Influence of the Ovine Genital Tract Microbiota on the Species Artificial Insemination Outcome. A Pilot Study in Commercial Sheep Farms

Abstract

<jats:p>To date, there is a lack of research into the vaginal and sperm microbiome and its bearing on artificial insemination (AI) success in the ovine species. Using hypervariable regions V3–V4 of the 16S rRNA, we describe, for the first time, the combined effect of the ovine microbiome of both females (50 ewes belonging to five herds) and males (five AI rams from an AI center) on AI outcome. Differences in microbiota abundance between pregnant and non-pregnant ewes and between ewes carrying progesterone-releasing intravaginal devices (PRID) with or without antibiotic were tested at different taxonomic levels. The antibiotic treatment applied with the PRID only altered Streptobacillus genus abundance, which was significantly lower in ewes carrying PRID with antibiotic. Mageebacillus, Histophilus, Actinobacilllus and Sneathia genera were significantly less abundant in pregnant ewes. In addition, these genera were more abundant in two farms with higher AI failure. Species of these genera such as Actinobacillus seminis and Histophilus somni have been associated with reproductive disorders in the ovine species. These genera were not present in the sperm samples of AI rams, but were found in the foreskin samples of rams belonging to herd 2 (with high AI failure rate) indicating that their presence in ewes’ vagina could be due to prior transmission by natural mating with rams reared in the herd.</jats:p>

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

“…This study is among the first to characterize the ewe vaginal microbiota among pregnant and non-pregnant ewes (Serrano et al, 2020). Additionally, it is the first investigation to document ewe vaginal microbial communities over time during gestation.…”

“…The OTU 77 was identified with 99.2% sequence similarity to Corynebacterium glutamicum, which is often considered non-pathogenic. Various Corynebacterium phylotypes and have been identified in the sheep vaginal microbiota in previous studies (Swartz et al, 2014;Serrano et al, 2020), as well as in cultivation-based studies (Sawyer, 1977;Manes et al, 2018). Certain members within the Corynebacteriaceae family are known ovine pathogens, such as Corynebacterium pseudotuberculosis, which causes caseous lymphadenitis (Gascoigne et al, 2020).…”

“…The OTUs 15 and 87 were classified within the Fusobacteriota phylum. Members of the Fusobacteriota phylum are often found in the vaginal microbiota of ruminants, including sheep (Swartz et al, 2014;Serrano et al, 2020). Members within this phylum are known for contributing to bacterial vaginosis and pre-term births or stillbirths in humans, sheep and other ruminants (Galvão et al, 2019).…”

“…A few cultivationbased studies have provided initial characterization of the ewe reproductive tract microbiota (Sawyer, 1977;Gatti et al, 2011;Manes et al, 2018). However, to the authors' knowledge, only two studies have performed 16S rRNA gene-based amplicon sequencing of sheep vaginal microbial communities (Swartz et al, 2014;Serrano et al, 2020).…”

Sneathia vaginalis sp. nov. (Fusobacteriales, Leptotrichiaceae) as a replacement of the species ‘Sneathia amnii’ Harwich et al. 2012 and ‘Leptotrichia amnionii’ Shukla et al. 2002, and emended description of Sneathia Collins et al. 2001

“…In animals, members of Sneathia could also be found by 16S rRNA gene pyrosequencing in vaginal samples from rhesus macaques [25, 26]. In cows and ewes, Sneathia phylotypes have been found to belong to uterine [27–29] and vaginal [30] microbiota, but their role associated with especially uterine health has been controversially discussed. Interestingly, one study describes Sneathia as a potential new bovine mastitis pathogen [31].…”