An Outbreak of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) in a German Boar Stud: A Retrospective Analysis of PRRSV Shedding in Boar Semen

德国某种公猪场爆发猪繁殖与呼吸综合征病毒（PRRSV）疫情：对公猪精液中PRRSV排泄情况的回顾性分析