Effect of ractopamine and different lysine concentrations in pig diets on pork chemical and sensory characteristics

Pork chemical and sensory characteristics of 48 barrows were used to evaluate the effect of ractopamine (5 PPM, Pay lean, Elanco Mexico) in diets formulated to three standardized ileal digestible-lysine (SID-Lys) levels. All diets had 3.3 Mcal EM/kg, and 14.5 % crude protein (CP), this represent a 10 % lower CP content than that recommended by the laboratory and the literature. Pigs (initial BW 77.2 +/- 3.42 and final BW 110.0 +/- 3.0 kg) were randomly alloted to one of four treatments: C) Control diet, 0.65 % SID-Lys; RHL) ractopamine, high lysine level, 1 % SID-Lys; RNL) ractopamine, normal lysine level, 0.8 % SID-Lys; RLL) ractopamine, low lysine level, 05 % SID-Lys. After 28 d of ad libitum intake, pigs were killed; from each pig, four 2.5 cm thick chops were used for chemical and sensory analyses. Adding RAC in diets with 14.5 % CP increases (P<0.01) intramuscular fat in 25 %. A higher increase (until 50 %) was achieved when RAC was used in a diet with a low SID-Lys. Pork chop consumer acceptance was evaluated using a panel that consisted of 60 consumers. They were not able to detect differences in texture, flavor and aroma (P>0.17), but they detected a higher juiciness (P<0.02) in chops from pigs fed the RLL diet. By improving marbling and juiciness, RAC-containing diets supplemented with low levels of crude protein and low SID-Lys can improve pork quality.