Weller J I, Golik M, Seroussi E, Ron M, Ezra E
Institute of Animal Sciences, ARO, The Volcani Center, Bet Dagan 50250, Israel.
J Dairy Sci. 2008 Jun;91(6):2469-74. doi: 10.3168/jds.2007-0915.
Twinning rate was analyzed in the Israeli Holstein dairy cattle population by the multiple-trait animal model, and a daughter design genome scan for quantitative trait loci was performed. Each parity was considered a separate trait. Heritabilities of twinning rate were very low, but increased by parity from 0.01 in first parity to 0.03 in fifth parity. All genetic correlations among parities were >0.77, but all environmental correlations were <0.07. Genetic correlations between twinning rate and female fertility (measured as the inverse of the number of inseminations to conception) in the first 3 parities were negative for all 9 parity-by-trait combinations. All environmental correlations were very small, but generally negative. The overall genetic trend since 1985 was positive at 0.02% twinning/yr, whereas the phenotypic trends were positive for parities 3 and 4 and negative for the other parities, but all trends were quite small. A total of 5,221 cows, daughters of 11 sires, were genotyped for 73 markers spanning all 29 autosomes. There were 9 markers with significant effects on twinning rate at P < 0.05, for a false discovery rate of 0.4; thus, about 5 of these probably represent true effects. Significant effects were found on chromosomes 1, 6, 7, 8, 14, 15, and 23. Of these, 3 effects were significant at P < 0.01, for a false discovery rate of 0.24. All 11 families were analyzed by interval mapping of chromosome 7. Only 2 families showed nominally significant effects, but chromosome-wise significance at P < 0.05 was not obtained for either family. Suggestive evidence of quantitative trait loci near the beginning of the chromosome and near position 50 cM were found in both families. Sire 3070 also had a significant effect for female fertility near the beginning of the chromosome. There was also evidence for a third quantitative trait loci at the end of the chromosome for sire 2357.
采用多性状动物模型分析了以色列荷斯坦奶牛群体的双胎率，并进行了用于数量性状基因座定位的女儿设计基因组扫描。每个胎次被视为一个独立的性状。双胎率的遗传力非常低，但随着胎次增加，从第一胎次的0.01增加到第五胎次的0.03。各胎次间的所有遗传相关均>0.77，但所有环境相关均<0.07。在前3个胎次中，双胎率与雌性繁殖力（以受孕所需配种次数的倒数衡量）之间的所有9种胎次-性状组合的遗传相关均为负。所有环境相关都非常小，但总体为负。自1985年以来的总体遗传趋势为正，双胎率每年增加0.02%，而表型趋势在第3和第4胎次为正，在其他胎次为负，但所有趋势都相当小。对11头公牛的5221头女儿进行了基因分型，检测了覆盖所有29条常染色体的73个标记。有9个标记对双胎率有显著影响，P<0.05，错误发现率为0.4；因此，其中约5个可能代表真实效应。在染色体1、6、7、8、14、15和23上发现了显著效应。其中，3个效应在P<0.01时显著，错误发现率为0.24。对染色体7进行区间定位分析了所有11个家系。只有2个家系显示出名义上的显著效应，但两个家系均未获得染色体水平上P<0.05的显著性。在两个家系中均发现了染色体起始附近和50 cM附近存在数量性状基因座的提示性证据。公牛3070在染色体起始附近对雌性繁殖力也有显著影响。对于公牛2357，在染色体末端也有第三个数量性状基因座的证据。
