Vaginal and uterine microbiota at Estrus in crossbred cattle

Abstract

The bovine reproductive tract harbors diverse microbial communities that play a key role in fertility, uterine defense, and reproductive success. This study aimed to characterize the vaginal and uterine microbiota of crossbred cows during estrus using 16S rRNA gene sequencing. Vaginal and uterine samples were collected from cows in estrus, DNA was extracted, and sequencing was performed on the Illumina MiSeq platform targeting the V3–V4 region of the 16S rRNA gene. At the phylum level the dominant bacteria in vagina and uterus were Pseudomonadota, Bacillota, Bacteroidota and Actinomycetota, At the species level, the top detections in estrus were Methylobacterium spp. Brevundimonas spp. Romboutsia spp. Curvibacter fontanus Staphylococcus spp. Phocaeicola spp. and Acinetobacter spp. Alpha diversity metrics indicated higher richness and evenness in vaginal estrus samples compared to uterine estrus samples. The vagina and uterus share a large core community, but the relative abundances differ between sites, notably the high relative abundance of Methylobacterium in the uterus during estrus. These findings highlight a balanced microbial ecosystem during estrus, with protective commensals dominating.