299 Differences in Microbial Community Composition between Uterine Horns Ipsilateral and Contralateral to the Corpus Luteum in Beef Cows on day 15 of the Estrous Cycle

The objective of this study was to evaluate the uterine microbiota composition of cows on day 15 of the estrous cycle. Non-pregnant Bos taurus beef cows (n = 23) were exposed to a pre-synchronization step followed by the 7-d CO-Synch estrus synchronization protocol. On days -10, -3, 0 (exogenously induced ovulation), 7 and 14, transrectal ultrasonography was performed to evaluate ovarian structures, ensure synchrony, and determine the side of ovulation. Cows were harvested on day 15 and individual swabs were collected from each uterine horn using aseptic techniques. DNA was extracted and the entire (V1-V9 hypervariable regions) 16s rRNA gene was sequenced. Sequences were analyzed using the QIIME2 Pipeline. Across all samples, 22 phyla, 130 families, 215 genera, and 90 different species were identified. Butyrivibrio, Bacteroidales RF16 group, Clostridia_UCG-014, and Moraxellaceae, had different (P < 0.05) relative abundances in the ipsilateral compared with contralateral horns, whereas Proteobacteria, Acinetobacter, Bradyrhizobium, Lachnospiraceae FCS020 group, Nanoarchaeota, Woesearchaeales, and Prevotellaceae YAB2003 group tended (P < 0.10) to differ between ipsilateral and contralateral horns. In conclusion, there were significant differences in the composition of the microbial community of the ipsilateral and contralateral horn of cows on day 15 of the estrous cycle.