Cold temperatures will increase a horse's energy requirement as the need to maintain core body temperature increases. The temperature below which a horse needs additional energy to maintain body warmth is called the lower critical temperature. The lower critical temperature for a horse is estimated to be 41°F with a summer coat and 18°F with a winter coat (upper critical temperature is estimated at 86°F). However, the lower critical temperature can be affected by individual horse characteristics. A horse with short hair that is exposed to cold, wet weather will have a lower critical temperature higher than that of a horse with a thick hair coat and fat stores who is acclimated to cold weather.
Another factor that can influence lower critical temperature is the size of the animal. Smaller animals have a greater surface area relative to body weight and can lose heat more rapidly than a larger animal. A weanling might reach their lower critical temperature before a mature horse. More importantly, cold weather can slow growth because calories are diverted from weight gain to temperature maintenance. To minimize a growth slump during cold weather, young horses should be fed additional calories.
Energy needs for a horse at maintenance increase about 1% for each degree below 18°F. For example, if the temperature is 0°F, a 1,000 pound idle, adult horse would need an approximately two additional pounds of forage daily. It is best to provide the extra energy as forage. Some believe that feeding more grain will help keep a horse warmer. However, not as much heat is produced as a by-product of digestion, absorption, and utilization of grain as is produced from the microbial fermentation of forage. Most data suggest that the need for other nutrients do not change during cold weather.
During winter months, heavy hair coats can often hide weight loss. Regular body condition scoring is recommended to gauge weight and assess horse health. If a horse starts to lose body condition, increases in feed are recommended. Conversely, if a horse starts gaining excessive body condition, reducing the feed is necessary. Sorting horses by age, body condition, and nutrient requirements makes it easier to feed groups of horses appropriately. Horse hooves generally grow more slowly in the winter. However, horses should still be trimmed every six to twelve weeks. The trimming or shoeing interval depends on each horse and the amount of hoof they grow.
Horse hooves are very susceptible to developing ice or snow balls in their hooves during the winter. These balls are compacted ice or snow that make it difficult for the horse to walk, increase the chance of slipping and falls, and can put increased pressure on tendons and joints. Hooves should be picked clean daily, especially after a heavy snow. Some have suggested that non-stick sprays and Vaseline applied to hoof soles helps to reduce the risk of snowball build up.
Horses have better traction on snow and ice when left bare foot compared to being shod. If the horse must be shod, care should be taken to avoid slipping and compaction of snow and ice in the hoof. Snow pads and studs that are attached to shoes can be used to help offset the effects of slipping and snow compaction in the hoof. Sole bruising can also be a problem in the winter, especially when working on uneven or frozen ground. For more information on horse winter care visit our winter care website.
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