The Response of Fecal Microbiota and Host Metabolome in Dairy Cows Following Rumen Fluid Transplantation

Abstract

Rumen fluid transplantation (RFT) has been used to rebuild rumen bacterial homeostasis, reshape rumen function, and restore rumen fermentation, whereas the effect of RFT on fecal microbiota and host metabolism in cows remains poorly understood. In our study, a combination of 16S rRNA sequencing and serum non-targeted metabolomics was performed to investigate the response of fecal microbiota and serum metabolome in dairy cows following RFT. Twenty-four prepartum dairy cows were randomly assigned to 3 groups (n = 8) for infusion of either saline (Con), fresh rumen fluid (FR), or sterilized rumen fluid (SR) after calving. Fourteen days after calving, fecal microbiota and serum metabolome were analyzed. The sequencing data of fecal samples revealed no changes in alpha diversity and relative abundance of dominant genera such as Ruminococcaceae UCG-005, Rikenellaceae RC9 gut and Eubacterium coprostanoligenes. However, the other genus level taxa, such as Eubacterium oxidoreducens, Anaerorhabdus furcosa, Bacillus and Selenomonas, showed distinct changes following RFT. Serum metabolome analysis showed that FR or SR infusion affected amino acids metabolism, bile acids metabolism and fatty acids metabolism (including linoleic acid, oleic acid and palmitic acid). Furthermore, correlation analysis showed that taxa from genera Clostridiales were positively correlated with metabolites involved in tryptophan and bile acid metabolisms, such as OTU1039 from genera unclassified o_Clostridiales was positively correlated to indoleacetic acid and taurolithocholic acid. These results suggest that RFT altered the composition of the fecal microbiota and modulated microbial metabolic pathways, which is vital for the development and safety assessment of rumen microbial intervention strategies.

Keywords: dairy cows; fecal microbiota; rumen microbiota transplantation; sequencing; serum metabolome.

FIGURE 1

Principal Coordinate Analysis (PCoA) of fecal microbial community based on unweighted (A) and weighted Unifrac distance (B). PERMANOVA anaysis with 999 permutations is shown. Con, saline; FR, fresh rumen fluid; SR, sterilized rumen fluid.

FIGURE 2

The significantly different OTUs were present in the heatmap. The OTUs was performed stabilizing transformation (log2 fold change) and pairwised comparisons using DESeq2. Con = saline, FR = fresh rumen fluid, SR = sterilized rumen fluid. *P < 0.05, **P < 0.01.

FIGURE 3

Significantly different serum metabolites between fresh rumen fluid (FR) and saline (Con) cows, and sterilized rumen fluid (SR) and Con cows. Pathway analysis was performed using the significantly different serum metabolites between FR and Con cows (A), and SR and Con cows (B). Con, saline; FR, fresh rumen fluid; SR, sterilized rumen fluid.

FIGURE 4

Correlation between transplantation-sensitive operational taxonomic units (significantly differed OTUs) and serum metabolites following rumen fluid transplantation. Red represents a positive correlation, and blue represents a negative correlation. Only strong (Spearman’s |r| > 0.40) and significant (P < 0.05) correlations are presented in the figure. *P < 0.05, **P < 0.01.