Table_3_Impact of oestrus synchronization devices on ewes vaginal microbiota and artificial insemination outcome.XLSX

IntroductionThe low pregnancy rate by artificial insemination in sheep represents a fundamental challenge for breeding programs. In this species, oestrus synchronization is carried out by manipulating hormonal regimens through the insertion of progestogen intravaginal devices. This reproductive strategy may alter the vaginal microbiota affecting the artificial insemination outcome.
MethodsIn this study, we analyzed the vaginal microbiome of 94 vaginal swabs collected from 47 ewes with alternative treatments applied to the progesterone-releasing intravaginal devices (probiotic, maltodextrin, antibiotic and control), in two sample periods (before placing and after removing the devices). To our knowledge, this is the first study using nanopore-based metagenome sequencing for vaginal microbiome characterization in livestock.
ResultsOur results revealed a significant lower abundance of the genera Oenococcus (Firmicutes) and Neisseria (Proteobacteria) in pregnant compared to non-pregnant ewes. We also detected a significant lower abundance of Campylobacter in the group of samples treated with the probiotic.
DiscussionAlthough the use of probiotics represents a promising practice to improve insemination results, the election of the suitable species and concentration requires further investigation. In addition, the use of progestogen in the synchronization devices seemed to increase the alpha-diversity and decrease the abundance of harmful microorganisms belonging to Gammaproteobacteria and Fusobacteriia classes, suggesting a beneficial effect of their use.

引言 绵羊人工授精妊娠率偏低是育种项目面临的核心挑战之一。对于该物种，当前通过植入孕激素阴道内置装置（progestogen intravaginal devices）调控激素给药方案来实现发情同步化（oestrus synchronization），该生殖策略可能会改变阴道微生物组（vaginal microbiome），进而影响人工授精的结局。
方法 本研究对47只母羊的94份阴道拭子（vaginal swabs）样本的阴道微生物组进行了分析，这些母羊的孕酮释放型阴道内置装置（progesterone-releasing intravaginal devices）接受了四种不同处理：益生菌、麦芽糊精、抗生素以及空白对照，且采样分为两个时间节点：装置植入前与装置移除后。据我们所知，本研究是首次将基于纳米孔的宏基因组测序（nanopore-based metagenome sequencing）技术应用于家畜阴道微生物组的表征分析。
结果 相较于未妊娠母羊，妊娠母羊体内的酒球菌属（Oenococcus，厚壁菌门Firmicutes）与奈瑟菌属（Neisseria，变形菌门Proteobacteria）的丰度显著降低。此外，我们还在益生菌处理组的样本中检测到弯曲杆菌属（Campylobacter）的丰度显著下降。
讨论 尽管使用益生菌是改善人工授精结局的极具潜力的手段，但筛选合适的菌种与使用浓度仍需进一步研究。此外，发情同步化装置中孕激素的使用似乎提升了α多样性（alpha-diversity），并降低了γ-变形菌纲（Gammaproteobacteria）与梭杆菌纲（Fusobacteriia）中有害微生物的丰度，这表明该类装置的使用具有有益效果。