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

Abstract

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.

In Vitro Interaction between Mycoplasma agalactiae and Small Ruminants’ Endogenous Bacterial Strains of Enterococcus spp. and Coagulase-Negative Staphylococcus

“…Since Ma has the ability to colonize the mammary gland and the vagina [ 9 ] and LAB and Staphylococcus spp. seem to be part of the microbiota of these anatomical sites [ 18 , 19 , 20 , 25 , 50 ], the present study describes the in vitro interactions between Ma and wild strains of CNS and Enterococcus spp. isolated from raw milk and vagina, respectively, of clinically healthy small ruminants.…”

“…In our opinion, this offers a favorable environment for Ma and suggests that the vagina could represent a possible ecological niche of Ma in small ruminants. Indeed, the genus Mycoplasma has recently been described as the second most abundant in the vagina of ewes [ 20 ]. Although the presence of LAB in the vagina of small ruminants seems sparse, their use and the necessity to study them have been suggested in small ruminants due to their well-known antimicrobial potential [ 18 , 20 , 51 ].…”

“…Specifically, two species of Enterococcus , E. hirae and E. mundtii , previously isolated from raw sheep and goat milk, respectively, could represent a possible antimicrobial strategy not previously contemplated for the control of CA [ 16 ]. However, the question remains as to whether this antimicrobial effect against Ma is exclusive to Enterococcus strains from the milk of small ruminants or whether this antagonism could occur with LAB strains in other anatomical locations such as the vagina, where Ma [ 6 , 7 ] and LAB can be present [ 17 , 18 , 19 , 20 ], and therefore, there is a possibility that they coexist and interact with each other in this anatomical location.…”

“…This bacterial genus has been able to colonize an important variety of habitats, thanks to the plasticity of their genome, such as the milk of ruminants through their presence in milking stations [ 22 , 23 ]. They are very common in small ruminants’ milk [ 24 , 25 ], and although their presence in the ewe’s vagina has been detected, they have only been scarcely described [ 18 , 20 ]. To the authors’ knowledge, there are no data available regarding the presence of enterococci in the vagina of goats as no metagenomic studies have been published.…”

Temporal changes in ewe vaginal microbiota throughout gestation

“…However, the sponges also worked to homogenize the populations of bacteria present regardless of the point in the ewe’s estrous cycle when the sponge was inserted ( Manes et al, 2010 ; Gatti et al, 2011 ; Martinez-Ros et al, 2018 ; Quereda et al, 2020 ). Other studies evaluated the vaginal microbiota of sheep using an alternate method – 16S rRNA gene sequencing ( Swartz et al, 2014 ; Serrano et al, 2020 ; Koester et al, 2021 ; Greenwood et al, 2022 ; Reinoso-Peláez et al, 2023 ). One of those studies ( Koester et al, 2021 ) was conducted in our laboratory and was based on three sampling time points.…”