The National Beef Surveillance programme screens cattle for exposure to M bovis on beef and drystock properties, at meat processing plants and on feedlot entry.
Previously samples have been taken during TB testing, but most TB testing now occurs in areas where M bovis is not so common.
From April 1, on-farm screening is transitioning to a more focused, risk-based surveillance of beef and drystock herds where there has been higher prevalence of M bovis.
This means it will no longer be routinely coupled with TB testing.
M bovis programme director Stuart Anderson says risk-based testing is a commonly adopted practice in contemporary disease surveillance programmes and involves focusing surveillance on populations where disease is more likely to be present, while maintaining an acceptable level of coverage for the population as a whole.
For the beef and drystock surveillance programme, testing is focused on herd types and regions where there has been a higher degree of association with the network of infected farms.
Network associations are analysed, modelled and used to determine where surveillance is most effectively implemented.
“This means that while surveillance will occur across New Zealand, there will be a higher intensity of sampling in some regions and for some types of herds, where the risk of contact with an M bovis confirmed property is elevated,” Anderson said.
Sampling for some herds will be specifically requested by the programme, while for others, participating veterinarians will use local knowledge to identify suitable herds for sampling.
The programme has partnered with SVS Laboratories to ensure that blood samples are tested to a high standard and results are delivered as quickly as possible.
SVS vets and veterinary technicians will manage sample collection with farmers able to liaise with their local service provider to find a time that is convenient for sampling to be undertaken.
In consultation with farmers, the vet will book and schedule sample collection at times when cattle are already being yarded for routine management practices such as pregnancy testing, vaccination, drenching or weighing.
“Taking samples for testing when cattle are yarded for other management procedures is an effective method that minimises disruption to farming activities,” he said.
Anderson says in some regions where TB testing occurs less frequently, farmers will now be more likely to be sampled as part of the M bovis beef and drystock surveillance programme.
More herd types will be selected for screening.
“This means more farms will be tested with sampling expanding to include additional herd types, such as dairy heifers, beef breeding animals and bulls,” he said.
No single herd production type will be exclusively targeted.
While all production types will continue to be sampled, there will be an increased intensity of sampling for dairy heifers and cattle from herds that acquire animals for trading or finishing.
“Heifers are a population group of interest, because testing them before they start lactation is a valuable opportunity to determine their status before they are covered by Bulk Tank Milk (BTM) surveillance,” he said.
“Herds that trade livestock are important for surveillance because they are more likely to be associated with the network of infected farms than herds that have fewer external trading links.”
The National Beef Cattle Survey is a screening test, not a final result.
The test determines if animals have been exposed to M bovis.
“While most farms are not expected to return a positive result, some herds will require further testing to confirm their infection status,” he said.
Anderson emphasises herds are not being sampled because the programme believes them to be infected.
“Negative testing in areas of higher risk provides greater assurance that M bovis is not widespread in the beef sector,” he said.
“With thousands of farms already sampled, the information we’ve collected from the National Beef Cattle Surveillance continues to build confidence that M bovis is not widespread in the beef sector,” he said.
M bovis was first detected in NZ in July 2017.
Since then, a total 262 farms nationally have been confirmed with M bovis, just 10 remain currently active; 170,486 cattle have been culled and $194.9 million paid in compensation to farmers in a national bid to eradicate the disease.
