Analysis of a Duroc x Pietrain F(2) pig resource population for quantitative trait loci affecting growth, body composition, and meat quality traits

A Duroc x Pietrain F2 pig resource population was created to discover quantitative trait loci (QTL) affecting growth, body composition, and meat quality traits. These pigs (1259 born) were finished in either a Modified Open Front (MOF) or a Test Station (TS) building. Body weight and ultrasound estimates of tenth rib backfat, last rib backfat, and longissimus muscle area were serially measured throughout development. Random regression analyses were performed to evaluate body weight gain and its components over time. Carcass and meat quality data collection included primal cut weights, backfat thickness, muscle pH, objective and subjective color information, marbling and firmness scores, and drip loss of boneless longissimus muscle chops. Additionally, chops were analyzed for moisture, protein, and fat composition as well as cook yield and shear force measurements. Palatability of chops was determined by a trained sensory taste panel.; Models that included genetic, permanent environment, and residual error variance components were used to evaluate the influence of finisher facilities on these traits. Pigs finished in the MOF were heavier at harvest and had more backfat at 22 wk of age and at harvest at the tenth and last rib than pigs raised in the TS. Body weight random regression analysis revealed that pigs reared in the TS grew more slowly at first, but then grew more quickly later in the finisher phase for the same overall weight gain from 10 to 22 wk of age as pigs in the MOF. Pigs raised in the MOF had a greater backfat accretion rate from 10 to 22 wk of age than pigs raised in the TS. Additionally, pigs raised in the MOF had greater decline in pH from 45 min to 24 h postmortem and had lower Warner-Bratzler shear force measurements than pigs raised in the TS. Thus, animals of similar genetic merit can show differences in phenotypes as influenced by finisher facilities.; A total of 510 F2 animals were genotyped for 124 microsatellite markers evenly spaced across the entire genome. Data were analyzed with line cross least squares regression interval mapping methods using sex and litter as fixed effects with covariates of carcass weight or harvest age for specific carcass and meat quality traits. Significance thresholds of the F-statistic for additive, dominance, and imprinted QTL were determined on chromosome- and genome-wise levels by permutation tests. (Abstract shortened by UMI.)...