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Publication - Consultation Paper

Bovine Viral Diarrhoea eradication scheme: consultation on phase five

Published: 21 Aug 2017
Part of:
Farming and rural
ISBN:
9781788511650

Through the Bovine Viral Diarrhoea (BVD) Advisory Group we have agreed to consult the next phase of the BVD eradication scheme.

35 page PDF

345.3kB

35 page PDF

345.3kB

Contents
Bovine Viral Diarrhoea eradication scheme: consultation on phase five
Proposals for Phase 5

35 page PDF

345.3kB

Proposals for Phase 5

Through the BVD Advisory Group, we have agreed to consult on the following proposals for the next phase of the eradication scheme that would:

  • Increase pressure on "not negative" herds to investigate the cause of BVD exposure in their herd
  • Increase pressure on "positive" herds and protect neighbouring holdings/herds
  • Require tissue sampling to be done via an official (primary/secondary) tag
  • Improve the effectiveness of the check test
  • Speed-up reporting of lab results to the BVD database
  • Track PIs back to herd of birth
  • Prevent dispersal of animals immediately prior to a change of herd status

We would welcome views on the following proposals to ensure that they progress the eradication scheme and do not hinder it by introducing measures that are impractical, unenforceable or counter-productive.

Proposal 1 - Testing requirement for "not negative" breeding herds

Under the current BVD Order, keepers of breeding cattle herds must screen their herd annually for BVD and in doing so obtain a BVD herd status. If the status is "not negative" animals cannot be moved out of the herd unless they have an individual negative BVD status, they are going direct to slaughter or (under exceptional circumstances) they can move under licence. Currently, there is no legal requirement to investigate the cause of the "not negative" herd status.

To increase pressure on herds with a "not negative" BVD status, we plan to introduce a new testing requirement that forces cattle keepers to investigate the cause of BVD exposure in their herd.

This new testing requirement would apply to all "not negative" herds that have had a "not negative" BVD status for at least 13 months. In these herds, the cattle keeper must determine an individual status for each animal. For many herds, this "sweeper test" would require only partial testing of the herd as some animals will already have an assumed status or individual status due to previous testing in the herd: animals that already have a status will not need to be retested.

Question 1: Do you think that keepers of cattle breeding herds that have recurring annual "not negative" BVD statuses should investigate the cause of BVD virus exposure in their herd?

Question 2: Should there be exemptions to the "sweeper test" where farms have a breeding herd but also buy stores for further fattening or finishing? If so, how would this work in practice?

Question 3: How long should affected herds be given to complete the "sweeper test"? Should it be completed relatively quickly, e.g. between 1 and 3 months?

Question 4: To take account of "Trojan cows" (which appear healthy but are carrying a PI calf) should the "sweeper test" include calf screening for 12 months following completion of the individual testing?

Proposal 2 - Restricting cattle in " BVD positive" herds

PIs are known to be the main cause of BVD infection, excreting large volumes of virus from the moment of birth until death. For this reason, 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 virus positive animal in the herd. Once the virus positive animal has been removed from the holding, or the animal has been re-tested, allowing the presence of virus to be ruled out, the BVD herd status reverts to "not negative". The prompt removal of PIs will reduce the level of on-going and new infections in Scotland.

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

  • Prohibiting cattle movements by restricting "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 their known virus positive animals, or retesting them with a negative result. The options for removal are to kill on farm or send direct to slaughter. This measure would need to allow a reasonable time period for re-sampling of suspect animals to confirm that they are PIs.
  • 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 non- PI cattle.

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? If so, what would you consider to be a reasonable time frame to allow the keeper to resample or remove the suspect PI/ PI animal(s) from their holding? Should moves on to the holding be permitted, but limited to animals with an individual BVD negative status that have been vaccinated against BVD by a vet.

