Copper testing of livestock

Vet's vision
with Phil Rennie
Tauranga Vets

With the end of the facial eczema challenge close at hand, and with it the need for ‘zinc supplementing season’, it is important to check your stock’s copper reserves.

Zinc competes with copper for absorption at the gut level, which may lead to very low copper levels leading into winter, when zinc supplementation finishes.

Variation in supplementary feed offered further complicates the situation. As well as those expecting to give birth, young stock also have high copper requirements for growth and development.

Many farms adopt quite different supplement feed plans to ensure stock are fed adequately. For instance, significant amounts of palm kernel can be added to the diet and markedly increase copper levels in some herds.

However this is not always the case, especially when the level of palm kernel fed is fit for daily maintenance energy requirements, as opposed to being an additional energy source for weight gain.

To optimise productivity cattle trace element is recommended. Testing should be done pre-calving for pregnant stock and late autumn/early winter for growing stock.

Liver biopsies provide the most accurate information, as it is a direct measure of the amount of copper stored in the liver.

Samples from five animals from the group are usually sufficient to give an indication of the herd copper levels.

Alternatively blood tests can be taken from 8 animals, can provide a ‘snapshot’ of copper levels in the blood on the day of sampling.

Deficient animals can be easily identified this way however the results do not provide any information on the amount of copper stored in the liver, so herds close to deficiency may appear normal on blood tests, and hence the need for increased copper supplementation will not be detectable.

Registered copper supplements are typically either in injectable or oral bolus forms.

If you have any questions about copper or other trace mineral testing of your stock, feel free to contact your local vet clinic.

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