Department of Animal Sciences, University of Florida, Gainesville, FL, USA.
Department of Animal Science, North Carolina States University, Raleigh, NC, USA.
J Appl Genet. 2024 May;65(2):383-394. doi: 10.1007/s13353-024-00859-y. Epub 2024 Mar 25.
Composite breeds, including Brangus, are widely utilized in subtropical and tropical regions to harness the advantages of both Bos t. taurus and Bos t. indicus breeds. The formation and subsequent selection of composite breeds may result in discernible signatures of selection and shifts in genomic population structure. The objectives of this study were to 1) assess genomic inbreeding, 2) identify signatures of selection, 3) assign functional roles to these signatures in a commercial Brangus herd, and 4) contrast signatures of selection between selected and non-selected cattle from the same year. A total of 4035 commercial Brangus cattle were genotyped using the GGP-F250K array. Runs of Homozygosity (ROH) were used to identify signatures of selection and calculate genomic inbreeding. Quantitative trait loci (QTL) enrichment analysis and literature search identified phenotypic traits linked to ROH islands. Genomic inbreeding averaged 5%, primarily stemming from ancestors five or more generations back. A total of nine ROH islands were identified, QTL enrichment analysis revealed traits related to growth, milk composition, carcass, reproductive, and meat quality traits. Notably, the ROH island on BTA14 encompasses the pleiomorphic adenoma (PLAG1) gene, which has been linked to growth, carcass, and reproductive traits. Moreover, ROH islands associated with milk yield and composition were more pronounced in selected replacement heifers of the population, underscoring the importance of milk traits in cow-calf production. In summary, our research sheds light on the changing genetic landscape of the Brangus breed due to selection pressures and reveals key genomic regions impacting production traits.
复合品种，包括 Brangus，广泛应用于亚热带和热带地区，以利用 Bos t. taurus 和 Bos t. indicus 品种的优势。复合品种的形成和随后的选择可能导致选择和基因组群体结构变化的明显特征。本研究的目的是 1）评估基因组近交程度，2）鉴定选择的特征，3）在商业 Brangus 牛群中赋予这些特征的功能作用，4）比较同年选择和非选择牛的选择特征。共有 4035 头商业 Brangus 牛使用 GGP-F250K 阵列进行了基因分型。同源性 RUN（ROH）用于鉴定选择特征并计算基因组近交程度。数量性状位点（QTL）富集分析和文献搜索确定了与 ROH 岛相关的表型特征。基因组近交程度平均为 5%，主要来自于五代或五代以上的祖先。总共鉴定了九个 ROH 岛，QTL 富集分析揭示了与生长、牛奶成分、胴体、繁殖和肉质特征相关的特征。值得注意的是，位于 BTA14 上的 ROH 岛包含多形性腺瘤（PLAG1）基因，该基因与生长、胴体和繁殖特征有关。此外，与产奶量和组成相关的 ROH 岛在该群体的选择替代小母牛中更为明显，突出了牛奶特征在奶牛生产中的重要性。总之，我们的研究揭示了由于选择压力导致 Brangus 品种遗传景观的变化，并揭示了影响生产特征的关键基因组区域。
