Fact Sheet No. 7: Copper Deficiency
By John Maas, DVM, MS Diplomate, ACVN & ACVIM Extension Veterinarian School of Veterinary Medicine University of California-Davis

Description and Cause

Copper deficiency in beef cattle has been recognized more commonly in California. Copper deficiency causes significant economic losses where it occurs. Copper deficiency in cattle is complicated because it can be the result of:

• very low copper in the diet-a primary copper deficiency, or
• interference with copper absorption in the animal due to molybdenum and/or sulfates in the food or water-a secondary copper deficiency.

Regardless of the reason for the copper deficiency, the problems exhibited by the animals are the same. Some of the common symptoms seen in cattle with copper deficiency include:

• diarrhea,
• unthrifty appearance,
• poor weight gains,
• light hair coats (angus are grey, Herefords are yellow),
• swollen, painful joints,
• broken bones,
• rear leg weakness of paralysis in calves,
• infertility,
• anemia,
• and decreased resistance to disease.

The problems seen will vary from herd to herd and are not easily predictable. However, when copper deficiency does occur, it invariably causes losses in production, health, and profits.

The most commonly observed results of copper deficiency in cattle are diarrhea and poor weight gains, particularly in calves. The diarrhea may be easy to see when it is constant and profuse; however, it may only be noticed as soiling of the back of the hind legs and tail. Signs of diarrhea and/or weight loss are not specific for copper deficiency and could be caused by parasites, selenium deficiency, BVD virus, or a number of other conditions. The other signs of copper deficiency (broken bones, infertility, anemia, etc.) that can occur in cattle may be subtle or occur only as the deficiency worsens. The fact that copper deficiency lowers the immune response and can make the cattle more suspectable to disease and less responsive to vaccines is of particular importance to the health of the heard

Dietary Requirements for Copper

The diet of cattle (pasture, range, hay, etc) should contain about 4-10 parts per million (ppm) of copper to supply the needs of cattle. Less than this amount results in a primary copper deficiency; however, if excess molybdenum and/or sulfates are present in the feed or water there can be marked interference with copper utilization by the cattle and copper deficiency lowers will result. Cattle will usually perform normally when the copper to molybdenum ratio is from 5:1 to 10:1 in the diet. When the copper to molybdenum ratio falls to 2:1 or less, one can expect severe interference with copper utilization and a resulting copper deficiency to occur. While molybdenum and sulfates are the most common interfering substances in cattle's diets, other situations can drastically interfere with copper nutrition and these include:

• soil ingestion due to overgrazing,
• excess cadmium,
• excess zinc,
• and excess calcium, particularly as limestone.

Testing for Copper Status

It is easy to see that copper nutrition in cattle can be complicated by a number of factors. While it is possible to test feed, soil, and water for all the various minerals mentioned above, it is more practical to test the cattle to determine their copper status and make any necessary changes based on those findings.

The University of California's Veterinary Diagnostic Laboratory and other UC Laboratories are available for routine testing of animal and feed samples for copper, as well as a number of other nutrients. Your veterinarian can test animals within your herd for copper status using serum samples (serum is the straw colored fluid in blood left when red blood cells are removed). If the serum copper concentration is below 0.5 ppm in your cattle, it is diagnostic of a copper deficiency. Screening the herd with serum copper analysis is quick and inexpensive, however, it is primarily of value to identify advanced deficiency situations.

Copper metabolism is complicated by the fact that most of the copper in the body is stored in the liver and it is the liver copper level that gives the true reflection of the copper status of the animal. The serum copper concentration begins to drop only after the liver copper reaches very low levels. That is why serum copper is a good screening tool; however it is not a good measurement for marginal deficiencies or for monitoring the cow herd after supplementation with copper begins. On a practical level this means that liver samples from a few cows for copper analysis is necessary for monitoring the effectiveness of copper supplementation. This is important for two reasons:

• to be sure that the copper supplementation is solving the deficiency,
• and because excess copper is extremely toxic to cattle, to be sure that excess copper supplementation is not occurring.

Liver samples from cattle can be obtained by two common methods:

• when normal animals are slaughtered a small piece (3 ounces) of liver can be saved and frozen (indefinitely) until analyzed,
• and your veterinarian can take liver biopsy samples from live cattle (usually 4-7 animals are sufficient) and these can be analyzed.

Liver biopsy can place animals at increased risk of Redwater and your veterinarian will usually administer penicillin after the liver biopsy procedure.

Prevention

Copper deficiency can be managed by supplementation of the cattle by a variety of methods. Injectable copper glycinate has been used for many years to treat and prevent copper deficiency. Recently, this injectable product (Moly-Cu -Schering-Plough) was removed from the market for manufacturing reasons and while it is still legal to use, it is not known when or if this injectable product will be available again. This copper injection product provided adequate copper supplementation for six months in most cases.

Copper can also be added to salt-mineral mixes to aid in supplementing the cattle. With diagnosed copper deficiency, these mixes are usually formulated to contain 0.2% to 0.5% copper, with the higher levels reserved for severe deficiencies. The above levels of copper in salt-mineral mixes assumes intakes of about one ounce of salt-mineral mixture per cow per day to meet the cows' copper requirements.

Also, copper can be added to total rations via a premix or can be added to molasses-based supplements to meet the copper requirements for the cattle. A relatively new method of copper supplement is the copper oxide bolus (Copasure -Schering-Plough) which is given orally and provides supplementation for up to 12 months. This product works very well; however, it has the disadvantage of having to be given via balling gun and the capsule is water soluble, so that it will melt if rained on. Whatever the method of supplementation it is extremely important to remember that while a little copper may be good, too much copper can be extremely toxic.

Copper Toxicity

All of the methods mentioned above can provide excellent supplementation for cattle. However, sheep are much more sensitive to copper toxicity than are cattle and if sheep are allowed access to copper supplements formulated for cattle in most circumstances the sheep will experience significant death losses. When copper is fed in excess of requirements it tends to accumulate in the liver. With minimal stress, the stored copper can cause death in cattle or sheep within a few hours to a few days. As the excess copper being fed accumulates in the liver there are no outward signs in the animals and death can occur at any time. Treatment of copper toxicity is invariably unsuccessful. Therefore, it is extremely important for you and your veterinarian to monitor any copper supplementation program with liver samples on at least a yearly basis.

Copper deficiency occurs commonly in California and new analytical methods make diagnosis and control much easier. Working with your veterinarian and UC livestock advisors prevention of both copper deficiency and the possibility of copper toxicity is relatively straightforward even though the metabolism of copper in cattle can be very complicated.