Can diseased horses graze?
In recent years, horse owners have been overwhelmed with warnings about carbohydrates, fructans, metabolic syndrome, laminitis, and a flood of other statistics related to grazing horses.
Horses have enjoyed unrestricted grazing for centuries, however, with over-grazing, newer varieties of pasture grasses, recently diagnosed metabolic complaints, and problems with equine obesity, grazing has come under closer scrutiny. While most horses can still graze day after day without developing problems, some classes of horses should have limited pasture access to avoid the serious metabolic upsets triggered by consumption of the carbohydrates (sugars) in fresh grass. These classes include horses with a history or current diagnosis of laminitis, obesity, and/or equine metabolic syndrome.
Is there a “best time” to allow these susceptible horses to graze? Photosynthesis influences sugar levels in grass. During daylight hours, grasses manufacture and store sugars as they absorb water, sunlight, and carbon dioxide. These stored sugars are used to fuel plant growth during the night. Therefore, sugar levels are at their highest in late afternoon and at their lowest in the very early morning hours.
Horses that are sensitive to carbohydrate levels in pasture grass can graze with the least amount of risk from the predawn hours until around 10:00 a.m.
Horses that are sensitive to carbohydrate levels in pasture grass can graze with the least amount of risk from the predawn hours until around 10:00 a.m. This is a time period when stored sugars have been used and have not yet been replenished by photosynthesis. Sensitive horses should not be allowed to graze when sugars are being built up and stored, usually during the sunlight hours and through the early hours of the night.
Time (season) of year, rainfall, temperature, frequency of mowing, plant types, and grazing pressure also influence the sugar levels in pasture plants.
Most horses can enjoy unrestricted access to pasture. For extremely sensitive horses, there is no completely safe time to graze. These horses are best managed on lower-carbohydrate hay (less than 12% non-structural carbohydrates) with access to a drylot for exercise and social contact.