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

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

Proposal 3 - Use of primary/secondary tags for tissue tag sampling

Where cattle keepers choose to use tissue tagging to obtain an animal's individual BVD status, the use of the primary/secondary cattle identification tag for sampling is considered to be best practice. Use of the primary/secondary tag ensures that calves are sampled early in life, thus allowing early PI identification and removal. Cattle would also benefit from better welfare due to fewer tags in ears. Use of primary/secondary tags, or management tags carrying the official identification number, also reduces transcription errors on the submission form and at the testing laboratories.

For all tissue sampling, including animals born on a non breeding holding, we are proposing to make it a requirement to use only primary/secondary tags for sampling. This would mean that tissue tagging would be restricted to calves of up to 28 days old. Older animals would have to be individually tested by blood sample. A provision would need to be made for samples that have provided insufficient material for testing or given inconclusive results, or other failures due to factors beyond the keeper's control.

Question 9(a): Do you think that all tissue tag sampling should be carried out using only a primary/secondary tag?

Question 9(b): If not, do you agree that "not negative" herds are restricted to only using primary/secondary tags?

Question 10: The proposed restrictions to tissue tag sampling would limit tag testing to calves in the first 28 days of life. If keepers wish to test older animals, should they be permitted to use management tags for this purpose?

Question 11: An alternative to limiting tissue tag sampling to primary/secondary tags would be to require all tissue sampling tags to carry the animal's official identification number. This approach would allow cattle keepers to continue to use management tags for tissue sampling, provided that the tags were printed with the official identification number. Would you agree that management tags used for BVD tissue sampling must be printed with the animal's official identification number?

Question 12: Where the tissue tag has failed to produce a sample that is suitable for BVD testing, should management tags be allowed for retesting or should the animal be re-sampled by a private veterinarian i.e. blood tested?

Question 13: Where a virus positive animal is retested to establish whether it is a PI or only transiently infected, should the retest sample be limited to a blood sample taken by the vet or is it acceptable for the keeper to re-sample using a management tag?

Proposal 4 - Amendment to improve effectiveness of the check test

Effective check testing relies on the selection of representative cattle for antibody testing.

In the current BVD Order, the standard check test requires sampling of 5 animals per management group. A "management group" is defined as animals that have been housed or grazed together for at least the past two months. Thus larger herds would be expected to have several different "management groups" and therefore a check test of multiple sets of 5 animals. However, many larger herds are check tested using 5 animals only. This approach runs the risk of missing BVD exposure and therefore giving a herd a BVD negative status when, in fact, there is a disease risk.

To improve the effectiveness of the check test we propose to amend the BVD Order so that the number of animals included in the standard check test must be 5 animals per "management group", with the total number tested being equivalent to at least 10% of calves born in the herd in the last 12 months. There could also be similar changes to the dairy check test where 10 animals per "management group" are tested with the total number tested being equivalent to at least 10% of calves born in the last 6 months.

Question 14(a): Do you think that the check test should be amended to make it more effective? One possibility is to increase the number of samples submitted for a breeding herd check test to a number equivalent to at least 10% of the number of calves born on that holding in the past 12 months, in addition to meeting the requirement for sampling 5 animals from each management group (10 animals in the case of the dairy check test).

Question 14(b): Do you agree that increasing the minimum number of samples taken at a check test would result in a more robust test?

Proposal 5 - Faster reporting of test results to the ScotEID database

The current BVD Order allows 40 days from date of testing for BVD results to be reported on the ScotEID database. The approved BVD laboratories have become more efficient at processing samples and uploading results since the start of the scheme. The laboratories have stated that 40 days for reporting results is now recognised as excessive; test reporting can be done in a much shorter time.

We are proposing to reduce the BVD test result reporting time to 5 working days.

Question 15: Do you think that the timescale for a BVD approved laboratory to report the result of sample be reduced to 5 working days?

Proposal 6 - Notification of herds from which PIs originate

PIs are born infected with BVD, as the calf of a PI dam or a dam that was transiently infected with BVD during pregnancy. Studies show that PIs are born when their mothers are infected in the interval between 18 and 120 days of pregnancy. Thus, a PI can only be born if there was a PI in the herd or the herd was otherwise exposed to BVD during the risk period of the pregnancy.

