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

## TL;DR

Scientists used gene editing to create cattle with increased muscle growth and altered metabolism, which could improve beef production efficiency.

## Contribution

This study demonstrates the use of CRISPR/Cas12Mix to knockout the MSTN gene in cattle, resulting in enhanced early growth and metabolic changes.

## Key findings

- MSTN-knockout calves showed significantly higher body weight and body measurements compared to controls.
- Serum metabolomics revealed 225 and 129 differential metabolites linked to lipid, amino acid, and carbohydrate metabolism.
- Metabolic pathways like arginine, proline, and tryptophan were significantly altered in edited calves.

## Abstract

Improving growth efficiency in beef cattle is an important goal in animal farming. This study focused on a gene that limits muscle growth and examined whether genetic modification could improve early growth in cattle. A group of Xinjiang Brown cattle with changes in this gene was produced, and body development and blood composition were evaluated at one month of age. The results showed that these cattle had higher body weight and better body development than normal cattle, along with clear changes in blood substances related to energy use. These findings suggest that regulating genes involved in muscle growth can promote early growth and influence overall metabolism. This study provides new scientific evidence for developing more efficient beef cattle and supports the sustainable development of animal agriculture.

Myostatin (MSTN) 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 MSTN-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. MSTN-knockout calves exhibited significantly higher body weight, hip width, chest girth, and abdominal girth than controls (p < 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 MSTN knockout in cattle, conferring early growth advantages, accompanied by systemic metabolic reprogramming.