After several weeks with no infected Mycoplasma bovis properties in New Zealand, a new active dairy property has been confirmed, prompting more testing of older imported semen.
While not unexpected, the new finding highlights the need for ongoing vigilance as the eradication programme reaches its halfway mark and nears the end of its delimiting stage, M bovis programme director Simon Andrew said.
As the programme gets closer to the end of this phase, the focus will shift more towards background surveillance, which carries a much lower annual cost, he said.
Meantime, following several weeks with no infected properties, a new active dairy property has been confirmed in the Ashburton district.
It is not in the now-cleared Wakanui area and has not been previously infected.
“The infection was confirmed just last week, through our network surveillance. The investigation into the infection source for the new farm is ongoing,” Andrew said.
“It is too early to confirm what strain type the infection is, but it neighbours a farm with links to the Wakanui cluster that was infected with the original strain type of M bovis.”
Andrew said the risk of transmission via imported semen is considered very low, especially after the introduction of a new import health standard last year.
“But low risk is not the same as no risk.”
The Ministry for Primary Industries assesses the M bovis introduction risk of bovine semen imported before April 2022 as very low due to required antibiotic treatments, and bovine semen imported after that date is subject to improved antibiotic treatments or PCR testing for M bovis.
Andrew said as an extra precautionary measure, the programme will undertake more testing of older imported semen over the next year to improve the understanding of the risks presented by imported bovine semen and help protect the gains made to date.
Farmers planning to use bovine semen imported into NZ before April 2022 are urged to contact their supplier to discuss whether that semen has been treated with a specific antibiotic protocol, has been tested, or will be subject to MPI testing.
In September 2022, a new strain of M bovis was identified on a dairy farm in Mid Canterbury, which has now been depopulated, cleaned, disinfected, and all movement restrictions have been lifted.
Imported semen is considered the most likely source of introduction of this new strain.
“Our extensive network surveillance combined with bulk milk testing and beef surveillance has not identified this strain anywhere else, but the extra testing of older imported semen will provide another extra layer of assurance,” Andrew said.
Advice to farmers right across NZ is to be vigilant with biosecurity practices and in keeping accurate NAIT records.
“Accurate NAIT records allow us to trace animal movements quickly and minimises disruption for the farm.”
“As we move into winter a lot of farmers will be sending cattle out to grazing.
“It’s important that farmers talk to graziers to let them know they expect their cattle to be separated from other herds to mitigate the risk of contracting any infectious disease, not just M bovis.”
The bull buying season has kicked off and farmers need to be vigilant when purchasing and moving bulls off and on farm.
If the bulls are from a beef property, they are considered a low-risk stock class.
If M bovis test results are unavailable, then the best indicator of the level of risk from these bulls is the health status of the herd(s) they’ve have been running with.