On the market now are low-starch products, but experts say not every horse will benefit from them.
Studies have shown that low-starch diets are most beneficial in horses suffering from equine metabolic syndrome, insulin resistance, Cushing’s syndrome, PSSM (polysaccharide storage myopathy) and laminitis.
“Diet is key [with these conditions],” says Lori Warren, Ph.D., PAS, of the Equine Nutrition Institute of Food and Animal Agriculture at the University of Florida. “It’s all about finding alternative sources of calories, getting away from starch as a calorie source and moving toward more highly digestible fibers. PSSM horses fed low-starch diets usually show a relatively quick improvement. Low-starch diets for the others mentioned are really more about maintenance, so the diet won’t aggravate the condition.”
Even though the digestive tracts of humans and equines are designed very differently, diets high in soluble carbohydrates can bring on or aggravate similar conditions in both people and horses.
Soluble carbohydrates are the starchy portions of plants that are broken down in the digestive tract. This type of carb exists in high concentrations in cereal grains like rice, wheat, corn, barley, and oats.
In the late 1980’s, endocrinologist Gerald Reaven proposed that a high soluble carbohydrate diet caused insulin resistance, a condition which can result in obesity, diabetes, high blood pressure and heart disease in humans. Reaven’s hypothesis flew in the face of the American Heart Association’s position that a low fat, high carb diet would prevent heart disease.
Two decades later, an equine specialist made a similar connection between consumption of a traditional diet of grains and molasses, and insulin resistance in horses.
Equine Grain-Associated Disorders (EGAD)
Equine Grain-Associated Disorders (EGAD) is a term which encompasses both digestive and metabolic disorders in horses. Digestive problems are the result of rapid carbohydrate fermentation and insulin resistance and include:
- Colic, the number one cause of death in horses
- Gastric ulcers
- Laminitis, which is inflammation in the hoof that can lead to chronic lameness and is the second most common cause of death in horses
Metabolic conditions can include:
- Exertional rhabdomyolysis or tying-up, which damages muscle tissue
- Osteochondrosis, a disease of the cartilage of young horses
- Fluctuations in growth rate
- Flexure deformities
- Oxidative stress
All these equine disorders have been linked to long-term consumption of feeds high in sugar and starches.
Traditional Feeds Don’t Always Offer Balanced Nutrition
Traditional horse feeds contain large amounts of cereal grains (typically barley, corn or oats) and low quality forage, which is plant material eaten by grazing animals. Most of these feeds do not contain many important vitamins and minerals.
Traditional feeds can lead to a poor nutritional state in which your horse is deficient in some nutrients and has an excess of others. Your horse’s digestive tract isn’t designed to efficiently process low quality hay or cereal grains.
Horses need between 14 and 32 Mcal of digestible energy (DE) per day. Mcal is the unit of measure used in equine nutrition. An Mcal, or megacalorie, is the equivalent of 1,000 calories of human nutrition.
The amount of digestible energy your horse needs per day depends on his or her size, workload and/or stage of life, per the following table:
|Workload/Stage of Life||Weight (lb)||Daily Mcal DE|
|Lactation, 1-3 months||1,100||28.3|
|Growth & Training||990||26.4|
|NRC Nutrient Requirement of Horses, 1989|
NRC Nutrient Requirement of Horses, 1989
Do I Need to Rethink What I’m Feeding My Horse?
Racehorses, for example, need a high level of soluble carbs in order to quickly replace glycogen stores. Studies show the best way to do that is with a moderate to high soluble carbohydrate feed.
According to Brian D. Nielsen, Ph.D., PAS, Dipl. ACAN, a professor of animal science at Michigan State University, if your horse is mature and fit, with a body condition score in the thin to moderate range, and has a high energy demand, feeding a traditional high starch diet is probably fine.
However, if your horse suffers from a grain associated disorder such as metabolic syndrome, insulin resistance, Cushing’s syndrome, PSSM (polysaccharide storage myopathy), or laminitis, for example, a low starch diet is preferable.
Traditional feed containing primarily corn and oats runs about 40 to 60 percent starch. A controlled starch feed is generally 20 to 24 percent starch. A low starch feed runs in the 12 to 15 percent range.
Low starch feed might contain chopped or pelleted timothy or alfalfa, beet pulp, soy hulls and rice bran. Corn and soybean oil can be added to increase the calorie count.
Species-Appropriate Nutrition for Horses
Studies show that if you feed your horse like the grazer and fiber-fermenter he is, you can limit his risk of acquiring a grain related digestive or metabolic disorder. And your horse can better digest the nutrition he gets from forages when they are not fed with grains.
Newer feeding programs are based on high quality forage. The best hays are immature grasses with 10 to 40 percent legume content. If hay or grass is low in protein, your horse may have a deficiency of amino acids. All forages lack some of the vitamins and minerals your horse needs, so a supplement, including salt, should also be provided.
If your horse requires additional energy, you can add high-fat products and fermentable fiber to the forages.
Include grains only as necessary for growing, lactating or hard working horses, and keep them at or below 10 percent of total rations.
Depending on your horse’s energy requirements and health challenges, a species-appropriate, forage-based feeding program can give him the nutrients he needs for optimum performance and reduce his risk for digestive and metabolic disorders associated with diets high in sugars and starches.