Not all horse feed calories are created equal. Understanding the different energy measures helps you choose the right feed for your horse’s needs. Whether you’re keeping weight off an easy keeper prone to laminitis or fueling an eventer for peak performance, understanding how your horse’s feed delivers energy is crucial.
This guide breaks down everything you need to know about energy in horse feed, from reading between the lines on ingredient lists to choosing the right fuel for your horse's needs.
But feed labels can be confusing: what's the difference between DE, NSC's, WSC's and ESC's?
- DE = Digestible Energy
- NSC = Non-Structural Carbohydrates
- ESC = Ethanol-Soluble Carbohydrates
Why do these matter? And why do feed labels not list NSC levels - even though it’s something many horse owners need to know?
The Energy Confusion: DE vs NSC vs ESC
Most horse owners know to check protein and fat levels, but energy measurements are where things get tricky. Here's what each one actually tells you:
DE (Digestible Energy): The "How Much" Measurement
- What it is: Total available energy, measured in Mcal/kg or MJ/kg.
- What it tells you: How much fuel your horse gets - but not what kind of fuel.
- On feed labels: Almost always listed.
- Think of it like: Calories in a meal - you know the amount, not whether they come from sugar, oil, or slow-burning carbs.
NSC (Non-Structural Carbohydrates): The "How Fast" Measurement
- What it is: Sugars, starches and fructans that digest quickly in the small intestine.
- What it tells you: Whether energy hits fast (sugar spike / hot) or slow (steady burn / cool).
- On feed labels: Rarely listed.
- Think of it like: Energy drink vs oatmeal - same calories, totally different delivery and blood sugar response (for humans that is - oats are high GI for horses but low for humans).
WSC (Water-Soluble Carbohydrates): The "Total Pasture Sugar" Measurement
- What it is: Sugars (ESC) and Fructans that are dissolved when feed is tested in water. This is the key measurement for sugar content in grass and hay.
- What it tells you: The total amount of simple sugars and the highly fermentable sugar, Fructan. Fructan is indigestible in the foregut and rushes to the hindgut, where fermentation releases toxins that can trigger laminitis in sensitive horses.
- On feed labels: Often used when testing hay or pasture analysis reports, but rarely on commercial feed labels.
- Think of it like: The total sweetness of a fruit (ESC) plus the parts that give sensitive horses digestive issues (Fructan).
NSC (Total Risk) = WSC + Starch WSC (Total Soluble Sugar) = ESC + Fructan
ESC (Ethanol-Soluble Carbohydrates): The "Sugar Rush" Measurement
- What it is: Simple sugars that hit the bloodstream fastest.
- What it tells you: Immediate glucose impact.
- On feed labels: Almost never listed.
- Think of it like: Pure sugar content - the most rapid-fire energy source.
Read more about Digestible Energy (DE) and ESCs in Horse Feed.
Carbohydrate Formulas in Equine Nutrition
1. NSC (Total Risk) Equation
NSC (Non-Structural Carbohydrates) = WSC + Starch
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NSC represents the total amount of easily digestible or fermentable carbohydrates in a feed (like hay or concentrate). This is the value most often tested for horses with metabolic issues (EMS, laminitis, Cushing's) because a high NSC indicates a high risk of glucose spikes (from starch and ESC) or hindgut acidosis (from fructans).
2. WSC (Total Soluble Sugar) Equation
WSC (Water-Soluble Carbohydrates) = ESC + Fructan
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WSC is measured by soaking the feed in water. It captures all simple sugars plus the complex sugar, fructan.
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ESC (Ethanol-Soluble Carbohydrates) are the simple sugars (glucose, sucrose, etc.) that are rapidly absorbed in the small intestine, leading to a quick blood sugar spike.
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Fructan is a structural carbohydrate that is not digested in the small intestine. It passes into the hindgut where it ferments rapidly, causing digestive upset and posing a major laminitis risk in sensitive horses (especially those on lush pasture).
3. Fructan Calculation
Fructan = WSC - ESC
Why Feed Companies Don’t List NSC Levels (And What to Look for Instead)
Feed bags and websites don't usually list NSC levels because it's expensive to test and it varies between feed batches. On the rare occasion it is listed, the number likely reflects one particular batch, so it’s only an estimate for the bag you buy.
But that’s not really a problem. You can often estimate whether a feed has high or low NSC levels simply by reading the ingredients and knowing which ingredients are high or low in NSCs.
In simple terms:
- Low-GI feed: Uses low NSC ingredients such as soy hulls, seeds, and oils — no grains.
- High-energy performance feed: Includes high NSC ingredients such as grains.
Decoding Ingredients: The NSC Detective Guide
Because NSC levels aren't listed, the ingredient list becomes your roadmap. Here’s how to interpret it — remembering that while higher NSC feeds aren’t suitable for metabolic horses, they are beneficial for performance horses needing more energy.
