Sperm DNA Fragmentation in Rams Vaccinated with Miloxan

Sperm DNA fragmentation was analysed in 113 semen samples obtained from different rams over a period of one year. Semen samples were collected from: unvaccinated rams between January and June (Control group 1; CG1); vaccinated rams at least 70 days after vaccination between October and December (Control group 2; CG2); vaccinated rams 20 days after vaccination (Vaccinated group 1; VG1); and vaccinated rams 40 days after vaccination (Vaccinated group 2; VG2). Results show Miloxan, the vaccine of interest in this study, increased the percentage of sperm cells with fragmented DNA by 10-fold on average (from 6.5±7.9 to 63.4±24.2). However, the negative impact of vaccination on sperm DNA fragmentation appeared to reversible; near normal levels of sperm DNA fragmentation had been restored 40 days after vaccination (21.7±10.6). On the basis of these data, the use of semen samples from vaccinated animals should be avoided until at least one month after vaccination.