- BVD is caused by a virus, bovine viral diarrhoea virus (BVDV)
Infection can result in a wide range of clinical signs including:
- Weakening of the immune system, leaving cattle more susceptible to other infections
- Scours and pneumonia in calves
- Reproductive problems, including failure to conceive, abortion and birth defects in older cattle
- Calves that survive infection during early pregnancy are born persistently infected (PI) with the virus. Many will develop a fatal condition called mucosal disease in the first two years of life
Introduction and spread
- Purchase of PI cattle (possibly as unborn calves in pregnant cattle) is the most important means of introduction.
- PI calves are the main transmitters of virus to other cattle.
- Economic losses can be very high.
- Persistently infected bulls are excluded from AI centres due to the presence of BVDV in their semen.
- Possible future restriction on live exports.
- Test programme using blood and milk samples.
- Identification and removal of PI animals is recommended, coupled with biosecurity measures to prevent re-infection.
- Vaccination with killed vaccine may be used within any of the programmes, but it is mandatory in the Vaccinated Monitored Free (VMF) program.
- Double fencing 3 meters wide mandatory for the BVD accredited programme. Not mandatory on the VMF programme.
- Added animals from non-accredited herds must be placed in isolation and tested for BVD
- Bulk tank milk test (BTM)
- First lactation test (FLT): Individual milk samples from all first lactation cows
- Check test: test for BVD antibodies in sentinel group of the 5 homebred cattle in each separately managed group of cattle aged 9-18 months. See technical document for details AFBI Cattle Health Scheme : Certification Standards
These are used in a structured way in: