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Read the latest M. bovis facts & figures / Weekly Update - 27 November 2020

COVID-19 information

milker in shed

Bulk tank milk screening

Ongoing and regular testing of bulk milk from farms nationwide is a key part of the Mycoplasma bovis Programme.

Monthly national screening of bulk tank milk samples can help us find infected herds otherwise undetected due to incomplete or inaccurate movement records.

It may also identify infected herds faster as animal movements can only be traced once the source Confirmed Property is found.

  • How is bulk tank milk screened?

    Dairy companies have been directed to provide bulk tank milk samples for testing, and every dairy supplying milk for commercial processing has a sample from their bulk tank milk tested each month.

    • Samples are taken, as part of the normal milk collection process.
    • Tanker operators take the samples at the point of collection – farmers don't have to do anything extra.
    • A single sample is tested for each month milk is supplied.
    • The sample is ELISA tested for the presence of M. bovis anti-bodies.

     

  • What happens if the result detects M. bovis could be present?

    If the screening test indicates that M. bovis could be present the Programme will contact the farmer and provide information about the next steps.

    Farms with a 'detect' result will be placed under a Notice of Direction (NOD) restricting cattle movements while sampling and testing of the herd is carried out to determine its disease status.

    A 'detect' result does not mean that the farm is infected.

    More than 97% of farms with a 'detect' result are found to be clear of infection after on-farm investigation is completed. However, it is very important to ensure that herds are tested as soon as possible to make sure they are clear.

  • Why bulk milk testing is important

    The first national screening of bulk milk was undertaken in spring 2018 and has proven extremely valuable, by:

    • Giving assurance that infection is not widespread around the country.
    • Finding a small number of infected farms who have yet to be found through animal movement tracing.
    • Highlighting the reliability of the ELISA test to produce a low rate of false positive/detect results.

     

    The success of the spring 2018 programme led to the M. bovis Programme, in consultation with industry, deciding to put in place a continuous programme for screening of bulk tank milk.

  • What's changed about the testing process?

    Based on what we learned during the spring 2018 surveillance, a few changes have been made to the testing process:

    • All supplying dairies are tested on a monthly basis. 
    • The ELISA test is being used as this has proven to be a better screening tool for bulk milk testing than the PCR test.
    • All farms with ELISA-detect test results will be contacted within 2 weeks of testing (not sampling).
    • Farms with a detect test result are placed under a Notice of Direction (NOD) restricting cattle movements, while sampling and testing of the herd is carried out to determine the farm’s disease status.
    • 'Non detect' test results will be reported to farmers once a long-term solution to do so is up and running. In the meantime, it’s not practical to manually report the large volumes of 'non detect' results.
  • Bulk milk negative (non-detect) test results

    The volume of negative (non-detect) results means an automated way of sharing these results with farmers is needed. We're working on a sustainable and integrated solution for reporting 'non-detect' results and once we have this in place these results will be provided.

    It’s important to remember that a bulk tank milk 'non-detect' test result does not prove absence of infection. Nor does a bulk tank milk 'detect' test result prove presence of infection. M. bovis infection status can only be determined by on-farm testing of the herd.

    A 'detect' result does not mean that the farm is infected. More than 97% of farms with a 'detect' result are found to be clear of infection after on-farm surveillance is completed.

  • Who to contact

    For questions about the bulk tank milk screening programme:

    You may also wish to contact your local dairy company manager.

Find out more about the screening – fact sheet [link to external PDF]