MSTN gene editing does not alter reproductive capacity but modifies gestational metabolism in Mongolian cattle

The extended sexual maturity and prolonged gestation period of cattle limit their economic viability and hinder the breeding of superior genotypes. Reproductive efficiency is a critical factor in evaluating the economic value of cattle. Myostatin (MSTN) is a negative regulator of skeletal muscle growth. When it mutates, it promotes muscle development, providing a new strategy for modern beef cattle breeding. Although previous studies on MSTN gene-edited animals mainly focused on the mechanism of muscle growth, studies evaluating their reproductive performance and pregnancy outcomes are still limited. This study compared MSTN gene-edited Mongolian cattle (MT) with wild-type Mongolian cattle (WT) and Luxi cattle to assess the effect of MSTN editing on reproductive efficiency. Key parameters include reproductive organ morphology, hormone levels, blood metabolic profiles, and metabolomic changes during different gestation stages. The statistical analysis results of reproductive organs (n = 10) and reproductive data (n = 20) showed that, compared with the WT Mongolian cattle, the MT cattle did not differ significantly Studies have shown that blood metabolites in estrus rate, pregnancy rate, calf birth rate, as well as the size of the ovaries and uterus (P > 0.05). Moreover, the dystocia rate of MT Mongolian cattle is significantly lower than that of WT Mongolian cattle (5.1% vs. 10.5%). Compared to WT cattle, the calves of the MT Mongolian cattle were heavier (P = 2.56815E-08), and the reproductive performance of the Mongolian cattle was better than Luxi cattle, specifically manifested as higher pregnancy success rate (WT-M vs. WT-L, 92.4% vs. 85.9%, MT-M vs. MT-L, 90.5% vs. 83.1%) and lower dystocia rate. The results of untargeted LC-MS metabolomics indicated that at different pregnancy stages, the MT cattle showed enhanced glucose metabolism, reduced lipid synthesis, lower circulating essential amino acids, and reduced tryptophan synthesis (n = 6). The results of serum ELISA at different pregnancy periods showed that the levels of E2 decreased and the levels of P4 increased in MT cattle (n = 3). These changes showed a regular pattern throughout the pregnancy cycle. These findings demonstrated that the MSTN gene editing did not compromise the reproductive performance of cattle, supporting its potential application in beef cattle breeding program.