During cold weather, the horse requires additional energy to maintain its internal body temperature and keep warm. The exact amount of energy depends on the severity and extent of the cold period. When environmental temperatures (including wind chill) drop below 0°C (referred to as the critical temperature), significant amounts of energy are used by the horse to maintain its internal body heat.
For each 1°C decrease below the critical temperature, the horse requires a 1% increase in digestible energy to maintain a consistent body temperature. Wind chill, moisture, and coat thickness will affect the critical temperature. The horse’s thick winter coat has an insulating effect against cold and wind….. read full article in Eques Winter 2015 Issue