Interactive Effects of Ractopamine and Dietary Fat Source on Quality Characteristics of Fresh Pork Loins and Bellies

摘要

Crossbred pigs (n = 216) were used to test the interactive effects, if any, of ractopamine (RAC) and dietary fat source on quality characteristics of fresh pork loins and bellies. After receiving a common diet devoid of RAC for 1 wk, pens (six pigs/pen) were assigned randomly to one of four treatments arranged in a 2 x 2 factorial design with 5% fat (beef tallow or soy oil) and RAC (0 or 10 ppm). The longissimus muscle (LM) from pigs fed RAC received higher American (P = 0.010) and Japanese (P = 0.041) color scores, and was less red (P = 0.002) and yellow (P = 0.005) than the LM from pigs fed diets devoid of RAC. Moreover, pigs fed RAC and tallow had higher marbling scores than all other treatment combinations (RAC x fat source; P < 0.040). Neithersubjective (bar-suspension) nor objective (compression test) measurements of belly firmness were affected by RAC; however, bellies from pigs fed soy oil were softer (P < 0.013) than bellies of pigs fed tallow. Additionally, RAC did not affect (P > 0.11)fat or lean color of bellies, but pigs fed tallow had lighter (P = 0.036) and redder (P = 0.023) belly fat than soy oil fed pigs. Results indicate that feeding pigs 10 ppm RAC improved quality characteristics of the longissimus muscle (LM), but did not affect fresh belly quality; conversely, dietary fat source had little to no impact on fresh loin quality, but, as expected, markedly affected the firmness of fresh pork bellies.