Psoroptic mange, caused by Psoroptes ovis mites, is affecting Belgian Blue cattle’s welfare and production potential. The Belgian Blue cattle—known for its high degree of muscling, low feed conversion ratio and high beef quality—is highly susceptible for this disease. In this study, we phenotyped 1975 Belgian Blue cattle from more than 100 different groups on commercial beef farms for their psoroptic mange susceptibility. Substantial individual differences were observed within these management groups, with lesion extent differences up to ± 15%. Animal models showed that estimated heritabilities were low for lesion extent and severe lesion extent (0.07 and 0.09, respectively) and 0.12 for the number of mites. A genome wide association study for mange susceptibility revealed signals on BTA6, BTA11, BTA15 and BTA24. In these regions, candidate genes GBA3, RAG2, and TRAF6 were identified. Despite the challenges in phenotyping for psoroptic mange due to the timing of screening, the continuous evolution of lesions and different management conditions, we successfully conducted a study on the genetic susceptibility to psoroptic mange in Belgian Blue cattle. Our results clearly indicate that psoroptic mange is under polygenic control and the underlying candidate genes should be studied more thoroughly. This is the first study providing candidate genes for this complex disease. These results are already valuable for Belgian Blue breeding, however, further research is needed to unravel the architecture of this disease and to identify causal mutations.

中文翻译：

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比利时蓝对螨虫的易感性的遗传和基因组分析


由绵羊牛皮癣螨引起的牛皮癣正在影响比利时蓝牛的福利和生产潜力。比利时蓝牛以肌肉发达、饲料转化率低和牛肉品质高而闻名，非常容易感染这种疾病。在这项研究中，我们对来自商业肉牛场 100 多个不同群体的 1975 头比利时蓝牛进行了干癣敏感性表型分析。在这些管理组中观察到显着的个体差异，病变程度差异高达±15%。动物模型显示，病变范围和严重病变范围的估计遗传力较低（分别为 0.07 和 0.09），螨虫数量的估计遗传力为 0.12。一项针对疥癣易感性的全基因组关联研究揭示了 BTA6、BTA11、BTA15 和 BTA24 上的信号。在这些区域中，鉴定出了候选基因 GBA3、RAG2 和 TRAF6。尽管由于筛查时间、病变的不断演变和不同的管理条件而导致牛皮癣表型分析面临挑战，但我们成功地进行了比利时蓝牛牛皮癣遗传易感性的研究。我们的结果清楚地表明，螨虫受多基因控制，应更彻底地研究潜在的候选基因。这是第一项为这种复杂疾病提供候选基因的研究。这些结果对于比利时蓝猫的育种已经很有价值，但是，还需要进一步的研究来揭示这种疾病的结构并确定因果突变。