EquineWhat Is NSC in Horse Feed? Sugar and Starch Explained
If your horse is insulin resistant, has foundered, or just gets fat easily, you've probably heard someone say "keep the NSC low." This guide explains what NSC in horse feed actually is, why it matters, where it hides in your horse's diet, and how to read the numbers without a nutrition degree.
- NSC stands for non-structural carbohydrates: in practice, sugar plus starch.
- Sugar and starch raise blood sugar and insulin faster than fiber does, which matters most for horses with insulin resistance, PPID or a history of laminitis.
- Hay and pasture usually supply more sugar and starch than the bagged feed, because horses eat so much more of them.
- Add starch + sugar on a feed tag to estimate NSC. Many tags don't list them at all.
- A whole-diet target around 10–12% is often mentioned for sensitive horses, but your vet should set the right target for your horse.
What NSC means
NSC stands for non-structural carbohydrates. These are the carbohydrates a horse digests mainly in the small intestine, where they break down into glucose (blood sugar) relatively quickly. The two main groups are:
- Sugars, including simple sugars and fructans. Molasses is almost all sugar.
- Starch, the energy store in grains like corn, oats and barley.
The other carbohydrates in feed are structural carbohydrates: the fiber in plant cell walls, such as cellulose and hemicellulose. Horses can't digest fiber with their own enzymes. Instead, microbes in the hindgut ferment it slowly into volatile fatty acids, which provide steady energy without a big rise in blood sugar. That's why hay, beet pulp and soybean hulls are often described as "safe" energy sources.
WSC, ESC and starch: the lab terms
If you've seen a hay test or a technical feed sheet, you may have seen these abbreviations:
- Starch: measured on its own.
- ESC (ethanol-soluble carbohydrates): mostly simple sugars. This fraction is most closely tied to blood sugar and insulin responses.
- WSC (water-soluble carbohydrates): simple sugars plus fructans. WSC is always equal to or higher than ESC.
Because of this, you'll see NSC calculated two ways: ESC + starch or WSC + starch. Many veterinary guidelines for metabolic horses use ESC + starch. When you compare numbers, check which one you're looking at, because WSC + starch can be several points higher for the same hay.
Why sugar and starch matter for horses
When a horse eats sugar and starch, glucose enters the bloodstream and the body releases insulin to move it into cells. In a healthy horse fed sensible amounts, this is normal.
The concern is horses with insulin dysregulation, the core problem in equine metabolic syndrome (EMS) and common in horses with PPID (Cushing's disease). These horses release unusually high amounts of insulin in response to sugar and starch, and high insulin is strongly linked to endocrinopathic laminitis, the most common type of laminitis. That link is the main reason vets recommend lower-NSC diets for these horses.
Sugar and starch matter for other horses too:
- Large starchy meals can overwhelm the small intestine, so some starch reaches the hindgut. There it ferments rapidly, which is linked to digestive upsets, colic and hindgut acidosis.
- Gastric ulcers are associated with high-starch, low-forage diets.
- Horses with certain muscle disorders, such as PSSM, are often managed with low-starch, higher-fat diets.
- Easy keepers gain weight readily on calorie-dense, starchy feeds.
Where NSC hides in your horse's diet
It's easy to focus on the bagged feed and forget the biggest part of the diet. Here's a rough picture of typical sugar + starch ranges. Real values vary a lot by product, field, cutting and season.
| Feed | Typical sugar + starch | Notes |
|---|---|---|
| Corn | Very high (often 60–70%+) | Mostly starch |
| Oats | High (often 40–50%) | Traditional grain |
| Sweet feeds | Often 30% or more | Grain plus molasses |
| Low-starch pelleted feeds | Often about 10–20% | Check the tag or maker |
| Ration balancers | Often about 10–20% | Fed in small amounts |
| Grass hay | Often about 8–18%, sometimes higher | Only a test tells you |
| Spring or fall pasture | Can exceed 20–25% | Changes daily |
| Plain beet pulp | Low (often under 12%) | Molassed versions are higher |
Now think about quantities. A 1,000 lb horse might eat 20 lb of hay and 3 lb of feed a day. Even if the feed is a little higher in NSC than the hay, the hay supplies far more total sugar and starch simply because there's so much more of it. That's why testing your hay is often the most useful single step for a sensitive horse.
