Investigation of myofiber composition changes and molecular mechanisms in rabbit meat quality development during growth.

BACKGROUND: Rabbit meat is a high-protein, low-fat food with recognized nutritional benefits, often labeled as “healthy meat” and “nootropic meat.” However, its low-fat content leads to relatively poor flavor. Myofibers are the main components of rabbit meat, and their type composition determines the overall metabolic characteristics of the meat, which ultimately affects fresh meat quality. During the growth of rabbits, muscle fibers transform into one another. Nevertheless, the changes in the relative composition of myofiber types as domestic rabbits grow, and the molecular mechanisms behind myofiber transition, remain unclear. This study aimed to analyze the changes in the relative composition of myofiber types in rabbits of different ages and explore the roles of various potential molecules in rabbit myofiber transition at the transcriptional level using whole transcriptome technology. RESULTS: Significant differences were observed in the relative composition of gluteus (GLU) and gastrocnemius (GAS) muscle fiber types, which impacted rabbit meat color and taste. During growth, the relative composition of GLU muscle fiber types differed significantly between 1-day-old and 14-day-old rabbits. Transcriptome analysis of GLU muscle from these two age groups revealed extensive molecular changes during myofiber transition, including 3,194 differentially expressed mRNAs, 366 circRNAs, 1,394 lncRNAs, 343 miRNAs, 180 differentially expressed transcription factors, and 2,717 genes with significant alternative splicing. These differentially expressed molecules were associated with multiple signaling pathways involved in myofiber transition, such as the AMPK, calcium, PI3K-Akt, MAPK, Hippo, and mTOR pathways. Comprehensive co-expression and protein-protein interaction analyses identified an active interconnected module containing 38 co-expressed proteins related to myofiber transition. Based on the ceRNA (competitive endogenous RNA) theory and these 38 key molecules, a lncRNA/circRNA-miRNA-mRNA network was constructed, involving 9 mRNAs, 10 circRNAs, 18 lncRNAs, and 14 miRNAs. CONCLUSIONS: This study investigated how the relative composition and content of myofiber types change during different growth stages of rabbits, and revealed the complex dynamic biological mechanisms underlying myofiber transition in rabbits through whole transcriptomics. The results of this study can help identify appropriate targets for regulating myofiber transition, thereby facilitating the development of high-quality rabbit meat. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12864-026-12587-0.