High Quality Content by WIKIPEDIA articles! Ractopamine is a drug that is used as a feed additive to promote leanness in pigs raised for their meat. Pharmacologically, it is a beta-adrenoceptor agonist. It is the active ingredient in products known as Paylean for swine and Optaflexx for cattle, developed by Elanco Animal Health, a division of Eli Lilly and Company, for use in food animals for growth promotion. Ractopamine is known to increase the rate of weight gain, improve feed efficiency and increase carcass leanness in finishing swine. Its use in finishing swine yields about 3 kilograms of additional lean pork and improves feed efficiency by 10%. In steers and heifers, ractopamine use increases hot carcass weight by about 5.5 kilograms and 5 kilograms, respectively.