The myostatin gene, a member of the transforming growth factor β superfamily, is essential for regulating skeletal muscle mass in mice. Researchers identified mutations in the myostatin gene in two double-muscled cattle breeds, Belgian Blue and Piedmontese, which are known for increased muscle mass. The Belgian Blue mutation involves an 11-nucleotide deletion in the third exon, causing a frameshift that eliminates most of the mature, active region of the protein. The Piedmontese mutation is a missense mutation in exon 3, resulting in a substitution of tyrosine for an invariant cysteine in the mature region of the protein. These mutations are similar to those in myostatin null mice, suggesting that myostatin performs the same function in both species and is a potential target for genetic manipulation in other farm animals. The myostatin gene is highly conserved among vertebrates, and the mutations in the Belgian Blue and Piedmontese cattle breeds are responsible for their double-muscling phenotype. These findings indicate that myostatin mutations have occurred at least twice in cattle. The study also showed that myostatin mutations in cattle result in reduced sizes of internal organs and a modest increase in muscle mass, unlike in myostatin-deficient mice. Despite some drawbacks, such as reduced female fertility and lower offspring viability in double-muscled cattle, the Belgian Blue breed benefits from increased muscle mass and feed efficiency. The results suggest that myostatin is a conserved gene with a wide biological function across the animal kingdom, and its manipulation could have agricultural applications in other meat animals. The study also highlights the importance of genetic research in improving livestock production.The myostatin gene, a member of the transforming growth factor β superfamily, is essential for regulating skeletal muscle mass in mice. Researchers identified mutations in the myostatin gene in two double-muscled cattle breeds, Belgian Blue and Piedmontese, which are known for increased muscle mass. The Belgian Blue mutation involves an 11-nucleotide deletion in the third exon, causing a frameshift that eliminates most of the mature, active region of the protein. The Piedmontese mutation is a missense mutation in exon 3, resulting in a substitution of tyrosine for an invariant cysteine in the mature region of the protein. These mutations are similar to those in myostatin null mice, suggesting that myostatin performs the same function in both species and is a potential target for genetic manipulation in other farm animals. The myostatin gene is highly conserved among vertebrates, and the mutations in the Belgian Blue and Piedmontese cattle breeds are responsible for their double-muscling phenotype. These findings indicate that myostatin mutations have occurred at least twice in cattle. The study also showed that myostatin mutations in cattle result in reduced sizes of internal organs and a modest increase in muscle mass, unlike in myostatin-deficient mice. Despite some drawbacks, such as reduced female fertility and lower offspring viability in double-muscled cattle, the Belgian Blue breed benefits from increased muscle mass and feed efficiency. The results suggest that myostatin is a conserved gene with a wide biological function across the animal kingdom, and its manipulation could have agricultural applications in other meat animals. The study also highlights the importance of genetic research in improving livestock production.