The Department for Agriculture, Environment and Rural Affairs (DAERA) has published the criteria for the mandatory use of interferon-gamma (IFN-g) blood tests for bovine TB in Northern Ireland.

Initially, herds with 10 or more skin reactors at a disclosure TB test or herds with more than 40 reactors within a rolling 12-month period will be required to undertake mandatory IFN-g testing in Northern Ireland.

This mandatory testing will not apply to beef fattening herds.

Mandatory IFN-g testing for livestock that have given an inconclusive reaction to a skin test in non-breakdown or singleton reactor herds where TB has not been confirmed is also being introduced.

The changes will come into effect from June 29, 2026.

TB blood test

The Minister of Agriculture, Environment and Rural Affairs, Andrew Muir said today (Wednesday, June 24) that the IFN-g test "is an important diagnostic tool which assists the bovine TB skin test in the early detection and removal of positive bovine TB reactor animals."

The minister said that making it compulsory, where qualifying criteria have been met, has been a long-standing policy objective.

He added: “My department will now work closely with those farmers whose herds are suffering a bad TB breakdown to maximise the effectiveness of the IFN-g test.

The move, which does not require a legislative change, will bring Northern Ireland into line with policy elsewhere in the UK and Ireland.

TB test

The interferon-gamma test is a diagnostic test for TB, approved by the World Organisation for Animal Health and is also noted as an official test for this disease in European legislation.

It is primarily used to supplement the use for the tuberculin skin test within TB breakdowns and is particularly important for identifying infection at an earlier stage than the skin test.

Its use to date in Northern Ireland has been on a voluntary basis with DAERA offering it to some herd owners whose herds are suffering a bovine TB disease outbreak.