Solutions to the problem of bovine TB
Badger Trust’s view is that to solve the problem of bovine TB, the government needs to change the focus to cattle. Badger Trust set out in detail our recommendations on cattle measures as part of the government’s bTB eradication policy in our submitted response to their ‘Call for Views’ in April 2021.
Science tells us that the badger can only play a very small part in the spread of bovine TB. Cattle continue to account for almost every case of infection cow to cow – over 94%. The remainder come from a variety of sources including ‘unknown’.
The government has been reluctant to use the most effective methods to take the steps needed to stop bTB. The focus needs to be on cattle and cattle-based measures:
Better cattle testing
Unfortunately, unlike the Covid PCR test which is highly reliable, the bovine TB skin test – which Defra insists that farmers in England use – is highly unreliable.
It has been known since at least 20131 that the sensitivity (positive individuals identified) can be as low as 49% at standard test interpretation. This means that one in two to one in five (50% - 20%) infected animals could be missed each time a herd is tested. No matter how many times a herd is tested, there will still be animals with bTB in the herd, able to pass the infection on to others and the environment.
There is of course a cost to all this, both financially and in terms of the impact on farmers. The cost of testing is covered by the taxpayer, and disease surveillance will continue to be a requirement.
It makes more economic and scientific sense to use the most reliable test available and ensure that every test is worth taking.
However, to date, the government has spent many millions of taxpayers' money and farmers have spent many hundreds of thousands of theirs, on a strategy that can make very little difference because the problem can remain hidden in the herd.
Unless the ‘hidden reservoir’ in the English cattle herd is addressed, no other measures will make any meaningful difference to disease rates, or the costs of compensation and slaughter.
Immediate sharing of results with local vets
Results of the routine test go to the farmer, so local vets don’t automatically get notified of the details about a herd outbreak. As a result, they can’t rapidly advise their clients on any preventative measures they might take, for example:
voluntary highly localised movement controls
voluntary restrictions on shared grazing or slurry / manure spreading
consideration given to co-grazing with non-bovine livestock
vehicle and general hygiene
Failing to share test results with local vets inhibits the ability of local communities to help manage disease transmission and prevent further outbreaks.
Controls on cattle movement
Purchasing cattle has risks, but the government has still not made it mandatory or even possible for farmers to avoid and reduce the risk by introducing robust controls on cattle movement.
If newly purchased cattle are carrying bTB, this will infect the herd. A post-movement test is designed to pick up disease and prevent this. This measure cannot work if the cattle have already been able to mix in the new herd. According to the DEFRA 2019 Survey, only half of purchasing farmers isolate bought cattle, and 17% never isolate them from the herd on arrival.
Results from the DEFRA Farm Practices Survey (2019)2 show that of those that had bought cattle in the last 12 months;
18% of purchasing farms did not find out the date of the pre-movement test
26% of purchasing farms did not find out the date of the source farm’s last routine test
33% of purchasing farms did not find out the source farm’s TB risk area
23% of purchasing farms did not find out the testing frequency of the source farm
Best practice, where farmers take responsibility for checking the above and purchasing only from lower risk farms, should be standard and compensation only paid where farms comply. Farmers should also be expected to pay for additional bTB testing due to risky cattle purchasing practices; the taxpayer should no longer be expected to carry this cost.
The High risk area (HRA)3 should have been isolated from the Edge Area (EA) and Low Risk area (LRA) many years ago, but this step has yet to be taken. Cattle movements from the EA into the LRA also need to be prevented as some parts of the EA have a disease prevalence that is nearly as bad as it is in the HRA. Cattle should always be allowed to be moved into a higher risk area but never out of it.
The Risk Based Trading Group stated in 2013 that if “a voluntary approach was not successful, a mandatory approach must be considered to ensure the success of risk-based trading.” This is long overdue.
Effective slurry management
Bovine TB can persist in slurry for six months and could survive in the environment for much longer. Other substrates bTB can survive in include hay, silage, soil, faeces and water4 and recently it has been discovered that it can survive and replicate within single celled organisms that can themselves survive drought and other environmental stressors. The practise of spreading slurry on a neighbour's land may inadvertently be spreading the disease there too.
There are a number of measures farmers can take to reduce the risk of cattle contracting bovine TB from the environment. Like measures employed during the foot and mouth outbreak, farmers, their employees or contractors should employ careful cleansing measures at the farm gate (including vehicles and footwear) and also at market.
