The objective of this study was to evaluate the performance and the quantitative characteristics of carcass of immunocastrated, barrows and females in the finishing phase fed with diets containing 10ppm of ractopamine. One hundred and twenty animals were used, with initial weight of 99.1±5.3kg, distributed in a randomized blocks factorial design in 2 x 3 (two ractopamine levels, 0 and 10ppm and three sex), five replicates of four animals each. The inclusion of 10ppm of ractopamine in the diet improved (P<0.05) feed conversion in pigs, independent of sex. The inclusion of ractopamine damaged (P<0.05) the weight gain of the immunocastrated and increased (P<0.05) the weight gain of the barrows and the females, without, however, affect (P>0.05) quantitative carcass characteristics of pigs. The sex was determining factor in performance and carcass quantitative traits and the females had higher (P<0.05) hot carcass yield for immunocastrated male and they have yield above (P<0.05) the barrows. Immunocastrated males and females had higher (P<0.05) percentage of lean meat for barrows. The results of this study highlight the need for studies to adjust the nutrient levels of diets containing ractopamine to immunocastrated pigs.
additives; beta-agonists; carcass; performance; immunocastration
