HALOTHANE GENOTYPE BY WEIGHT INTERACTIONS ON PIG MEAT QUALITY

The effects of slaughter weight on pork quality as influenced by halothane genotype and breed (Lacombe: LAC, NN-genotype; Yorkshire: YRK, NN-genotype) were investigated in 312 carcasses ranging in weight from less than 65 kg to greater than 105 kg. When adjusted to a warm carcass weight of 87 kg, the longissimus of LAC pigs has normal color and structure scores (2.96 and 2.99, respectively), while halothane-sensitive pigs (HSL, nn-genotype) and XBD (HSL x LAC, Nn-genotype) pigs had inferior color (2.69 and 2.83) and structure (2.55 and 2.74) scores on a 5-point scale with 3 being desirable. The results were corroborated with objective measurements of meat quality including expressible juice, drip, protein solubility and muscle color. At lighter carcass weights (65-75 kg), XBD pigs had pork quality characteristics similar to those of LAC pigs, while at heavier carcass weights (95-105 kg) pork quality from these pigs more closely resembled those of the HSL pigs. Subjective pork color and structure scoring of 85-kg YRK and LAC carcasses suggested they were normal and equivalent to each other. However, objective evaluation of pork quality found that YRK carcasses had 15 g kg-1 greater expressible juice, 8 g kg-1 greater drip and 7 g kg-1 less soluble protein than LAC carcasses, indicating meat from YRK carcasses would have lower processing yields than meat from LAC carcasses. LAC carcasses had 6 kg kg-1 greater intramuscular fat on a wet-matter basis than YRK. These results suggest that the dominance of the halothane gene as it affects pork quality may increase with increasing slaughter weight, and LAC pigs produce higher quality pork than YRK pigs.