Iron in the Equine Diet
Horse owners who are interested in equine nutrition and actively involved in planning the composition of their horses diet will know that iron intake has become a subject of much discussion. Terms such as iron overload are easy to find using a Google search and the risks associated with free radicals and oxidative stress are often coupled to the amount of iron in the equine diet. Iron levels in typical equine diets have been targeted as the reason for many equine health issues including metabolic conditions reduced immune function poor hair coat and hoof wall and developmental disease in growing horses. The internet has several popular websites available for the average horse owner to educate themselves about iron in the equine diet. Frequently these sites also have products offered for sale or have links to sites that sell products that are supposed to help the horse with iron overload. So just what is iron overload in the equine diet and do horse owners really need to worry about it?
Iron is a trace mineral which in small amounts is essential for life but can be toxic if overfed. Iron uptake from the digestive tract of horses is very tightly regulated by a system of hormonal controls. Iron is primarily responsible for oxygen transport in the blood and muscle in the form of compounds called hemoglobin and myoglobin respectively. Threequarters of a horses total iron stores are located in the liver spleen and muscles. Within the liver and spleen a large percentage of the iron is located in the macrophages large white blood cells making iron an important part of the horses immune system. Iron is a constituent of some enzymes and therefore responsible for several metabolic processes in the equine body. And finally as a component of lactoferrin found in mares milk it is essential for its bactericidal role in the mammary gland of the mare as well as the gut of the newborn foal.
Iron is transported from the small intestine into the enterocytes cells lining the gut wall by transporter proteins responsible for the transfer of several different trace minerals. Horses control iron uptake in their digestive tracts through a hormone called hepcidin so that as more iron is transported through the gut wall more hepcidin is produced thereby downregulating the transfer of iron into the horses circulatory system. Hepcidin also
