Assessing Carbohydrates in Horse FeedBy Dr. Joe Pagan · August 24, 2012
Directly measuring the amount of sugar in the horse’s ration is not easy to do and can be quite expensive. Instead, it is preferable to indirectly estimate the sugar content of feeds and forages by measuring several components of a feed and calculating nonstructural carbohydrate (NSC) content.
The equation to calculate NSC on an as-fed basis is: NSC (%) = 100 - moisture (%) - crude protein (%) - crude fat (%) - neutral detergent fiber (NDF) - ash (%). This calculation will measure all forms of sugar in the feed including simple sugars and polysaccharides such as starch. All of these carbohydrates will be absorbed as simple sugars if they are digested by the horse’s digestive enzymes, so nutritionally speaking they can be lumped into this single category.
There is a wide range in digestible energy (DE) and NSC among common horse feeds. Typically, the NSC content is lowest in straw and mature hays. Legume hays are usually higher in NSC than grass hays and cereal grains have the highest concentration of NSC. Molasses is also high in NSC, containing a level between corn and barley, but its overall DE content is lower because it contains 25% water.
As a rule, the lower the cell wall content of a feed, the higher the NSC and energy density. This is because horses digest over 95% of the NSC and typically only about 40 to 50% of the cell wall. There are certain feedstuffs, however, that contain much more digestible cell wall such as beet pulp and soy hulls. These “super fibers” have digestible energy values that are intermediate between hays and cereal grains.