Grass hay tends to be higher in calcium than phosphorous, but the ratio between the two is fairly narrow. If you add more than about a half pound of rice bran to that, you can push the phosphorous up to a level that would get into the danger zone, especially if you're feeding grain or a bran product that's not fortified with calcium.
If your horse is losing weight or is sluggish, you may need to add grain to his diet. Now you have to decide if you want a sweet feed or pelleted product. Sweet feeds containing molasses are useful for more sluggish horses because they have more carbohydrates (sugars), which may make your horse a little more energetic. Anecdotal evidence shows that some horses get more active and reactive when fed a sweet feed versus an extruded (a processed feed similar to pellets but less dense) or pelleted product, which is lower in sugar but provides the same amount of energy per pound. Oats are not a high-energy feed. Either whole or crimped, one pound of oats contains just about the same amount of energy as one pound of excellent quality hay.
Corn is a perfectly good feed for horses, but people have gotten into trouble by not understanding it. A one-pound coffee can filled with corn contains two times the amount of energy as the same amount of oats, and if you suddenly feed the corn in the same amount as you do oats, a horse can get into trouble and even founder. Corn also is prone to mold. There are many concentrate mixes out there that contain a mixture of corn, oats and/or barley with added vitamins and minerals. Choose one from a reputable company that is designed specifically for the athletic horse.
Your feed room should have one closed container for grain, if your horse needs it, with a couple of bags of hay cubes in case your hay is not the best quality. There should be extra salt blocks and some electrolytes to replace essential compounds lost through sweating for days when your horse works extra hard. That's really all you need. Except for the most stressed-out horses, vitamin and mineral supplements are unnecessary if you're using good quality hay and feed.
The bottom line is that your horse needs good quality hay or pasture, a 10 to 12 percent protein concentrate feed in amounts necessary to maintain good body condition (usually no more than 4 or 5 pounds per day, divided into two feedings), salt and water. You should alter fat levels only if your horse is losing weight.
Sarah Ralston, VMD, PhD, is board certified by the American College of Veterinary Nutrition and is an associate professor in the Department of Animal Science at Rutgers University. She was trained in dressage to Grand Prix.
This article first appeared in the January 2000 issue of Dressage Today magazine.
