Thirteen years ago when routinely formulating rations for dairy cattle based on laboratory analysis of grain, forage, and water supplies, I observed a connection between iron intake and some health disorders. When supplemental sources of iron were removed, health and breeding usually improved in these herds. The health of animals with a high iron intake usually health responds to supplementation of higher than normal levels of antioxidant nutrients such as Vitamin E, selenium, zinc, and copper. As a mineral, iron binds with zinc and copper and reduces their absorption through the intestinal wall. Zinc and copper are essential for the growth of good quality hooves.
Copper is essential for good tendons and ligaments.
In a series of 3000 hay samples analyzed in the Maddy Feed Lab one year, the average iron content was 431 ppm which is about 10 times greater than the NRC iron requirement of 40-50 ppm for cattle and horse rations. Oats contain about 85 ppm iron, molasses about 750 ppm and dicalcium phosphate supplies, as a major calcium and phosphorus source in cattle and horse feeds, contains 6,000 - 14,000 ppm of iron. The iron in water supplies is usually in a very available and reactive form especially in clear water. In rust colored water, the more apparent iron may not be as harmful since it is already oxidized. From my observation, areas of the country that commonly have iron in well water supplies seem to have a greater incidence of laminitis occurring.