M. bovis Programme Director Stuart Anderson says in spring 2020 the Programme saw the effect of untraceable young stock from 2018, in particular dairy heifers entering the milking platform for the first time.
“We now have 2019-born heifers due to calve and come into lactation for the first time this winter. Where we can, intercepting infected dairy heifers before they mix on a milking platform and contribute calves to the population, will reduce the risk of possible spread within and between more farms.
“To do this, we have expanded our National Beef Cattle Surveillance over April and May to include testing 2019-born dairy heifers, with a rapid seasonal push to test a larger number of dairy heifer groups in areas where we have seen a higher prevalence of M. bovis – Canterbury, Otago and Southland.”
Canterbury cluster progress
The first of the cluster of properties confirmed infected with M. bovis in Mid Canterbury in spring 2020 have been cleaned, cleared and able to get back to farming free of the disease.
The M. bovis Programme expect to have all the properties identified in spring 2020 (seven remaining) fully depopulated with cleaning and disinfection completed by the end of May, and Restricted Place notices revoked in June.
Depopulation plans for the few remaining infected properties are being worked through.
“Being under movement restrictions isn’t easy and is a significant disruption to farmers, let alone finding you have M. bovis infected animals and having to work through eradication,” says Stuart Anderson.
“I’d like to acknowledge the hard work that those farmers affected by M. bovis are putting in, and the support communities and neighbours are providing to them."
Five Star Beef update
Before eradication can be achieved, the feedlot must be depopulated and cleared, and MPI’s Chief Science Adviser, Dr John Roche, is working with international animal health and feedlot farming experts to determine the appropriate approach.
The timing of depopulation has not been decided yet, but this property will be one of the last, due to the risk of reinfection. As a large operation sourcing cattle from around 400 farms, the property is at risk of being infected again, if infection remains in the farming community.
Sam McIvor, chief executive of Beef + Lamb New Zealand, says following its infection with M. bovis, Five Star Beef (FSB) has been useful to the Programme in serving as a way to test incoming animals from source properties.
“This has saved a lot of farmers' time and all of these source stock have tested negative, building our confidence that M. bovis is not widespread in the beef industry.”
Five Star Beef is visited regularly to ensure it complies with the Restricted Place notice and biosecurity controls. FSB is highly compliant. The most recent inspection confirmed no evidence of boundary weaknesses between the feedlot and neighbouring farms, that could result in any cattle breakouts.
Current conditions include no live cattle movements off the feedlot other than to processing and no over the fence contact between cattle within and outside the boundaries of the Restricted Place.
Additional conditions for lower risk pathways off the site are in place. These include animal products, personnel, clothing and protective gear, equipment, effluent and vehicles. As an extra precaution, neighbouring farms with cattle are being tested at six-month intervals.
This plan will be in place until depopulation when a new plan focussed on avoiding reintroduction of infection will be needed.
Epidemiological investigation is ongoing to determine the pathways of transmission within the Canterbury cluster. As all the farms in the current cluster have links to the network of infected farms, there are far more likely pathways coming from within the cluster of farms, than from the feedlot. Investigations continue to confirm movements of infected animals are the more probable cause of the Canterbury cluster.
Remaining vigilant and not easing off is the key to tracking down and eradicating M. bovis, so New Zealand can farm free from the disease.
Farmers can help stop the spread
Poor NAIT records have cost the eradication programme and farmers, significantly increasing the time and resources required to trace and eliminate M. bovis from infected stock. This has meant that more farms have been infected or have had to be placed under movement controls than would otherwise have been necessary.
"Failure to record animal movements in NAIT means that a larger number of farms need to be placed under movement controls than would otherwise be necessary, because the Programme cannot be certain where and when animals moved,” says Sam McIvor.
“This means that one farmer not doing their NAIT properly can lead directly to other farmers’ businesses being impacted. No farmer I know would want to be responsible for this.
"Graziers need to recognise that cattle from different clients must be kept separate on the grazing property and we encourage farmers to require this in the contract. This is necessary to prevent infection spreading between stock and then returning to the home blocks in spring. This is known to have occurred in Canterbury."
DairyNZ chief executive Dr Tim Mackle says it is crucial all farmers have biosecurity practices in place to protect their herd, their business and the wider farming community.
“Many farmers are shifting stock at this time of year. It’s important to ensure that all animal movements are recorded in NAIT to protect our national herd against M. bovis and other biosecurity risks. Up-to-date records mean that animals can be tracked quickly, reducing the risk of any new clusters of disease.”
Dr Mackle says trading raw milk also carries risk for spreading M. bovis.
“As we move towards calving, we recommend farmers use milk that has a low risk of containing M. bovis bacteria. This includes calf milk replacer powder, acidified milk or pasteurised milk. Go to dairynz.co.nz/mbovis for information on how to acidify milk.”
More than three years in and the Programme is still seeing farming practices that contribute to the spread of M. bovis:
- Insecure property boundaries.
- Mixing cattle on grazing blocks.
- Not recording on and off farm animal movements.
- Single NAIT numbers for multiple properties (same owner) and not recording cattle movements between those properties.
- Shared milking platforms.
- Inconsistent information from farmers.
To reduce the risk of disease spread, for many diseases not just M. bovis, these are some practices that farmers must be doing to protect their own and other farmers’ herds:
- Animal movements recorded in NAIT (this is how we can track risk animals quickly and lock them down).
- Recording on and off farm animal movements – even between your own properties.
- Retags linked in NAIT to previous tag so history is carried through.
- Keeping herds separate, including at grazing.
- No sharing untreated milk or colostrum.
- Secure farm and paddock boundaries.
Removing risky farming practices is a smart investment in stock health and productivity. Information is available on reducing the risk of disease spread and on-farm biosecurity at: