By Judi Nayeri of Ma’s Acres Dairy Goats
Copper (Cu) is an essential nutrient required in minute quantities for all species of livestock. All vary in their needs but it is an important dietary requirement in goats. Copper is a building block in a great number of enzymes which in turn function in a number of body systems to maintain a balance providing vitality, health and productivity. Copper is essential for the formation of collagen which provides a matrix for the phosphorus and calcium deposition leading to proper bone formation. Elastin is another product necessary for healthy formation of the walls of major blood vessels and arteries, as well as a building block for long elastic ligaments, tendons and skin. Copper contributes to proteins that convert iron in the liver to forms that can be incorporated into the hemoglobin in the red cells. This also occurs in the intestine. It is essential to the development and maintenance of myelin which is the insulating material of axons and nerve fibers making it an important component in the development of the central nervous system. Copper is involved in melanin synthesis, insulin function, and lipid metabolism. As mentioned above, copper is involved in iron metabolism and protects the body from oxidants. At higher levels (ie: 100 mg Cu/day) it contributes to stimulated growth, feed efficiency and the control of nematode parasites.
Acute copper toxicity in goats is rare, but constant small excesses can eventually lead to problems. There is a capacity to store up to 1000 mg Cu/kg DM (dry matter) in the liver. A major stressor could cause metabolic changes that could lead to a significant release into the bloodstream causing toxicity. Keep in mind, although this is possible, it is uncommon in goats. Chronic copper toxicity, which is more likely, has two stages. The first stage is the pre-hemolytic stage. During this stage the accumulation of copper in the liver exceeds 1000 mg Cu/kg DM. This can take from a few weeks to more than a year to occur. The second stage is the hemolytic crisis. Copper is released from the liver. The plasma copper level raises causing anemia, jaundice and bloody urine. This can last hours to days. Ammonium molybdate or sodium sulphate in the diet will reduce the absorption of copper if a chronic toxicity is detected.
The liver normally contains 200-300mg Cu/kg DM. Concentrations <20mg Cu/kg DM along with <0.5 mg Cu /l in plasma is copper deficiency. Long term this will lead to hypo chromic microcytic anemic (small red cells with decreased oxygen carrying capacity). Based on functions previously discussed, there can be improper bone development and uneven bone growth. This can lead to generalized osteoporosis and occasional bone fractures. Copper deficiency can also lead to connective tissue disorders as well as defects in articular cartilage, ligaments and tendons; cardiovascular disorders, depigmentation of hair, scouring, infertility and increased susceptibility to disease. When does are deficient during the third trimester, the kids may demonstrate neonatal or congenital ataxia because of insufficient myelin synthesis in the fetal brain. There may also be a delayed ataxia at 1-2 months affecting mostly the hindquarters with a paralysis or failure in mobility due to insufficient myelin synthesis after birth for proper development of the spinal cord nerves. Clinically this may mimic the neurological form of CAE, encephalitis virus infection in young kids or even polio. Other less critical forms of deficiency may be fading coat colors, unthriftiness, persistent parasitism, or hair loss at the tip of the tails. The tip of the tail will be bald and the hair will separate in opposite directions causing a “fish-tail” appearance. Be careful not to confuse this with tail biting.
Actual requirements for copper in the goat’s diet vary in the literature. It is important to remember that absorption is more important than the actual concentration in the feed. Absorption in young animals on a liquid diet can be up to 90%. This is more efficient than in older animals. There are elements or trace minerals which may be consumed or produced by microorganisms in the gut that may interfere with the absorption of copper. Recent data suggest 8-10 mg Cu/kg in the diet, but higher levels in goat milk suggest a higher need in the feed of lactating does. There are conflicting reports in the literature whether higher intake increases growth and efficiency in young animals.
Final recommendations of the National Research Council of the National Academies are lactating does 15 mg Cu/ kg DM, mature bucks 20 mg Cu/kg DM and young goats 25 mg Cu/kg DM. This assumes recommended ratios of other trace elements be adhered to or the benefit may be nullified due to the absorption being blocked. Additionally, alfalfa is a good source of copper higher than most temperate grasses and acid soils may produce plants higher in copper as opposed to alkaline soils.
Complete commercial goat feeds are the route of choice to avoid copper imbalance and its consequences. There are multi-species or goat/sheep feeds but these will not contain the proper balance of the needed trace minerals for goats. Other species do not tolerate or need copper to the extent of goats. For example sheep will become toxic at the levels required by goats. The best choice is to use the commercial feed specific to goats which will contain the proper ratios of trace minerals or if you choose another method to feed your herd, offer free choice mineral specifically designed for goats. There are commercial products available to correct a deficiency, but some have more bioavailability than others. Consult your veterinarian first if you have concerns, confirm your diagnosis and follow his recommendations if supplementation is needed.
There is a lot of detailed information available. References are available upon request.
Information provided is general in nature and is provided without guarantee as to results. The information is not intended to be and should not be construed as legal advice.