Nearly 10,000 chickens have been slaughtered as part of contingency plans to deal with any bird flu outbreak in Northern Ireland.
10,000 chickens were gassed in a test cull
Veterinary experts preparing for the potentially fatal disease used gas to
destroy poultry in Moy, County Tyrone.
Officials stressed there was no fear of infection in the birds, who were no longer to be used for laying eggs.
NI's Chief Veterinary Officer Bert Houston said there was a "low risk" of bird flu spreading to Northern Ireland.
However, he said that the authorities had to be prepared.
"We will need to be able to depopulate large numbers of birds humanely and with the minimum amount of human contact if this comes in," he said.
H5N1 BIRD FLU VIRUS
Principally an avian disease, first seen in humans in Hong Kong, 1997
Almost all human cases thought to be contracted from birds
Isolated cases of human-to-human transmission in Hong Kong and Vietnam, but none confirmed
"We identified an opportunity for us to trial and test our abilities to do that on the ground in a situation where it had to be done in any event."
Health chiefs have warned that the UK would have just weeks to prepare for a pandemic if a mutated avian virus begins to spread from Asia.
All Chinese and Russian chicken products have already been banned from ports in Northern Ireland.
In a two-day operation Department of Agriculture and Rural Development (DARD) staff used carbon dioxide gas on 9,400 caged chickens.
Officials from Britain and the Irish Republic studied the methods, which have already been employed in Canada.
A smaller broiler flock kept in a house was destroyed in an earlier cull.
A DARD spokesman insisted the latest batch would have been killed anyway under a routine management process.
"This was a laying poultry flock at the end of its productive life," he said.
"DARD took this opportunity to test its slaughter procedures as part of it's contingency planning for epizootic disease.
"The birds have not been culled as part of any suspicion of avian flu."
Meanwhile, government officials on both sides of the Irish border met on Wednesday to discuss attempts to counter the avian influenza threat.
In particular, the meeting focused on the measures both departments have been putting in place to increase their respective levels of wild bird surveillance.
Wildlife experts gave ornithological advice on bird migration paths from northern Europe to Ireland.
Later a DARD statement said: "Both departments agree with the current view that the risk of high pathogenic avian influenza being imported onto the island
is probably 'low or remote'.
"Nonetheless, the two departments are committed to implementing the EU Commission decision to step up surveillance and have been taking steps to
increase surveillance levels."