What is your horse currently eating? What are you looking to find for your horse? How often do you come to the barn, thus how often do you think you'd be giving your horse some feed? Does the horse currently get any feed, supplements? What kind of hay and how much? Is the horse on pasture, what are the stats of the horse, age, breed, body condition?
A ration balancer might be a good choice for your easy keeper, in this case TC lite, or TC 30% could be a wonderful addition to your horses diet. These choices are low in fat, low in starches/sugars and will supply vit/mins to your horse, you don't need to feed very much of either. TC uses fixed formulations, the feeds contain biotin, probiotics, digestive enzymes, organic minerals, mycotoxin binders.
Check out the website to learn more: http://www.triplecrownfeed.com
I feed my easy keeper and growing youngster (who's pretty much an easy keeper), TC 30% and whole oats. They get most of what they need from 1 1/2 pounds of 30% a day and I add oats as needed if they need extra calories.