Parts of Co. Armagh are on Bovine Viral Diarrhoea (BVD) alert.
This follows an upsurge of the disease on farms close to Markethill, Keady and Killylea.
Over 70 initial positive results have been returned in six herds after ear tagging of calves this year.
Farmers are being urged to take steps to prevent livestock contacting neighbouring cattle at boundaries, as the virus may be circulating in herds and thus present a risk.
The rolling 12-month animal level incidence of BVD in Northern Ireland (NI) reached an all-time low point for the programme of 0.29% in February 2021.
However, a subsequent upturn in incidence has resulted in the figure at the end of April 2022 being 0.34%.
Since the start of 2022, 0.77% of animals tested in dairy herds in the Armagh Divisional Veterinary Office (DVO) area have returned initial positive or inconclusive results.
This is over two and a half times the average disclosure rate across dairy herds in NI.
Across all cattle herd types, the Armagh DVO area has the highest animal level of disease this year, at 0.69%, over twice the average level.
According to Animal health and Welfare NI (AHWNI), it is very important to keep cattle, including youngstock, away from cattle in other herds during the grazing season.
Every effort should be taken to avoid contacts, by having either double or electric fencing, or by managing grazing alternately in conjunction with neighbouring farmers, especially when cattle are grazing aftermath and field edges after silage making.
The occurrence of some of the latest BVD outbreaks may be linked to the introduction of purchased stock into the herd.
To reduce the risks involved when cattle are purchased, sellers should be asked whether BVD has been present in their herd during the previous year, and at what stage any positives were removed.
Owners of BVD-positive cattle are being asked not to move or sell cattle until at least three weeks have elapsed from when the last BVD-positive bovine animal was culled.
Cows or heifers that were within the first four months of pregnancy at the time when the positive animal was present should not be sold on, unless appropriate isolation measures have been put in place and additional BVD antibody tests have been carried out by the farm’s private vet.
In several recent cases, BVD positive calves were alive in specific herds last year during the period in which the dams of this year’s BVD-positive calves were susceptible to the virus.
So the source of this year’s outbreak is most likely last year’s infectious calves. These cases are a reminder of the importance of isolating and culling BVD persistently infected (PI) cattle at the earliest opportunity.
Farmers should also careful to carry out thorough cleaning and disinfection of areas that could be contaminated with the virus.