Biomarkers of Adipose Color: A Multi-Omics Analysis Unravels the Molecular Landscape of White and Yellow Fat in Kazakh Horse

Fat color is one of the most important economic traits influencing consumer preference and the market value of meat products. To explore the molecular mechanisms underlying abdominal adipose tissue color differentiation in the Kazakh horse, this study employed a multi-omics strategy, integrating targeted metabolomics (fatty acid and amino acid profiling), untargeted metabolomics, and transcriptomic analyses. Two types of adipose tissue, white adipose tissue (WAT) and yellow adipose tissue (YAT), were selected for systematic comparative analysis. Fatty acid composition analysis revealed no significant differences between WAT and YAT in total saturated and unsaturated fatty acid content (P > 0.05). However, the levels of C15:0 and C17:1 were significantly higher in YAT than in WAT (P < 0.05), with C21:0 showing a very significant increase (P < 0.01). In contrast, the level of C22:1n9 was significantly lower in YAT (P < 0.05). Amino acid analysis indicated that the aspartic acid content in WAT was approximately 3.3 times higher than in YAT (P < 0.01). Further integrative analysis of metabolomic and transcriptomic data identified LPGAT1, AKT2, and ADH5 genes, along with metabolites such as stearate and myo-inositol, as potential key regulatory factors and biomarkers associated with fat color differentiation. This study provides a theoretical foundation for understanding the molecular mechanisms governing adipose tissue color variation in horses and their implications for meat quality.