This study was conducted to evaluate ractopamine supplementation in diets without amino acid adjustment for finishing barrows. A total of 72 barrows with an initial weight of 68.61±3.89 kg were separated into six ractopamine supplementation plans during 30 days before slaughter (0 ppm, 5 ppm, 10 ppm, 20 ppm, 5 ppm for 15 days followed by 10 ppm for 15 days, and 10 ppm for 15 days followed by 20 ppm for 15 days), with six replicates and two animals per experimental unit. Ractopamine supplementation improved feed conversion. Supplementation with 5 ppm ractopamine increased average daily gain. The levels of 10 and 20 ppm and gradual supplementation reduced feed intake and nutrient intake. There was no effect of supplementation on hot carcass weight and carcass length. Ractopamine supplementation reduced backfat thickness and increased muscle depth, percentage of lean meat, amount of lean meat content and bonus carcass. The supplementation of diets with 5 ppm of ractopamine without amino acid adjustments improved performance and carcass characteristics of finishing pigs 30 days before slaughter
additive; Agonist β-Adrenergic; carcass, nutrition; performance.
