Meta-Analysis of the Ractopamine Response in Finishing Swine

Ractopamine HCl (RAC) is a phenethanolamine β-adrenergic agonist used as a feed supplement that repartitions nutrients from fat deposition to increased protein synthesis and muscle protein accretion without deleteriously affecting pork quality. This literature review, as well as meta-analyses of the available results, was undertaken to evaluate the live performance, carcass, and pork quality responses to the various dietary inclusion levels (0, 5, 10, and 20 mg/kg) of RAC. Consensus of literature and meta-analysis indicated that pigs fed RAC, regardless of dietary inclusion level, gained faster (P < 0.001) and more efficiently (P < 0.001) and produced heavier (P = 0.024), more muscular (P < 0.001) carcasses than pigs fed untreated control diets. Furthermore, carcasses from pigs fed diets containing 10 and 20 mg/kg (but not 5) of RAC were trimmer (P < 0.001) and had greater percentages of fat-free lean (P < 0.001) than carcasses of untreated controls. The literature indicates that dietary RAC has no deleterious effects on fresh pork color, firmness, and water-holding capacity; and, although some studies have noted a reduction in marbling, i.m. fat content, or both, meta-analysis of the available information reveals that RAC does not (P = 0.994) alter marbling or i.m. fat content. Inclusion of RAC in swine finishing diets will, therefore, effectively improve performance and carcass compositional attributes that are economically relevant to today's swine producers.