Copper is a complicated trace element with the amount available to animals varying over different times of the year and affected not just by the amount available in the feed but by many other interfering factors such as molybdenum and iron. Soil or pasture analysis does not give an accurate idea of how much copper is available to cattle.
Copper deficiency decreases reproductive performance in adult cattle and limits growth rates in young stock.
For herds getting multiple sources of copper such as those being fed palm kernel, receiving copper through the water and being injected with copper, there is a high risk of toxicity. Measuring copper levels can give a warning that there may be cows at risk of toxicity.
The liver is the organ where copper is stored within the body, so we must measure how much copper is present within the liver to know how much copper reserves a cow has. There is little correlation between blood (serum) and liver copper levels. Even at low copper levels there is huge variation in the blood copper levels measured. This means that measuring blood copper levels alone does not give an accurate measure of how much copper is present in the liver. The best way of measuring copper levels is by taking a sample of liver.
Other minerals such as selenium and B12 (cobalt) can also be measured using either liver or blood samples.
Livers from cull cows sent to slaughter premises can be tested for trace elements. However, cows selected as culls are often not representative of the herd as a whole and so the results can sometimes be difficult to interpret at a herd level. The samples are not taken directly from the cow once the organs have been removed during the slaughter process and on occasion, there have been instances where the wrong livers have been sampled.
The procedure is carried out under local anaesthetic, so the cows feel the initial needle enter to inject the local anaesthetic but this then blocks feeling to the area – similar to us visiting the dentist. Following this a small nick is made in the skin and a biopsy punch is inserted into the liver to remove a small sample. Following sampling, cows can be returned to the herd.
To make the biopsy easier, we ask that cows have a full belly of feed to ensure the liver is pushed up by the rumen into the correct position for sampling.
Elements are a new range of oral trace element of supplements for dairy cattle, specifically developed by Franklin Vets for the North Waikato and South Auckland area.
They are extremely cost competitive, and move away from the traditional sulphate mixes, towards chelates, and amino acid blends that we believe have better uptakes.