Quick Reference: NSC Levels in Common Ingredients
| Ingredient | NSC % | Ingredient | NSC % |
|---|---|---|---|
| Corn / Maize | 70–75% | Beet Pulp | 8–12% |
| Barley | 55–60% | Soy Hulls | 5–10% |
| Molasses | 54% | Alfalfa / Lucerne | 8–12% |
| Oats | 40–45% | Timothy Hay | 10–14% |
| Spring Pasture | 18–25% | Vegetable Oils | 0% |
High NSC Red Flags
- Any cereal grains (oats, barley, corn, wheat)
- Sweet ingredients (molasses, corn syrup, sugar beet syrup)
- Processed grains (steam-flaked, micronized, extruded)
Low NSC Green Lights
- Fibre sources (beet pulp, soy hulls, alfalfa)
- Oils and fats (zero NSC)
- Legumes (lupins, peas — moderate NSC)
Read about Micronization and low-GI ingredients.
NSC Requirements: Matching Feed to Horse
The right NSC level depends entirely on your horse's metabolism and workload. As a guideline, a low-GI feed should have under 15% NSCs.
Metabolic Horses (EMS, Laminitis-Prone, Insulin Resistant)
- Target NSC: Under 12% (some need under 10%)
- Why: Prevents glucose spikes that trigger metabolic episodes
- Energy source: Fibre and fat, not starch or sugar
- Feed type: Low-GI formulations
Leisure Horses (Light Work, Easy Keepers)
- Target NSC: 12–18%
- Why: Steady energy without weight gain
- Energy source: Primarily forage-based
- Feed type: Maintenance or low-energy concentrates
The Hidden NSC Sources: Forage Matters Too
Don’t forget that forage contributes significant NSC:
High NSC Forages
- Spring pasture: 18–25%+ NSC (dangerous for metabolic horses)
- Some hays: 15–20% NSC
Lower NSC Forages
- Timothy hay: 10–14% NSC
- Late-cut grass hay: 8–15% NSC
For metabolic horses, test your hay — it might be contributing more sugar than their feed.
Reading Between the Lines
Genuine Low-GI Feed Ingredients
- Lists beet pulp, soy hulls or alfalfa in top ingredients
- Contains added oils or fats
- Minimal or no cereal grains
- Minimal molasses — look for 2.5% max
Marketing Spin Red Flags
- "Lower starch" (compared to what?)
- Still lists oats, barley or corn
- Unspecified molasses or sweeteners
- Vague “cool” claims without NSC disclosure
Making Smart Feed Choices
For Metabolic Horses
- Calculate total diet NSC (feed + forage)
- Test hay if possible
- Choose feeds with disclosed NSC under 12%
- Avoid grains
- Prioritise fibre and fat for energy
For Performance Horses
- Match NSC to work intensity
- Feed higher NSC before work, lower NSC for recovery
- Monitor for tying-up or metabolic issues
- Adjust based on individual response
For All Horses
- Introduce feed changes gradually
- Monitor body condition and behaviour
- Work with an equine nutritionist for complex cases
- Remember: forage first, concentrates second
The Bottom Line
Understanding NSC levels — whether listed or hidden in ingredients — gives you the power to choose feeds that match your horse's metabolic needs. Whether you're preventing the next laminitis episode or fuelling a champion, the right energy source makes all the difference.
For personalised feeding programs, consult a qualified equine nutritionist who can factor in your specific horse’s needs, workload and health status.
Fiskens Nutritional Science
Fiskens feeds are formulated in collaboration with qualified equine nutritionists for optimal performance and balance. With over 60 years of expertise in equine nutrition, Fiskens is a trusted leader in developing scientifically-backed feed solutions that support horse health and performance across all disciplines.
Superior nutrition that won’t break the bank!
Molasses Blood Sugar Impact — GI vs GL
GI tells you the sugar-spiking impact of an ingredient. But if only a small amount is consumed, then the impact is lower — which is where glycaemic load (GL) comes in.
GL considers both the GI of individual ingredients and their quantities. When 97.5% of a feed like our Ultra Low GI consists of fibre-based and oil-based ingredients with minimal NSCs, the overall blood sugar impact remains extremely low despite the presence of molasses.
As an analogy, a single grain of sugar has a very high GI but effectively zero GL — its impact on blood glucose is insignificant. In a feed like our Ultra Low GI, dominated by ultra-low GI ingredients such as soy hulls (GI ≈ 7) and oil-rich seeds, the tiny amount of molasses (2.5% max) has a negligible effect on the overall glycaemic load.
Horse feeds generally contain palatability enhancers — sweeteners — to encourage intake, but these are not always disclosed. This matters in low-GI feeds, which is why we specify 2.5% molasses max in our Ultra Low GI Feed.