Use of ractopamine in finishing pigs: general concepts

Abstract

β-adrenergic agonists are among the many additives used in pigs in recent years as possible replacements for antibiotic growth promoters. The main representative of β-adrenergic agonists is ractopamine, included in the category of phenethylamines, which is the most widely used additive in swine production in Brazil. Ractopamine modifies metabolism re-directing nutrients to a greater synthesis of muscle over the formation of adipose tissue. As a result, animals have higher meat:fat ratios, which is appreciated by consumers. In this sense, due to better efficiency in forming muscle, there is an improvement in weight gain and feed conversion. Due to the mode of action, ractopamine is administered in finishing diets prior to slaughter in animals that have already reached maturity and their protein holding capacity is decreasing. However, ractopamine is a synthetic catecholamine and can generate physiological changes in animals, inducing modifications in behavior going against the currents of animal welfare, and may also negatively affect quality of the meat. This review summarizes the main concepts concerning ractopamine such as its mechanisms of action, characteristics, effects, and its limitations of use.