Iron in the Equine Diet

increases the amount of iron sequestered or captured by the macrophages in the blood stream. Circulating free iron Fe2 liberated from spent red blood cells or macrophages is transferred back into the small intestine via bile. This process limits any excess of oxidative free iron Fe2 in the bloodstream that might accumulate as a result of normal red and white blood cell turnover. All of these processes serve to limit and regulate the amount of iron actually present in the horses body to what the horse actually needs metabolically and to prevent excessive free iron from accumulating.
Once the iron absorbed from the small intestine is actually in the bloodstream it is transported by a protein called transferrin to the liver and spleen for production of hemoglobin myoglobin or a storage form of iron called ferritin. Ferritin stored in the liver and spleen keeps extra iron not immediately needed by the horse in a safe nonreactive form so it is available for use by the horse when needed.  Excessive free iron Fe2 in the circulatory system of the horse will cause oxidative stress and tissue damage consistent with what is called iron overload but fortunately the equine metabolism is wellequipped to ensure that this rarely ever happens.
Facts About Iron and Horses
There is plenty of misinformation on the internet about the effects of excessive iron in equine diets. Always look for peer reviewed research if you are in any doubt about anything you read online. The reality is that horses do need iron in their diets. According to the National Research Council NRC 2007 Nutrient Requirements of Horses mature horses require a daily intake of 40 mg of available iron per kg of dry matter intake. That means a mature 500 kg horse eating 2 percent of his body weight in dry matter will eat 10 kg of dry matter per day thus 40 mgkg x 10 kg 400 mg of available iron is necessary daily for normal metabolism in our horse. As the workload of a horse goes up the dry matter intake also increases as does the requirement for available iron. NRC has established that growing foals and pregnant or lactating mares need 50 mgkg of dry matter intake. Your horses diet probably provides iron in excess of that but it has been wellestablished in research that not all of that iron is available to horses and in addition to