Surprisingly, the easiest way of feeding your horses during the cold winter months, is actually the simplest. Feed a high quality hay, preferably free-choice. The majority of horses will eat about 2 - 2.5% of their body weight in hay per day. The average daily free-choice hay intake, for example of my horse Rio who is 1250 lb) is 26 - 33 lbs/day, or about a half a bale of hay per day (based on a 65 pound bale). For temperatures below the critical temperature of -15°C (0°F), you will need to feed an additional 2% more hay. If temperatures drop to -40°C (-40°F), your horse will need an extra 10 - 12 pounds more hay than it ate at temperatures above –15°C.
It is important to use highly digestable hays and supply a sufficient amount. Coarse overmature hays are very low in energy and high in indigestible fibre, so in cold weather, when the energy demands are high, this type of hay will not supply the energy that is required. In addition, if this hay is fed without sufficient water consumption, it can cause impaction. Remember that during cold weather, your horse will drink less water.
Grain can be added to the diet during cold weather, but caution must be used when adding grain to horses unaccustomed to grain as laminitis can occur. All horses fed grain should be gradually introduced over a period of 7 - 10 days.
Vitamins A, D and E can be supplemented. Mineral/vitamin combinations can be supplemented but remember to have a fortified 2:1 calcium-phosphorus mixture with grass hay and a 1:1 mixture when feeding alfalfa hay.
It is VERY important to provide heated water, if possible. Temperatures should be between 2-10°C as this will help maintain digestive function. Although some horses will eat snow, snow is not a substitute for water.
If your horse is turned out 24/7, it would be recommended to provide them with protection from the wind. Bedding areas behind snow fences or among trees will enable your horse to lie down and conserve body heat. If possible, a well bedded south or east facing shed would be helpful for young and older horses.
Remember that horses are animals that are well-adapted to cold temperatures. If you meet their food, water and shelter needs, your horse will be safe, healthy and comfortable during the cold winter months.