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Electrolytes for Performance HorsesBy Kentucky Equine Research Staff · June 19, 2015

Overall health and well-being of horses depends on many nutrients, including electrolytes such as potassium, sodium, and chloride. Forage contains high amounts of potassium, and when fed in adequate quantities, normally meets daily potassium requirements. In contrast, most forages are deficient in sodium and marginal in chloride. As a result of the many factors that affect intake and the rate of loss of sodium, potassium, and chloride, electrolyte supplements should be provided to horses that exercise heavily and sweat freely.

These minerals can be provided to horses in their ration or as a separate supplement. Most salt blocks and other supplements do not contain potassium. Therefore, if the roughage portion of diet is restricted (less than 1% body weight on a dry matter basis) or high sweat losses occur as a result of hot summer weather and moderate to heavy work, potassium supplementation may be necessary.

Restore SR, an electrolyte supplement designed by Kentucky Equine Research, can be top-dressed on the daily grain ration to supply potassium, sodium, chloride, and magnesium. Sodium is provided through a proprietary slow-release mechanism, allowing it to be released gradually into the gastrointestinal tract for sustained absorption. (Horse owners in Australia can use of Restore or Endura-Max, another electrolyte designed by Kentucky Equine Research.)

Electrolytes are sometimes added to drinking water, especially for heavily exercised horses. However, horses should be introduced to electrolyte solutions gradually and water intake monitored, as electrolyte solutions can result in reduced water consumption in some equines. If electrolytes are added to water, a bucket of plain water should also be available. Similarly, addition of electrolytes to feed should be approached conservatively to avoid decreased feed intake.

Along with daily supplementation, administration of hypertonic electrolyte pastes such as Restore Paste (in Australia, look for this as Restore Paste or Endura-Max Paste) before or during competition is widely practiced by endurance riders. Electrolyte pastes may contain sodium chloride, a 50:50 mixture of sodium chloride, and potassium chloride mixed with water. While such salt pastes provide a portion of the electrolytes lost in subsequent work, another method of action is stimulation of the thirst response. This encourages voluntary water consumption in order to maintain extracellular fluid volume during the ride and aid post-exercise recovery of fluid losses.

In the horse, the gastrointestinal tract is an important source of fluid and electrolytes utilized both during and after prolonged exercise. The importance of dietary fiber in increasing this gastrointestinal fluid reservoir underscores the need to maintain quality roughage in horses that are training and competing in prolonged events, such as endurance rides. Depletion of this reservoir appears to be one of the main reasons for persistent body weight losses during recovery from high-level exercise.