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As many farmers know, the M. bovis Programme runs extensive background surveillance screening in both the dairy and beef sectors.

This activity serves two purposes:

  • It indicates areas where we may have to look more closely
  • It provides assurance that the disease is not widespread.

Background surveillance is made up of two workstreams:

  • Bulk Tank Milk (BTM) surveillance, and
  • National Beef and Drystock surveillance.

These surveillance activities have been optimised over time, as we have learned more about M. bovis and how it presents in cattle.

Background surveillance will continue throughout all phases of the eradication journey and will be a key component in providing the confidence needed to be certain our Eradication Programme has been successful.

Bulk Tank Milk (BTM) surveillance

The BTM surveillance data collected over the past 12 months has revealed zero confirmed infected dairies.

Throughout the year, there are many opportunities for M. bovis to enter a herd. This could include buying in new stock, heifers returning from grazing, introduction of bulls, and break-ins from neighbouring properties.

Regular BTM screening is conducted throughout the year as it is important that dairies are screened at different stages of the lactation cycle to give us the best chance of detecting infected dairies.

Every dairy farm in New Zealand supplying milk for commercial processing has a BTM sample tested at least monthly, using the samples tanker operators take at the point of collection. No action is required from farmers.

The Programme will be reinstating fortnightly BTM screening in July, August and September for 2023.

Over the last five years, we have observed the ability of the ELISA test to detect infection ‘sensitivity’ is high in early lactation. By undertaking BTM screening fortnightly in this period, we increase the opportunity to detect infected herds quickly.

As with previous years when we have tested fortnightly, this additional screening won’t impact the routine milk quality/composition testing that farmers already provide. This change is designed to reduce the risk of missing any infection that potentially remains.

This spring, 2021-born heifers are entering the milking herd for the first time and in many cases, this will be the first time these animals have been tested for M. bovis.

BTM statistics

Information for January to June 2023

  • 10,624 dairy suppliers screened at least once.
  • 67,871 BTM tests performed.
    From these results, there were only:
        o   34 detect results
        o   33 confirmed as not infected
        o   1 still to complete investigation.

This surveillance gives us the confidence that M. bovis is not widespread in our national dairy herds.

National Beef and Drystock surveillance

The National Beef and Drystock surveillance provides comprehensive screening of the beef sector via the following three streams:

  • on-farm beef and drystock cattle sampling
  • sampling at meat processors, and
  • feedlot testing (pre-entry).

All streams aim to provide ongoing evidence that infection is not widespread in the beef and drystock sector.

We know on-farm testing can be disruptive and we are conscious of the impact this has on farmers. For this stream, cattle on beef and drystock properties are blood sampled and tested for M. bovis by local vets, working with farmers to undertake sampling while cattle are yarded during routine farm management activities such as pregnancy testing, drenching, or vaccinating. This approach is intended to minimise the impact and disruption to farmers as much as possible.

The blood samples are tested to determine the presence of antibodies to M. bovis using an ELISA test. The findings from these surveillance streams to date indicate that M. bovis is not widespread in the beef sector.

Beef and Drystock surveillance statistics

Information as of 18 July 2023

  • 990,984 animals (approximately) have been sampled as part of the National Beef and Drystock surveillance.
  • 5,658 results were reported from all beef surveillance streams, to date.
    From these results, there was only:
       o   1 property tasked for sampling.

This surveillance has given us strong confidence that M. bovis is not circulating in the beef industry, with no infected properties detected via drystock surveillance.

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