Getting the correct balance of trace elements

It is well known that having adequate levels and the correct balance of trace elements is crucial for optimal herd performance. Many producers rightfully spend significant amounts on trace element mixes and blends, however, what I find surprising is the number of farmers that do no or very little mineral testing.

Regular lab testing is essential to understand if you are:

• Supplying enough minerals, obviously if you are supplementing trace elements, but the levels are still low the cows will be underperforming leading to lost production, repro problems etc. In this situation either increasing the levels supplied or changing products will be the answer.
• Giving the correct balance of minerals, sometimes we see that giving a lot of one mineral will lead to a decrease in the body of another mineral leading to a deficiency that was not there originally. A common one we see in this area is supplementing Zinc leads to a reduction in copper absorption. Discussion with your vet and timing your monitoring is important in these situations.
• Are you giving an excess of minerals? If you are supplying more of a trace element than is required you are wasting money at best, however at worst an oversupplementation can lead to toxic levels leading to production losses and deaths.

Testing should be done at various times of the year depending on which mineral you wish to check and the stage of lactation/pregnancy of the animals.

Many minerals can be analysed satisfactorily via a simple blood test such as Selenium and Vitamin B12. However, copper can be a bit trickier, while there should always be a small amount of copper circulating in the blood the vast majority of the body's copper is stored in the liver and slowly released into the blood. If a blood test shows low copper, this is a true result as the liver is ‘empty’ and significant production is being lost. However, if blood levels are normal this tells us nothing about the liver copper levels which can be low, normal or high. We need to know liver levels to get supplementation levels correct through peak production, dry period, mating etc. Liver samples can be obtained from cull cows at the works, however before doing this ask yourself if these cows are representative of the whole herd, are they empty for a reason, are they old, etc. etc. Also, there have been occasions where mix-ups occur at the works. One example that I saw was a client sent cull Friesian cows, but the lab report was for Hereford steers! For these reasons, we strongly recommend checking copper levels via a liver biopsy on farm. This way we can ensure a representative sample is selected, matching the age profile of the herd.

Have a chat with your FVS vet today about instituting a tailored mineral testing program for your herd.

Dr Brent Neal BVSc MANZCVS Veterinary Pharmacology