Effects of bluetongue virus infection on sperm quality in bulls: A preliminary report

During the recent bluetongue virus (BTV) outbreak in Germany, semen quality in bulls naturally infected with BTV-serotype 8 was evaluated. Bluetongue status was assessed by both serology and polymerase chain reaction (PCR). Six bulls became BTV–PCR positive between September and November 2007 without showing clinical signs. Between April and May 2008, all six bulls were PCR negative but remained seropositive. Semen data from non-infected test bulls recorded between 2006 and 2007 were matched for season and age and used as controls. BTV-8 infection had no effect on sperm volume and concentration, but reduced sperm motility was seen after thawing (January–August 2008: 44.1 ± 12.7% vs. 58.0 ± 7.9% in the uninfected bulls; P < 0.001). Malformed sperm in both in fresh and thawed semen from BTV-positive animals was above the 20% permitted maximal limit from December 2007 to February 2008. Infection with BTV-8 transiently impaired semen quality in bulls.