Three suspected cases of foot-and-mouth disease are still under investigation in the North after Department of Agriculture officials detected antibodies against the disease in several flocks of sheep.
As a result of the tests, 64 sheep on a farm near Magherafelt, Co Derry, were culled as a precaution. The farm is within the restriction zone set up around the Donnelly farm at Ardboe, Co Tyrone, the scene of the North's second outbreak on Good Friday.
The North's Agriculture Minister, Ms Brid Rodgers, said the cull was being carried out as a precautionary measure and tests on sheep on other farms in the vicinity were clear. The fact the animals had built up antibodies to foot-and-mouth did not mean that they had the disease but only that they had been exposed to the virus in the past, she added.
Yesterday, vets were examining sheep at a farm at Torr Head near Ballycastle on the north Antrim coast after antibodies were found in one blood sample there.
On Wednesday, a farm in neighbouring Murlough Bay was placed under restrictions when 18 sheep of a 325-strong flock showed blisters consistent with the disease. Results on the sheep are expected from the Pirbright laboratories in Surrey by the weekend.
Both farms are around 15 miles from the last confirmed outbreak at Cushendall, Co Antrim, just over three weeks ago.
Meanwhile, a survey by the Confederation of British Industry (CBI) published yesterday said the outbreak had "seriously affected" business confidence in the North. The CBI's assistant director for Northern Ireland, Ms Deirdre Stewart, said the repercussions went far beyond the agricultural industry.
"Both the service sector and other areas of manufacturing are reporting its negative impact on business," she added.