Infectious Bovine Rhinotracheitis
IBR caused by BHV-1 is endemic in the UK, with seropositive animals found in 96% of dairy herds.1 Dairy heifers are frequently infected as they enter the milking herd and the majority of UK dairy herds contain a mixture of both naïve and latently infected animals.
Infected animals go on to become latent carriers of the virus and under periods of stress the dormant BHV-1 can reactivate/recrudesce resulting in viral shedding and potential infection of other animals in the herd. Latently infected animals are important in maintenance of disease within a herd.
Whilst clinical IBR is less commonly seen in the beef breeding herd, vaccination of the adult cows may be used as part of a strategy to control IBR in the youngstock. The key requirement from such a vaccination programme is to reduce the amount of virus shed by the adult cows.
The impact from an acute outbreak of IBR in young naïve animals is obvious, but the impact of infection in an endemically infected dairy herd is less so. However recent studies2,3 have shown improved annual yields of between 251 and 793 litres in uninfected cows, representing a gain of up to £151/cow/year*
1. Woodbine K.A., et al. (2011) BMC Veterinary research 5-5
2. Statham J. M. E., et al. (2015) Veterinary Record 2015 177: 339
3. Sayers R.G., (2016) Journal of Dairy Science In Press
* Jul-17 - Promar milk minder dairy costings average 19.07ppl margin over purchased feed