A meta-analytical study was conducted to evaluate the performance and characteristics of the carcass of finishing pigs fed with diets containing ractopamine. Eighteen experiments containing four treatments and 2.991 animals were used. The treatments were composed of 0, 5, 10 and 20 ppm of ractopamine levels. The variables of performance and the quantitative characteristics of the carcass were analyzed. The average duration of the experimental periods was 28 ± 0.32 days. The average initial and final weights were 74.7 ± 10.9 kg and 107.6 ± 9.7 kg, respectively. No effect of ractopamine levels on the feed intake, hot carcass weight, carcass length and backfat depth was observed. The ractopamine levels influenced the weight gain, the feed:gain ratio, the dressing percent, the lean meat percentage of the carcass and the loin eye area. A linear effect was verified from the lysine levels of the weight gain, gain:feed ratio, hot carcass weight, backfat depth and lean meat percentage of pigs feed diet with 20 ppm of ractopamine. Effect from the loin eye area in function from the lysine levels in the diets containing 10 and 20 ppm of ractopamine was observed. Most of the variables was not influenced by the lysine levels. Levels of 15 ppm of ractopamine optimize the swine performance, while levels of 20 ppm of ractopamine optimize the quantitative carcass characteristics. Weight gain, backfat depth and lean meat carcass percent of swine fed diets containing ractopamine are optimized with 1.0% of true digestible lysine.
additives; carcass characteristics; lean meat; lysine; nutrition
