Horses love to eat, hence the phrase “eat like a horse.” They’ll graze on pasture for hours on end, but there are certain times during the year when too much pasture can have a negative effect on your horse’s body.

A concern for horses and ponies grazing lush pastures is the risk of founder or laminitis from excessive consumption of soluble carbohydrates (starch and sugar) found in the pasture. Laminitis is inflammation of the hoof’s laminae, which can result in temporary to permanent lameness.

Too Much Sugar

Like humans, horses can develop health problems when they consume too much sugar.

“Over-consumption of pasture is (a) frequent cause of laminitis due to a horse’s excessive intake of soluble carbohydrates or sugars present in grass,” said Marty Adams, PhD, PAS, equine nutritionist for Southern States Cooperative.

Cool-season grasses like fescue, orchardgrass, and timothy can contain fructan concentrations. Fructans are sugars that are not digested in the small intestine, but are fermented in the large intestine to produce lactic acid. They can drastically increase the risk of colic and laminitis.

Grasses’ sugar content increases when they’re stressed due to freezing conditions or poor fertilization. Sugar levels are at their highest under the afternoon sunlight, as this is the time when the light intensity and photosynthesis rate are at their highest.

Research has shown that when pasture grasses are properly fertilized during cool seasons, they are less stressed and produce less sugar and fructans. So a good management practice is to conduct regula