M.bovis testing for replacement heifers

You will all no doubt be aware of the regular Mycoplasma bovis surveillance testing through bulk tank milk. The start of the season brings with it unfortunately an increase in “detect” results which leads to these farms being placed under Notice of Direction (NOD) and stress for the farmers involved at an already stressful time of year.

Fortunately, most of these farms are quickly blood tested and cleared from the program. However, the surveillance testing lab reports that this is not always the case and that they are discovering some new infections.

A common route of introduction of Mycoplasma bovis infection onto dairy farms has been the return of replacement heifers that were infected while they were reared and bred at a grazing property. These infections are being picked up by the routine bulk milk tank testing but unfortunately by this time they have already mixed with the rest of the cows meaning the whole herd becomes infected and must be depopulated.

Replacement heifers can be tested prior to returning to the dairy platform to allow earlier detection and preventing the spread of infection to the whole herd. MPI fund this as part of their surveillance testing so there is no cost to you. Ideally, this testing would occur after breeding bulls have been removed from the group to ensure any risk of infection they have placed on the heifers is picked up. As we will be seeing many of your heifer groups for pregnancy testing soon, this would be ideal timing for testing to ensure you are not bringing heifers infected with M. bovis home.

If you have heifers grazing off-farm, get in touch with us to discuss testing options to protect your herd.

Dr Ilyse Jennens, BVSc (Dist) MANZCVS Medicine of Dairy Cattle – Farm Vet at Franklin Vets Waitakaruru