CKMT2 Promotes Breast Muscle Growth in Qiangying Ducks via Enhancing Myoblast Proliferation and Differentiation

The duck meat industry is economically vital in animal husbandry; however, the genetic mechanisms governing skeletal muscle development and muscle yield remain incompletely understood. In this study, RNA sequencing (RNA-seq) was used to identify differentially expressed genes (DEGs) in breast muscle tissues between high and low breast muscle weight (BMW) groups of Qiangying ducks. A candidate gene, CKMT2 (mitochondrial creatine kinase 2), was subsequently validated at the cellular and individual levels. RNA-seq analysis identified 540 DEGs, including 411 upregulated and 129 downregulated genes. GO and KEGG enrichment analyses revealed enrichment in fatty acid metabolism, fibrinolysis, and PPAR signaling pathways—processes closely linked to energy homeostasis and muscle growth. Functional validation demonstrated that CKMT2 overexpression significantly promoted myoblast proliferation and myotube differentiation (p < 0.05), while knockdown exerted the opposite effects. At the genetic level, the GG genotype of CKMT2 SNP (G.76,602,082 G>A) was associated with significantly higher BMW compared to the GA and AA genotypes (p < 0.05). These findings provide novel insights into the molecular basis of muscle weight variation in meat ducks and establish CKMT2 as a key regulator of skeletal muscle growth via modulation of myoblast proliferation and differentiation. This study contributes to the theoretical foundation for improving duck muscle yield through genetic selection.