Quantitative trait loci mapping of calving and conformation traits on Bos taurus autosome 18 in the German Holstein population
Quantitative trait loci mapping of calving and conformation traits on Bos taurus autosome 18 in the German Holstein population
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DOI：
10.3168/jds.2009-2553
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发表时间：
2010-03-01
影响因子：
3.5
通讯作者：
Kuehn, Ch.
中科院分区：
文献类型：
--
作者：
Brand, B.;Baes, C.;Kuehn, Ch.
采用连锁分析、连锁不平衡分析、联合连锁和连锁不平衡分析，对德国荷尔斯泰因牛牛常染色体18 （BTA18）产犊和构象性状的数量性状位点（QTL）进行了定位。对6个父系同父异母家族共1054只动物的BTA18染色体端粒区28个遗传标记进行了基因分型，研究了产犊性状、体型性状和乳型性状。使用单一估计的育种值，分别分析了母体和直接对产犊难和死产的影响。最初通过单独连锁和连锁不平衡分析确定的QTL，可以通过对乳房综合指数、乳房深度、前乳房附着、前乳房放置、体深、臀角以及对产犊难易和死产的直接影响进行联合连锁和连锁不平衡分析来证实。乳型性状、体深性状和产犊性状的QTL峰同时存在，限制性对数似然比曲线形状相似。采用混合模型，包括母系遗传等位基因的固定等位基因效应和随机多基因效应，对最可能QTL位置两侧的标记进行关联分析。结果表明，微卫星标记DIK4234（位于53.3 Mb）与产妇对死产的影响、对产犊难易程度和体深的直接影响有关。母系遗传DIK4234等位基因对产犊的影响比较表明，母系和直接影响呈正相关。此外，母系遗传DIK4234标记等位基因与体深的关联暗示构象性状可能为产犊性状的QTL提供了功能背景。对于乳腺型性状，QTL峰的高度重合以及QTL位于体细胞评分QTL所在区域的位置表明，乳腺型性状的QTL效应可能与乳腺健康性状的QTL效应对BTA18的影响相关。我们的研究结果表明，BTA18中端粒区影响构象性状的位点也可能对产犊和乳房健康性状的遗传变异有影响。需要进一步的分析来确定影响构象和产犊性状的因果突变，并调查与构象、产犊和乳房健康性状相关的基因座的影响的相关性。
Linkage, linkage disequilibrium, and combined linkage and linkage disequilibrium analyses were performed to map quantitative trait loci (QTL) affecting calving and conformation traits on Bos taurus autosome 18 (BTA18) in the German Holstein population. Six paternal half-sib families consisting of a total of 1,054 animals were genotyped on 28 genetic markers in the telomeric region on BTA18 spanning approximately 30 Mb. Calving traits, body type traits, and udder type traits were investigated. Using univariately estimated breeding values, maternal and direct effects on calving ease and stillbirth were analyzed separately for first-and further-parity calvings. The QTL initially identified by separate linkage and linkage disequilibrium analyses could be confirmed by a combined linkage and linkage disequilibrium analysis for udder composite index, udder depth, fore udder attachment, front teat placement, body depth, rump angle, and direct effects on calving ease and stillbirth. Concurrence of QTL peaks and a similar shape of restricted log-likelihood ratio profiles were observed between udder type traits and for body depth and calving traits, respectively. Association analyses were performed for markers flanking the most likely QTL positions by applying a mixed model including a fixed allele effect of the maternally inherited allele and a random polygenic effect. Results indicated that microsatellite marker DIK4234 (located at 53.3 Mb) is associated with maternal effects on stillbirth, direct effects on calving ease, and body depth. A comparison of effects for maternally inherited DIK4234 alleles indicated a favorable, positive correlation of maternal and direct effects on calving. Additionally, the association of maternally inherited DIK4234 marker alleles with body depth implied that conformation traits might provide the functional background of the QTL for calving traits. For udder type traits, the strong coincidence of QTL peaks and the position of the QTL in a region previously reported to harbor QTL for somatic cell score indicated that effects of QTL for udder type traits might be correlated with effects of QTL for udder health traits on BTA18. Our results suggest that loci in the middle to telomeric region on BTA18 with effect on conformation traits may also contribute to the genetic variance of calving and udder health traits. Further analyses are required to identify the causal mutations affecting conformation and calving traits and to investigate the correlation of effects for loci associated with conformation, calving, and udder health traits.