BVD: Proposal for A National Eradication Programme
Background
Bovine Viral Diarrhoea (BVD) is a non-notifiable viral disease, which causes a
complex of diseases in cattle, the most significant of which interfere with
reproduction, affect the foetus and lead to mucosal disease.
Of particular importance in disease terms is infection during pregnancy with surviving
calves become Persistently Infected (PI) which is the major cause of spread as they
shed virus throughout their lives without necessarily showing any signs of infection.
BVD has been identified as an industry priority given the significant financial cost to
the beef and dairy sectors. It appears to be widespread within the Scottish cattle
population and, in addition to affecting productivity and causing welfare problems, it
can lead to greater susceptibility to infection by other diseases.
Eliminating BVD-related disease would have enormous health and production
benefits, resulting in improved productivity and financial returns for the whole
industry and rural economy.
History to date
Since 2000, there have been a number of BVD control programmes in operation, but
no comprehensive national strategy. The Cattle Health Certification Standards
(CheCS) has ensured that BVD programmes exist in various parts of the country and,
as a result, there are a number of herds now able to demonstrate freedom from BVD.
Regional initiatives such as those in Shetland have shown to be successful in
eradicating BVD for significant geographic areas. Other initiatives have also proven
to be successful, for example in January 2008, the Luing Cattle Society held the first
BVD-free sale at Castle Douglas.
Proposal summary
Building on regional initiatives and lessons drawn from these, a sustainable and
cohesive national strategy could eradicate BVD from Scottish herds over a five year
period. This would further build on Scotland’s reputation for the highest health and
welfare status and deliver major public benefits to individual businesses and the food
and farming industry.
An eradication programme would require public funding of around £7-8 million over
five years. The current of cost of BVD to the national herd – at an estimated £30 per
cow, for 20% of the national herd – is approximately £3.3 million annually. Benefits
are estimated conservatively at around £4.5 million annually at primary producer level
through a production increase of 5000 calves a year, with significant additional
economic value at processing level and through upstream and downstream service
providers. In addition, an estimated five per cent increase in biological efficiency
across 20 per cent of the national herd would create an immediate dividend in
working towards climate change targets.
Five year programme proposal – in detail
Years one and two
This would primarily be a knowledge transfer/awareness raising phase and would be
used to develop the practical side of the eradication programme, prior to
implementation (most notably the tag tissue test process).
Vaccine would be encouraged in risk situations and regional initiatives would
continue as at present. It is assumed that the prevalence of BVD in the national herd
remains on or around current levels.
The certification process should also be established as a core element of the trading of
breeding animals and the use of the standard BVD health declaration should be made
mandatory at breeding sales in year two.
Costs in years one and two are very small, as it is mostly a continuation of existing
programmes, with additional knowledge transfer.
Years one and two estimated cost: £100,000, plus some sponsorship.
Year three
Year three would mark the beginning of the tissue sampling and tagging process
which would be made compulsory across the country.
In addition, legal controls should be implemented on trading PI animals. This would
be supported by notifying positive animals on the movement database and tissue test
tags carrying a secure logo/code to verify they are official. In addition, similar legal
controls would be required for imported stock, which must be able to demonstrate
freedom from BVD to Scottish standards.
Year three estimated costs: Tags cost £2.50, with built-in automated virus screening
an additional £3.50. Assuming a bulk discount could be secured, the cost could be
estimated at around £5.00 per calf. Across all calves born (550,000), the cost would
be £2.75 million.
Where positive test results are recorded, the programme would have to track back into
those herds to screen PI dames and non-breeding animals. Estimated cost: £250,000.
Total cost: £3 million
Year four
There are two options at this stage.
Option A: use the traditional approach and screen all herds, by testing five calves per
management group with an antibody test. Any positive herds would be subject to
movement controls and the entire calf crop tested.
Estimated numbers to be tested:
*Figures below refer to the model in George Caldow’s SAC report “Options for
national BVD control and eradication in Scotland”, April 2009
Beef herd: 185,900* antibody tests, with 8373* follow-up virus screening.
For the dairy herd, there would need to be an element of bulk milk screening, with
follow-ups on any positives.
Option A costs: assuming 200,000 samples with associated vet/lab fees at £10 per
test, the cost would be £2 million.
Option B: repeat the national herd tissue sample tag programme as per year three.
Positive herds would have movement restrictions imposed until the disease was
eradicated in the herd.
Option B costs: £2.75 million as per year three, with an estimated 200 herds (2% of
herds) to be designated as BVD-free.
Year four estimated costs: £2-2.75 million
Year 5
Screen all herds by testing five calves per management with an antibody test
Year five estimated costs: Again assuming a worst case scenario of 185,900
antibody tests at £10 each, the cost of this testing would be £1.9 million. At this
stage, it is assumed there would be no need for the follow-up screening as per year
four.
Post five-year programme activity
Ongoing protection of BVD-free status would be underpinned by ongoing controls to
maintain the biosecurity of Scottish herds, in particular the use of pre and postmovement testing where non accredited/certified animals were being imported.
Vaccine use many also have a role within importing herds to reduce the risk of
disease entering the country.
Summary of costs
Years one and two:
£100,000, plus sponsorship
Year three:
£3 million
Year four:
£2-2.75 million
Year five:
£1.9 million
Total:
£7-7.75 million*
*This figure does not include any compensation for the slaughter of PI calves. A
capped £1 million compensation fund (targeted mostly at year three) could deliver
around £500/farm.