Managing forage carbohydrate content
Quick facts
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Forages high in carbohydrates (sugars) can be problematic for horses prone to laminitis and metabolic disease.
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Forages with 10 to 12 percent or less carbohydrates are thought to be safe for sensitive horses.
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Cool-season grasses in pasture and hay can be higher in carbohydrates.
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Soaking hay for short durations can reduce carbohydrate content in hay.
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A mature alfalfa-grass mix can be ideal for horses with laminitis.
Carbohydrate sensitivity in horses
Horses require carbohydrates in their diet. But some horses are sensitive to the carbohydrate content of hay and pasture forages. This could lead to health problems such as:
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Laminitis (founder)
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Equine metabolic syndrome
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Cushing’s syndrome
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Some forms of tying-up
Forages high in carbohydrates, whether hay or pasture, can be problematic for horses with these conditions.
Insulin resistance refers to when a horse poorly responds to the hormone insulin. As a result, they develop high blood sugar (glucose). This occurs in horses with the following conditions.
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Obesity
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Metabolic syndrome
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Cushing’s disease
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Pasture-associated laminitis
Horses prone to insulin resistance include obese or fat horses, and horses over 15 years old.
Safe carbohydrate levels
Currently, it’s thought that a safe carbohydrates content for sensitive horses is 10 to 12 percent or less.
Testing your hay is a good starting point for determining its carbohydrate content. Make sure you take a representative sample. Simply looking at a forage sample or species of forage won’t give you a good estimate of carbohydrate content.
If necessary, you can reduce the carbohydrate content of hay by soaking it in water for 15 to 60 minutes. Please see soaking your horse’s hay for more information.
Please see grazing horses prone to laminitis and metabolic disease to learn about grazing horses that are sensitive to carbohydrates.
What carbohydrates are in forage?
Cool-season grasses are common in horse pastures and hay fields in the upper Midwest. Most of these grasses can be higher in carbohydrates. These carbohydrates are in the form of fructans and simple sugars like glucose.
Horses absorb glucose in the small intestine, which triggers an insulin response. Thus, diets high in simple sugars (and starch found in grain) aren’t a good option for insulin resistant horses. These diets will result in persistent high blood sugar in insulin resistant horses.
Fructans pass to the horse’s hindgut and ferment without triggering insulin. Horses prone to laminitis shouldn’t be fed forages high in fructans. When microbes ferment fructans in the hindgut, it disrupts the microbial balance and creates an acidic environment. As a result toxins get released into the bloodstream and exacerbate laminitis.
Forage carbohydrate content
There are no grasses consistently low in carbohydrates.
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Most cool-season grasses like orchardgrass and fescue can be higher in carbohydrates.
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Most warm-season grasses, like teff, tend to be lower in sugar content.
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These grasses aren’t winter hardy and can’t compete with cool-season grasses in the spring and fall.
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These grasses have potential for better summer pasture yields.
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Alfalfa hay or pasture can be a solution for horses sensitive to carbohydrate content. Compared to grass, alfalfa tends to be:
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Higher in digestible energy
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Higher in protein
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Higher in calcium
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Lower in carbohydrates
More calories can result in body weight gain which can contribute to obesity, Metabolic syndrome, and laminitis.
Reviewed in 2018