Metabolomic fingerprinting of production animals under genetic selection and chemical exposure

Abstract

Metabolic performance contributes to the health and productivity of production animals through its associations with endogenous metabolic status and energy converting efficiency from feed to body mass. Genetic selection and chemical treatments are the common intrinsic and external approaches utilized in practice to improve the metabolic performance of production animals through altering their metabolic performance. These manipulations are expected to elicit diverse and unexpected metabolic events across different functional components of production animals, therefore posing challenges in the identification and characterization of the most significant metabolic changes as well as their underlying mechanisms. Metabolomics, as a high-throughput platform capable of detecting both subtle and extensive metabolic changes in a complex biological system, is being utilized to examine the altered metabolic performance of production animals. In this project, the most prominent metabolic events elicited by genetic selection and chemical exposure (rutin and oxidized oil) in dairy cows and pigs were examined by liquid chromatograph-mass spectrometry (LC-MS)-based metabolomic fingerprinting and biochemical analyses, resulting in the following novel knowledge: (1) The increased incidence of hepatosteatosis in Contemporary Holstein (CH) might be induced by the insufficient biotransformation of choline to phosphatidylcholine, instead of choline deficiency. The lack of phospholipids in the liver prevents the incorporation of triacylglycerols into very-low density lipoprotein (VLDL) for lipid export, causing fatty liver and lipid metabolism disorder primarily during the parturition or early lactation (2) Rutin, a health-promoting natural flavonol, undergoes extensive ruminal microbial metabolism in dairy cows, forming 4-methylcatechol as a dominant, bioavailable, and bioactive metabolite. In addition, the biotransformation of rutin to 4-methylcatechol inhibits the microbial metabolism of tyrosine to p-cresol, a toxic and odorous compound in animal production. (3) Feeding oxidized oil selectively affects amino acid metabolism in pigs through transcriptional regulation and direct chemical reactions which results in changes in redox balance and compromises growth performance. Overall, these results demonstrate the capability of metabolomic fingerprinting as a highly efficient tool for examining the metabolic events induced by genetic selection and chemical exposure and provide guidance for developing new approaches and practices to enhance the productivity and health of production animals.