Halothane genotype, pre-slaughter handling and stunning method all influence pork quality

Seventy-six Landrace and four Large White x Landrace pigs (n = 80) of 90-13 4 kg liveweight were randomly allocated to a 2x2x2 factorial experiment to determine the effect of halothane genotype [heterozygous for the halothane gene (Nn) and homozygous dominant (NN)], pre-slaughter handling (minimal an d negative) and stunning method (CO2 stunning and electrical) on pork quali ty. The rate of muscle pH decline post-slaughter of the nz, longissimus tho racis et lumborum (LTL) muscle was faster in Nn pigs compared with NN pigs (0.86 and 0.30 pH units/h, respectively). Pork from Nn pigs was also paler in colour, had higher percentage drip loss and purge and lower sarcoplasmic and myofibrillar protein solubility compared with NN pigs. Pork from CO2 s tunned pigs had a lower drip loss compared to pork from electrically stunne d pigs (5.80 and 7.28%, respectively - means of both genotypes combined). T enderness of pork assessed at 24 h post-slaughter was not influenced by gen otype, pre-slaughter handling or stunning method. However, pork from Nn pig s aged for 5 days post-slaughter was less tender than NN pigs (5.84 and 4.8 4 kg, respectively). Pale, soft and exudative pork was produced in all nega tively handled Nn pigs, regardless of stunning method. The average amount o f ecchymosis-affected muscle trimmed from carcasses of electrically stunned pigs was higher compared to pigs stunned with CO2 (65 and 0.7 g, respectiv ely). These data indicate that although halothane status was the most impor tant factor influencing pork quality, pre-slaughter handling and stunning m ethod also influenced meat and carcass quality. (C) 2000 Elsevier Science L td. All rights reserved.