Youngerman S M, Saxton A M, Oliver S P, Pighetti G M
Department of Animal Science, The University of Tennessee, Knoxville 37996, USA.
J Dairy Sci. 2004 Aug;87(8):2442-8. doi: 10.3168/jds.S0022-0302(04)73367-6.
The ability to identify objectively cows that are more or less susceptible to mastitis has been a long-standing goal. Genetic markers associated with inflammatory responses during mastitis could aid in selection of these cattle. One potential marker is CXCR2, a chemokine receptor required for neutrophil migration to infection sites, which contains single nucleotide polymorphisms (SNP) within the gene. The objective of this experiment was to evaluate the association of CXCR2 SNP genotypes with subclinical and clinical mastitis. Thirty-seven Holstein and 42 Jersey cows that completed at least 2 full lactations were used. Quarter foremilk samples were collected for bacteriological examination quarterly and when cows exhibited clinical mastitis. Subclinical mastitis was defined as the presence of the same pathogen in the same quarter in at least 2 of 3 consecutive samples. A significant association was detected between CXCR2 SNP +777 genotype and percentages of subclinical mastitis cases in Holsteins. Holsteins expressing genotype GG had decreased percentages of subclinical mastitis, but genotype CC cows had increased percentages of subclinical mastitis. Significant differences in clinical mastitis incidence were not detected between genotypes for either breed. This approach of genetically identifying mastitis resistant cows may represent an effective means of marker-assisted selection for mastitis and other inflammatory diseases involving neutrophils.
客观识别对乳腺炎易感性较高或较低的奶牛的能力一直是一个长期目标。与乳腺炎期间炎症反应相关的遗传标记有助于选择这些奶牛。一个潜在的标记是CXCR2，它是中性粒细胞迁移到感染部位所需的趋化因子受体，该基因内含有单核苷酸多态性（SNP）。本实验的目的是评估CXCR2 SNP基因型与亚临床和临床乳腺炎的关联。使用了37头荷斯坦奶牛和42头泽西奶牛，它们至少完成了2次完整泌乳。每季度以及当奶牛出现临床乳腺炎时，采集前乳区的乳汁样本进行细菌学检查。亚临床乳腺炎定义为在连续3个样本中的至少2个样本中，同一季度存在相同病原体。在荷斯坦奶牛中，检测到CXCR2 SNP +777基因型与亚临床乳腺炎病例百分比之间存在显著关联。表达GG基因型的荷斯坦奶牛亚临床乳腺炎百分比降低，但CC基因型奶牛亚临床乳腺炎百分比升高。两个品种的不同基因型之间在临床乳腺炎发病率上未检测到显著差异。这种通过基因识别抗乳腺炎奶牛的方法可能代表了一种针对乳腺炎和其他涉及中性粒细胞的炎症性疾病进行标记辅助选择的有效手段。
