Bovine Viral Diarrhoea (BVD)
BVD virus interferes with reproduction, detrimentally affects the unborn calf, contributes to calf pneumonia and other diseases by reducing their ability to fight off disease, and can cause severe diarrhoea. The most important effect is on pregnant cows, which may abort the foetus, or cause calf deformities. If the cow is infected during the first third of the pregnancy, the calf may become persistently infected with the virus (a 'PI' calf). The PI calf will shed the virus throughout its life, sometimes developing a severe fatal disease called mucosal disease (but often appearing healthy).
The Effect in Your Herd
Economic losses from BVD infection are a combination of detrimental effects on reproduction and conception rates and an increase in calf disease because the virus affects the immune system making calves more vulnerable to pneumonia and other diseases. Estimated financial losses are around £45,000 for a 100 cow beef herd over ten years, and at least twice this figure for a similar sized dairy herd. (Figures from SAC BVD reference)
The Route of Transmission
The most important route is through the respiratory secretions from PIs, so screening for these and removing them is vital. Farmers can separate cattle with 3 metre fencing to eliminate nose-to-nose contact from neighbouring farms, and/or vaccinate the herd to prevent pregnant animals from becoming infected. Bulls can shed the virus in semen for up to 10 weeks after infection, so should not be used for this time after exposure. Vaccination of breeding stock is used to prevent the production of further PIs whilst the disease is being eliminated from a herd.
|Disease & Status||Animals to be tested||Action required|
|1. 1st check test||
Five homebred unvaccinated 9-18 month old young stock from each separately managed group.
If clear, move to step 2
If positive, move to step 3.
|2. 2nd check test||Repeat the check test on the subsequent calf crop, 12 months after step 1.||
If clear, the herd is Accredited free from BVD.If positive, move to step 3.
|3. Eradication of disease||The whole herd is screened and PI animals removed. Calves born in the 12 months after removal of the last PI need to be tested.||
Once herd and unborn calf screen complete, move to step 1.
|4. Maintenance of Accreditation||The check test as described in step 1 is repeated annually||
If clear, accreditation is maintained.
|5. Dairy bulk testing||Bulk tank or 1st lactation heifer bulk samples are used to monitor the milking herd in addition to the check test.||
Repeat at 3 monthly intervals.
- Other testing options are available if animals in this age group are not present in the herd at the time of testing, please contact us for further details.