Abstract：
In accordance with the infinitesimal model for quantitative traits, a very large number of genes affect nearly all economic traits. In only two cases has the causative polymorphism been determined for genes affecting economic traits in dairy cattle. Most current methods for genomic evaluation are based on the \"two-step\" method. Genetic evaluations are computed by the individual animal model, and functions of the evaluations of progeny-tested sires are the dependent variable for estimation of marker effects. With the adoption of genomic evaluation in 2008, annual rates of genetic gain in the US increased from ∼50-100% for yield traits and from threefold to fourfold for lowly heritable traits, including female fertility, herd-life and somatic cell concentration. Gradual elimination of the progeny test scheme has led to a reduction in the number of sires with daughter records and less genetic ties between years. As genotyping costs decrease, the number of cows genotyped will continue to increase, and these records will become the basic data used to compute genomic evaluations, most likely via application of \"single-step\" methodologies. Less emphasis in selection goals will be placed on milk production traits, and more on health, reproduction, and efficiency traits and \"environmentally friendly\" production. Genetic variance for economic traits is maintained by increase in frequency of rare alleles, new mutations, and changes in selection goals and management.
摘要：
根据数量性状的无穷小模型，大量的基因影响着几乎所有的经济性状。仅在两种情况下，确定了影响奶牛经济性状的基因的致病多态性。目前大多数基因组评估方法都是基于“两步法”。遗传评估是由个体动物模型计算的，子代测试父代的评估函数是评估标记效应的因变量。随着2008年基因组评估的采用，美国的年度遗传增益率从产量性状的50-100%增加，低遗传性状从三倍增加到四倍，包括女性生育能力，畜群-生命和体细胞浓度。逐渐消除后代测试方案导致具有女儿记录的父亲数量减少，并且几年之间的遗传联系减少。随着基因分型成本的降低，基因分型的奶牛数量将继续增加，这些记录将成为计算基因组评估的基本数据，最有可能通过应用“单步”方法。不太强调选择目标将放在牛奶生产性状上，更多关于健康，繁殖，效率特征和“环保”生产。经济性状的遗传变异是通过增加稀有等位基因的频率来维持的，新的突变,以及选择目标和管理的变化。
