A 90-day safety study of meat from MSTN gene-edited Mongolian cattle in mice

The knockout (KO) of the myostatin (MSTN) gene can increase muscle production in Mongolian cattle; however, the safety of MSTN-KO beef has not been evaluated. In this study, we fed mice varying concentrations of MSTN-KO beef and monitored physiological and tissue changes. Compared with the control group fed with wild-type beef, mice fed with MSTN-KO beef did not show significant changes, including weight gain, food intake, and organ weight. Furthermore, most blood parameters of the experimental groups remained stable. Serum metabolomics analysis confirmed that MSTN-KO beef had a limited impact on the mice’s overall metabolism, with only 24 differential metabolites identified. Our findings from this 90-day trial show no toxic effects of MSTN-KO Mongolian beef on mice. This directly addresses the long-standing lack of toxicity data for such gene-edited beef. Notably, this is the first study to fill the research gap, and the evidence generated in this work actively supports the safety assessment of MSTN-modified animal-derived foods.