0137 The endometrial microbiome in transition cows fed an energy-restricted diet

Abstract

The objective of this study was to evaluate the effect of negative energy balance (NEB) on the endometrial microbiome of transition cows. Ten Holstein cows blocked by parity, BW, and BCS were randomly assigned to two groups: control (CTL) and NEB (80% of the net energy required). Endometrial cytobrush samples were collected at 14 and 35 d postpartum (DPP) and DNA was extracted using a QIAamp DNA Micro Kit. Based on next generation sequencing of 16S rRNA genes, 403 operational taxonomic units (OTUs) were detected. All continuous variables were analyzed by ANOVA. A comparison of the alpha diversity, based on the number of OTUs present, revealed no significant differences in uterine microbiome diversity between 14 and 35 DPP in the CTL group, but significantly (P < 0.05) lower diversity 14 and 35 DPP within the NEB group. The CTL group microbiome on 14 DPP showed significantly (P < 0.05) higher diversity compared with the NEB group. At genus level, the majority of OTUs detected were shared between 14 and 35 DPP (CTL, 47/68 [69%]; NEB, 40/65 [61.5%]) within both groups. However, in the CTL group, there were 16 OTUs detected at 14 DPP that were not present at 35 DPP, while 5 OTUs found at 35 DPP were not detected at 14 DPP; in the NEB group, 4 OTUs at 14 DPP were not detected at 35 DPP, whereas 21 OTUs detected at 35 DPP were not present on 14 DPP. At phylum level, on 14 DPP, Proteobacteria (39.2 vs. 0.46%) and Firmicutes (44.3 vs. 33.7%) were higher in CTL compared with the NEB uterine microbiome; Bacteroidetes (29.9 vs. 8.9%), Fusobacteria (14.3 vs. 3.4%), and unassigned (20.1 vs. 1.4%) phyla predominated in NEB compared with CTL. On 35 DPP, the CTL microbiome was predominated by Cyanobacteria and Proteobacteria sequences, while the NEB microbiome was predominated by Firmicutes and Bacteroidetes. Differences in Proteobacteria and Bacteroidetes levels at 14 and 35 DPP, respectively, were statistically significant (P < 0.05). Relative abundances of Actinobacteria, Cyanobacteria, and Proteobacteria were significantly higher at 35 DPP compared with 14 in NEB cows. No significant differences were detected in CTL. Our preliminary data although inconclusive due to small sample size and individual animal microbiome variations suggest that there might be some microbiome composition differences between the CTL and NEB at 14 and 35 dpp.