Pasture is the wild card. Grass makes sugar in sunlight and stores it, so sugar levels tend to rise through sunny days, spike in spring growth and in fall, and can stay high after frosty nights. Many owners of at-risk horses limit grazing, use grazing muzzles, or graze early in the morning. Ask your vet what's safe for your horse.
How to find NSC on a feed tag
In the US, feed tags aren't required to list sugar or starch, so many don't. Here's how to work with what you have:
- Look for an advertised NSC. Many low-starch feeds print an NSC percentage on the bag or website. It's often the most useful number.
- Add starch + sugar. If the guaranteed analysis lists Starch (max) and Sugar (max), add them. Because these are maximums, the actual value is often a bit lower.
- Ask the manufacturer. Most companies will share typical values if you call or email.
- Look it up. The Equine Feed Guide lists published sugar and starch for dozens of feeds and shows where each number came from.
See our guide on how to read a horse feed tag for a line-by-line walkthrough.
How much NSC is too much?
You'll often hear 10–12% NSC used as a cutoff for horses with insulin resistance or laminitis risk, and some veterinary guidelines suggest keeping the whole diet under about 10% (as ESC + starch) for high-risk horses. These are guidelines, not rules. The right target depends on your horse's diagnosis, test results, weight and how they respond. Your vet may suggest something stricter or more relaxed.
Two more numbers people discuss:
- Whole-diet NSC is what matters most. A feed that's 14% NSC fed at 1 lb a day adds very little to a diet built on 20 lb of 9% hay.
- Starch per meal. You'll see about 1 gram of starch per kilogram of body weight per meal mentioned as a common upper limit for reducing digestive risk. For a 1,000 lb (about 455 kg) horse, that's roughly 455 g of starch per meal. Ask your vet whether this applies to your horse.
A quick example
Say your 1,100 lb horse eats 20 lb of grass hay at 12% NSC and 3 lb of a feed at 13.5% NSC:
- Hay: 20 lb × 12% = 2.4 lb of sugar + starch (about 1,090 g)
- Feed: 3 lb × 13.5% = 0.4 lb (about 184 g)
- Whole diet: about 2.8 lb out of 23 lb, or roughly 12.2%
In this example the hay supplies about 85% of the sugar and starch. Switching feeds would barely change the total; testing or changing the hay might. The Equine Feed Guide does this math for you.
Low NSC doesn't always mean low calorie
A common mix-up: low NSC is not the same as low calorie. Many low-NSC feeds get their energy from fat and digestible fiber instead of starch. A high-fat, low-starch feed can be great for a hard keeper with PSSM, and too rich for an overweight pony. If weight loss is the goal, total calories matter as much as sugar and starch. Ask your vet about both.
Frequently asked questions
What does NSC stand for in horse feed?
NSC stands for non-structural carbohydrates. In practice it means the sugar and starch in a feed, the parts that are digested quickly into blood sugar.
Is 10% NSC the limit for a laminitic horse?
10–12% is a commonly mentioned guideline, and some veterinary guidelines suggest under about 10% (as ESC + starch) for high-risk horses. It's not a fixed rule. Your vet should set the target for your horse.
Does soaking hay lower NSC?
Soaking hay in water removes some water-soluble sugars, but the amount varies widely between hays and soaking methods. Ask your vet whether soaking makes sense for your horse.
Why don't all feed tags list starch and sugar?
In the US, starch and sugar aren't required on horse feed labels. Many low-starch feeds list them voluntarily; for others, ask the manufacturer.
Is beet pulp low in NSC?
Plain, unmolassed beet pulp is generally low in sugar and starch. Some products have molasses added back, which raises the sugar. Check the label.
Sources and further reading
- National Research Council. Nutrient Requirements of Horses, 6th revised edition (2007).
- Equine Endocrinology Group (EEG). Recommendations for the diagnosis and management of equine metabolic syndrome and PPID (updated periodically).
- American Association of Equine Practitioners (AAEP): owner resources on laminitis and metabolic disease.
- University extension horse programs (for example, University of Minnesota and Penn State Extension) on forage carbohydrates and hay testing.
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