THE EFFECT OF THE HALOTHANE GENE ON PORK PRODUCTION AND MEAT QUALITY OF PIGS REARED UNDER COMMERCIAL CONDITIONS

Production and meat quality traits were evaluated on 74 commercially raised heterozygous pigs (Nn) and 50 homozygous normal pigs (NN) at the halothane locus, with an average carcass weight of 79.7 kg. Eight-week weight, average daily gain and age to market, as well as measures of carcass quality (i.e., dressing percent, grade site fat and muscle depths and predicted lean yield) did not differ among pigs with Nn and NN genotypes. The longissimus dorsi muscle from Nn and NN pigs had similar subjective colour and structure scores. Reflectance meter readings (CIE L*-values) were significantly higher on chops from Nn than from NN pigs taken from the centre (57.4 vs. 55.6) and from the anterior portion (56.2 vs. 54.5) of the loin. Drip loss among Nn pigs was higher than among NN pigs for chops taken from the centre (4.8 vs. 3.8 g 100 g-1) and from the anterior portion (3.7 vs. 2.9 g 100 g-1) of the loin (P < 0.01). Soluble protein was 1.7% lower (P < 0.001) in Nn pigs compared with the NN pigs. Barrows attained market weight earlier (P < 0.05) than gilts, but they had a lower dressing percentage (P < 0.05) and greater grade fat depth (P < 0.001) and had 1.2% less predicted lean yield of carcass (P < 0.001) than gilts. Since meat quality declined without concomitant increases in growth rate or improvements in carcass quality, it was concluded that the intentional use of the halothane gene should be discouraged.