Investigation of uterine microbiota in postpartum dairy cows and barn environment by quantitative PCR technique

The objective of this study was to investigate uterine microbiota in postpartum dairy cows and barn environment by quantitative PCR and to evaluate the correlation between the microbiota in the uterus and barn environment. The study was carried out in 2 seasons of the year: summer (June to August 2017) and winter (October 2017 to March 2018) on Holstein dairy cow farm, Okayama Livestock Research Institute, Japan. A total of 116 samples, including 68 uterine and fecal samples, were collected from 9 cows in summer and 8 cows in winter, at 1 and 2 months after calving. Additionally, 48 samples of barn environment including airborne dust, bedding, feed and water samples were collected 6 times throughout each season. The quantative PCR results showed significant differences (P < 0.05) in the uterine and fecal microbiota of dairy cows at 1 and 2 months after calving. In summer, total bacteria at 2 months postpartum were higher than those at 1 month after calving, while total bacteria were the same in winter (P > 0.05). Bacteroidetes and Firmicutes in uterus and feces between 1 and 2 months after calving were not significantly different in both summer and winter (P > 0.05). The populations of Bacteroidetes, Firmicutes, and total bacteria were found to be highest in bedding compared to those in feed, airborne dust, and water from the barn environment (P < 0.05). Bacteroidetes, Firmicutes and total bacteria in uterus were closely related with those in bedding in summer, however they had the negative correlation with the microbiota of barn environment in winter, especially with fecal microbiota.