Your Horse's Winter Energy Needs

carbohydrates.
Non fibrous carbohydrates include starch and simple sugars. These can be digested rapidly in the stomach and small intestine of the horse to the basic sugar glucose. Glucose is readily taken up by the tissue of the small intestine and transported into the bloodstream where it is moved through the actions of insulin into body tissues to be stored either as glycogen or body fat. From there it is available to the horse for use as energy in metabolic functions including work. Dietary sources of sugars and starches are primarily grains and manufactured feeds.
Fats are also an excellent source of calories for horses. Fats contain approximately 2 25 times the calories of starch on a weight for weight basis so they can contribute significantly to the energy balance of your horse in extremely cold weather. Fat must be digested and absorbed in the stomach and small intestine of the horse so if you are feeding fat as an energy source it is important to feed it in small meals to avoid forcing undigested fat into the hindgut. Fat is not handled well by the microbes in the cecum and if overfed will reduce hindgut function potentially cause loose oily manure gas and in some cases colic.
Protein is not a primary energy source but can be used for energy when fed in excess of metabolic requirements. The horse has no ability to store protein for future use so excess protein is frequently used for energy. The carbon skeleton of the protein molecule can be used for energy and the nitrogen containing part of the protein molecule is excreted through the function of the liver and kidneys. Protein can contribute significantly to the energy balance of the horse in winter.
Forages The Perfect Energy Source for Your Horse
For most mature horses doing light to moderate work during a temperate winter climate forages such as grass or alfalfa hay will provide most of their energy needs. Horses that are working growing senior and pregnant or living in extreme winter weather conditions may need more energy from additional feed sources usually grains containing additional protein fats and starches.
Beware of the assumption that average hay is always average. Hay can vary hugely in its energy generating capability depending on the analysis. Hay that is high in lignin an indigestible substance that accumulates in the forage as it matures is much less digestible and will yield less