What's All the Fuss About NSC?

The level of non-structural carbohydrates (NSC), the combination of sugars and starches in the diet, is an increasing area of focus when choosing a feed for your equine companion.

While all horses don’t require a low NSC diet, even healthy horses don’t necessarily thrive on super high NSC sweet feeds and straight grain diets that were traditionally fed in years past.

Unfortunately, there is no universally recognized low, moderate and high NSC ranges for equine feeds. However, the U.S. feed industry tends to categorize feeds containing less than 20% NSC as low; whereas, those with less than 12% NSC are considered very low. Concentrates with NSC levels in the 20s are often referred to as moderate and traditional performance feeds are considered high NSC feeds when they are 30+% NSC.

While some horses with metabolic issues may not tolerate a higher NSC diet, remember some horses actually do benefit from a certain amount of starch and sugar in the diet. Although NSC% is valuable information for the horse owner, we need to keep in mind the context of the amount of each individual feedstuff or feed a horse will eat each day when comparing various feed options. The NSC% in a feed product shouldn’t be the only consideration when choosing a feed. First, consider that the primary forage fed is likely the primary contributor of starch and sugar in the equine diet. Second, one must consider the amount fed of each individual feed product and add it all up to get the TOTAL NSC for the diet.

For example, lets assume that an 1100 Lb horse is consuming 2.5 % of his/her BW in grass hay that is tested and confirmed to be 10% NSC. Then he/she has the option of two performance feeds to meet his/her needs:

1) Product #1 to be fed at 1 Lbs per day with an NSC of 16% or 2) Product #2 to be fed at 5 Lbs per day with an NSC of 11%

So let’s do the math!

Hay1100lb x 0.025 = 27.5 Lbs of hay27.5 Lbs x .10 NSC = 2.75 Lbs of starch & sugar

Product #11 Lbs x .16 = 0.16 Lbs of additional starch & sugar

Product @25 Lbs x 0.11 = 0.55 Lbs of additional starch & sugar

So you can see that the hay is the primary source of starch & sugar in the diet and although Product #1 has a higher overall NSC, it has a much lower feeding rate. Thus, it contributes less starch & sugar (NSCs) than Product #2.

Both feeds (Product #1 & #2) can be great options for minimizing NSC intake, but the decision to feed one over the other is a function of the overall dietary needs of the horse.