I will personally stick with Ration Balancers from now on! Right now I feed Enrich 32 as it's the only one available to me. I LOVE the results I get with it! I have a 5yr old barrel prospect on it and two coming yearlings on it as well.
For extra calories I give oats as I don't have a lot of options here. The babies get MAYBE 1lb a day simply as a treat. My mare just got upped and will be getting about 2lbs a day.
FeedXL program online works wonders. Will let you know when minerals are low or too high and what it needs. All of my friends use it as well as me and is highly recommended by everyone I talked to about it as well as the site. Costs only a small bit for a month in which you can create diets for a whole year just by changing the grass legumes intake.... brilliant program!!!!
I also would recommend adding more hay but I would add Total Equine to the feed program as well as a table spoon of baking soda and a table spoon of whole flax seed. The latter two additions will help your horse with the fermentation gasses that are produced by the hay and hindgut stress created by the hay. The total equine will provide a level base of nutrients and energy that are sometimes lacking in the hay quality over the course of a year.
Hope this helps!