Depending on what your horses are doing will depend on what grain to give. If you want something that is just like a filler then I would just feed a supplement grain. Its not relay grain and both nutrena and Purina sells a type of feed like that. I think Purina is called naturals essentials, and it comes in i think 3 bags. (Have not look in some time) Depending on what your horses need. If your horses are just pasture horses then grass and the supplement should be fine. However if they work then thats a whole new topic. Depending on what they do, how many hours.... So forth. Let me know.