Where a PI is identified on a holding other than the holding of birth or the holding(s) where the risk period of pregnancy took place, restrictions are currently only placed on the holding of residence, even though the holding(s) of pregnancy risk period must have had a BVD risk at the time the PI was developing in utero, and the holding of birth (if different) will have experienced BVD exposure when the PI calf was born. Depending on the testing being carried out, BVD infection on the holding(s) of pregnancy risk period and birth may not have been recognised, posing an on-going risk to those herd(s) and potentially to cattle on neighbouring farms.

We are proposing to add a new requirement that will track PIs back to their herd(s) of pregnancy risk period and birth. Regardless of where and when a confirmed PI is identified, the holding(s) where the dam was resident during days 18-120 of pregnancy should be recognised as BVD "not negative", as should the holding of birth (if different).

Where full BVD investigation has already been carried out in the identified herd(s) since the removal of the PI restrictions would be unnecessary. No action could be taken on herds outside Scotland.

Question 16: Should the holding where the dam was resident on days 18-120 of pregnancy and the holding of birth be automatically given a "not negative" status as soon as the PI is identified? If so, what would we need to consider in order to avoid penalising holdings that have already carried out BVD investigations?

Question 17(a): When tracking a PI back to their herd of birth, should this be restricted to confirmed PIs (i.e. those that have had a second positive antigen result at least 3 weeks after the first sample)?

Question 17(b): If so, it may result in less confirmatory testing: are you concerned about this?

Question 18: When tracking a PI back to their herd of birth, would this be better handled as an advisory matter, e.g. by sending a letter to the holding(s) concerned, possibly copied to their vet?

Proposal 7 - Post-sample movement restrictions

Cattle keepers can find themselves in the position of having inadvertently moved their animals illegally when they have not realised that the herd status has changed from BVD "negative" to "not negative".

Ideally cattle keepers should check their herd status on the ScotEID BVD database before they move cattle without individual status to another holding or the market.

To prevent the dispersal of animals immediately after a change of herd status, we are proposing to put a movement restriction in place where a cattle keeper has submitted samples and is waiting for the results of the annual (beef) check test, the movement of any animals off the holding that do not have an individual BVD status must be delayed until the result of the annual check test is uploaded to ScotEID.

Question 19: Do you think with the proposal to restrict the movement of untested animals off a holding until the results of the annual beef check test have been received?

Question 20: Could imposition of movement restrictions encourage cattle keepers to delay their annual check test until after young stock sales, with possible loss of eligible age animals?

Question 21: Should more use of ScotEID be encouraged, e.g. through guidance or at road shows rather than via legislation?

Question 22: Does this proposal unfairly penalise beef breeding herds that have had a BVD negative status for several years?

Proposal 8 - Increased pressure on BVD "positive" herds and protection of neighbours

Retaining PIs keeps the source of BVD virus on the farm and risks infecting the herd and creating new generations of PIs. In addition, PIs may put neighbours at risk of infection through direct or indirect contact. We propose publishing the location details of farms where one or more virus positive animals are retained. Pending detailed consideration, location details could be any or all of: CPH, keeper's name, farm address. The details could potentially be provided as a list or a map.

In order to ensure correct information, publication would need to be delayed for a period after disclosure of a virus positive animal to give the keeper opportunity to re-test the animal and confirm it either as transiently-infected or a PI.

Question 23: Do you think that the Scottish Government should publish location details of virus-positive cattle?

Question 23(a): If you answered yes to question 21, how long should cattle keepers be given between first disclosure of a virus positive animal and publication of its location?

Question 23(b): If you answered yes to question 21, what format would you like to see for publication of PI location? Examples could include: a list of CPHs published on ScotEID; an interactive map; written notification to neighbours.


Contact

Email: Ian Murdoch, Ian.Murdoch@gov.scot

Phone: 0300 244 4000 – Central Enquiry Unit

The Scottish Government
St Andrew's House
Regent Road
Edinburgh
EH1 3DG