This year’s national BVD survey is set to highlight areas where management and careful vaccination planning can come together to take eradication across the UK one step closer. And respondents can also win a prize.
TEXT CHARLOTTE GRIME
Bovine viral diarrhoea has a significant impact on the UK herds’ health, welfare, productivity, and profitability. A recent Europe-wide study found that in endemically infected herds, cattle that were not protected against bovine viral diarrhoea (BVD) produced up to 1.8 litres less milk per day during early lactation, compared with those that were protected against the disease, even in the absence of clinical signs of infection.
The good news is that great strides have been made towards eradicating this disease during the past decade thanks, in part, to the data gathered and evidence from Boehringer Ingelheim Animal Health’s BVD survey.
This has gathered information from all parts of the UK and all types of cattle farming system to produce an up-to-date snapshot of what producers are doing on their units to control and eradicate this costly disease. The information gathered is analysed and can be important when it comes to developing future policies. Since the survey began in 2016, much has changed in terms of BVD control. BVD eradication schemes now exist in all parts of the UK, testing and surveillance options have improved, data showing herd BVD status is widely available, markets and auction houses support clear identification of stock, and price bonuses exist for stock of known BVD-virus status.
Tailored questions
After a two-year break, the National BVD Survey is running again in 2024, as announced at Dairy-Tech earlier this month.
“This is the seventh time the survey will run and, as before, questions are tailored to each nation reflecting national control and eradication schemes,” says Boehringer Ingelheim Animal Health vet adviser Becca Cavill. “Whether dairying in Scotland or Northern Ireland, where compulsory schemes have been in place for some time; in Wales, where the funding for Gwaredu BVD scheme ceased at the end of 2023; or England, where engagement with national schemes is voluntary, the threat and ramifications of this virus remain very real,” she adds.
BVD control programmes require a co-ordinated and systematic approach made up of: determining herd status, usually by tag and test, although the scheme in Wales favoured blood screening; identifying and removing persistently infected (PI) animals; protection of the herd through vaccination; and robust biosecurity planning.
Starting with determining herd BVD status, the proportion tagging all calves born, dead or alive, is highest in England, at 45% (see Figure 1). In Wales, 22% of producers opted for ear tagging and this is most likely due to the nature of the eradication programme, which is centred on the use of youngstock blood-screening to check and test cattle.
“Working in conjunction with the herd’s vet, PI animals can be identified and the advice is always to cull them from the herd,” says Dr Cavill.
Despite this being the advice for several years, many producers still keep and aim to rear these PIs (see Figure 2). “But this is misguided for two main reasons. A PI animal will never thrive or reach its potential and, even more importantly, is a reservoir of BVD infection.
Virus factory
“PI animals act as a ’virus factory’ shedding huge amounts of BVD virus that can result in the infection of pregnant animals and lead to the birth of further PI calves and the perpetuation of the BVD cycle. PIs will also infect their peers, resulting in immunosuppression and an increase in the incidence of calf diseases, such as pneumonia. It simply is not a risk worth taking,” she stresses.
“We know from our previous survey results that some producers are still selling PI animals. And a significant number of producers fail to routinely test for BVD, so for anyone buying or selling stock it’s imperative to ensure they have strict biosecurity measures in place. “Biosecurity failures are the number-one reason for BVD breakdowns, in both naïve and vaccinated herds,” she adds.
Analysis of the 2021 survey results showed that biosecurity measures varied hugely from unit to unit, with some having none in place. “In vaccinated herds, the virus may enter as a result of mis-timing when killed vaccines are administered,” says Dr Cavill.
Bovela is a modified live vaccine that has a simple one-shot primary course, followed by annual boosters. “This can be much easier to manage than the initial three doses required with killed BVD-vaccination protocols. This means that Bovela is often easier for producers to use in all-year-round calving herds.”
Timing complications
Survey responses in 2021 showed that producers in each nation found it necessary to restart vaccination programmes due to timing complications. Most commonly this was due to going beyond the 12-month booster window, followed by missing the six-month booster and mis-timing the second shot. “And while the virus could have crept in when the herd’s protection was compromised, leading to associated losses, it’s also expensive and time-consuming to restart a vaccine programme,” says Dr Cavill.
The ‘Mind the gap’ vaccination planning tool, which can be found at www.makebvdhistory.co.uk, can help producers to plan heifer and milking-cow vaccine administration timings. “Simply input service and calving dates and it does the work. And it’s always worth discussing with the herd vet, particularly if producers want to make changes to their vaccination programme,” she concludes.
Take part and win
The 2024 National BVD Survey will run for one month from its launch at DairyTech 2024 on February 7. Producers can take part by scanning the QR code. All respondents will also be sent a report analysing the results of the survey. Beats Studio Buds True Wireless Bluetooth in-ear headphones, worth £120, are also up for grabs for 10 lucky participants, so what are you waiting for?
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