Farmers will have 28 days to cull BVD-positive calves before full restrictions on movements into and out of their herd are put in place, new proposals from DAERA state.

If a herd is closed-up, movement restrictions will remain in place for 21 days after all animals that are persistently infected (PI) with BVD have been culled.

The extra window aims to limit the spread of the virus to other farms as healthy cattle can temporarily pick up BVD, and become known as transiently infected animals. This differs from PI animals, which became infected with BVD in the womb and shed the virus for their entire lifetime.

But as well as these herd restrictions, the DAERA proposals state that if a herd is closed-up because of retained BVD animals, all female cattle over 12 months old will remain under movement restrictions for 41 weeks after the last BVD positive is removed.

This targets females that become temporarily infected with BVD during pregnancy and later give birth to a PI calf. These cases are known as Trojan animals and DAERA states they will “play an increasingly significant role in spreading BVD” as NI moves towards eradicating the disease.

Restricted females will only be able to leave the herd before 41 weeks if they either give birth to a BVD negative calf, test negative for BVD under both antigen and antibody tests, or test positive for BVD antibodies before pregnancy.

Health risk

While the proposed restrictions are strict, it is likely to only affect a small number of farms that pose a significant animal health risk to all other herds in NI.

The latest figures show that 141 BVD positive calves are alive in 98 herds across NI. Of these, 36 animals in 28 herds were alive more than four weeks after the test result was received.

Untested

New legislation is also being proposed which would give DAERA powers to restrict herds that do not test calves for BVD within required timescales.

The current rules state that newborn calves must be tissue tagged within 20 days, and a further seven days is allowed for the sample to arrive at a testing laboratory.

There were over 18,062 animals aged over 30 days with an unknown BVD status in NI at the start of October, including 2,614 imported animals.

“The department would … initially intend to use the power to target those herds that contain the highest number of BVD unknowns,” DAERA guidance states.

Pre-2016

The final proposal aims to make it a legal requirement to test animals that do not have a BVD status and were born before March 2016 when tissue tagging become compulsory in NI.

All cows that give birth to a BVD-negative calf are assigned a negative status, so this applies mostly to older stock bulls on farms. DAERA figures show that of the 2,141 animals that were born before March 2016 and still do not have a BVD status, almost three-quarters are male.

DAERA prepared for further steps on BVD

The new proposals on BVD eradication are set out in a consultation document which is open to responses from the public until 20 December 2022.

However, DAERA states that the measures are likely to change as progress is made with eradication.

For example, the 28-day grace period for culling a positive animal before herd restrictions are put in place will gradually reduce and will eventually be enforced immediately, as is the case in the Republic of Ireland and Scotland.

Agriculture Minister Edwin Poots described the proposals as “a significant step forward in eradicating BVD” but added “they will not be the end of the journey”.

The minister is clear that further measures will be considered by DAERA, including neighbour notifications where farmers are warned about the risk of BVD if someone in their local area retains PI animals.