Ractopamine and Immunocastration: Effects on enhanced pork loin

Abstract Text: The consumer is increasingly demanding high quality meat produced under the criteria of respect for the environment and animal welfare. The aim of this study was to evaluate the influence of ractopamine (RAC) in pig diets as well as castration method, physical or immunocastration, on the quality of pork loin. Male pigs were commercial selected Agroceres ® - AGPIC 337 (initially with n = 120 males). In maternity phase (0-21 days old) half of the piglets were physically castrated at 05 (five) days postpartum. The males underwent immunocastration (Vivax ® - Pfizer Animal Health) in two doses of 2ml, 8 and 4 weeks before slaughter. For half of the pigs physically- and immunocastrated, ractopamine was included (RAC, 7.5ppm, Ractosuin ® - Ourofino Agribusiness) in feed for 21 days (± 2 days) before slaughter. After the slaughter were randomly selected 5 carcass of each treatment  and removed the m Longissimus dorsi (LM). The experiment was completely randomized designer ranged in a 2x2 factorial with 5 repetition. There was no difference (P > 0.75) for the meat water content, however  RAC in the diet resulted in  more protein ( P < 0.05) and less ether extract fat (P <0.05) in the muscle, even though there was no effect on carcass yield. The addition of RAC also resulted in less tender meat (P < 0.01) at 24h postmortem. The meat from the animals fed RAC had higher meat yield by the injection process (enhancement). However, there was no influence of RAC in weight loss by exudation (purge loss) (P ≥ 0.78) indicating an improvement pork loin juiciness.  Immunocastration and RAC had a negative impact while physically castrated males with RAC a positive impact on cooking loss, which favor higher income by providing greater juiciness.

Keywords: Swine, castration method, meat quality