Ractopamine

A beta-adrenergic agonist used as a feed additive that increases nitrogen retention and protein synthesis, enhancing lean muscle growth and feed efficiency in pigs and cattle. By repartitioning nutrients toward muscle and away from fat, it produces leaner carcasses with improved yields. Its use is controversial: it is permitted with maximum residue limits in some countries but banned in the European Union, China, and many others over animal-welfare and food-safety concerns. International trade disputes have followed these divergent rules, and exporters to restrictive markets operate certified ractopamine-free programs verified by testing of feed and tissues.