Composition and functions of rumen and endometrial microorganisms associated with endometritis in dairy cows

Abstract

Despite the attention given in the recent years to the microbiological causes of endometritis and the potential sources of uterine microbiota infestation, more questions than answers remain in this research field. This paper describes an experiment carried out at the livestock farm of the Leningrad region on 6 dairy cows of the Holsteinized Russian Black Pied breed of the second lactation in the period after calving. The animals were divided into two groups (n = 3): Group 1 included clinically healthy animals, Group 2 included animals diagnosed with purulent-catarrhal post-calving endometritis. Metagenomic sequencing was performed using the MiSeq genomic sequencer (Illumina, Inc., USA) with the MiSeq Reagent Kit v3 (Illumina, Inc., USA). Based on the next-generation sequencing of microbiota of endometrial scrapings, 7 phyla of microorganisms were detected in clinically healthy cows and only 4 phyla of microorganisms in cows diagnosed with endometritis. The increase in the proportion of Fusobacteriota taxon bacteria permanently present in endometrial scrapings and the decrease in Bacteroidota phylum bacteria in the group of animals with endometritis could be related to the occurrence of this disease. Bacteria Alloprevotella, Campylobacter, Caviibacter, Falsiporphyromonas, Veillonella present only in the endometrial tissue of sick cows may be the etiological origin of endometritis. In the rumen of animals with endometritis, there was an increase in Bacteroidota phylum microorganisms (p≤0.05) against a decrease in Firmicutes phylum bacteria (p≤0.05) compared to the clinically healthy group. Using the PICRUSt2 software package (v.2.3.0), it was shown that the microbiome of cows diagnosed with endometritis showed inhibition (p≤0.05) of the potential of 9 metabolic pathways compared to healthy animals. This could have negative consequences for the body of animals and be a consequence of metabolic disorders.