Roles of host genetic and its sperm microbiota on reproductive success in healthy rabbit

Although the effects of sperm microbiota and sperm quality have been previously described, recent studies provide that modifications of female genital triggered by seminal components could be of significant importance to identify some disturbances associated with fertility. So, sperm microbiota could play a key role in sperm quality and contributing to fertilization. To understand how sperm microbiota diversity is influenced by the host genetics, the symbiotic bacteria in four inbred lines breed in the same animal facility, and its effects on sperm quality were analyzed. Forty healthy rabbits of four Spanish commercials inbred lines were utilized in this investigation (three based on litter performance called A, V and LP and one selected on daily body weight gain called R). Significant variations in the seminal concentration, morphology and some motion parameters were found among inbred lines, but sperm motility and viability were similar among inbred lines. After mating, inbred lines selected for litter size had the same fertility rate, significantly higher than inbred line selected in litter size (82±3.3%, 79±3.5% and 89±4.5% versus 61±3.7%, for the A, V and LP vs R lines, respectively, p<0.05). Bacteria belonging to Proteobacteria, Firmicutes, Fusobacteria and Bacteroidetes were identified in sperm microbiota. At the genus level, the bacterial community composition in the sperm microbiota was influenced by host genetics. A total of 35, 16, 34, and 51 genera were accurately detected in the A, V, LP, and R lines, respectively. Moreover, Enhydrobacter, Ferruginibacter, Myroides Paracoccus, Rheinheimera, Tepidiphilus, Tetradesmus obliquus and Thauera genera were present only in the inbred lines selected for litter size. Besides, the discriminant analysis revealed Lysinibacillus and Flavobacterium genera as potential biomarkers. Thus, these two genera may play a key role in fertility. Our results demonstrated the existence of a rabbit inbred line-specific variation in bacterial occurrence in sperm microbiota. Also, fertility differentials among inbred lines that were not predicted by routine semen analysis could be explained in part by the symbiotic state of the semen microbiota.