Identification of halothane genotypes by calcium accumulation and their meat quality using live pigs

Abstract

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°C. Significant differences (P < 0·001) in deterioration (%) of Ca2+ accumulation, 12% for NN, 35% for Nn, and 81% for nn pigs, were observed after 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.