Heart and respiration rates of fat horses take longer to return to normal, which indicates they aren't properly conditioned. Overweight, non-conditioned horses fatigue quicker and are more likely to have serious injuries. A conditioning and training program should reduce the body fat of horses, while getting their cardiovascular, muscular and skeletal systems ready for performance. Proper feeding is important to keep performance horses cool in the summer. Oats isn't a cool grain.
Corn is a cooler grain to feed in summer than oats.
But don't feed more than about 23 percent of corn in a ration. Fat added to the ration at 6-8 percent helps provide more energy for performance and aids in keeping horses cool, too. It takes about 30 days for horses to adapt to fat-added rations. Feed a fine, high-quality hay, too. Coarser hays produce more internal body heat.