Too much dietary sugar is neither ideal for humans nor horses. And avoiding it in equine diets can be as challenging as human diets. So how much is too much? Factors like age, breed, workload, and reproductive status all affect a horse’s nutritional needs and how sugar is processed.
While a high-sugar diet may be appropriate during periods of intense exertion or recovery from illness, it carries serious risks when overused or misapplied. Excess sugar intake has been linked to issues like insulin resistance, laminitis, and dehydration.
Practical strategies can help you limit intake, support overall health, and ensure sugar levels are appropriate for your horse.
Dietary Concerns and Considerations
Fiber is a critical energy source for horses, thanks to the hindgut’s fermentation process for breaking down forages. However, this delicately balanced digestive environment can be disrupted by excess starches and sugars, which are digested more rapidly.
“If we provide too much starch and sugar in the diet the horse’s own enzymes and absorptive processes cannot cope and the sugars flood into the hindgut along with those bacteria that feed off them,” writes Dr. Tom Shurlock in his GWF Nutrition Limited article. “Their end products are more acidic…which results in the disruption of the environment and…a rise in toxic end products called ‘endotoxins’.”
Certain breeds and types, including Arabians, ponies, and donkeys, may be more sensitive to high-sugar diets due to genetic predisposition or evolutionary adaptation to more intense, nutritionally scarce environments. These animals, along with horses suffering from endocrine conditions like equine metabolic syndrome (EMS) or Cushing’s disease, often have lower tolerance for sugar and starch intake and require careful rationing.
Why Feed a High-Sugar Horse Diet?
While low-sugar, low-starch diets are often recommended for metabolic health, there are times when higher-sugar feeding can be useful. Performance horses in intense training or competition need quick, readily available energy, and sugars and starches meet this need by being rapidly absorbed in the small intestine.
High-sugar feeds can also help horses with poor appetites or needing to gain weight. These feeds are often more palatable and encourage intake. In cold weather, high-calorie rations that include some higher-NSC ingredients can help meet elevated energy demands.
Even when appropriate, high-sugar diets should be approached with caution. Intake must be monitored, especially in horses prone to insulin resistance or digestive issues.
Common Issues with Sugar in the Diet for Horses
Horses with lower energy needs should avoid high-sugar diets, especially if not in active performance. Excess starch and sugar can lead to nutritional laminitis.
Prolonged high-starch feeding may also cause insulin resistance, much like diabetes in humans, and increases laminitis risk. NSC-rich feeds such as cereal grains ferment quickly, raising stomach acidity and contributing to ulcers. If starch overloads the small intestine, it can lead to digestive issues like acidosis and colic.
Seasonal changes also affect sugar levels in forage. In spring and fall, cool-season grasses like orchardgrass, timothy, and bluegrass can store more sugar due to chilly overnight temperatures, increasing the risk for sensitive horses with unrestricted pasture access.
The University of California-Davis Center for Equine Health describes equine metabolic syndrome (EMS) as a disorder involving abnormal insulin regulation, increased fat deposition, and difficulty losing weight. Horses with EMS may respond to meals high in carbohydrates with prolonged insulin spikes.
How to Minimize or Regulate Sugar
Active, healthy horses can tolerate some starch. However, be mindful of meal size, as too much at once can lead to digestive or metabolic issues.
Finding the right balance depends on many factors, including the horse’s life stage, breed, performance level and sugar level of the feed. Ration ingredients vary widely in sugar content, with beet pulp and alfalfa meal being lower in NSCs and grains like corn, oats, and barley being much higher. Hay choice matters too, with warm-season grasses generally having less sugar than cool-season types. Choosing ration ingredients wisely, with your horse in mind, helps to keep sugar levels in check and supports overall health and performance.
