Released May 2, 2007
BROOKINGS, S. D. -- What do you do when forage alone is not enough to meet horses’ nutritional needs? Most often the answer contains the phrase “Well, it depends,” as horses on average voluntarily consume 1.5 to 2 percent of their body weight daily, and in grazing situations may consume three percent of their body weight of air dry forage depending on the forage digestibility, physiologic state and the associated passage rate. Concentrates for added energy should be included sparingly, and oftentimes improving forage quality will address the horses’ increasing nutritional demands. If you find that advice as clear as mud, you are not alone.
Horses are classified as non-ruminant herbivores, meaning they do not have a complex multi-chambered stomach like that of cattle, but still primarily consume forages. This type of digestive system has many advantages, notably the fact that they are not packing around the equivalent of a 55-gallon drum of stomach contents. Conversely, horses’ stomachs and small intestines digest available sugars and protein very efficiently for energy and tissue repair right away, and the leftover insoluble fiber is subjected to fermentation in the large intestine, further utilizing the energy potential of these structural carbohydrates.
These advantages that allow horses to move gracefully and athletically also explain why horses are often affectionately referred to as “hay burners,” and why they’re sometimes chided for the inordinate amounts of forage they appear to have the ability to consume. Because of their relatively small stomachs, horses forage constantly, up to 20 hours a day, and are programmed to be highly selective. Given the opportunity they will pick and choose leaves and tender stems while casting aside the coarse mature stems and any other foreign material that may be presented to them. Waste can be considerable in free choice situations, and this often contributes to the assumption that horses consume excessive amounts of forage.
Weather systems can also affect eating habits, triggering increases in consumption. Similarly, periods of extended cold weather increase horses’ maintenance requirements because the temperature drops below their thermal neutral zone. Likewise, increased activity may also stimulate increases in intake in an effort to meet the increased energy demands. Inclement weather, for example, may prompt some owners to change diet and reduce exercise on the assumption that these decisions are in the best interest of the horses. That’s not necessarily the case.
Unlike cattle, horses are unable to effectively ruminate (chew their cud) or eructate and acute pain associated with a digestive disorder, termed colic, may coincide with events such as those described above. Colic can be a result of excess gas production associated with fermentation, compaction attributed to a reduction in water consumption or excessive intakes of low quality forages, or a restriction resultant from lack of gut fill.
During spring, increased recreational activity, cyclic nutritional demands, and unpredictable weather extremes may necessitate changes to your horses’ diet. In these instances when intake alone will not meet the increased energy demands, make diet changes gradually, maintain exercise routines, and be sure horses have access to free choice water.
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Contact: Mark Ullerich, SDSU Extension equine specialist, (605) 688-5412, mark.ullerich@sdstate.edu
