Trace Minerals for California Beef Cattle 

University of California, Cooperative Extension

Copper

    Copper (Cu) is a trace mineral required in the diet of beef cattle and is the second most common cattle mineral deficiency worldwide. Because Cu is involved in numerous roles in the body, a variety of symptoms occur when Cu is low in the diet. The classic example is lack of color in normally colored livestock: "bleached-out" Herefords and gray color in black cattle. Cattle may have inadequate levels of Cu without these classic symptoms. Bone fractures and/or weak bones may be seen with low dietary Cu. Delayed shedding-off of winter hair coat has been reported in Cu-deficient cattle. A distinct diarrhea may indicate high molybdenum levels, which makes Cu less available and thus deficient when dietary Cu levels are adequate. Due to Cu's essential role in numerous body functions, supplementation efforts for Cu deficient cattle are usually beneficial.

Diets low in Cu result in cattle with primary Cu deficiency. When molybdenum or sulfur levels are high, they impair Cu absorption and will result in secondary Cu deficiency in cattle even when forage Cu levels appear adequate. Primary Cu deficiency can cause infertility and/or diarrhea syndromes.  Secondary Cu deficiency can also cause infertility or diarrhea; however, infertility due to secondary Cu deficiency (excess molybdenum and/or sulfur) may not respond to Cu supplementation.

Copper intake should be 5 to 8 times molybendum intake, but should not exceed 50 ppm of the total diet. When sulfur concentration of the diet exceeds 0.2 percent, Cu should be increased in the diet. Water, usually well water or hot springs water, may have substantial amounts of sulfur that reduce availability of Cu. Copper deficiency is usual seen on severely leached soils and on alkaline soils due to high molybdenum causing reduced Cu availability. Water from alkaline soils is more commonly high in sulfur, which may add to interference.

Diets containing 4 to 10 ppm Cu are usually adequate. High dietary molybdenum (5 to 6 ppm dietary molybdenum) or high sulfate levels will decrease Cu absorption or availability and necessitate higher dietary Cu levels. In some cases of high molybdenum, serum Cu levels will be normal but Cu deficiency occurs. In those cases, additional cooper supplementation is required to overcome inference by high molybdenum levels.

Normal serum Cu levels are 0.8 to 1.5 ppm.  Serum Cu levels do not accurately predict Cu stores in the liver. Therefore, liver samples provide more information about Cu status and are the preferred tissue for assessing Cu status. Liver samples are obtained by liver biopsy under practical working conditions by a veterinarian. Liver samples can also be obtained from animals that die or have been slaughtered. Copper levels over 100 ppm on a dry basis in liver (or 35 ppm on a wet weight basis) indicate supplementation is not needed.

Both Cu and zinc status in serum and liver has been found to vary among cattle breeds. Limousin cattle have been found to have higher liver Cu levels than other breeds, and Cu deficiency occurs more frequently in Simmental and Charolais cattle compared to other breeds.

Excess Cu can be harmful. Cattle have a range of acceptable Cu levels. Salt mixes containing up to 0.7 percent Cu have been fed without apparent problems. However, sheep cannot tolerate high levels of Cu and have a much smaller range of tolerable Cu levels. Sheep exposed to Cu levels for cattle may develop Cu toxicity. Therefore, Cu supplemented salt for cattle should not be made available to sheep. Copper sulfate (bluestone) can also be harmful to fish at high concentrations.  Undiluted Cu sulfate should therefore be protected from mixing with water or entering water supporting fish.

All on-farm mixing of Cu sulfate should done in a well-ventilated area and inhalation minimized.