GENETIC-PARAMETERS OF BACKFAT THICKNESS, AGE AT 100 KG AND MEAT QUALITY TRAITS IN PIETRAIN PIGS

Genetic parameters were estimated for Pietrain pigs using a derivative-free restricted maximum likelihood procedure applied to a multiple trait individual animal model. Two production traits, ie age (AGE) and average backfat thickness (ABT) adjusted to 100 kg liveweight, and 4 meat quality traits, pH of Semispinalis muscle at 45 min post mortem (pH1), ultimate pH (pH(u)), drip loss (DL) and cooking loss (CL) of a sample of Semimembranosus muscle, were considered. The data consisted of 5 464 boars tested for AGE and ABT in a single station between 1986 and 1992, of which 1 276 were measured for meat quality traits. The heritabilities of AGE, ABT, pH1, pH(u), DL and CL are 0.30, 0.45, 0.04, 0.07, 0.04 and 0.24, respectively, with standard errors ranging from 0.02 to 0.03. AGE and ABT exhibit an unfavourable genetic correlation (-0.44 +/- 0.05). The genetic correlations between the meat quality traits are high, with the exception of pH1 which is almost independent of DL and CL. Both pH1 and pHu show positive, ie unfavourable, genetic correlations with ABT (0.26 +/- 0.15 and 0.22 +/- 0.12, respectively) and AGE (0.15 +/- 0.28 and 0.60 +/- 0.21, respectively). DL tends to be unfavourably correlated with ABT (-0.20 +/- 0.17), but shows favourable genetic correlations with AGE (0.77 +/- 0.19). CL is almost independent of both AGE (0.07 +/- 0.12) and ABT (-0.04 +/- 0.08).