Bone Growth in Young Horses: The Importance of Vitamin K

Probably best known for its blood-clotting properties, vitamin K serves other functions in the horse’s body.

Another important role of vitamin K involves bone metabolism. Osteocalcin, a blood-clotting protein also involved in bone mineralization, may be more sensitive to low vitamin K activity than other blood-clotting proteins. The liver is capable of efficiently extracting the required amount of vitamin K from the bloodstream, even when circulating concentrations of vitamin K are low. This explains why it may be possible for a horse’s bone tissue to be deficient in vitamin K, while the level is adequate for clotting of blood. Osteocalcin may therefore be a far more sensitive marker for vitamin K status than are the blood coagulation factors.

Natural sources of vitamin K in equine diets are phylloquinone (K-1), found in green leafy plants, and menaquinone (K-2), which is produced by bacteria in the digestive system. Both phylloquinone and menaquinone are converted to the active vitamin (hydroquinone) in the liver.

In young horses, significant bone growth occurs prior to foals having a completely functional hindgut and prior to eating a significant amount of green forage. Ongoing research may help to explain more about vitamin K requirement and action in diets for growing horses.

DuraPlex, a nutritional supplement developed by Kentucky Equine Research(KER), is designed to support bone quality and maintain correct bone metabolism, and is especially useful for horses that are laid up because of an injury. DuraPlex is available in the U.S. and can be top-dressed on feed to provide nutrients necessary for optimal bone health. In Australia, ask for Bone Food.