大白猪生产和繁殖性状遗传趋势的分析

 配合混合模型，用非求导的REML方法（DF-REML）分析估计了大白猪生产和繁殖性状的表型和遗传趋势。165日龄体重、90kg体重平均背膘厚和总产仔数的表型趋势分别为1.64、-0.23和0.11，遗传趋势分别为0.76、-0.14和0.01。结果表明，大白猪品系选择试验的165日龄体重和90kg体重背膘厚两个主选性状的选择是显著有效的，生长速度逐代提高，背膘厚逐代下降。辅助的体型选择使得大白猪体型结构逐渐向结实型发展。产仔数的遗传趋势是弱的有利变化，表明在对生长速度与背膘厚合并选择时，对繁殖性能的影响很小。

Analysis of Genetic Trends for Productive and Reproductive Traits in Large White Pigs

Data from a selection experiment of Large White pig for high growth rate and low backfat thickness were used to estimate phenotypic and genetic trends in productive and reproductive traits. The traits in this study include: age corrected weight (CORRW), weight corrected backfats (CORRBF), total number of piglet born (NOBT), number of piglet born alive (NOBA), piglet birth weight (PBW), piglet weaned weight (PWW), and conformation traits.Estimates of breeding value were obtained by mixedmodel procedures using a multipletrait derivativefree restricted maximum likelihood (MTDFREML).The phenotypic trends were estimated by regression phenotypic value of the traits on generation number. The genetic trends were estimated by regression of estimated breeding value on generation number.Estimates of the phenotypic and genetic trends of NOBT, CORRW and CORRBF were 0. 11 and 0.01, 1.64 and 0.76, -0.23 and -0.14 respectively. The results suggested that the selection experiment of Large White pig for high growth rate and low backfat thickness is insignificantly effective. The two trait selections have no effect on reproductive traits because the genetic trends of NOBT and NOBA were in a desired direction.