THE EFFECT OF SHACKLING ON PORK QUALITY FROM PIGS OF DIFFERENT GENOTYPES

Abstract

Over a 3-yr period, two experiments were conducted on 465 pigs to evaluate the effect of genetic line and shackling on pork muscle quality. In exp. 1, 343 gilts and barrows of two stress-resistant genotypes (Lacombe and Yorkshire) were compared for 45 min pH and temperature (To), and ultimate meat quality. In exp. 2, 102 gilts and barrows of a stress-susceptible (Halothane+/+), a stress-resistant (Halothane−/−) and a heterozygous genotype (Halothane+/−), were compared for the same parameters. In both experiments, following electrical stunning (head to back; 400 V, 1.7 A), pigs were shackled by alternate hind legs for 3–4 min including bleeding time. Color, pH, percent drip loss, percent expressible juice, percent soluble protein, shear force measurements, as well as subjective evaluation of color and structure were performed for the midsection of the longissimus muscle. Results of exp. 1 showed that Lacombe pigs produced meat with significantly higher processing attributes (lower drip loss and expressible juice, higher soluble protein) and lower shear force values than Yorkshire pigs. Shackling had no significant effect on longissimus muscle quality. In exp. 2, genetic line had a significant effect on pork quality. Although shackling showed significant interaction with sex on 45-min measurements for pH and To, shackling was found to have little effect on ultimate meat quality. It was concluded that genotype had a major influence and shackling had a very minor influence on longissimus muscle quality. Key words: Pig, shackling, meat quality, stress susceptibility