Effects of ractopamine plus amino acids on growth performance, carcass characteristics, meat quality, and ractopamine residues of finishing pigs
The aim of the study was to evaluate the effects of adding ractopamine (RAC) and amino acids (AA) to the diet on growth performance, carcass characteristics, commercial cuts yield, meat quality and residues in liver and muscle. Ninety-two crossbred castrated pigs (97.96 ± 2.32 kg) were randomly assigned to one of two dietary treatments: a Control diet with 0 mg kg-1 of RAC and a RAC+AA diet with 10 mg RAC kg-1, for the last 27 days. Pigs of RAC+AA group had greater average daily gain (ADG), gain to feed ratio (G:F) and final bodyweight (P≤0.05) and tended to have lower average daily feed intake (ADFI) (p=0.084) than Control pigs. Carcasses from RAC+AA animals were heavier than controls (P≤0.05). Dressing percentage and backfat depth were not affected (P>0.05) by diet. Weights of head and skin were not different between treatments, but RAC+AA pigs had greater weights of boneless center loin, ribs, boneless ham and shoulders, tenderloin, neck, rear shank and trimmings (P≤0.05). The addition of RAC+AA did not affect crude protein and water content of loins but tended to reduce ether extract (P=0.08). Drip loss, pH, and cooking loss in pork were not different. Shear force tended (P=0.092) to be higher in RAC+AA. No differences in L* and b* color coordinates were found but a* values were lower in RAC+AA. Hue angle and chroma did not differ. Confidence limits at 90% were determined for residues in muscle and liver, obtaining values from -2.7 to 3.4 μg kg-1 and -6.7 to 10.6 μg kg-1, respectively, both below the limits established by Codex Alimentarius. Dietary inclusion of RAC+AA at 10 mg RAC kg-1 in the diet of finishing pigs improved growth performance and produced heavier carcasses and commercial cuts, had minimal effects in pork characteristics and produced pork and liver with RAC residues below limits from Codex Alimentarius.