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.