Interactions between minerals
Copper deficiency has been identified as a serious problem for grazing ruminants. A deficiency may be due to low concentrations of Cu in forage and can be further exaggerated when Mo, Fe and S levels are elevated. Molybdenum and sulphur interfere with Cu absorption by forming thiomolybdates that bind Cu, resulting in compounds that cannot be absorbed by the animal. Decreased liver Cu levels can be caused by excessive Fe in the diet. In the same study, Mo appeared to have an additive action with Fe by decreasing liver Cu, while S and Fe had independent effects on Cu. The antagonistic mechanism of Fe is not well understood. Excessive dietary Zn can also negatively affect absorption of copper.