Genetic and genomic approaches to improve dairy health, food quality and farm profitability through enhanced immune response

准确和系统地记录农场疾病取决于许多环境因素，包括数据记录做法、牛群管理和病原体暴露。因此，疾病性状的遗传力很低，一般在5%以下。另一方面，免疫反应(IR)特征具有控制疾病的功能，对于遗传率高得多的动物(~25%)，免疫反应(IR)特征被更好地定义。因此，虽然疾病记录是验证任何改善健康的选择策略的先决条件，但对IR的选择可能比对特定疾病或单一病原体的直接选择更有效地增加对广泛病原体的抵抗力。免疫系统的设计是为了控制传染病，免疫反应强劲的人预计会有健康优势。在圭尔夫大学，研究人员开发了一种专利测试系统，以识别具有平衡和增强或高免疫反应(HIR)的动物。HIR奶牛已被证明患疾病的风险较低，包括乳房炎，这是奶牛最昂贵的疾病。预计HIR动物需要较少的治疗干预，包括抗生素，从而改善牛奶和肉类的质量。提高对HIR技术了解的下一个关键步骤是进行全基因组关联研究，以确定与各种IR表型相关的潜在遗传标记，并创建具有IR表型和基因型的奶牛参考群体，用于免疫反应的基因组评估。这项研究的结果有望为免疫反应特征在遗传和基因组选择指标中的潜在应用提供新的见解，以改善固有的动物健康、食品质量和农场利润。

Accurate and systematic recording of on-farm disease is subject to many environmental factors, including data recording practices, herd management and pathogen exposure. As a result, the heritability of disease traits is quite low, generally below 5%. Immune response (IR) traits, on the other hand, function to control disease and are better defined for each animal with a much higher heritability (~25%). Therefore, while disease recording is a prerequisite for the validation of any selection strategy to improve health, selection for IR is likely to be a more powerful way to increase resistance to a broad range of pathogens than direct selection for a particular disease or single pathogen. The immune system is designed to control infectious disease and individuals with robust immune response are expected to have health advantages. At the University of Guelph, researchers have developed a patented test system to identify animals with a balanced and enhanced or High Immune Response (HIR). HIR dairy cattle have been shown to be at lower risk of diseases, including mastitis, the mostly costly disease of dairy cows. HIR animals are expected to require less therapeutic intervention, including antibiotics, thereby improving milk and meat quality. The next critical step to improve understanding of the HIR technology is to perform genome-wide association studies to determine potential genetic markers associated with the various IR phenotypes and to create a reference population of cows with IR phenotypes and genotypes for genomic evaluation of immune response. The results of this study are expected to provide novel insight into the potential inclusion of immune response traits in genetic and genomic selection indices to improve inherent animal health, food quality and farm profitability.