Unless you are living in an area with very mild winters, your pasture grasses will shrivel and turn brown over the winter. However, that plant is not dead and horses will be more than happy to eat it. This could send insulin dangerously high for a horse with EMS [Equine Metabolic Syndrome].
It Only Looks Dead
Winter pasture doesn’t look very appetizing and it’s certainly true that it is not as nutritious but with careful planning it can actually be relied upon to reduce the need for hay and other supplemental feeding. The trick is to graze it enough to prevent it going to seed during the regular season then stop grazing long enough for a good amount to accumulate but not long enough for it to go to seed. This preserves the nutritional value as much as possible. The practice is called stockpiling.
If the nutritional value is reduced, shouldn’t that make it safe for EMS horses to graze? Unfortunately, while everything else goes down the one thing that makes the grazing safe or not for EMS horses is high.
Dormant grasses survive the winter depending on their tolerance to freezing. Freezing expands and explodes cells, leading to loss of fluid and electrolytes. Grasses increase their freezing tolerance through high levels of simple carbohydrates. This means their levels of storage carbohydrates, either fructan or starch, depending on the species, will be high. Even more importantly the level of simple sugar is also high.
These carbohydrates are concentrated in the stolons and crowns of the grass, close to ground level. Under peak grazing season conditions the horse would not graze that close to the ground, clipping grass off at a height of about 2 inches. However, the wilted, soggy mess of dormant winter grass sits close to the ground and it doesn’t take the horse long to figure out where the most sugary parts are.
Making sure the horse has plenty to eat before turning out on winter pastures will help but it’s no guarantee he won’t eat too much of the high sugar treat. Snow coverage won’t be protection either. Many horses are determined enough to paw through the snow and can eat enough to get laminitic. It happens every year.
The cold weather itself may be a risk factor for laminitis since insulins often fluctuate widely in cold weather. This is on top of the cold induced pain many EMS horses suffer as a result of impaired circulation https://wp.me/p2WBdh-D9. Don’t compound the risk of painful feet by allowing access to winter grass.
Eleanor Kellon, VMD