BVD update
The law regarding BVD changed in Wales on 1st July 2026. The following is a summary of the most important points but for full guidance visit:
Guidance for Farmers: complying with bovine viral diarrhoea legislation in Wales | GOV.WALES
Lots more useful information and resources can be found at
Test Types – these need arranging with veterinary guidance
Antibody test – exposure to BVD – a positive result shows that the virus has entered, and could still be in the herd.
Antigen test – live virus – a positive test shows that the animal is currently infected with BVD. To check if the infection is temporary or lifelong (a PI or persistently infected animal) this test should be repeated after 3 weeks. Tests can be done on bloods, or using specialised ear tags (Tag and test).
Pre-movement test – a blood antigen test carried out within 60 days of the animal moving off the holding
Post-movement test – a blood antigen test carried out within 20 days of the animal moving on the holding. If the animal has already been BVD tested, a copy of the negative result from the vendor supplied to the vets will cover this testing requirement. Bear in mind that BVD vaccinated cattle still need testing to prove they are not PIs.
Testing
Each herd will need an annual screen for BVD, using the antibody test to look for exposure. This is 5 animals from each separate management group e.g. the spring calvers and the autumn calvers, or cattle housed at home and on a second rented premises.
A clear herd screen, where all animals test negative for having ever seen the virus, sets you to a ‘BVD Green’ status, and you can continue trading as normal until the next annual screen. You should only buy from green herds, or animals that have tested virus negative.
If any of your screened animals test positive for BVD exposure (antibody), your herd status will be set to ‘BVD Red’. Herds will also get their status set to red under the following conditions:
· No herd screen within the last 12 months – the status will reset to green if the screen is clear
· Animals bought from a red Welsh Farm, without a clear pre-movement test within 60 days of the movement. By law, this shouldn’t happen.
· Animals bought from outside Wales, without a clear post-movement test within 20 days of the animal arriving. See above for already tested cattle.
‘Red’ herds
There are extra restrictions placed on red herds, to prevent the spread of BVD.
· Cattle may not move off the holding without a clear pre-movement blood test, unless going direct to slaughter.
· Any animals confirmed as PIs cannot ever go to another farm, they can only go to slaughter, and we would advise doing this as soon as possible to prevent spread
Converting from a red herd to a green herd
To do this requires proving that you have no PI animals on farm. Each animal must be tested for live virus – the easiest way is to tag and test. Once all PIs are removed, the herd will go back to green status.
Calves born in the 12 months after the herd goes back green will need testing for virus within 20 days of birth. This includes stillborn and aborted calves. This can also be done with tag and test, as you can buy official ear tags that sample for BVD testing when the calf is tagged.
The requirement to test calves is because PIs are generated in the uterus – a calf is either born a PI or born clear. Testing for 12 months after PIs are removed means every animal on the farm (fetuses included) is BVD tested, with a few months’ safety margin thrown in.
Finally…
We would recommend switching to official tag and test tags as standard practice. Should the herd go red on the annual screen, any calves which are tag and test negative at birth will automatically be given clear status as they cannot be PIs. Therefore they will not need testing again for the herd to go green, but they will still need a pre-movement test whilst the herd remains red. Eventually, when all the cattle on the holding are tag and tested, you’ll go green automatically… The additional cost, at time of writing, is £2-70 to £4-10 per sample, depending on the lab used. Testing can be arranged with your tag supplier when the tags are bought.
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