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 regular soil sampling and analysis to ensure you apply the appropriate fertilizer which, in turn, will provide a safer pasture for your horses.
Manage Pasture Intake
Excessive caloric consumption is another concern for horses and ponies on pasture. A mature horse on a good-quality two- to three-acre pasture can easily consume more calories than he needs to meet and maintain daily energy requirements. Horses that become obese can develop insulin resistance, which causes abnormally high levels of blood glucose and insulin. Additionally, Adams said, equine nutrition research has shown that horses with a history of grass or grain founder can become insulin resistant.
A specific worry for pastured horses is management of horses that are known to have insulin resistance, equine metabolic syndrome, and pituitary pars intermedia dysfunction (PPID, or equine Cushing's disease). Researchers have determined that horses with insulin resistance have a greater glycemic response to starch and sugar content of horse feeds, which results in higher blood glucose and insulin levels and makes them much more susceptible to laminitis.
So, remember to monitor horses’ grazing and manage it, if needed, to reduce the risk of obesity and intake of soluble carbohydrates that might trigger laminitis in horses with these issues.
Pasture and Grazing Management Tips
Consider these options when developing your pasture and grazing management plans:
- Perform regular soil sampling and analysis of your horse pastures and use it to determine proper rates of fertilizer application (limestone for pH control as well as nitrogen, phosphorus and potassium) for proper growth and persistence.
- If a horse hasn’t had access to lush grass recently (in the early spring or when moving from a pasture with less forage, for example) introduce him to the pasture gradually, only allowing one to two hours of grazing the first day and slowly increase the time by an hour per day until he’s turned out for a full day. Some horses and ponies might need to have their grazing restricted in the spring and summer; consider turning these individuals out in drylots or using a grazing muzzle.
- Body condition score your horses and consider limiting pasture access for any horse that has or is at risk of having a body condition score of 6 (on a scale of 1 to 9) or more.
Source : TheHorse