Nutritional Tips for Winterizing Your Horse

As the days get shorter and the holiday decorations fill the aisles at stores, people start to think about preparing for winter horse keeping. The good news is that horses are better adapted to handling cold temperatures over excessively high temperatures. In fact, the temperature at which horses begin to expend extra energy to keep themselves warm is much lower than the temperature that most people begin to layer on coats.

The temperature horses begin to expend extra energy to maintain their optimal internal temperature is called the Lower Critical Temperature (LCT). This value is dependent on body condition, hair coat, wetness and wind chill. A horse in good body condition with a dry winter coat has a LCT of 18°F, while a horse with a wet coat or a thin coat needs to expend energy to maintain internal temperature at 59°F. A horse's coat offers considerable insulation and its impact is something to keep in mind when blanketing horses with a full or partial body clip. Wind chill will significantly decrease the Effective Ambient Temperature, or the “feels like” temperature, and should be accounted for when determining the impact of winter weather on a horse’s nutrient requirements if they are outside. This is particularly true for those horses that choose not to use the shelter provided!

As temperatures drop, the horse maintains body temperature through behaviors such as huddling together and positioning their body with tail toward the wind as well as through physiological changes. During cold weather, hair stands on end to create insulation, blood flow to extremities is decreased to maintain core body temperature and the horse’s metabolic rate goes up to generate heat. In extreme cold, the horse will shiver to create body heat; however, this is a very energy expensive way for the horse to maintain body temperature and should be avoided.

Whether your winter is cold and rainy or you rarely see a day above freezing, it requires a combination of management and feeding practices to keep horses in good body condition over the winter. From a management perspective, keeping horses dry and out of the wind is extremely important and will dramatically increase their ability to handle cold weather.

Setting horses up to maintain body weight throughout the winter starts with ensuring horses enter the winter in good body condition. This can be challenging as pasture in most parts of the country is declining throughout the fall, both in the quantity available and the quality of the forage. Keeping a close eye on body condition and pasture condition through the fall and supplementing declining pasture with hay before major body condition losses helps prevent situations where we are attempting to add weight going into winter.

On the other hand, trying to pack on the pounds so a horse goes into winter with extra body condition is not necessarily a healthy approach. Many horses, particularly as they age, are at risk for the development of metabolic conditions and excess body weight (BCS 7+) has been linked to higher risk of development of insulin resistance and laminitis. Instead, look to achieve a healthy body condition (BCS 5-6) going into winter and feeding and managing to maintain. 

It is a common misconception that “hotter” feeds, like oats or corn, generate more internal heat and are, therefore, a good addition to the horse’s diet in the winter. Quite the opposite is true; relatively little heat is produced digesting cereal grains but a significant amount of heat is produced through fermentation of fiber in the hindgut of the horse. Increasing forage availability during the winter is a better way to help horses maintain their body temperature without major calorie cost. As an added bonus, forage is a better choice for maintaining digestive health.

Providing additional forage, particularly as temperatures dip below freezing, will assist in offsetting the additional energy required for temperature maintenance. If additional forage is not an option, a feed high in digestible fiber can be a good addition. Look for feeds with ingredients such as beet pulp, soy hulls and alfalfa. For the harder keeper, a high fat feed or fat supplement is a good addition to high quality forage to maintain weight without overfeeding concentrates.

Finally, no winter feeding article would be complete without mentioning water! Horses require a source of clean, easily accessible water at all times. Although horses will eat snow in the wild to meet part of their water needs, a horse cannot consume enough snow to meet their water requirements. Horses prefer water to be warmed to 45°F and will increase water intake accordingly. Consistent water intake throughout winter is key for maintaining digestive function and decreasing colic risk.

For information on nutrition-related topics, feel free to reach out for a nutritional consultation to ensure your winter feeding program meets your horse’s needs.

Nicole Rambo, Ph.D.