GENETIC-PARAMETERS OF PORK QUALITY AND PRODUCTION TRAITS IN YORKSHIRE POPULATIONS

Parameters of pork quality traits and relationships with production traits were studied in 7 halothane-negative Dutch Yorkshire populations. (Go) variances due to genotype and batch (day of slaughter) were estimated using a REML procedure fitting an animal model. High heritabilities (0.52 and 0.41) and a rather strong negative genetic relationship (-0.37) were found between carcass lean% and intramuscular fat%. Growth rate and feed intake showed less important relationships with intramuscular fat% (r(G)'s -0.09 and 0.22, respectively). Traits related to waterholding capacity and colour (pH, drip loss, reflectance, etc.) were measured at the slaughterhouse as well as in the laboratory. The genetic variance of these traits was of the same magnitude as the variance due to batch effects (about 20%). In a principal Component (PC) analysis with 10 quality traits, the first two PCs explained a large proportion of the variance (66%). After rotation, these two PCs could be well interpreted as representing the DFD or the PSE characteristics. Heritabilities of both PCs were close to 0.20. Genetic relationships between laboratory and slaughterhouse traits (r(G)'s up to -0.79) demonstrated good opportunities for genetic improvement of waterholding capacity and colour, using relatively inexpensive measurements like pH and reflectance at 45 min and 20 h post mortem. Carcass lean% and growth rate had no unfavourable correlations with waterholding capacity or colour traits. (Residual) daily feed intake, however, showed moderate to strong associations, especially with colour (r(G)'s up to -0.58), indicating an increased risk of the DFD aberration in pigs with a high feed intake and/or indicating a change in muscle fibre type distribution.