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

农场疾病的准确和系统记录受到许多环境因素的影响，包括数据记录实践、畜群管理和病原体暴露。因此，病害性状的遗传力很低，一般在5%以下。另一方面，免疫应答（IR）性状起着控制疾病的作用，并且对每只动物更好地定义，具有更高的遗传力（~25%）。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，但与直接选择特定疾病或单一病原体相比，选择IR可能是一种更强大的方式来增加对广泛病原体的抗性。免疫系统旨在控制传染病，具有强大免疫反应的个体预计具有健康优势。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奶牛已被证明具有较低的疾病风险，包括乳腺炎，这是奶牛最昂贵的疾病。HIR动物预计需要较少的治疗干预，包括抗生素，从而改善牛奶和肉类质量。提高对HIR技术的理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，用于免疫应答的基因组评价。这项研究的结果有望为遗传和基因组选择指数中潜在的免疫反应性状提供新的见解，以改善动物固有的健康，食品质量和农场盈利能力。

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.