Autumn Trace element testing

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Reproductive efficiency, cow health and milk production are integral parts of a successful dairy farm. The cow has a requirement for essential nutrients to perform at her best. A trace mineral is one that is present in low concentrations in the body tissues and fluids of cattle, where removal from the diet will consistently interfere with survival and reproduction.

Trace elements are mostly gained through nutrition, although cow health, production and stage of life and pregnancy can all impact on their availability for physiological processes. This means that the diet is very important, and the soil type greatly impacts on how much of these elements are present in the grass that your cows consume.

Below is a map of our area with different soil types and deficiencies relative to selenium and cobalt (vitamin B12) in NZ

Trace elements impact on a cow’s immune system, bone strength, milk production, energy metabolism, and skin and hair quality. This can directly affect your somatic cell count, mastitis cases, number of sick and lame cows, herd and youngstock growth rates, reproduction and milk production efficiency. If you have experienced selenium deficiency in your cows at calving, you will have seen firsthand the impact on retained membranes.

Getting the trace elements right in your herd requires monitoring the end product (the COW). This is most important, because although feed and soil testing can be valuable to build a picture of your farm, this is not the only measure of what the cow will receive. Many trace elements have complex interactions with other substances that can impact on absorption or availability. For instance, copper can be bound by many other molecules in the water and in the rumen of the cow, which then reduces the ability for the cow to absorb it. Since too much of these trace elements can often also be toxic for the animal, getting it right is very important.

Once we have tested the animal (and this test must be reliable and able to be compared to a properly validated reference range), we need to take her age, stage of lactation, and stage of pregnancy into account. These three things impact the animal’s requirement for various trace elements. For example, copper is required for strong bone formation. A deficiency in rising 2-year-old heifers just prior to calving, results in a high number of broken legs.

We also need to ensure the cow will have enough trace element for her future requirements. A cow getting a daily dose of trace elements through her feed ( via a pellet, cone dose, mixer wagon or mineralizer) or water (dosatron or peta dispenser), is a different scenario to one being dried off and sent to crop at a run off block with only a loose lick over the winter.

For these reasons, we have made a list of the key trace elements we recommend you discuss with your vet about testing in your dairy cattle. This list includes the main elements that we can test for, and when it is most important to check them. There are other trace elements (such as zinc and manganese) that are also important for dairy cattle, but current lab testing methods are either unreliable or too costly for routine sampling. Please let us know how we can help you to ensure your cows have optimum trace element supplementation in your herd.  We are happy to help.


  • Liver copper
  • Blood Selenium


  • Liver or blood copper
  • Blood or liver selenium
  • Blood or liver B12 (cobalt)
  • Inorganic iodine

Pre-dry off;

  • Liver copper
  • Blood selenium
  • Blood or liver B12 (cobalt)

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