Rodriguez-Zas S L, Southey B R, Heyen D W, Lewin H A
J Dairy Sci. 2002 Oct;85(10):2681-91. doi: 10.3168/jds.S0022-0302(02)74354-3.
A longitudinal-linkage analysis approach was developed and applied to an outbred population. Nonlinear mixed-effects models were used to describe the lactation patterns and were extended to include marker information following single-marker and interval mapping models. Quantitative trait loci (QTL) affecting the shape and scale of lactation curves for production and health traits in dairy cattle were mapped in three U.S. Holstein families (Dairy Bull DNA Repository families one, four, and five) using the granddaughter design. Information on 81 informative markers on six Bos taurus autosomes (BTA) was combined with milk yield, fat, and protein percentage and somatic cell score (SCS) test-day records. Six percent of the single-marker tests surpassed the experiment-wise significance threshold. Marker BL41 on BTA3 was associated with decrease in milk yield during mid-lactation in family one. The scale and shape of the protein percentage lactation curve in family four varied with BMC4203 (BTA6) allele that the son received from the grandsire. Some map locations were associated with variation in the lactation pattern of multiple traits. In family four, the marker HUJI177 (BTA3) was associated with changes in the milk yield and protein percentage curves suggesting a QTL with pleiotropic effects or multiple QTL in the region. The interval mapping model uncovered a QTL on BTA7 associated with variation in milk-yield pattern in family four and a QTL on BTA21 affecting SCS in family five. The developed approach can be extended to random regressions, covariance functions, spline, gametic and variance component models. The results from the longitudinal-QTL approach will help to understand the genetic factors acting at different stages of lactation and will assist in positional candidate gene research. Identified positions can be incorporated into marker-assisted selection decisions to alter the persistency and peak production or the fluctuation of SCS during a lactation.
一种纵向连锁分析方法被开发出来并应用于一个远交群体。使用非线性混合效应模型来描述泌乳模式，并根据单标记和区间作图模型进行扩展以纳入标记信息。利用孙女设计在美国的三个荷斯坦奶牛家族（奶牛公牛DNA库家族一、四和五）中定位影响奶牛生产和健康性状泌乳曲线形状和尺度的数量性状基因座（QTL）。将六个牛常染色体（BTA）上81个信息性标记的信息与产奶量、乳脂率、乳蛋白率以及体细胞评分（SCS）的测定日记录相结合。6%的单标记检验超过了实验水平的显著性阈值。BTA3上的标记BL41与家族一中泌乳中期产奶量的下降有关。家族四中乳蛋白率泌乳曲线的尺度和形状随儿子从祖父那里继承的BMC4203（BTA6）等位基因而变化。一些图谱位置与多个性状泌乳模式的变异有关。在家族四中，标记HUJI177（BTA3）与产奶量和乳蛋白率曲线的变化有关，表明该区域存在一个具有多效性的QTL或多个QTL。区间作图模型在家族四中发现了一个与产奶量模式变异相关的位于BTA7上的QTL，在家族五中发现了一个影响SCS的位于BTA21上的QTL。所开发的方法可以扩展到随机回归、协方差函数、样条、配子和方差成分模型。纵向QTL方法的结果将有助于理解在泌乳不同阶段起作用的遗传因素，并将有助于定位候选基因研究。确定的位置可以纳入标记辅助选择决策中，以改变泌乳期间的持久性和产奶高峰或SCS的波动。
