News & Advice

Depopulation of Mycoplasma bovis infected dairy herds

Apr 1, 2018 | Biosecurity, Dairy

Scott McDougall, Principal Senior Scientist and Managing Director, Cognosco

The Ministry for Primary Industries (MPI) has announced that they will proceed with the depopulation of the remaining 22 farms where Mycoplasma bovis has been confirmed. This will involve removal of about 22,000 animals. 
This decision comes as MPI has gained confidence that the M. bovis is likely to be relatively recently introduced into New Zealand, and that the disease is confined to a small number of farms with direct connections. The national bulk milk survey has not detected any previously unknown clusters of this disease, with only one additional herd being identified. Thus MPI appears to be confident that the extent of the disease spread is now well defined, and that eradication is technically feasible. 
While the impact on the individual herd owners is not to be underestimated, the benefit to the dairy and beef industry of remaining M. bovis free is substantial. In countries where M. Bovis is endemic, high levels of biosecurity and ongoing routine monitoring for M. bovis are required. This increases costs and potentially limits animal movements. 
From a local perspective, it appears that the North Island is effectively free of M. bovis and the government is implementing tighter surveillance of cattle movements across Cook Strait to ensure that the North Island remains free. 
The important message is that biosecurity measures should be beefed up, and care should be taken in purchasing animals, with a high level of scrutiny of purchased stock in terms of previous disease history. It appears that spread of M. bovis thus far in New Zealand is linked with direct animal movements, emphasising the importance of running closed herds. 
The M. bovis outbreak has also highlighted issues with compliance to the NAIT system. Damien O’Connor has been quoted as saying that only 57% of farmers record the required movements within 48 hours on NAIT, and that perhaps only 30% of animal movements are properly recorded. The NAIT system was designed to deal with disease outbreaks such as M. bovis. The ability to rapidly and reliably track animal movements is critical in disease outbreak monitoring and control. So ensuring that animal movements are accurately and quickly reported in the NAIT system is vital for disease control in New Zealand. 
So remain vigilant for unusual recurrent and non-responsive cases of mastitis, unusual outbreaks of lameness, and outbreaks of pneumonia and head tilt in calves. If you see any one of these symptoms, and particularly if you see all three sets of symptoms, please contact your Veterinarian. 
Please note, the information above is correct at at the time of publication. For recent updates, please visit our website please visit 

Share This