or pelletted varieties and each type serves a purpose.
Likewise, there are feeds for different life stages, i.e., growing, mature, or senior. Most horses do not require additional vitamin supplements if fed the appropriate commercial feed. It goes without saying that horses should have a constant supply of fresh water. Horses on hay drink far more water than horses on pasture. It is also recommended that horses have access to a trace mineral salt block at all times.