Psoroptic mange is a severe dermatitis caused by a mite infection with Psoroptes ovis. The lower weight gain, inferior leather quality and treatment costs cause economic losses (Lonneux et al., 1998). Moreover, the animals suffer from itch, crusts andwounds, leading to decreased animal welfare.Belgian Blue cattle are extremely sensitive to this disease (Losson et al., 1999). The breed represents 51% of all cattle in Belgium, corresponding to 1.3 million Belgian Blue animals. A recent questionnaire (Sarre et al., 2012) demonstrates that 75% ofall beef farms in Flanders are confronted with mange. The strong breed predisposition is an indication of contributing genetic factors in the development of psoroptic mange. Therefore a genome wide association study with the 50K bovine SNP-panel will beperformed, which first requires a clear phenotype definition. It is the aim of this study to establish an objective phenotype allowing to differentiate mange susceptible and more resistant animals based on measurable clinical and parasitological parameters. The resulting definition can also be applied to epidemiological studies as a standard to facilitate more efficient sampling in wider geographical areas, since the method is more objective. In addition, a standardized phenotype might allow to combinesmaller datasets in a metaanalysis.
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机译：人工授精是一种严重的皮炎，是由螨虫引起的。较低的增重，较差的皮革质量和处理成本会导致经济损失（Lonneux等，1998）。而且，动物患有瘙痒，结rust和伤口，导致动物福利下降。比利时蓝牛对该病极为敏感（Losson et al。，1999）。该品种占比利时所有牛群的51％，相当于130万比利时蓝动物。最近的问卷调查（Sarre等，2012）表明，法兰德斯所有牛肉农场中有75％面临着管理问题。强大的品种易感性指示了在人类man的发展中有遗传因素。因此，将与50K牛SNP面板进行全基因组关联研究，这首先需要明确的表型定义。这项研究的目的是建立一个客观的表型，以根据可测量的临床和寄生虫学参数来区分易感和抗药性更强的雄性动物。由于该方法更客观，因此所得定义也可以作为标准用于流行病学研究，以促进在更广泛的地理区域内更有效地采样。此外，标准化的表型可能允许在荟萃分析中合并较小的数据集。
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