Comparative analysis of vaginal microflora in healthy postpartum cows and cows with incomplete uterine involution by 16S rRNA gene sequencing

This study aimed to uncover the characteristics of vaginal microflora alterations between healthy postpartum cows and those with incomplete uterine involution. Vaginal swabs were collected from both healthy cows and those with incomplete uterine involution at 5, 10, 15, 20, 30, and 40 days postpartum. 16S rRNA sequencing was employed to analyze the features, changing trends, and differential species of the vaginal microflora between the two groups. The outcomes indicated that during the early postpartum phase, the diversity of vaginal microflora in cows with incomplete uterine involution was significantly lower than that in the healthy group. At the phylum level, the abundances of the Fusobacteriota and Bacteroidota in the vaginas of cows with incomplete uterine involution were significantly higher than those in healthy cows at 5 days postpartum. Fusobacteriota also showed significantly higher abundance in the vaginas of cows with incomplete uterine involution at 20 days postpartum. Furthermore, Synergistota was significantly higher in the vaginas of cows with incomplete uterine involution at 30 days postpartum, while significantly lower at 5 days postpartum. In contrast, the abundance of vaginal Firmicutes was significantly lower in cows with incomplete uterine involution at 5, 15, and 20 days postpartum. At the genus level, the abundances of Fusobacterium, Porphyromonas, and Prevotella in the vaginas of cows with incomplete uterine involution were significantly higher than in the healthy group during the postpartum period 5–20 days. Additionally, the abundances of Anaerosalibacter, unidentified_Clostridia_vadinBB60_group, Rikenellaceae_RC9_gut_group, UCG_005, Ureaplasma, and UCG_010 showed significant differences between the healthy cows and cows with incomplete uterine involution. These differential vaginal microflora might serve as potential microbial targets for the early detection of incomplete uterine involution in postpartum dairy cows. Nevertheless, current research has yet to establish a correlation between the changes in the diversity and abundance of vaginal bacterial and postpartum uterine involution in dairy cows.