Virginiamycin is an antibiotic of the streptogramin class. Products containing virginiamycin are registered for in-feed use in poultry, pigs, cattle, sheep and horses. The approved uses include improvement of the growth rate and feed conversion efficiency in growing pigs, poultry (broilers) and turkeys, and reduction of the risk of acidosis in cattle and sheep. Veterinarians also prescribe products containing virginiamycin for the prevention of necrotic enteritis in chickens. In horses products containing virginiamycin are used to reduce the risk of laminitis.