Slurry should only be spread on pasture after it has been stored for six months. Given how little is known about bTB’s persistence in the environment, there should be no exceptions to this rule, especially as this practice could pass bTB to wildlife.
Additional biosecurity measures
Good basic biosecurity standards should be a minimum requirement on every farm before compensation is paid to farmers for loss of cattle to bovine TB.
Effective biosecurity methods:
Effective slurry management
Cattle movement (to market/shows) and purchase
Careful cleaning of vehicles
Keeping wildlife out of feed stores and farm buildings
Wildlife and environmental risk
It is possible to keep badgers and other wildlife out of cattle housing and feed stores relatively inexpensively using electric fencing5. This is a simple measure that can be easily deployed, removed and redeployed around sensitive areas as required. It is disappointing that industry is willing to spend far greater sums culling than it is in protecting both cattle and wildlife.
Herd health plans should be developed for all cattle farms on the basis that the risks inherent in the current trading environment mean that any farm can suffer breakdown at any time. Bovine TB advice (including health plans) should be universal rather than only applied after a breakdown, when it’s too late.
The DEFRA 2019 Farming Practices Survey shows:
Only 24% of farms have installed sheeted gates (to prevent wildlife from accessing buildings)
52% (only just over half) of farms have raised feed troughs and mineral licks (to prevent badgers using them)
29% of farms spread slurry on grazing land, a small percentage of which is from other farms
Only 33% of farms that spread slurry wait 6 months before spreading
Only 36% of farms double fence between livestock and other herds
Only 37% of farms carry out disinfectant regimes (footbaths, wheel sprays, etc.)
Only 15% of farms fence off badger setts and latrines (despite the culling of hundreds of thousands of badgers)
Only 17% of farms ‘badger proof’ buildings
Worse, of the above measures, between 20% and 33% of farmers have stated that they would never implement them. Unless these measures are made mandatory and unless compensation is linked directly to compliance with them, bTB will persist in the environment.
The most effective and fastest solution to the bTB problem is a cattle vaccine. Despite culling badgers since 2013 under the current policy, costing many millions of taxpayer’s money, the government is only now field testing a cattle vaccine. The investment in cattle vaccines has been pitifully low, only a tiny fraction of the total cost of the strategy thus far.
Bovine TB will not be eradicated by killing cattle or a species of wildlife, whatever Defra Ministers claim. Smallpox was eradicated through vaccination; polio is virtually eradicated (also through vaccination); rinderpest was declared eradicated (through vigilance and vaccination) in 2011.
A note about badger vaccination
Badgers are not to blame for bTB in cattle. However, if the government insists on focussing on badgers, we believe that vaccination should be the only means of tackling bTB in this protected wildlife species.
Badger vaccination offers numerous advantages over culling and is the most effective way of reducing the disease in the badger population and any potential risk of badgers passing bTB back to cattle. It reduces the prevalence in adults, the severity of disease, the likelihood of becoming infectious and also the likelihood of cubs testing positive. Badger vaccination also allows badger populations to remain healthy and stable and at carrying capacity for the land area they inhabit without perturbation.
Healthy, unstressed badgers are less likely to develop bTB or become infectious. Currently no assessment is made of the level of disease before culling let alone a distinction between infected or infectious.
Badger vaccination has been shown to reduce the risk of an uninfected animal catching the disease by around 76%6, this benefit is also passed down to new born cubs. It also slows the progression of the disease in infected badgers.
Vaccination is the only appropriate approach in terms of animal welfare, has the lowest impact in ecological and environmental terms, and also financially - as shown by the Derbyshire Wildlife Trust vaccination project which estimates an approximate cost of £827 per badger vs £1,000 per culled badger. It is also accepted and far more positively viewed by the public than the alternative.
Culling badgers causes huge suffering (as thousands take too long to die8), stress and the break-up of stable badger clans and territories, leading to much greater movement9 and bTB spread between badgers, and a greater likelihood of healthy badgers becoming ill.
Non selective culling of badgers makes no sense as a wildlife intervention.
Farm Practices Survey (Autumn) 2019 - England, DEFRA, 2019
Pilot Badger Culls in Somerset and Gloucestershire Report by the Independent Expert Panel, 2014
Riordan P, Delahay RJ, Cheeseman C, Johnson PJ, Macdonald DW (2011) Culling-Induced Changes in Badger (Meles meles) Behaviour, Social Organisation and the Epidemiology of Bovine Tuberculosis. PLoS ONE 6(12): e28904.
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