Targeted Livestock Metabolomics: A Review of Liquid chromatography–Mass Spectrometry-Based Approaches

With the advancement of sophisticated analytical techniques, such as nuclear magnetic resonance spectroscopy and mass spectrometry (MS), metabolomics has become a powerful tool for analyzing and quantifying small molecules in cells, tissues, and biofluids. Among MS-based methods, liquid chromatography-mass spectrometry (LC-MS) is widely used due to its high analyte coverage, sensitivity, and selectivity. Targeted metabolomics quantifies predefined metabolites, in contrast to untargeted approaches that profile all detectable metabolites. This review provides an overview of targeted LC-MS methods and applications in livestock metabolomics, focusing on ruminants and swine, and covering research from the past decade. We discuss sample preparation, LC-MS instrumentation, and method validation, as well as emerging trends including combined LC techniques, integration of targeted and untargeted approaches, and multiomics studies. Current limitations, future directions, and a general workflow for method development are also addressed.