all the feed companies have websights. See what brands are local to you and read the description of the various feeds. Usually they have a recomendation for what your horse is doing.
IE I feed Legends brand foods. As that's what the local store carries. Depending on work load they either get legends performance, or legends pleasure. There's also different ones for seniors, really easy keepers, and pasture puffs.
Usually come out ahead to feed a good brand commercial feed that matches your horses needs. We get posts on here over and over about people feeding cheap feeds, or grain only, then they come on here and want cures for rainrot, bad feet, low weight, tieing up, colicy, etc etc, most of the times these problems can be traced to poor nutrition.
Oh an molasses laced oats and corn is garbage food for a horse. Sure it will add weight but that's like you eating nothing but Donuts.