Longitudinal study of the bovine cervico-vaginal bacterial microbiota throughout pregnancy using 16S ribosomal RNA gene sequences.

The microbiota composition of the bovine female reproductive tract influences reproductive efficiency, susceptibility to genital pathogens, and the health of newborn calves. However, knowledge about cervico-vaginal microbiota during gestation is scarce. Therefore, the present study aimed to analyze the taxonomic profile of the cervico-vaginal bovine microbiota throughout pregnancy and after calving using high-throughput sequencing of a fragment of the 16S ribosomal RNA gene. Healthy nulliparous Holstein heifers (n = 13) with similar age and body conditional score were selected to collect samples from the cervico-vaginal area with a sterile swab at 5 timepoints. We sequenced the V1-V2 region of the 16S ribosomal RNA gene and analyzed data using the DADA2, phyloseq and vegan R Studio packages. No differences were observed in alpha and beta diversity across sampling points, accounting for the stability of the microbiota throughout pregnancy. The most abundant phyla are Firmicutes, Bacteroidota, Proteobacteria and Actinobacteria, and are present as the main taxa in all five sampling points. Also, several of the least abundant taxa can be observed to change with time. Our comprehensive study of the cervico-vaginal bacterial microbiota during the gestation period contributes to the knowledge of microbiota dynamics on the bovine reproductive tract during and after pregnancy and can serve as a baseline for future research and the development of potential therapeutic interventions.