Virginiamycin S1 is primarily used as an antibiotic in veterinary medicine to promote growth and improve feed efficiency in livestock, particularly in poultry, swine, and cattle. It is effective against Gram-positive bacteria, making it valuable in preventing and treating bacterial infections in animals. Additionally, it is often included in animal feed as a growth promoter, helping to enhance overall health and productivity. Its use in agriculture supports the reduction of disease outbreaks, ensuring healthier livestock and improved meat production. However, its application is carefully regulated to minimize the risk of antibiotic resistance.