Southwood O I, Kennedy B W
University of Guelph, Ontario, Canada.
J Anim Sci. 1991 Aug;69(8):3177-82. doi: 10.2527/1991.6983177x.
Best linear unbiased predictors (BLUP) of breeding values for additive direct and additive maternal genetic effects were estimated from 3,944 purebred Yorkshire and Landrace first-parity litters recorded on the Quebec Record of Performance Sow Productivity Program and born between 1977 and 1987. Breeding values for gilts, dams, and sires were estimated using an individual animal model for measures of litter size of total number born (NOBN), number born alive (NOBA), and number weaned (NOWN). Environmental trends were estimated from average herd-year solutions, and genetic trends were estimated by regression of estimated breeding value on year of birth. Environmental trends were positive for all traits in both breeds but were significant only for NOWN in Landrace (.051 +/- .021 pigs/yr). Genetic trends were very small but were mainly negative for direct breeding value and combined direct and maternal breeding value. Significant estimates of genetic trends (P less than .05) were observed only within the Yorkshire breed, and these ranged from -.012 +/- .004 to .004 +/- .002 pigs/yr.
利用1977年至1987年间记录在魁北克母猪生产性能记录计划中的3944窝纯种约克夏和长白猪第一胎产仔数据，估计了加性直接遗传效应和加性母体遗传效应育种值的最佳线性无偏预测值（BLUP）。使用个体动物模型，对产仔总数（NOBN）、活产仔数（NOBA）和断奶仔猪数（NOWN）等产仔数指标，估计了后备母猪、经产母猪和公猪的育种值。根据平均群体年份解估计环境趋势，通过将估计育种值对出生年份进行回归来估计遗传趋势。两个品种所有性状的环境趋势均为正向，但仅长白猪的NOWN显著（0.051±0.021头/年）。遗传趋势非常小，但直接育种值以及直接和母体综合育种值主要为负向。仅在约克夏品种内观察到显著的遗传趋势估计值（P<0.05），范围为-0.012±0.004至0.004±0.002头/年。
