Copper is involved in the antioxidant system via its involvement in the enzymes Cu–Zn superoxide dismutase (SOD) and ceruloplasmin. Copper–Zn SOD is responsible for dismutation of superoxide radicals to hydrogen perox- ide in the cytosol (Halliwell and Gutteridge, 1999). Cerulo- plasmin is a Cu transport protein that also exhibits oxidase activity. It oxidizes ferric iron (Fe+3) to ferrous iron (Fe+2) without the production of free Fe+3 that can cause oxida- tion and peroxidation to tissues . Ceruloplasmin is an acute phase protein that increases during disease and may be important in scavenging superoxide radicals Copper deficiency in cattle is generally due to the pres- ence of dietary antagonists, such as sulfur, molybdenum and iron (Fe) that reduce Cu bioavailability . Dietary requirements for Cu are greatly increased by high concentrations of molybdenum and sulfur.