Leitch H W, Smith C, Burnside E B, Quinton M
Centre for the Genetic Improvement of Livestock, University of Guelph, ON, Canada.
J Dairy Sci. 1994 Jun;77(6):1702-18. doi: 10.3168/jds.S0022-0302(94)77112-5.
Stochastic simulation was used to study the effect of selection and mating strategy on rates of genetic response and inbreeding with a closed nucleus breeding program for juvenile and adult schemes with 8 males and 64 females selected to produce 1024 progeny (512 females). Selection strategies considered using all available information or only individual and sibling records. Selection of sires was either unrestricted or restricted to between full-sib families. The effect of avoidance of mating of relatives to limit inbreeding was also evaluated. Four mating designs were examined: each dam was mated to 1, 2, 4, or all sires. Mating designs involving one sire per dam and more than one dam per sire were referred to as hierarchical. Use of several mates per dam resulted in a factorial mating design. Selected parents were mated either randomly, best to best, or best to worst. An index based on relative inbreeding to response ratio was used to describe the effectiveness of strategies for reducing inbreeding relative to changes in rates of genetic response. Strategies that lower index values were preferred and include selection on BLUP or approximations of BLUP and factorial mating designs that involve the random mating of dams to several sires. Factorial mating designs were effective for a range of heritabilities. Avoidance of matings of full sibs and restriction of selection of sires to between full-sib families enabled appreciable reductions in the index. Nucleus breeding programs based entirely on the selection of juveniles were not indicated because they had higher index values than adult schemes.
采用随机模拟方法，研究了封闭核心育种计划中选择和交配策略对遗传反应速率和近亲繁殖的影响，该计划包括幼体和成年方案，选择8只雄性和64只雌性以产生1024个后代（512只雌性）。选择策略考虑使用所有可用信息或仅使用个体和同胞记录。父本的选择要么不受限制，要么限制在全同胞家系之间。还评估了避免亲属交配以限制近亲繁殖的效果。研究了四种交配设计：每个母本与1只、2只、4只或所有父本交配。每个母本涉及1只父本且每个父本涉及多个母本的交配设计被称为分层交配。每个母本使用多个配偶导致了析因交配设计。选定的亲本要么随机交配，要么最好与最好交配，要么最好与最差交配。基于相对近亲繁殖与反应比率的指数用于描述相对于遗传反应速率变化减少近亲繁殖策略的有效性。较低指数值的策略更受青睐，包括基于最佳线性无偏预测（BLUP）或BLUP近似值的选择以及涉及母本与多个父本随机交配的析因交配设计。析因交配设计在一系列遗传力范围内都有效。避免全同胞交配以及将父本选择限制在全同胞家系之间能够显著降低指数。完全基于幼体选择的核心育种计划并不适用，因为它们的指数值高于成年方案。
