Comparative metabolome analysis of serum changes in sheep under overgrazing or light grazing conditions

Abstract

Background Overgrazing is a primary contributor to severe reduction in forage quality and production in Inner Mongolia, leading to extensive ecosystem degradation, sheep health impairment and growth performance reduction. However, no clear information about the effect of overgrazing on sheep health and nutritional metabolism is available because no objective biomarkers are currently evident. We hereby hypothesize that reduced sheep growth performance under overgrazing conditions would be associated with metabolic and immune alterations. This study used an untargeted metabolomics analysis by conducting ultra-high-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) of sheep serum under overgrazing and light grazing conditions to identify metabolic disruptions in response to overgrazing.Results The sheep daily body weight gain as well as serum biochemical parameters associated with immune responses, protein synthesis and energy production (immunoglobulin G, albumin, glucose, and nonesterified fatty acids) were significantly decreased with overgrazing than under the light grazing condition. In contrast, other serum parameters such as alanine and aspartate aminotransferase, alkaline phosphatase, total bilirubin, blood urea nitrogen, and interleukin-8 were markedly higher in the overgrazing group. Principal component analysis discriminated the metabolomes of the light grazing from the overgrazing group. Multivariate and univariate analyses revealed alternations in the serum concentrations of 15 metabolites (9 metabolites exhibited a marked increase, whereas 6 metabolites showed a significant decrease) in the overgrazing group. Major alterations of fatty acid oxidation, bile acid biosynthesis, and purine and protein metabolism were observed.Conclusions These findings offer metabolic evidence for putative biomarkers for overgrazing-induced changes in serum metabolism. Target-identification of these particular metabolites may potentially increase our knowledge of the molecular mechanisms of impaired sheep health and reduced sheep growth performance under overgrazing conditions.

Effects of different feeding methods on serum biochemical indexes, metabolic indexes, immune indexes, and intestinal microorganisms of Nanjiang yellow goats

“…found that serum GLU levels in overgrazed were significantly lower than those in the lightly grazed group [11] , this is consistent with that we found the serum GLU content is more in SSMF group. And Grigol et al in comparing the effects of different grazing times on the health status of dairy cows, found that an increase in the time spent on grazing led to a decrease in the BUN levels of the animals [12] .…”