Scottish Bovine Viral Diarrhoea eradication scheme: consultation on phase five responses

Proposal 2 - Restricting cattle in "BVD positive" herds

PIs are known to be the main source of BVD infection, excreting large volumes of virus from the moment of birth until death. For this reason, at this stage of the Scottish BVD eradication scheme, BVD control is centred on the identification of PI animals and the removal of these cattle from the herd.

In April 2017 we introduced a new BVD "positive" status to highlight herds that pose a higher BVD risk for those purchasing or moving cattle. This "positive" status only applies to holdings where there is a known virus positive animal in the herd. Once the virus positive animal has been removed from the holding, or re-tested with a negative result, allowing the presence of virus to be ruled out, the BVD herd status reverts to "not negative". Prompt removal of PIs reduces the level of on-going and new infections.

To increase pressure on "positive" herds to remove their PI(s) promptly we sought views on the following two proposals:

• Preventing spread of BVD to brought-in animals by preventing "positive" herds from purchasing, or otherwise bringing in, animals. This prohibition would be in addition to the restrictions already in place for "not negative" herds for animals moving off the holding. Restrictions on bringing in animals would remain in place until the herd has achieved a "not negative" status by removing all known virus positive animals, or re-testing them with a negative result. The options for removal are to kill on farm or send direct to slaughter. If adopted, this measure would need to allow a reasonable time period for re-sampling of suspect animals to determine whether they are PIs or only transiently infected with BVD.
• Reducing infection risk within the herd and to neighbours by adding a new requirement to isolate virus positive animals. As soon as a PI is suspected (first positive antigen result received, or calf born from a virus positive dam) the animal must be isolated from the rest of the herd, e.g. by housing in a separate airspace from cattle that are not virus positive.

Question 5: Do you think that holdings that contain one or more live PIs should not be allowed to move cattle on to that holding?

61% of respondents supported the proposal to stop the movement of cattle onto a holding that contains one or more virus positive animals. 29% of respondents did not support the proposal, with another 7% not sure either way.

Figure 6: Do you agree that holdings with one or more live PIs should not be allowed to move cattle to that holding?

This question asked whether moves on to a holding with a live virus positive animal should be permitted, and if so, should these moves be limited to cattle with an individual virus negative status that have been BVD vaccinated by a vet. Respondents were asked to give a reasonable time frame to allow a suspect PI/ PI animal(s) to be resampled or removed from the holding before restrictions on purchasing animals are imposed. 86% of respondents explained their answer by providing comments.

Views on the movement of animals onto a holding with one or more live virus positive animals were mixed. 27% of respondents indicated that moves onto this type of holding should not be allowed. It was generally agreed that such a restriction would increase the economic pressure to eliminate PIs. 16% of respondents supported the exemption to allow vaccinated, BVD negative animals to move onto BVD positive holdings. One respondent thought that there should be an exemption for the purchase of bought-in store cattle destined for slaughter. Several respondents were concerned that restricting movements and monitoring exemptions would be difficult to enforce in practice. 9% of respondents did not agree with restricting cattle movements on to a holding with a live PI. They pointed out that adopting this proposal could have a severe impact on business, with one respondent highlighting that some farm operations depend upon a constant turnover of stock. Several respondents thought that movements onto a holding with a live PI would be at the farmers own risk.

40% of respondents submitted their views on a reasonable time frame for resampling and/or removal of virus positive animals from a herd. The results are shown in Figure 7.

Figure 7: Responses to time frame for resampling and removal of virus positive animals from herd

Question 6: Do you think that all virus positive cattle should be housed separately from animals with an unknown or negative BVD status?

73% of respondents supported the proposal to house virus positive animals separately from those with an unknown or negative BVD status. 1% did not support this proposal and 6% were unsure.

Figure 8: Do you agree that all virus positive cattle should be housed separately from animals with an unknown or negative BVD status?

84% of respondents provided comments to explain their decision. Among those who supported the proposal, there was a strong consensus that housing virus positive animals separately from other animals would reduce spread of infection. Several respondents thought that it would be beneficial to the eradication scheme by encouraging early removal of PI animals from the herd. Respondents who disagreed with the proposal commented that it would not be practical for a lot of herds as many farms do not have isolation facilities. Common feedback from those that disagreed showed they were in favour of prompt removal of PIs from the herd, some suggesting compulsory slaughter, rather than allowing PIs to be retained on farm, housed or otherwise. Both those in favour and those against the proposal pointed out that it would be difficult to enforce the housing requirement for PI animals.

Question 7: If virus positive animals must be housed, would inspection of these premises improve compliance?

Just over half of the respondents, 53%, agreed that inspection of premises that house a virus positive animal would improve compliance. 23% of respondents did not agree and 21% were unsure that inspection would improve compliance.

Figure 9: Would inspection of premises where virus positive animals are housed improve compliance?

There was strong agreement from the respondents who supported this proposal, saying inspections would have to be regular and random to ensure compliance where farmers are housing virus positive animals. One respondent suggested that guidance should be provided outlining the minimum requirements for suitable housing. Several respondents indicated that inspections would be essential to ensure that housing provided an appropriate level of biosecurity and alleviated animal welfare concerns. One respondent suggested that inspections would also be a good opportunity to discuss the farmer's BVD eradication strategy.

Almost of a third of those who did not agree that inspection would improve compliance wanted to see these animals culled as soon as possible, rather than kept in isolation. Others did not agree as they felt the inspections themselves would be impractical and difficult to enforce. 3% of respondents suggested that the inspection was only representative of the day of the visit and would not guarantee continued compliance.

Question 8: If virus positive animals must be housed, how could we prevent inadvertent spread of BVD virus to other cattle via clothing / footwear / equipment?

94% of respondents commented on this question.

The most common response was for keepers to implement a robust biosecurity plan on their farm. This was supported by 24% of respondents but many admitted that keeping a PI on the farm would always be a disease risk. One respondent suggested that risk could be reduced by having a greater emphasis on biosecurity via cattle health plans, veterinary visits and QMS inspections all working together. Another suggested a health plan could be prepared to allow each producer to confirm how the spread of disease will be prevented. Along with a robust biosecurity plan, 13% of respondents supported a requirement to use dedicated equipment, including separate clothing, when handling virus positive animals.

There was a general consensus that preventing inadvertent spread of BVD virus would be difficult to achieve in practice. 21% of respondents provided comments to explain their concerns, which focused on farmer attitude to biosecurity and ability to implement effective biosecurity measures, and the lack of suitable equipment and buildings to house and handle animals safely. One respondent commented that advice on biosecurity, footbaths, separate clothing and handling is often acknowledged by farmers but not implemented. 3% of respondents supported the use of vaccination to protect the herd while 13% pointed out that culling the PIs as soon as possible ( i.e. not housing them) was the most effective way to avoid further risk.

There was a general acknowledgement of the risk of inadvertent spread of BVD virus, and support for biosecurity training for farmers. This was backed by 10% of respondents, suggestions ranged from training and advice from the private veterinary surgeon to "knowledge exchange" materials being provided to farmers. One respondent suggested that a consultation should be carried out with a veterinary surgeon, alongside easily accessible and digestible information on biosecurity being disseminated through the main livestock and farming bodies in Scotland.