Bulk tank milk screening for Mycoplasma bovis (M. bovis)

How does M. bovis screening work for dairy cattle?

We screen dairy herds throughout New Zealand for M. bovis. 

Tanker operators currently take samples from all commercial dairy processors at the point of collection. From early 2025, non-commercial dairies will need to submit their own samples.

How often does screening happen?

Screening is monthly, with increased frequency in July, August and September.  

Many factors affect our ability to detect M. bovis antibodies produced by infected cows, including: 

• the number of infected cows contributing to the milk supply 
• the stage of infection 
• average milk production per cow 
• vat volume.  

This is why we screen dairies at different stages of the lactation cycle — to give us the best chance of detecting infection.

What do the screening results tell us?

We use an M. bovis ELISA (enzyme-linked immunosorbent assay) test. This looks for the presence of M. bovis antibodies that cattle produce to fight infection.  

A detect result indicates that antibodies are present but doesn’t confirm infection. It also means our team will do a risk assessment to decide whether further on-farm sampling and investigation is required to determine infection status. 

When are bulk tank milk screening results available?

Only farmers with a detect result that requires on-farm investigation will be notified of the results.