Merging metabolomics, genetics, and genomics in livestock to dissect complex production traits

Metabolomics is a multidisciplinary approach that combines several disciplines to characterise metabolomes in terms of the identification and quantification of all detectable metabolites present in a biological sample in a single experimental design or approach. Merging metabolomics with genetics and genomics in livestock provides intermediate phenotypes (or molecular phenotypes) that lie (in the middle) between the genomic space and the external or final phenotypes (e.g., production traits and disease resistance) contributing to understand the biological bases of complex traits. Heritability estimates have defined the extent of the genetic contribution on metabotypes (that are metabolomic-derived phenotypes). Metabotypes can be used to predict final phenotypes. Metabolite-based genomewide association studies carried out in cattle and pigs have identified mQTL on genes or close to genes whose function can directly explain the variability of the level of the corresponding metabolites. Despite the technological limits of the analytical platforms that cannot provide a complete and exhaustive picture of all metabolites present in a biofl uid or tissue, metabolomics provides new traits and biomarkers. Metabolomics might establish next generation phenotyping approaches that are needed to refi ne and improve trait descriptions and, in turn, prediction of the breeding values of the animals to cope with traditional and new objectives of the selection programmes.