Copper

Written by Andrew Cribb, Owner/Veterinarian East Coast Farm Vets

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We’ve been pregnancy testing heifers over the past month and we’ve witnessed first-hand the advantages of implementing an effective animal health plan that includes trace elements.

The abundance of feed across many parts of the district will have you believing the mineral profile is healthy, however, copper is known to be often very deficient in animals in the region and therefore, knowing the levels in all of your stock classes is valuable information.

Copper is a crucial trace element for cattle, impacting growth, fertility, immune function, and calf survival.

It readily crosses the placenta of pregnant animals and is instrumental in developing the insulation around nerve fibres in the developing foetus.

The second major function of copper involves a dual role in skeletal development, providing the scaffolding for bone growth and facilitating the hardening of bones from cartilage. This is vital for healthy foetal growth, the development of a robust skeletal frame and the prevention of broken bones.

The impact of copper deficiency is most evident in lambs, presenting as swayback, but it can affect the nervous system of all new-borns. This, in turn, can reduce the "get up and go" of new-born lambs and calves, which is particularly important during severe weather.

The best way to assess copper status in cattle is through liver sampling, either from slaughtered animals or via biopsy. Liver copper levels below 45 umol/kg fresh weight indicate deficiency. Blood tests can provide some insight but are only reliable for a clinical deficient copper status. Visual signs, such as coat colour changes, are also not dependable indicators due to other influencing factors.

Cattle require 10mg per/kg of dry matter with sheep only requiring half the amount of 5mg/kg and there are several ways to supplement stock. While there is no dose-dependent response to copper (where more copper equals better performance), achieving well-established copper levels is essential to rectify immediate deficiencies, particularly during critical times, such as pregnancy.

Because copper metabolism is complex, supplementation should be tailored to stock class and seasonal needs. Some commonly used options are:

• Subcutaneous injections – provide a short-term boost (one to two months) but pose the highest risk of acute copper toxicity if overdosed.

• Intra-ruminal boluses – offer a controlled, slow release of copper for six to nine months, making them ideal for pregnant cows.

• Pasture topdressing – application of copper sulphate (6-12kg/ha) in autumn or spring can increase copper content, thought high molybdenum soils may reduce effectiveness. Pastures should not be grazed until rain has washed fertiliser off the herbage.

Deficiencies tend to develop over winter and spring as copper availability in pastures declines. Breeding cows require significant copper reserves to support both lactation and foetal development. If their copper levels are adequate, their calves will also be born with sufficient stores.

While correcting deficiencies is essential, long-term and intensive supplementation increases the risk of copper toxicity, which can be fatal. Establishing a "copper budget" is key – knowing where your copper is coming from, what may be impeding uptake, and through ongoing monitoring of fertilisers, season and time, ensuring supplementation matches the needs of each stock class.

This article was published in the Gisborne Herald on 08/03/25.