Starch and Sugar: The Sweet Spot
Starch and sugar are always an area we are learning more about. We know that starch and sugar play a key role in horse diets along with the hay. Let’s talk about the careful balancing act between too little and too much starch and sugar.
Energy can be a tricky subject to teach on as it’s complex. Hay (forage) and fibers are fermented by the hindgut microbes and produce VFAs- volatile fatty acids. (VFAs). These are short chain fatty acids that may produce up to 70% of the energy needs. They also play a role in glucose production.
Now, that said, carbs do play a role in horses’ diets! Maintaining the proper level (not too low, nor too high) is key especially if you have a performance horse in speed events. Starch is a “quick burst” energy source and is digested in the small intestine. Show jumpers and barrel racing horses are examples of horses that benefit from this energy source. Stored glycogen is used during prolonged exertion, making starch important for endurance and recovery. After exercise, the body restores muscle and liver glycogen stores using glucose from dietary starch. Starch-based energy fuels muscle contractions, supports thermoregulation, and aids recovery post-exercise.
How much is too much?
Horses have varying needs for starch and sugar. Work with a qualified professional for best results. Some horses need a bit of a starch boost when on weight gain diets, but my preference is always to stay under 20% NSC for ”grains”. There is a benefit to getting more calories per pound, which can benefit the horse by reducing the overall volume of feed per meal. We know that hindgut acidosis is a real and serious threat so we must respect the math! (See my other teaching on this)
How low is too low?
Yes, I maintain NSCs can be low and I have seen horses become sluggish from being on hay that was uber- low in NSC and also not on a strong concentrate. Typically if the hay is at a good level there is no problem.
For many horses, energy needs can be met primarily with forage and fat-based sources rather than heavy starch intake. However, for high-performance horses, carefully managed starch is essential for fueling peak performance. All horses need some starch and sugar for muscle function.
Growing horses are a special class, and dropping NSCs too low (below 12%) can be a disaster for the young horses! This is why testing hay regularly allows you to understand if your program is really meeting the needs. This class needs between 12-17% NSC on average and foals should NEVER be starch limited unless advised by a vet or professional due to fast growth. Again, we appreciate that growth can occur too rapidly on high starch diets, but the 12-17% NSC is not high starch. Forage based feeds should make up the bulk of the concentrate along with long stem hay/grass. Avoid sweet feeds!
Broodmares in late pregnancy and lactation need more energy and nutrition than most horses. Starch helps meet higher caloric demands without overloading the digestive system. Stallions benefit from starch to support the extra energy requirements of the breeding season. (And remember- more doesn’t mean “high”)
While starch has benefits, improper feeding can lead to issues like insulin resistance, laminitis, ulcers, or colic.
To avoid problems:
✔ Feed Small, Frequent Meals – No more than 0.5% of body weight per meal (e.g., 5 lbs for a 1000 lb horse).
✔ Pair with Fiber – High-quality forage slows glucose absorption and supports gut health.
✔ Use Digestible Forms – Processed grains if used (e.g., extruded, steam-flaked) improve digestibility.
✔ Avoid Excess in Metabolic Horses – Easy keepers, PPID (Cushing’s), and insulin-resistant horses do better on low-starch diets.
Don’t be scared of starch or sugar!
Know the facts and get help from myself of a colleague if you need support. This is not something owners are supposed to do themselves!
This article is my own work/IP but for more information check out https://thehorse.com/17160/sugars-and-starches-theyre-not-all-bad/
Photo is credit to The Horse.
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