Heterogeneity of Intramuscular, Intermuscular, and Subcutaneous Fat in Laiwu Pigs: Insights from Targeted Lipidomics and Transcriptomics

In the livestock industry, an excessive accumulation of subcutaneous fat diminishes the proportion of lean meat, while elevated intramuscular fat (IMF) content is associated with enhanced meat quality. However, the heterogeneity of various fat depots in pigs remains incompletely understood. Comprehensive tissue section, lipidomic, and transcriptomic analyses indicated that the maturity of IMF was significantly less than that of both intermuscular and subcutaneous fats. We identified 467 lipids across 29 lipid classes in total, revealing that IMF exhibits unique lipid composition and transcriptional profiles. More importantly, several lipids, including GalCer, S1P, CL, AcCa, PC-O, PE-O, and sulfatide, are highly enriched in intramuscular fat and may play pivotal roles in neuromodulation, mitochondrial function, lipogenesis, and membrane signaling. In conclusion, we unveiled unique lipid composition and molecular regulatory pathways of porcine IMF, offering new insights for the synergistic breeding that aims at optimizing pig backfat thickness and IMF content.