Multi-Omics Insights into Postnatal Skeletal Muscle Development in Duroc Pigs.

Skeletal muscles, accounting for 40% of mammalian body mass, exhibit pronounced heterogeneity due to their distinct anatomical locations. Animal husbandry has focused excessively on longissimus dorsi (LDM) development while neglecting other muscles. In this study, we integrated Bulk RNA Sequencing (bulk RNA-seq) and Liquid Chromatography-Mass Spectrometry (LC-MS) analyses of Soleus (SOL), Gastrocnemius (GAS), and Psoas major muscles (PMM) across three key stages in Duroc pigs. We identified nine critical genes (S100A1, MBOAT2, CA3, GYG2, ACTN3, ENO3, SLC3A2, SLC16A10, and GAPDH) and eight metabolites potentially involved in regulating both skeletal muscle development and fiber-type transformation. The heterogeneity between SOL and GAS was low at birth but increased gradually during development. In contrast, PMM exhibited higher heterogeneity than SOL and GAS from birth. Notably, expression levels of MYH7, MYH1, and MYH4 displayed stage-specific and muscle type-dependent variations. Moreover, we observed a developmental shift from the MAPK signaling pathway (1-21 d) to the regulation of the actin cytoskeleton (21-120 d). Pairwise comparisons between the SOL, GAS, and PMM revealed that the signaling pathways were enriched in muscle fiber-type switching. Collectively, through the integration of bulk RNA-seq and LC-MS data, this study provides novel molecular breeding strategies for the genetic improvement of meat-producing animals.