In an organic dairy or beef herd, an eradication or eradication and vaccination approach to BVD control should be considered. Due to the immunosuppressive effect of the virus, the "do nothing" option is not recommended. Continuous vaccination programmes can be acceptable if it is impossible to establish adequate biosecurity on the farm for some reason, but this should be combined with an initial eradication of PI animals (see below).

As a closed herd policy is a prerequisite for BVD control, organic farms should have a head start in addressing the issue. Those organic farmers who are planning to sell breeding animals to other organic farmers in the future or are already doing so should consider joining the BVD Accreditation Programme of the SAC Premium Cattle Health Scheme or Herdcare National Cattle Health Scheme.

·        Establish a genuine closed herd policy (no animals should enter the herd without being tested for BVD, unless they come from a BVD-free accredited herd).

·        Carry out an initial assessment of the herd situation (this is done by sampling for blood a certain proportion of animals from each age group within the herd, bulk tank milk samples can be used in dairy herds to gain initial information).

 A)    If the herd is known to be infected, there are several options:

1)      Do nothing. In a small herd (<80 cows), the situation may settle down until herd immunity once again wains and virus enters the herd over fences or with added animals (double fencing and closed herd policy will help to prevent re-entry). This may take several years. However, if the herd is suffering from increased levels of mastitis or other infectious diseases, this may be due to the immunosuppressive effect of BVD infection in the herd and other alternatives should be considered.

2)      Vaccinate all breeding animals including heifers and bulls prior to breeding. Annual vaccination thereafter should be considered.

3)      Vaccinate only heifers the first year and then continue to vaccinate all added animals and to revaccinate all existing animals in future years.

4)      Screen all cows for the virus by blood sampling or by using an initial individual milk screen to detect those that need to be screened for virus by blood. Cull virus positive animals (these animals spread the infection in the herd and are at risk of suffering a major disease crisis at some point of their life). The culling should be carried out as soon as the results are known. After this, vaccination or do nothing policy can be opted for, depending on the herd size and likelihood of re-infection from outside the herd.

5)      If option 4 is pursued, accreditation of freedom from BVD could be achieved. This may be of value if you are interested in selling breeding stock to other organic farmers at a premium.

OBS! On an organic farm, options preventing the re-introduction of the disease (closed herd policy, double fencing, screening of bought-in animals) and limiting the dependency on continuous vaccination should be sought, i.e. options 1 and 4/5.

B)     If the herd is known to be free of BVD, it is important to consider the following points:

1)      The herd is extremely susceptible to introduction of infection, which will result in clinical symptoms (diarrhoea, abortions, poor fertility, immunosuppression etc.), i.e. if vaccination is not introduced, herd health security needs to be improved: closed herd policy, double fencing, screening of bought-in animals etc.

2)      Accreditation of freedom from BVD should be considered. Otherwise bulk tank milk testing for BVD antibodies on 3-month intervals is recommended in order to monitor the situation.