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21 Aug 2018
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'We need to think about health and welfare' - zero tolerance approach to BVD
Bringing the industry together and protecting the gains made in the drive to eradicate BVD was the theme of the BVDZero Congress organised by Boehringer Ingelheim and held in Cowbridge, South Wales. Gaina Morgan reports.
The importance of only buying calves from BVD-free farms was highlighted by vet Rob Drysdale of Straightline beef, a business specialising in finishing beef from dairy herds.
The business buys about 4,500 calves a year direct from farms, and Mr Drysdale explained a ‘zero tolerance’ approach to BVD has been taken since 2017 following an outbreak of BVD, which cost the business between £4,500 and £5,000.
This cost was down to an outbreak of mild pneumonia and scouring which affected 17 out of a batch of 50 calves bought-in from the same farm and attributed to a single persistently infected calf.
Perception
Mr Drysdale stressed the concept of the public’s perception, as well as sustainability and efficiency, as tools to win farmers over to the importance of BVD zero tolerance. He emphasised that the disease affected profit and productivity, as well as having welfare and carbon footprint implications.
He said: “If the animal is not healthy it is not going to be happy. For farm assurance we need to think about health and welfare with two different hats on. Animals can be very healthy but still not very happy if the system is not good.”
He said one of the biggest issues was the use of antibiotics against a background of immunity suppression.
“BVD is a good immune suppressor so you end up using more antibiotics on the other animals without even realising it.
Health
“This is not good for health and in the long run this is not good in terms of what our consumers think about our systems either.”
Mr Drysdale added it was important to look at how the farmer understands disease and thinks about it, which is how it affects the pocket.
He said: “I am happy to pay more for my calves if they come from farms which are guaranteed BVD free because it obviously saves me a lot of money in the long run. If it can improve their productivity, then the farmers are happier to get involved as well.”
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Eradication progress update
Congress delegates heard that strategies for dealing with BVD in England, the devolved nations and the Isle of Man have evolved from the different needs, disease status and farming patterns.
Ireland is ahead, with the aim of becoming BVD-free by 2020, followed by Scotland and then Northern Ireland, with England and Wales expected to take another five years to eradicate the disease.
Cattle in Scotland are blood tested and, despite some hotspots in south west Scotland, early eradication is anticipated. Progress has reached such a sophisticated stage that strain typing of serum samples is enabling disease patterns to be mapped and tracked. One concern is more than half of those testing only tag live born calves.
Wales, in the second year of its eradication programme, is combining testing with the regular statutory TB tests to sample five animals at a time for BVD. The Welsh scheme, Gwaredu BVD, is unique as the screening programme is Government-funded and more than 50 per cent of farms chose to test in the first year, with 28 per cent of those found to be positive for BVD antibodies.
Retention is an issue and, with no compensation in Wales, 40 per cent of persistently infected (PI) calves are sold on while 42 per cent not immediately culled.
In Ireland, Northern Ireland and Scotland, testing is compulsory and Ireland prioritises prompt identification and removal of PIs, along with strict biosecurity, compensating famers for disposing of PI animals, although it is not illegal to hold them on-farm.
Tagging and testing in Northern Ireland and Ireland suits the smaller herd sizes there. In Northern Ireland, significant support from across the country’s agri-food sector has been crucial in achieving ‘substantial progress’.
Risk of buying pregnant cattle
The difficulties of maintaining BVD-free status and the need for absolute attention to detail were highlighted by Rothbury vet Anna Bruguera Sala.
Her case study, which won the 2018 BVD Zero award and was presented to the congress by Kath Aplin in her absence, highlighted the risk of buying-in pregnant cattle.
The case study described a farm in Northumbria which had been BVD-free for three years and was vaccinating calves, with a policy of only buying in vaccinated animals. However, it was re-infected following the purchase of some pregnant heifers, which gave birth to persistently infected (PI) calves even though they were vaccinated on arrival on-farm.
The heifers were also isolated in a quarantine field, isolated from the subsequently affected farm’s own stock, but in contact with neighbouring herds. A BVD test following a pneumonia outbreak among the calves established that three were PI.
The bought-in heifers had been tested for antigen but not for antibody. If they had been tested for antibody it would have highlighted they had potentially been exposed to BVD. It was not known whether the heifers were PI on arrival or whether they were infected over the fence shortly after arrival before they were fully covered by vaccination.
The likely immuno-suppressive effect of transient BVD infection meant there was also a cryptosporidiosis outbreak which was more severe than might have been expected. It spread to other calves, to sheep and to a member of staff.
Kath Aplin explained the case highlighted the importance of veterinary checked isolation protocols, and the use of tag and test at birth.
In the event, relatively prompt identification of the PI cattle was key in reducing the negative impact. Following the outbreak, tight biosecurity, screening and vaccine protocol compliance were implemented.
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