Q: I have water that has tested very high for iron (unsafe to drink). The well is located in an agricultural field, and used to irrigate a hay field that is then harvested and fed to my horses. Will the high levels of iron from the irrigated water be taken up by the hay and then transferred to the horses? What can excessive levels of iron do to horses? Can you test for iron levels in hay?
A: The National Research Council's maximum for iron is 500 mg/kg in the total diet for most species. Problems with equines have been observed when iron levels are above 1,000 mg/kg in the diet, and significant problems may exist when pastures grasses/hays are above 1,500‐ 2,000 mg/kg. There have been some cases where excessive iron in the forage has created interference in absorption and utilization of other trace minerals. Forage can be tested for iron levels. Equi-Analytical can test for iron. Other forage labs may also be able to perform the test if requested. Farms with excessive iron levels in water or forage can observe higher than normal incidence of developmental orthopedic disease in foals and yearlings. Interference may have been impacting copper, zinc and manganese utilization as well. Because it is not always feasible to move horses off high iron pastures (or water sources), adjust trace mineral intake and source to compensate for the high iron.
By Roy Johnson, Cargill