IDENTIFICATION OF HALOTHANE GENOTYPES BY CALCIUM ACCUMULATION AND THEIR MEAT QUALITY USING LIVE PIGS

The three halothane genotypes (NN, Nn, and nm) were identified by measuring the capacity for Ca2+ accumulation by sarcoplasmic reticulum in whole muscle homogenate preparations of M. longissimus dorsi with a Ca2+ specific electrode at 35-degrees-C Significant differences (P<0.001) in deterioration (%) of Ca2+ accumulation, 12% for NN, 35% for Nn, and 81% for nn pigs, were observed a er ageing the whole muscle homogenate preparations for 24 h in ice. Predictions of meat quality in live pigs (n = 34) based on the values for water-holding capacity, assessed as fluid (g/0.5 g wet wt LD), and pH (fluid) by using small biopsy LD samples (Cheah et al. 1993) were performed on all the halothane genotypes. The halothane genotype NN (n = 11) showed a fluid value of 0.37 +/- 0.01 and a pH (fluid) value of 6.62 +/- 0.03 as compared with 0.61 +/- 0.02 and 5.84 +/- 0.04, respectively, for the halothane genotype nn (n = 13). The Nn pigs (n = 10) showed fluid (0.49 +/- 0.03) and pH (fluid) (6.19 +/- 0.11) values between those values observed for the two homozygotes (NN and nn). Predictions of meat quality in live pigs from biopsy LD muscles were confirmed from assessments on post-mortem LD muscles based on pH1 and fibre optic probe (FOP) measurements. The extent of deterioration (%) in Ca2+ accumulation showed high correlations with fluid (r = -0.861) and pH (fluid) (r = 0.831) in the biopsy LD samples, and with pH1 (r = 0-663), FOP (r = -0.812), and drip (%) loss (r = -0.777) in the post-mortem LD samples.