Northern Ireland targets 'trojan' cows in fresh BVD clampdown

Breeding-age females in Northern Ireland herds with a BVD-positive animal will be barred from sale or transfer for up to 41 weeks under tough new rules coming into force on 1 March 2026.

The Department of Agriculture, Environment and Rural Affairs (DAERA) said the restrictions will apply to all females aged 12 months and over in affected herds.

The move directly targets the risk posed by so-called ‘trojan’ animals — pregnant cattle exposed to Bovine Viral Diarrhoea (BVD) during gestation whose calves may be born persistently infected.

In practice, that means a spring-calving heifer in a restricted herd could be unable to move off-farm until she has calved and her calf has tested negative.

The controls form part of the phased implementation of the BVD Control Order (NI) 2024 and mark the next stage in the eradication drive. Northern Ireland has been working towards eliminating BVD for more than a decade, with disease levels significantly reduced in recent years.

DAERA Minister Andrew Muir said: “The introduction of ‘trojan’ restrictions marks another essential step towards eliminating BVD from Northern Ireland.”

He described the movement of pregnant females carrying infected calves as “a hidden source of disease spread and one of the most difficult to control”, adding: “These new rules directly target that risk.”

Mr Muir said farmers had already made major progress. “Farmers across Northern Ireland have worked hard to reduce disease levels, and these additional controls will help protect that progress,” he said.

He urged herd keepers to work closely with their vets, maintain timely testing and understand their responsibilities. “Through these new requirements, herd keepers can safeguard their own herd, support their neighbours and help drive this disease out of our cattle population once and for all.”

Under the measures, breeding-age females in herds where a BVD-positive animal is identified will be restricted from moving off-farm for up to 41 weeks after the last infected animal has been removed.

Restrictions will remain until the female has calved and the calf has returned a negative BVD test. They may be lifted sooner if certain blood-testing conditions are met, including evidence of prior immunity or a clear antibody result taken at least 21 days after the removal of the last positive animal.

Movements will still be permitted direct to slaughter for BVD-tested animals, for disposal as an animal by-product, or exceptionally under licence from the Department.

The ‘trojan’ restrictions follow tighter herd-level measures introduced on 1 February 2026, under which herds are immediately restricted after any positive or inconclusive BVD result. The individual female controls had originally been due to begin on the same date but were deferred to allow updates to the NIFAIS database.

BVD is primarily spread by persistently infected (PI) cattle, which contract the virus in the womb and shed it throughout their lives. Transiently infected animals can also spread infection for a short period before recovering.

For producers trading breeding stock, particularly in-calf heifers and cows, the new rules could have significant marketing and cashflow implications where infection is detected.

However, with eradication now firmly within reach, the Department maintains that tighter controls on high-risk animals are essential to finishing the job.

Further guidance on how the measures will operate is available on the DAERA website.