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Copper Toxicity Diagnosed Locally

Copper toxicity has always been considered of extremely low risk in the NZ dairy industry due to our soils and pastures generally being deficient in several trace minerals, including copper.

Here in the Matamata-Piako area, up until the early 2000’s, copper deficiency was regularly diagnosed through blood sampling and liver biopsies and many older farmers will recall the need to bullet or inject the herd with copper prior to calving.

However, following the introduction of PKE approx. 20 years ago, copper status has significantly improved in those herds feeding up to 500Kg per cow, with only maiden heifers entering the herd with no prior exposure to PKE needing additional copper.

This is because PKE still contains between 3 – 5 x the copper of typical NZ pasture and therefore boosts copper levels when fed up to 500Kg per cow per annum.

Recently in a local herd where two cows died suddenly, blood tests and post-mortem results were consistent with Copper Toxicity. Further investigations revealed that in this particular herd, cows were being fed up to 1.5T PKE/cow/annum (approx. 4KgDM per day over the year). PKE was also being fed in trailers in the paddock, providing the opportunity of dominant cows to eat more and 150mg of additional copper being provided via daily mineral supplementation.

Further liver biopsies were taken from healthy cows in this herd which showed the problem was widespread and on this basis several management decisions were made to reduce the herd’s exposure to copper.

This case reinforces our previous communications on mineral supplementation and testing that regular (annual or biannual) trace mineral testing can help identify both deficiencies and toxicities.

If you are unsure of what your mineral status is, we are happy to advise on testing and supplementation.

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