Copper Supplementation
RVC has undertaken research on two dairy farms in the North Canterbury region to provide further insight into the effects of using injectable copper supplementation in mixed aged dairy cows.
We wanted to understand;
• What is the likely response in raising liver copper levels from a standard 2mL injection of a copper product (Copperguard)?
• How safe is a 4mL injection of copper to avoid risk of copper toxicity?
• How long do these injections persist to guide re-treatment recommendations?
• Is there a difference between formulations, Copperguard and MultiMin products?
With support from Virbac (suppliers of MultiMin & Copperguard) and EpiVets (research partners) a research study was designed to monitor changes in liver copper levels over time. To do this required collecting nearly 600 liver biopsies over several months. On each farm, we compared the effects of 4 different treatments;
1) 2mL Copperguard
2) 4mL Copperguard
3) 5mL MultiMin
4) No treatment (Control group).
Each treatment group was further split into two age groups, 3-5 and 6-10 year olds to determine if there was an age effect. A liver biopsy was collected prior to copper supplementation to determine a baseline, then cows were treated, then a further 6 liver biopsies were collected on the same cows for 70 days after injection. Changes in liver copper over time were then compared to the pre-treatment baseline to see what effect each treatment had on raising liver copper levels and also comparing these to untreated controls.
What were the results from copper supplementation by injection?
The graph below shows the average increase in liver copper across the two farms.
• Statistically significant increases in liver copper were only seen on one farm. On the other study farm, there was no difference between copper products or dosages compared to untreated controls.
• Increases in liver copper following an injection with either 2mL Copperguard or 5mL MultiMin were similar, as these doses contain similar concentrations of copper (100mg and 75mg copper respectively), but this was not statistically significant when compared to untreated controls.
• A 4mL dose of Copperguard significantly increased liver copper for 42 days after treatment when compared to untreated controls.
• A 4mL dose of Copperguard is unlikely to cause negative effects unless animals are already close to a toxic threshold. This highlights the importance of knowing baseline liver copper concentration before treatment to avoid copper toxicity
What can we conclude from this research study?
• Overall, there was wide variation in responses to copper supplementation across the two farms. Determining appropriate copper supplementation will be different for each farm and depends on baseline liver copper concentration. There is no ‘one-size-fits-all’ approach.
• There were no age differences in response to copper supplementation within the milking herd, 3-5 year olds responded to supplementation in a similar manner to 6-10 year olds.
• Cows with a lower baseline liver copper experienced greater increases in copper after treatment.
• On the same farm, there can be wide variation in how individual animals will respond to copper supplementation. Consequently, it is important to collect enough samples to establish the baseline to confidently estimate average responses to supplementation. And knowing the ‘starting point’ is important to determine if supplementation is necessary and to avoid toxicity.
• In animals with sufficient stored liver copper, a standard dose of either 2mL Copperguard or 5mL MultiMin may not provide much elevation in liver copper, so there may be diminishing returns from supplementation as liver copper levels increase.
• In copper deficient animals, a 4mL dose of Copperguard can be given to significantly boost copper storage levels.
• Other on-farm factors can contribute to variable responses to copper supplementation. For instance, high levels of molybdenum and sulphur in pastures can act as dietary antagonists and limit the amount of copper absorbed through the diet, thereby depleting liver copper reserves more quickly.
How should you monitor copper levels?
It is important to regularly monitor copper status within the milking herd, at least twice yearly.
Determining copper status is not as straightforward as collecting a blood sample, and it helps to understand how copper is stored in body. Copper is absorbed from the diet into the bloodstream, and any excess is stored in the liver. The liver releases copper into the blood as required, keeping the blood levels reasonably constant. So, blood tests alone won’t show the level of reserves in the liver. If we want to determine if there are sufficient copper reserves in the tank, then samples of liver are required. Samples of liver can be obtained either from cull cows or by liver biopsy. Please contact your primary vet to arrange liver biopsies or to obtain a slaughter collection form.
Sending cows to slaughter?
Organise to have some samples of liver collected from cull cows for monitoring copper and selenium levels.
Contact your primary vet for a slaughter collection form.
The copper content of pasture changes through the season, with higher levels seen over late-summer/autumn and lowest levels during late winter/spring. A cow’s copper requirements are highest in late pregnancy and during peak production, at a time when copper availability from pastures is at the lowest. Over winter, cows will utilise some of their stored liver copper, so it is crucial cows have enough liver stores leading into winter to meet these peak demands later. Therefore, monitoring liver copper levels in autumn and prior to this expected decline will ensure cows have enough copper to last through winter and spring. Sometimes copper supplementation may not be required, but if you don’t measure, then you won’t know.
Copper in youngstock
• Young cattle require relatively higher levels of copper for growth.
• Supplementation should start from 4 to 5 months of age and continue to include autumn and early spring periods.
• Contact your primary vet to develop a trace mineral programme as regular supplementation will be required.