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 transformation, 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 transformation 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 transformation, 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 transformation, 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 transformation. Based on the ceRNA 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 transformation in rabbits through whole transcriptomics. The results of this study can help identify appropriate targets for regulating myofiber transformation, thereby facilitating the development of high-quality rabbit meat.

Rabbit meat is a high-protein, low-fat food with recognized nutritional benefits, often labeled as “healthy meat” and “nootropic meat.