TB Free NZ – lessons from farmed deer test

Fiona Bannerman used a Farmers Club Charitable Trust bursary to investigate TB testing in farmed deer in New Zealand, with co-funding from MBIE NZ and a Moredun Foundation Scholarship (www.moredun.org.uk). See here for full report 

 

F Bannerman 

When discussing growth of the deer farming sector we have to remember that tuberculosis has the potential to have catastrophic effects, not just on individual herds, but on the industry as a whole.

SAC Consulting Veterinary Services, a division of Scotland’s Rural College, has been investigating diagnostic tests for TB in farmed deer. In order to facilitate this work we are working closely with Dr John Fletcher on behalf of the British Deer Farms and Parks Association. We are also working with DEFRA, Animal and Plant Health Agency, the Veterinary Deer Society, and UK governments and supermarkets. 

Given the high public profile of TB in cattle and badgers, it is of paramount importance that measured decisions are made with regards to TB control strategies for farmed deer. Therefore, when considering the approach for farmed deer in GB, it is important to investigate how TB is being tackled elsewhere. New Zealand has taken a lead role in the work to eradicate TB, with significant success. I found it very interesting and encouraging that control of TB in livestock is possible. Therefore NZ was deemed the country of choice with which to collaborate.

Turning back the clock, deer farming in the UK was developing steadily until about 1988, when TB was diagnosed in several herds. In response a farmer-funded Deer Health Scheme was established in 1989 and has existed for many years. However, the Health Scheme was not accepted by the industry as the skin test utilised proved to be inadequate. Understandably, concern arose over subsequent movement restrictions, deer farmers lost confidence in the Scheme and so the existing Scheme has had no members for several years.

Industry ready to expand

This uncertainty and nervousness caused the market for hinds to collapse and set deer farming back for 20 years. Currently the industry is seeking to expand. However, many of us are uneasy that the industry could experience similar setbacks and concerns have been raised that new deer herds have little security in purchasing breeding stock.

 

In order to address these concerns SACCVS would like to revive the Deer Health Scheme using an alternative testing procedure, one already established and proven in NZ. The object of this would be to create a pool of accredited herds from which people could buy deer with reasonable confidence that they were not infected with TB.

Therefore, a colleague and I undertook a study tour of NZ, to meet key opinion leaders and researchers within NZ’s Deer Industry, including deer farmers, specialist deer vets and scientists.

 Bannerman Graph

 

World-leading TB control 

NZ is considered a world leader in bovine TB control due to the approach involving, and funded by, both government and industry. Anyone who owns, or who is in charge of, cattle and/or deer have to be registered with the TBfree NZ programme. Regional committees, made up of volunteer farmers and other local stakeholders, communicate, advocate and support the delivery of the strategy in each region.

 

TBfree NZ, a part of Ospri (Operational Solutions for Primary Industries, a not-for-profit limited company created to help protect and enhance the reputation of New Zealand’s primary industries), has three main techniques to control, and eventually eradicate, TB in NZ: 

1) Disease Management – ongoing TB testing of all cattle and deer in NZ, and subsequent slaughter of any animals suspected of having TB 

2) Movement control – e.g. pre-movement testing, especially in areas with a high risk of TB infection.

3) Control of wild animal vectors which spread TB – TBfree NZ reports that if it can keep the possum numbers low enough for long enough over large areas, they can eventually eradicate TB.

Fiona Murray and I spent the majority of our time at NZ’s Disease Research Laboratory, where they have carried out pioneering work in the area of TB diagnostics in deer. Prof Frank Griffin and his team have developed a blood test, which has helped to reduce the number of infected deer herds in NZ from 250 to just two.

Blood test recognised 

This work has been nationally recognised within NZ as part of the ‘TBfree New Zealand’ programme and the success of this blood test has been recognised internationally by The World Health Organisation for Animal Health (OIE) as a valid test for diagnosis of TB in deer. 

The TB control protocol used for the majority of deer herds in NZ is: 

1) Skin test – using bovine tuberculin only.      

2) Any animal with reaction to skin test is blood sampled 10-30 days later.

Following our visit to NZ, SAC Consulting is now investigating adoption of NZ’s blood test. DEFRA has stipulated that the blood test must only be used following the comparative skin test, using both avian and bovine tuberculin. Unfortunately, this is not in line with NZ’s skin testing protocol.

The successful establishment of NZ’s blood test in GB cannot be guaranteed at this point in time; preliminary testing must be undertaken first. Once test performance under GB conditions is ascertained this knowledge will be shared with those involved in various aspects of the venison industry.

Bovine TB in deer – The facts

  • Caused by bacterium Mycobacterium bovis (M. bovis)
  • Infectious disease in deer, cattle, badgers and many other mammals.
  • Notifiable
  • One of the biggest challenges facing the cattle farming industry today.
  • TB surveillance in GB based on post-mortem inspection of farmed deer and screening pre-export
  • Unlike cattle there is currently no routine statutory TB testing programme for GB deer herds
  • APHA may require the testing of deer at owner’s expense
  • Consequences of a deer herd becoming infected with TB, in terms of movement restrictions, can be disastrous

 

Fiona Bannerman BVM&S MRCVS 

SAC Consulting Veterinary Services

Inverness

01463 243030

fiona.bannerman@sac.co.uk

www.sruc.ac.uk/consulting  

 

Visit funded by The Farmers Club, MBIE NZ and Moredun Foundation Scholarship (www.moredun.org.uk). See here for full report