Vaginal Microbiome Dynamics of Cows in Different Parities

SIMPLE SUMMARY: At present, research on the vaginal microbiome of dairy cows is mostly cross-sectional, and there is still room for research on the relationship between the vaginal microbiome and cow reproductive age. In this study, high-throughput 16S rRNA sequencing technology was used to explore vaginal microbiota differences in dairy cows of different parities and thus gain an in-depth understanding of cow reproductive physiology. Studies have found that vaginal microorganisms in cows change significantly before and after the first calving, and the importance of the first production of cows to the establishment and reproduction of subsequent vaginal microorganisms may be more important than previously thought. There was no significant change in the vaginal microbiota of calves in subsequent production, and the number of vaginal microorganisms gradually decreased with the increase in parity, but the vaginal microbiota tended to be stable. The specific mechanism of vaginal microbiome changes in dairy cows needs further study. ABSTRACT: At present, there is still room for research on the relationship between the vaginal microbiome and the reproductive health of dairy cows. In this study, high-throughput 16S rRNA sequencing technology was used to explore the differences of bacterial communities of dairy cows of different births, gain a deeper understanding of cow reproductive physiology, and maintain cow health. With the increase in parity, the number of vaginal flora decreased from 3511 to 469, but the number of species increased significantly, and Chao1 increased from 1226.41 ± 345.40 to 1467.76 ± 269.76. There was a significant difference in the number of vaginal microbiome functions between uncounted cows and calving cows. There was no significant difference in microbial diversity in calves. The relative abundance variation of vaginal microbiota in high-parity cows is less than that in low-parity cows. The amino acid metabolism of calves increased, the endocrine function of high-parity cows was enhanced, and the function of the vaginal microbiome increased after the first delivery, which gradually decreased with the increase in parity. This study also found that Methanobacteria and Caviibacter may be involved in amino acid metabolism and endocrine function, and they may play a key role in cow reproduction. This study provides an important theoretical basis for studying changes in vaginal microorganisms in dairy cows, improves the understanding of reproductive health and production performance, and provides a scientific basis for improving the reproductive management of dairy cows.