M. bovis Programme to make changes to on-farm sampling for many farms

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The Mycoplasma bovis (M. bovis) Programme is making changes to on-farm sampling protocols, and how it interprets results from ELISA testing of blood samples. The changes will reduce the amount of time that many farms spend under Active Surveillance and Notice of Directions in the future.

“This is a positive step forward in reducing the impact on farmers from sampling and testing for M. bovis. Our scientists have analysed the results from hundreds of thousands of samples. From that, they have refined our sampling criteria to effectively halve the number of rounds of sampling and testing required for many farms, while ensuring we still correctly identify infected management groups,” said Dr John Roche, the Ministry for Primary Industries' (MPI’s) chief science advisor.

The changes mean that, where possible, blood samples will be collected from more cattle each time a property is visited, but for many farmers only one round of sampling and testing will be required if the management-level results from the first round are negative. It is important to keep in mind that more testing might be required in the future if other risk events are found.

Most farms under Active Surveillance will only have to muster animals for one round of sampling, which will reduce the impact of on-farming testing on their operations. Beef + Lamb New Zealand technical policy manager Chris Houston said, “Many beef farmers will have to wait half as long to have an all clear, and get back to their business as usual. It could mean a reduction of up to 5 weeks of waiting for farmers to get a result, which is a great step forward.” 

DairyNZ’s biosecurity policy advisor Nita Harding, said that this is a positive change for many dairy farmers having to undergo on-farm sampling. “These changes will reduce the impact of on-farm sampling for many dairy farmers under Active Surveillance, and for most farms with a ‘detect’ bulk tank milk test results. The majority of these farms are not infected, and these developments in the testing mean we will be able to determine their disease status faster, and with less disruption to their farming activities.”

The programme is also changing the way it interprets ELISA results for blood samples, based on expert analysis of the hundreds of thousands of samples tested to-date. The threshold for designating an individual animal as a ‘reactor’ will increase (to a seropositivity ratio threshold of 90% or greater). Correspondingly, the percentage of ‘reactors’ per management group required for a round to be determined positive will decrease (to a cut-off point of 3%). There will no longer be suspicious rounds, only positive or negative.

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