The type of feed the horse eats is what determines what fuel is available for the horse to use during exercise. So it is important to figure out the optimal diet for your horses. Although there has been research showing the benefits of fat supplementation over feeding grain in equine diets, many people still prefer to add grain to the diet thinking it is better for their horses. This paper is one of the more recent showing that fat supplemented horses used less glucose during endurance exercise than the horses whose diet was supplemented with sweet feed. That means that that their limited glycogen stores are used up faster than when they are fed the higher fat diet. So, it is the horses fed higher fat without the grain whose energy systems will benefit in endurance exercise. And on top of what to feed for best performance is that the traditional high grain diet may be a root cause of many problems, including laminitis, obesity, diabetes and tying up.