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The objective is to quantify the average effects of exposure to BTV-8 under natural conditions on the production and reproductive performance of dairy cows in herds declared infected, in herds not declared infected located in the epizootic zone and to quantify a potential side effect of BTV-8 vaccination on fertility.
The effects of virus exposure and vaccination on performance were quantified using multivariate statistical models. Exposure of herds to BTV-8 is associated with a significant decrease in fertility and milk production. In addition, a decrease in fertility in undeclared infected herds located in the epizootic zone suggests that some of these herds may have been infected during the epizootic. Finally, vaccination against BTV-8 with an inactivated vaccine is associated with a very slight decrease in fertility. The major losses in performance associated with exposure, compared with the very limited side effects of vaccination, seem to justify the vaccination campaigns implemented in France from 2008 onwards (optional the first year and then compulsory).

Contact :
Simon NUSINOVICI, unit BIOEPAR
simon.nusinovici@oniris-nantes.fr

References :

• Nusinovici S., Seegers H., Joly A., Beaudeau F., and Fourichon C. (2012). Quantification and at-risk period of decreased fertility associated with exposure to Bluetongue virus serotype 8 in naïve dairy herds. Journal of Dairy Science 95:3008-20.
• Nusinovici S., Seegers H., Joly A., Beaudeau F., Fourichon C. (2012). Increase in the occurrence of abortions associated with exposure to Bluetongue virus serotype 8 in naïve dairy herds. Theriogenology 78:1140-51 .
• Nusinovici S., Souty C., Seegers H., Beaudeau F., Fourichon C. (2013). Decrease in milk yield associated with exposure to Bluetongue virus serotype 8 in cattle herds. Journal of Dairy Science 96(2):877-88.