Different grain feeds provide different supplements for your equine (sugar, salt, protein, etc). Sugar makes your horse "hot" or high spirited, salt is a good management tool that helps your digestive system but also relaxes muscles and joints, and protein provides amino acids for your horse and helps build bones, muscles, and the body soft tissues. If
my horse eats a sweet cob grain to hours before a race, then
she will be high spirited and ready to run a fast pattern because
of the high sugar content.