Ewe Vaginal Microbiota: Associations With Pregnancy Outcome and Changes During Gestation

Abstract

Reproductive performance is paramount to the success of livestock production enterprises focused on lamb meat production. Reproductive success is influenced by various factors, possibly including the reproductive tract microbial communities present at the time of copulation and throughout pregnancy. There are few publications that identify the vaginal microbial communities of livestock, and even fewer exist for sheep. To compare ewe vaginal microbial communities, vaginal swabs were taken from 67 Hampshire and Hampshire X Suffolk crossbred ewes from the Iowa State University sheep farm at a pre-breeding time point (S1) and after pregnancy testing (S2). Animals that were determined pregnant were sampled again within a few days of expected parturition (S3). DNA was extracted from these swabs, and 16S rRNA gene Illumina MiSeq amplicon sequencing was conducted to fingerprint the bacterial communities found within this system. Pre-breeding time point samples showed no differences in community structure between animals later found to be pregnant or non-pregnant, but significant changes were detected in species richness (Chao; P < 0.001) and species diversity (Shannon; P < 0.001) at the second sampling time point. A higher microbial diversity within the S2 time point samples may suggest a more stable environment driven by pregnancy, as this increased diversity is maintained in pregnant animals from the S2 to the S3 time point. Additionally, several bacterial phylotypes, such as Mannheimia, Oscillospiraceae-like OTUs and Alistipes, were more abundant at either the S1 or S2 time points in animals that established pregnancy, suggesting a beneficial effect on pregnancy outcome. This study identifies changes within the microbial communities of the ewe vagina before and during gestation and offers inferences on how these changes may impact pregnancy outcome. Information presented herein offers new knowledge about sheep vaginal microbial communities and serves as a starting point to help guide researchers to improve sheep reproductive performance in the future.

Impact of oestrus synchronization devices on ewes vaginal microbiota and artificial insemination outcome

“…Red represents a higher abundance for S1 compared to S2, while green represents a higher abundance for S2 compared to S1. 10.3389/fmicb.2023.1063807 Frontiers in Microbiology 09 frontiersin.org microbiota and pregnancy in sheep was conducted by Koester et al (2021), who observed a higher microbial diversity in pregnant ewes sampled after lambing, suggesting a more stable environment driven by pregnancy. This finding may however be interpreted with caution, since genital microbiome is diverse among animal species and breeds, and through the different stages of the female reproductive cycle (see Adnane and Chapwanya, 2022).…”

“…They observed that non-pregnant cows presented significantly less diversity than pregnant ones at the time of the administration of synchronization devices (day −21), but not in posterior stages. The most recent study analyzing the relationship between vaginal microbiota and pregnancy in sheep was conducted by Koester et al (2021) , who observed a higher microbial diversity in pregnant ewes sampled after lambing, suggesting a more stable environment driven by pregnancy. This finding may however be interpreted with caution, since genital microbiome is diverse among animal species and breeds, and through the different stages of the female reproductive cycle (see Adnane and Chapwanya, 2022 ).…”

A Distribution-Free Model for Longitudinal Metagenomic Count Data

“…Low abundance found in preterm [33] Sutterella Associated with metabolic/inflammatory variables across pregnancy in Gestational diabetes mellitus patients; hyperglycemia in the second and third trimester of pregnancy is an independent risk factor and a better predictor of prematurity. [44,45] ZIDF Facklamia More abundant in animals that failed to establish a pregnancy [46]…”

“…More abundant in animals that failed to establish a pregnancy [46] Ureaplasma High abundance of Ureaplasma is associated with preterm birth [30,47] FZINBMM Actinomyces Actinomyces infections in pregnancy are rare but, if they occur, have been linked primarily with preterm deliveries.…”

Characterization of bovine vaginal microbiota and its relationship with host fertility, health, and production

“…The vaginal microbiota of humans [12] and diverse livestock species such as mares [13], sows [14, 15] or ewes [16] has been characterized with the objective to decipher its relationship with fertility impairs [17] or vaginal infections [14]. Despite being underexplored, cattle were found to present a vaginal microbiota with a larger diversity than other species [18].…”