Rumen Fluid Metabolomics Analysis Associated with Feed Efficiency on Crossbred Steers

Virginia M Artegoitia,Ronald M Lewis,Andrew P Foote,Harvey C Freetly

doi:10.1038/s41598-017-02856-0

Abstract

The rumen has a central role in the efficiency of digestion in ruminants. To identify potential differences in rumen function that lead to differences in average daily gain (ADG), rumen fluid metabolomic analysis by LC-MS and multivariate/univariate statistical analysis were used to identify differences in rumen metabolites. Individual feed intake and body-weight was measured on 144 steers during 105 d on a high concentrate ration. Eight steers with the greatest ADG and 8 steers with the least-ADG with dry matter intake near the population average were selected. Blood and rumen fluid was collected from the 16 steers 26 d before slaughter and at slaughter, respectively. As a result of the metabolomics analysis of rumen fluid, 33 metabolites differed between the ADG groups based on t-test, fold changes and partial least square discriminant analysis. These metabolites were primarily involved in linoleic and alpha-linolenic metabolism (impact-value 1.0 and 0.75, respectively; P < 0.05); both pathways were down-regulated in the greatest-ADG compared with least-ADG group. Ruminal biohydrogenation might be associated with the overall animal production. The fatty acids were quantified in rumen and plasma using targeted MS to validate and evaluate the simple combination of metabolites that effectively predict ADG.

Highlights

Metabolomics, has been a useful approach to characterize the metabolism of rumen fluid in dairy cows[5,6,7,8]
The relative standard deviation (RSD) for peak intensity ranged from 1.26% to 5.37%, and retention time from 0.05% to 0.25% in the quality control (QC) sample
The RSD for peak intensity ranged from 2.5% to 8.1% and for retention time ranged from 0.03% to 0.31% in the discovery samples

Summary

Introduction

Metabolomics, has been a useful approach to characterize the metabolism of rumen fluid in dairy cows[5,6,7,8]. Phenotype differences on residual feed intake were associated with specific ruminal microbes and targeted metabolic pathway in dairy cows[8]. By definition when feed efficiency is defined as residual feed intake there is a difference in feed intake between the groups. We hypothesized that cattle that differed in ADG had differences in rumen metabolism. Untargeted metabolomics profile based on UPLC-quadrupole time of flight tandem mass spectrometry (qTOF-MS/MS) coupled to univariate and multivariate analysis was used to identify rumen metabolites that differed with feed efficiency and determine biomarkers in rumen fluid and plasma for ADG

Methods

Results

Conclusion