LAUSR

Studies of the miRNA expression profiles associated with the postnatal late development of skeletal muscle and IMF deposition are lacking in chicken. Here, we evaluated the patterns of muscle fiber growth and IMF deposition in breast muscle in the Chinese domestic breed called Gushi chicken, where we constructed four small RNA libraries from breast muscle tissues at 6, 14, 22, and 30 weeks. A total of 388 known miRNAs and 31 novel miRNAs were identified based on four small RNA libraries. Comparative analysis identified 92 significant differentially expressed (SDE) miRNAs based on six combinations. KEGG pathway analysis for the SDE miRNAs showed that metabolic pathways such as glycolysis and biosynthesis of amino acids were significantly enriched before 22 weeks, and pathways such as biosynthesis of unsaturated fatty acids and fatty acid elongation were significantly enriched after 22 weeks. This trend was consistent with the patterns of breast muscle fiber growth and IMF deposition in Gushi chickens. We also constructed miRNA‐mRNA interaction networks related to breast muscle development and IMF deposition. The results showed that miRNAs such as gga‐miR‐1a‐3p, and gga‐miR‐133a‐5p may play important roles in breast muscle development, and miRNAs such as gga‐miR‐103‐3p, and gga‐miR‐138‐2‐3p may have key roles in IMF deposition. This study determined the dynamic miRNA transcriptome in breast muscle tissue for the first time in Gushi chickens. The results provide a valuable resource for investigating the post‐transcriptional regulation mechanisms during postnatal late development of breast muscle and IMF deposition and for evaluating the muscular disease.