Rocha J L, Sanders J O, Cherbonnier D M, Lawlor T J, Taylor J F
Department of Animal Science, Texas A&M University, College Station 77843, USA.
J Dairy Sci. 1998 Jun;81(6):1681-9. doi: 10.3168/jds.S0022-0302(98)75735-2.
The potential of trait-based analysis to detect quantitative trait loci was investigated using blood group polymorphisms as the marker systems and milk and type traits in Holstein cattle as the quantitative traits. Within large half-sib families, animals were ranked on their predicted transmitted abilities or phenotypes, and blood group allele frequencies were compared between the upper and lower 5% tails of the distributions. Genotype frequencies within large families were also examined for evidence of selection. All of the major effects that had previously been detected using linear model analyses were identified by the trait-based analyses of a C blood group effect on rump angle, an L effect on milk yield and composition traits, an S effect on milk fat yield, and a direct effect of the M locus on milk and protein yields. These results provide additional support for the biological validity of these associations and also demonstrate the utility of trait-based analysis for the detection of quantitative trait loci within existing dairy breeding programs. However, just as in the linear model analyses, an analytical strategy should be utilized that allows the identification of the effects that are consistent across environments and genetic backgrounds.
利用血型多态性作为标记系统，以荷斯坦奶牛的产奶量和体型性状作为数量性状，研究了基于性状分析检测数量性状位点的潜力。在大型半同胞家系中，根据动物的预测传递能力或表型进行排名，并比较分布上下5%尾部之间的血型等位基因频率。还检查了大型家系中的基因型频率，以寻找选择的证据。先前使用线性模型分析检测到的所有主要效应，通过基于性状的分析均得以确定，即C血型对臀角的效应、L血型对产奶量和成分性状的效应、S血型对乳脂产量的效应，以及M位点对产奶量和蛋白质产量的直接效应。这些结果为这些关联的生物学有效性提供了额外支持，也证明了基于性状的分析在现有奶牛育种计划中检测数量性状位点的实用性。然而，正如在线性模型分析中一样，应采用一种分析策略，以便能够识别在不同环境和遗传背景下一致的效应。
