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

Abstract

This study evaluated differences in uterine microbiota composition between uterine horns ipsilateral and contralateral to the corpus luteum of beef cows on day 15 of the estrous cycle. Cows (n = 23) were exposed to an estrus synchronization protocol to exogenously induce synchronized ovulation. Cows were then euthanized on day 15 of the estrous cycle, and individual swabs were collected from uterine horns ipsilateral and contralateral to the corpus luteum using aseptic techniques. DNA was extracted, and the entire (V1-V9 hypervariable regions) 16s rRNA gene was sequenced. Sequences were analyzed, and amplicon sequence variants (ASVs) were determined. Across all samples, 2 bacterial domains, 24 phyla, and 265 genera were identified. Butyribirio, Cutibacterium, BD7-11, Bacteroidales BS11 gut group, Ruminococcus, Bacteroidales RF16 group, and Clostridia UCG-014 differed in relative abundances between uterine horns. Rikenellaceae RC9 gut group, Bacteroidales UCG-001, Lachnospiraceae AC2044 group, Burkholderia-Caballeronia-Paraburkholderia, Psudobutyribibrio, and an unidentified genus of the family Chitinophagaceae and dgA-11 gut group differed between cows that expressed estrus and those that did not. The composition of the microbial community differed between the ipsilateral and contralateral horns and between cows that expressed estrus and cows that failed to express estrus, indicating that the uterine microbiota might play a role in cow fertility.

Keywords: bovine; estrus; reproduction; uterine environment; uterine microbiome.

Figure 1

Relative abundance of phyla based on estrus expression and uterine horn position relative to the luteal bearing ovary (ipsilateral or contralateral) in non-pregnant beef cows on day 15 of the estrous cycle. Estrus: expressed estrus prior to ovulation. No estrus: failed to express estrus prior to exogenously induced ovulation.

Figure 2

Relative abundance of genera based on estrus expression and uterine horn position relative to the luteal bearing ovary (ipsilateral or contralateral) in non-pregnant beef cows on day 15 of the estrous cycle. Estrus was evaluated on experimental day 0 using an estrus detection aid and cows were considered to have expressed estrus when ≥50% of the rub-off coating was removed from the estrus detection patch.

Figure 3

Principal coordinate analysis plot for unweighted UniFrac distances based on horn position relative to the luteal bearing ovary (ipsilateral or contralateral) in non-pregnant beef cows on day 15 of the estrous cycle. Blue squares and red triangles represent ipsilateral and contralateral uterine horns, respectively. PERMANOVA p-value = 0.378.

Figure 4

Principal coordinate analyses plot for unweighted UniFrac distances based on estrus expression. Blue diamonds represent cows that expressed estrus and red circles represent cows that failed to express estrus. Estrus was evaluated on experimental day 0 using an estrus detection aid and cows were considered to have expressed estrus when ≥50% of the rub off coating was removed from the estrus detection patch. PERMANOVA p-value = 0.146.