Evaluating the Inoculating Bacterial Communities Within the Bovine Dam and Neonate After Applying an Ablation Technique to the Dam Vaginal Microbiome Prior to Parturition

Abstract The vaginal microbiota (VM) is the first contact of the neonate with microorganisms, which can attribute to neonatal health outcomes. The effects of an altered VM at parturition on neonatal microbial inoculation and passive transfer success has not been evaluated. Betadine lavages (BL) are commonly used to mitigate bacterial infections within the reproductive tract by ablating the VM. Ablation of the VM prior to parturition decreases microbial competition during neonatal microbial colonization, increasing the likelihood for pathogen inoculation. Thus, this study aimed to determine if an altered VM impacts neonatal and dam microbial inoculating bacterial communities in beef cow-calf pairs. Cows (n = 12) were randomly assigned to either control (CON) or BL (BLG) treatment groups two weeks prior to calving. Treatment BL was infused into the anterior vagina weekly until calving. Samples (dam-vaginal swab, dam-udder swab, dam-haircoat swab, and calf-nasal swab) were collected within 24 hours of parturition and stored at -80°C. The vaginal bacterial community composition was determined through sequencing of the V3-V4 region of the 16S rRNA gene using the Illumina Miseq platform. Alpha diversity was compared via two-way ANOVA; beta diversity was compared via PERMANOVA. Taxonomic differences were evaluated using the LEfSe platform. Microbiota data were analyzed using the R software package. Serial BL prior to parturition did not alter the alpha diversity of the dam-vaginal (P = 0.42), dam-udder (P = 0.53), or dam-haircoat (P = 0.21) microbiota but did alter the calf-nasal microbiota (P = 0.03). Moreover, the beta diversity did not differ within the dam-vaginal (P = 0.66) or dam-udder (P = 0.56) between BLG vs. CON, but there was a trend within both the calf-nasal (P = 0.08) and dam-haircoat (P = 0.09) for BLG pairs to have increased variation compared with CON. Within the calf-nasal microbiota, BLG had increased relative abundance of Actinobacteria and a decreased relative abundance of Proteobacteria compared with CON. Interestingly, previously reported IgG data from this study showed there was no difference in passive transfer status between CON and BLG calves, represented by no significant differences in calf serum (P = 0.88). However, BLG dam colostrum had increased IgG concentrations compared with CON dams (P = 0.04). Together, these results are indicative of physiological insults (BL) prior to parturition leading to an increased immune response in BLG dams which altered colostrum IgG. Thus, neonatal colostrum consumption could drive immune responses against inoculating bacteria resulting in differing nasal microbial communities between BLG and CON calves. Overall, this research contributes to our understanding of the vaginal microbiota and its importance in neonatal health outcomes and highlights the need for further research in this area to better inform management practices for optimal calf health and productivity.