The decision to extend was made following a veterinary risk assessment that found there is still a risk of avian influenza to poultry through direct or indirect contact with wild birds, DAERA said. However, the risk has decreased.
Biosecurity mitigation measures came into effect from 17 March, when the housing restrictions were lifted.
Some of the measure included ensuring that bird’s feed and water cannot be accessed by wild birds, avoiding transfer of contamination between premises by cleansing and disinfecting equipment, vehicles and footwear, separating domestic waterfowl (ducks and geese) from other domestic species and reducing the movement of people, vehicles or equipment to and from areas where poultry or captive birds are kept.
Northern Ireland’s chief veterinary officer Robert J Huey told farmers to remain vigilant for the signs of disease: "It is essential that bird keepers comply with the biosecurity requirements set out in the declaration of the prevention zone if they are to minimise the risk of infection. Key to this will be ensuring that their birds are separated from wild birds when outside."
Phasing in to allow shows
From 1 May, restrictions on gatherings will also ease, allowing for shows to commence. Single demonstration flocks will be introduced to allow shows from the end of May but this is subject to there being no further avian influenza suspects or outbreaks.
Gatherings of pigeons, aviary birds and birds of prey can continue to take place, DAERA said and the conditions of the general licence for gatherings remain in place.
If farmers take birds to shows in Great Britain, they can only return to Northern Ireland with a specific import licence and compliance with the requirements of such licence.
Housing restrictions were lifted in England two weeks ago and an avian influenza protection zone was put in place.
However, it was announced on Friday that the zone is to be lifted from 15 May and farmers in England will no longer follow specific disease prevention measures to reduce the risk of infection from wild birds.
Republic of Ireland
On Tuesday, the Department of Agriculture lifted housing restrictions for with immediate effect. Farmers were told to remain vigilant, monitor their birds for any signs of disease and implement strict disease control measures.
IFA poultry chair Nigel Renaghan said he was "ecstatic" about the lifting of housing regulations, and dubbed the management of the disease "a success story".