EFFECT OF HALOTHANE GENOTYPE, BREED, FEED WITHDRAWAL, AND LAIRAGE ON PORK QUALITY OF BELGIAN SLAUGHTER PIGS

A total of 434 Belgian Landrace (B) or Pietrain x B (PB) pigs, of know n halothane genotype (NN, Nn, and nn), were slaughtered in a commercia l abattoir. Pigs were either fed until loading or deprived of food ove rnight before delivery. Upon arrival at the abattoir, pigs were slaugh tered after different lairage times (within 1 h after arrival, after 2 to 3 h lairage, or 4 to 5 h lairage). Meat quality traits were measur ed on the carcass, as well as on a piece of loin. Halothane genotype w as the predominant factor determining meat quality traits related to t he PSE condition (P < .001 for pH 40 min after death, internal reflect ance, color L value; P < .01 for drip losses, transmission value). For these traits, nn pigs were always significantly different from Nn and NN pigs. Depending on the specific trait, Nn pigs were intermediate b etween NN and nn pigs, or close to NN pigs. For pH 40 min after death and drip losses, Nn and NN pigs were significantly different, whereas the difference between Nn and NN pigs was not significant for internal reflectance, color L value, and transmission value. Shear force and i ntramuscular fat content were apparently not related to the PSE condit ion and were not influenced by the halothane genotype (P > .05). Diffe rences in meat quality between B and PB pigs and between gilts and bar rows were rather unimportant compared with the effect of halothane gen otype. Overnight feed withdrawal had no effect on meat quality (P > .0 5 for all PSE-related traits). On the other hand, holding pigs a few h ours in lairage improved meat quality compared with immediate slaughte ring (P < .05 for pH and temperature in the loin 40 min after death, i nternal reflectance, color L value, transmission value, drip losses). This effect was more pronounced in stress-susceptible pigs than in str ess-resistant pigs.