Early Growth and Serum Metabolic Profiling of One-Month-Old MSTN-Knockout Xinjiang Brown Cattle via CRISPR/Cas12Mix

Myostatin (<i>MSTN</i>) is a key negative regulator of skeletal muscle development, and its deficiency can markedly enhance muscle growth. However, the application of CRISPR/Cas12Mix in large livestock remains limited. In this study, 11 Xinjiang Brown calves were generated via embryo-stage CRISPR/Cas12Mix editing, among which five were confirmed as <i>MSTN</i>-knockout. These five edited calves were compared with five unedited controls to evaluate early growth traits and serum untargeted metabolomics at one month of age. <i>MSTN</i>-knockout calves exhibited significantly higher body weight, hip width, chest girth, and abdominal girth than controls (<i>p</i> < 0.05). Untargeted metabolomics identified 225 and 129 differential metabolites in positive and negative ion modes, mainly enriched in lipid, organic acid, and amino acid metabolism. KEGG pathway analysis revealed significant alterations in arginine and proline, tryptophan, and carbohydrate metabolism. These results demonstrate that CRISPR/Cas12Mix efficiently mediates <i>MSTN</i> knockout in cattle, conferring early growth advantages, accompanied by systemic metabolic reprogramming.