Carbohydrates in Horse Diets

There is a lot of discussion these days about carbohydrates, the good and the bad.  In reality, they are all related.  Carbohydrates contain carbon, hydrogen and oxygen in varied chemical relationships. 

  • Sugars are the simplest of the carbohydrates and can be simple sugars such as glucose or more complex sugars. 
  • Starches are strings of sugars linked together in such a way that most starches can be broken down into glucose by the action of enzymes, primarily amylase. 
  • Fibers (lignin, cellulose, hemicelluloses etc.) are also chains of sugars that cannot be broken down easily by enzymes and must be fermented by the animal to release the energy. 

Starches and sugars are produced by plants as a means to store energy, so they contain energy that is more readily available than the energy in fiber.

Because horses produce less amylase, the enzyme used to break down starch, than some other animals, say perhaps pigs, they are more limited in their ability to digest large quantities of starch. However, they digest smaller quantities very efficiently and very effectively! 

Starches and sugars are a fairly concentrated source of Calories to be used as a source of energy when extra energy is required to maintain body condition and do more work.  In the wild, horses would consume seed heads (grain) when available in the fall to help them gain weight (added Calories) to be ready for winter, so starches and sugars are a part of the diet in horses in the wild.  Today’s working horse requires Calories, and a combination of fiber, starch, sugar and fat can be the best way to support the horse to maintain the balance of optimal health and optimal performance.

Fiber in Horse Feeds

In our previous post, we learned what fiber is and how a horse digests it,and we also learned that a horse consuming 1-1.5% of it’s bodyweight in quality roughage will satisfy its daily fiber requirements.

When it comes to any grain sources that may be added to your horses diet, fiber plays a much smaller role since the amount of fiber that is added by grains is relatively little, but the effect and digestive process is similar. 

When feeding the grain portion of the diet, ensure that your horse is not receiving high quantities of grain meals all at once – typically no more than 5-6 pounds of grain per meal at most. Because grains tend to be higher in starch than roughage, feeding too much at once can overwhelm the small size and quick rate of passage of food through the stomach and small intestine, and allow starches to pass undigested to the hindgut. Digestion of starches in the hindgut releases lactic acids that are toxic to the fiber-digesting microorganisms, which can result in a gas colic episode or laminitis.

Generally speaking, when you look at a the tag from a basic equine ration, the higher the crude fiber level listed, the lower the energy content of the feed.  Of course, there are other factors that must be looked at, such as the fat level, and also possibly the sources of fiber. 

Beet pulp, for example, is often referred to as a “super-fiber” due to the high level of fiber it provides while also providing roughly the same energy level as oats.  While soy hulls and dehydrated alfalfa are common ingredients used to increase fiber levels, a performance horse ration with a higher fiber level may make use of beet pulp to achieve both increased energy and increased fiber levels.