In 2016, the BVDFree England scheme was launched, and in 2018, the Agricultural and Horticultural Development Board anticipated that bovine viral diarrhoea (BVD) would be eradicated in England by 2022 (AHDB, 2018). The Ruminant Health and Welfare Group indicated that BVD will be eradicated by 2031.
Presently, indications suggest Scotland and Northern Ireland are achieving good outcomes with a compulsory programme; Wales is in consultation. The Animal Health and Welfare Review has allocated three years of funding for cattle farmers to engage with their veterinary practice to reduce endemic diseases, with particular attention to BVD. There is also an indication that there will be mandatory screening and culling from 2025.
From 2016 to now…
In 2019, AHDB indicated that 30 percent of English cattle herds had engaged with BVDFree. A later figure showed that the best part of 7,000 farmers had joined the initiative (BVDFree, 2019). All appeared to be developing well, with Stamp It Out funding and increasing veterinary and farmer engagement. Then along came COVID-19.
The impact on veterinary practice staff was, and remains, variable, but there were fewer individual face-to-face meetings and group gatherings halted; training moved online. The British Cattle Veterinary Association (BCVA) segmented BVD programme continues to update individual veterinary surgeons. Registration of veterinary BVD providers is sufficient to cover a map of the UK, so disease advice providers are wall-to-wall across the nation.
Updated research and figures
For the farmer, the advice is for each calf and the dams of any BVD-positive calves to be tested. The hunt is on to find persistently infected (PI) cows and for them to be destroyed. The term “destroyed” is now in use rather than “culled” because the aim is for national BVD eradication. It does not help the national cause to have positive animals moved on elsewhere for someone else to experience the disease.
When the facts and figures were originally promoted to get action on BVD control, it was indicated that 90 percent of UK herds had been exposed to the virus. That figure has been set into the agricultural awareness database. There is also a warning that 70 to 90 percent of all BVD virus infections can occur without the appearance of clinical signs (Booth and Brownlie, 2017).
It was indicated that 90 percent of UK herds had been exposed to the virus. That figure has been set into the agricultural awareness database
Early research indicated that a cow infected in utero before 110 to 120 days of gestation yields a calf born persistently infected and which excretes large volumes of pestivirus (Booth et al., 2016). The immune system of a calf is not fully developed before 110 days, and infection after 150 days yields a live calf at full term.
At the 2022 BCVA Congress the keynote session was on the Animal Health and Welfare Pathway, how it has developed, the funding available and the responsibility of veterinary practices. But the only presentation directly addressing BVD was from SRUC Veterinary Services (Henderson and Jones) on “the impact of thymus hypoplasia on the ability of cattle to respond efficiently to the challenge of endemic disease”. A study in progress may yield important indications for calf feeding and early management.
BVD impact and control
The three essential aspects of BVD control are the elimination of PI cattle, biosecurity and vaccination. Vaccination is targeted at keeping female cattle safe during pregnancy. This is because herds that do not have BVDv circulating (“naïve”) are at risk from introduction of the virus. While testing can be expensive and accurate interpretation of the results is essential, vaccination is well developed with effective products and support. Biosecurity may also be a real challenge for many farmers. The awareness is that all three arms have to operate effectively together.
The three essential aspects of BVD control are the elimination of PI cattle, biosecurity and vaccination […] The awareness is that all three arms have to operate effectively together
Where cows are infected in early pregnancy, the outcomes listed include low pregnancy rates, embryonic death, abortion, mummified foetus, birth defects, weak premature calves and live persistently infected calves. BVD virus circulating in a herd is known to have a considerable economic impact, with a reduction of milk production and calf growth and a lower resistance to disease.
Persistently infected calves that survive beyond six months of age can experience a change in symptoms, with the development of mucosal disease, severe clinical outcomes and death. Farmers who have controlled BVDv report that their calves have never grown so well, and farmers who have kept positive calves indicate that the subsequent expense of treatment for pneumonia, scour and ill health outweighs the first loss of destroying the calf.
How is the programme progressing?
However, there does not appear to be an easily accessible source demonstrating the progress of the how the national programme is progressing. How many PI cattle are being detected and destroyed? How many herds are actively currently engaging in a PI hunt? How many herds have worked at clearing the virus only to become infected later on?
There are, of course, national data sources that can be accumulated and information issued. A report from the BVD Eradication Group is awaited. It is indicated that veterinary practices are expected to provide data to Defra about progress with their clients in return for receiving money sourced from the Animal Health and Welfare Pathway. This is possibly one of the delays to progress. Instead of highlighting activity with BVD control, considerable energy has been spent promoting the Pathway.
Looking to the future
Veterinary professionals are likely aware of the fact that nowadays PI cows are being detected by laboratories and bulk milk tank samples are showing the presence of the virus. Milk processors are being influential with disease control contractual obligations.
Veterinary input cannot wait until a farmer fills out a form and invites the vet to conduct a review. And though there is no indication that practices are sitting back, COVID-19 has slowed everything down.
Many practices have identified the client herds that are free from BVD, those that are known to be infected and those where the status is unknown. However, much more information would be welcomed about successful biosecurity in practice. Pictures of double fencing are fine, but if nothing else, the foot and mouth outbreak showed how few cattle farms have convenient ring fencing and that movement around the countryside to fields that are not linked is commonplace.
If veterinary practices note the data for their own clients and are able to discuss the findings with surgeons who service neighbouring herds, then a combined thrust for an area BVD eradication initiative would be a significant move forward
There is a further aspect of disease control that veterinary practices may be able to develop for the benefit of clients and national eradication. Where the CPH number is known, the BVD status of herds is available. If veterinary practices note the data for their own clients and are able to discuss the findings with surgeons who service neighbouring herds, then a combined thrust for an area BVD eradication initiative would be a significant move forward. The idea is that all cattle farmers in a parish should be encouraged and advised by their own vets to engage in effective control, all at the same time.
