NADIS disease bulletins are written specifically for farmers, to increase awareness of prevalent conditions and promote disease prevention and control, in order to benefit animal health and welfare.

Farmers are advised to discuss their individual farm circumstances with their veterinary surgeon.

Copper Deficiency in Adult Cattle

Copper is an essential element in many enzymes that are essential for the normal functioning of the body. Copper is thus involved in transport of minerals in the blood, development of many body tissues, production of pigments and in the normal function of the immune system. Copper is also an important part of the antioxidant system, which protects the body against damaging chemicals. As copper is involved in so many places, copper deficiency has been linked to many problems. However the most commonly linked problem in adult dairy cattle is poor fertility.

True copper deficiency, that is cows being fed too little copper, is extremely unlikely in adult cattle. In virtually all cases copper deficiency occurs because the copper in the diet is bound by other elements, particularly sulphur, iron and molybdenum, which prevent its uptake by the cow.

Clinical signs

Many diseases are associated with copper deficiency. However, it is important to remember:

1) That for many of the diseases linked to copper deficiency, there is no conclusive proof that they are due to copper deficiency

2) These diseases are associated with many other factors than copper deficiency. Concentrating on a mineral deficiency may result in the actual cause being missed

Diseases in adult cattle linked with copper deficiency include:

· Mastitis and increased somatic cell counts

· Reduced milk yield and productivity

· Change in coat colour and poor hair growth

· Anoestrus, and poor oestrus behaviour

· Early and late embryo death

· Diarrhoea

Some farms will show only one sign, others several

Diagnosis

¨ Copper deficiency cannot be diagnosed on clinical signs alone. A proper veterinary investigation is essential.

¨ Diagnosis is not simple. The usual test is to measure copper in the blood. At least six animals per group must be tested, and preferably more. If the average of the group is low then it is likely that copper supplementation will be beneficial. However, because copper levels in the blood do not fall until liver stores are depleted after a long period of deficiency, cows can be copper deficient and have normal blood copper levels

¨ Some laboratories offer a service measuring blood ratios. The main effect of this seems to be an increase in the diagnosis of copper deficiency (or molybdenum toxicosis), although there is no conclusive evidence that animals with altered copper ratios need more copper.

¨ Liver copper is a better measurement as this falls before blood copper. However, the samples are difficult to take (unless there are cull cows available) and are more expensive to measure.

¨ In many cases the only solution is to give copper to a group of cows and see if there is a response. However, for such a test to show copper deficiency some cows must be untreated. Just treating all cows to see if there is a response to copper is not proof of copper deficiency, as most of the diseases linked to copper deficiency can get better without treatment

¨ Many of the problems associated with copper deficiency develop over a long period of time. If there is a dietary change over this period, the copper status can change, so that animals that were copper deficient appear normal and vice-versa.

¨ The animals sampled must be sampled before the problem began. If cows are not getting pregnant, they need testing when they are served, not at the time of pregnancy diagnosis.

¨ Analysis of the copper in the feed, alongside molybdenum and sulphur can be valuable in identifying a potential problem.

Treatment and prevention

Copper deficiency can be treated either orally or by injection. Several products are commercially available for this purpose ranging from copper sulphate in the feed to sophisticated boluses that release copper slowly over a prolonged period. There is little difference between them in terms of their value for treating copper deficiency.

This is also true for prevention, with both oral and injectable products being effective at preventing deficiency. However claims are often made that one is better than the other. Advocates of copper injections suggest that they are better because they bypass the absorption problem, whereas some advocates of oral treatment suggest that this route is better because it binds the rumen molybdenum, preventing its absorption. The best solution depends on the individual farm situation, this is best decided in discussion with your vet.

Whichever solution you choose, but particularly if you increase copper in the feed, it is essential to monitor the situation and ensure that copper levels don’t get too high. Copper toxicity is becoming more common in cattle, and most outbreaks have been associated with the feeding of unnecessarily high levels of copper.

Richard Laven PhD BVetMed MRCVS