1 Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin 2, Ireland.
3 Irish Cattle Breeding Federation, Highfield House, Shinagh, Co. Cork, Ireland.
Animal. 2014 Feb;8(2):224-35. doi: 10.1017/S175173111300195X. Epub 2013 Nov 20.
Dystocia and perinatal mortality are quantitative traits that significantly impact animal productivity and welfare. Their economic importance is reflected by their inclusion in the national breeding goals of many cattle populations. The genetic architecture that influences these traits, however, has still yet to be thoroughly defined. Regions of the bovine genome associated with calving difficulty (direct and maternal) and perinatal mortality were detected in this study using a Bayesian approach with 43 204 single nucleotide polymorphisms (SNPs) on up to 1970 Holstein-Friesian bulls. Several SNPs on chromosomes 5, 6, 11, 12, 17,18 and 28 were detected to be strongly associated with these calving performance traits. Novel genomic regions with previously reported associations with growth, stature, birth weight and bone morphology were identified in the present study as being associated with the three calving performance traits. Morphological abnormalities are a known contributor to perinatal mortality and the most significantly associated SNP for perinatal mortality in the present study was located in a region in linkage disequilibrium with the gene SLC26A7. This gene, SLC26A7, has similarities and colocalises with SLC4A2, which has previously been associated with osteoporosis and mortality in cattle populations. The HHIP gene that is known to be associated with stature in humans was strongly associated with direct calving difficulty in the present study; large calves are known to, on average, have a greater likelihood of dystocia. A stemloop microRNA, bta-mir-1256, on chromosome 12, involved in post-transcriptional regulation of gene expression was associated with maternal calving difficulty. Previously reported quantitative trait loci associated with calving performance traits in other populations were again identified in this study; with one genomic region on chromosome 18 supporting very strong evidence of an underlying causative mutation and accounting for 2.1% of the genetic variation in direct calving difficulty. Overlapping genomic regions associated with one or more of the calving traits were also detected substantiating the known genetic covariances existing between these traits. Moreover, some genomic regions were only associated with one of the calving traits implying the selective genomic breeding programs exploiting these regions could help resolve genetic antagonisms.
难产和围产死亡是影响动物生产力和福利的数量性状。这些性状的经济重要性反映在许多牛种群的国家育种目标中都包含了这些性状。然而，影响这些性状的遗传结构仍有待彻底定义。本研究使用贝叶斯方法，利用多达 1970 头荷斯坦-弗里森公牛的 43204 个单核苷酸多态性（SNP），检测到与分娩困难（直接和母体）和围产死亡相关的牛基因组区域。在本研究中，发现染色体 5、6、11、12、17、18 和 28 上的几个 SNP 与这些产犊性能性状强烈相关。本研究还鉴定了与生长、体型、出生体重和骨骼形态先前报道相关的新基因组区域与三种产犊性能性状相关。形态异常是围产死亡的已知原因，本研究中与围产死亡最显著相关的 SNP 位于与基因 SLC26A7 连锁不平衡的区域。该基因 SLC26A7 与 SLC4A2 具有相似性和共定位，SLC4A2 先前与牛群中的骨质疏松症和死亡率有关。本研究中，已知与人类身高相关的 HHIP 基因与直接分娩困难强烈相关；大的犊牛通常更容易难产。在染色体 12 上涉及基因表达转录后调控的茎环 microRNA bta-mir-1256 与母体分娩困难相关。本研究再次鉴定了先前在其他群体中与产犊性能性状相关的数量性状位点；染色体 18 上的一个基因组区域强烈支持潜在的致病突变的存在，并解释了直接分娩困难遗传变异的 2.1%。还检测到与一种或多种分娩性状相关的重叠基因组区域，这证实了这些性状之间存在已知的遗传协方差。此外，一些基因组区域仅与一种分娩性状相关，这意味着利用这些区域的选择性基因组育种计划可以帮助解决遗传拮抗作用。
