There’s an incredible amount of faulty information and faulty thinking about feeding horses, and some of our traditions are simply not in our horses’ best interest. This month I thought I’d talk about the horse’s natural diet and how the horse’s digestive system is designed to work, as the foundation for healthy feeding practices.
The horse’s natural diet
Horses are herbivores, meaning that they are designed to get all of their nutritional needs from plants. One of the hallmarks of the horse’s natural diet is variety. Whether grazing prairies or woodlands, wild or feral horses choose from at least 40 different types of plants. That strategy makes good sense because the more variety in the diet, the less chance there is for nutritional deficiencies to occur.
The horse’s natural diet mostly consists of grasses, but it also includes lots of other meadow and woodland plants, and it comprises not just leaves but stems, flowers, fruits, roots, bark, twigs, and even lichens. This too is a way that variety comes into play.
Another hallmark of the horse’s natural diet is that it contains lots of live plant material. Except in the dead of winter, most of the diet consists of fresh, living plant material that is rich in vital nutrients. Some of these nutrients are lost or inactivated when the plant dies or is harvested and stored for months. Just as it is with our own diets, fresh is best.
A third characteristic of the horse’s natural diet is that for most of the year it is high in fiber (mature grasses and other plants) and low in starchy and sugary foods such as grains (starchy) and lush grass (sugary). The horse’s digestive system, from teeth to tail end, is designed to make good use of this high-fiber diet, so the average horse can easily maintain a healthy weight on this diet without needing high-calorie foods such as grains.
A fourth characteristic of how horses naturally eat is that they graze or forage for food fairly continuously, for most of the day and night. Horses are not meal feeders like we are and like dogs, cats, and wild carnivores. Their entire digestive systems and feeding behaviors are geared toward fairly continuous intake of small amounts of food. Another important point is that horses graze mostly at or near ground level, not at chest height or above. Grazing for most of the day and night also means that the horse is moving around slowly for most of his waking hours.
The horse’s digestive system
As you can see in the diagram, the horse’s stomach is relatively small and the large intestine (the combination of cecum and large colon) is huge. Horses rely on the bacteria, protozoa, and other micro-organisms in their large intestine to break down dietary fiber and release nutrients that the body can then use. For horses, fiber is not just filler; it’s food.
Horses do have a long small intestine (about 75 feet long in the average size horse), and essential digestive processes go on there. The small intestine is the main site for digestion and absorption of starches and sugars, proteins, fats, vitamins, and minerals. However, there is a limit to the amount of nutrients the small intestine can digest and absorb as food moves down the digestive tract.
When a horse eats a meal containing a lot of starchy or sugary food, some of those starches or sugars will not be absorbed in the small intestine and will get dumped into the large intestine. In large amounts, starches and sugars play havoc with the microbes in the large intestine and with the health and function of the large intestine itself. Immediate effects include digestive upsets (colic, diarrhea, poor feed efficiency) and sometimes laminitis (“founder”). Less obvious but no less problematic are the health consequences of a chronically disordered intestinal tract, which range from allergies to arthritis.
Healthy feeding practices
Our horses do best when we feed them in a way that mimics their natural diet and feeding behavior as much as possible. That means providing lots of variety, not just one type of hay. Try to feed at least two different types of hay (e.g. orchard grass and timothy) as well as a little alfalfa. Quality is important, but so is variety.
Matching the natural diet means allowing the horse to graze on at least some fresh, living plant material each day. When pasture turnout is not available or not safe for your horse (something I’ll talk about at the end), then take him for a walk among the “weeds” each day and let him graze on what’s there. What you and I may consider weeds may be good food for your horse and provide something that is sorely lacking in his diet.
As the average horse’s diet is so lacking in variety and as most pastures and even hays may not fully meet the horse’s needs for vitamins, minerals, antioxidants, and other essential nutrients, I usually recommend feeding a good quality multivitamin-mineral-antioxidant supplement, such as Platinum Performance Equine. I also like to feed a blend of dried meadow herbs, in addition to or in place of the supplement.
Matching the natural diet also means feeding mostly high-fiber foods (e.g. mature pasture grasses and hays). Starchy or sugary foods that should be fed to horses in very limited amounts, if at all, include grains, molasses, and for some horses at certain times of the year, grass (I’ll explain why in a minute).
Grains include corn, oats, wheat, barley, rye, millet, rice, and sorghum. Whether they’re fed whole, broken up, or ground and mixed into a pellet, grains should be fed only as a supplement, when more calories are needed than the horse can get from forages (pasture and hay). But in most cases, increasing the amount of hay and adding a high-fat food (e.g. rice bran, vegetable oil, a fat-supplemented low-starch performance feed), or even beet pulp, is better than feeding a lot of grain.
Matching the horse’s natural feeding behavior means following the old horseman’s saying, “Feed little and often.” Horses do not do as well with meal feeding (e.g. a couple of large meals each day) as they do when hay or grazing is provided most of the time. Allowing the horse to graze or munch on hay for most of the day and night makes for a healthier digestive system and a calmer, happier horse. And while we’re at it, putting the horse’s food at ground level is better for the teeth, neck, and back than feeding at chest height or in a high hay rack or hay net.
If your horse is overweight or likely to become overweight when hay or grass is available for most of the day and night, then limit the total amount of hay fed or pasture turnout time per day. (Also add more exercise to his daily routine.) But still try to make it so that your horse has some food available most of the time. For example, the average size horse needs 15–20 lbs of hay per day if he has little or no access to good pasture. Divide that total daily hay ration into 3 or more feedings, and spread them out through the day and night.
I want to finish with a caution about fresh grass. Pasture grasses these days are not the same as the native grasslands on which horses have lived for millennia. In the spring and autumn especially, modern pasture grasses can have a very high sugar content, which is a problem for horses who are overweight or prone to laminitis. In these horses, grazing time should be limited or a grazing muzzle used during pasture turnout. I much prefer the grazing muzzle option for most horses, because the horse can still be turned out to move around and can still get a little fresh plant material, but you’ll be limiting how much of the high-sugar grass he eats. For most horses, a grazing muzzle is a much healthier alternative to being banished to a dirt lot.
