Coat score. A possible explanation for the zebuine selective sweep located on bovine chromosome 5: 47,670,001–48,100,000 bp

Over 65% of the world's cattle population resides in warm areas where heat stress conditions limit the breed of European taurine cattle. Composite breeds were developed to retain the main traits of both parental breeds. The skin plays a central role in animal response to heat stress. Research on the genetic architecture of skin traits has identified genes and regions related to warm resistance skin features. The aim of this study was to determine whether the indicine proportion accounted for coat type or whether there were genes of large effect segregating in Brangus. Bulls (<i>n</i><b> </b>=<b> </b>108) were genotyped using microarrays and their coat score and hair length were evaluated. Indicine-taurine genome-wide composition was estimated and GWAS was performed. Although significant correlations between indicine proportion and traits were not observed, four windows of SNPs on BTA4 and BTA5 explained more than 2% of the trait variance. The GWAS for coat score in summer showed the main peak on BTA5:46,941,446–48,030,219<b> </b>bp, accounting for 4.65% of the variance. Our results suggest that the variation in coat score and undercoat hair length in Argentinian Brangus bulls is associated with the presence of some particular gene variants, rather than with the whole indicine genetic content.

全球超过65%的牛群栖息于温暖地区，而热应激环境会限制欧洲普通牛（European taurine cattle）的养殖。为保留双亲品种的核心优良性状，科研人员培育出了合成肉牛品种。皮肤是动物应对热应激的核心器官，针对皮肤性状遗传结构的研究已鉴定出与耐热皮肤特征相关的基因及基因组区域。本研究旨在明确布兰格斯牛（Brangus）的瘤牛（indicine）占比是否与被毛类型相关，抑或是该群体中存在具有显著效应的分离基因。本研究以108头公牛为研究对象，采用基因芯片开展基因分型，并对其被毛评分与毛长进行评估；随后估算了瘤牛-普通牛全基因组组成，并实施了全基因组关联分析（Genome-Wide Association Study，GWAS）。尽管未检测到瘤牛占比与目标性状间存在显著相关性，但牛常染色体（BTA）4号与5号上的4个单核苷酸多态性（Single Nucleotide Polymorphism，SNP）窗口可解释超过2%的性状表型变异。夏季被毛评分的全基因组关联分析结果显示，牛常染色体5号上存在显著关联峰，区间为46,941,446–48,030,219 bp，可解释4.65%的表型变异。本研究结果表明，阿根廷布兰格斯公牛的被毛评分与底毛毛长变异，与特定基因变异的存在相关，而非与整体瘤牛遗传组分相关。