Assessment and genetics of stress resilience in dairy cattle

奶牛经常受到各种压力，对健康和生育力，福利和生产产生负面影响。健康和气候专家预测，随着气候条件继续不稳定，暴露于压力源（即病原体、真菌毒素和极端温度事件）的情况将增加。由于现在用于预防和治疗牲畜疾病的抗菌剂越来越少，因此需要探索替代策略，例如增加压力恢复力的遗传选择，以增强动物健康;预计压力恢复力动物将更健康，寿命更长，生产力更高。在拟议的研究中，我们计划使用微生物相关分子模式（MAMP）为奶牛开发免疫应激挑战，以便奶牛群体可以进行应激表型分析，这是目前不可能的。然后，这种新的健康表型将被用于计算遗传力估计，探索与其他测量的健康和生产性状的关联，并进行全基因组关联研究（GWAS），以确定与应激反应相关的遗传标记。最后，将评估压力表型动物对气候相关压力源的恢复力。鉴于压力对动物健康和生产的广泛影响，预计这种压力模型的开发将使加拿大育种公司（如SEMEX联盟）能够进行基因组选择，以改善奶牛健康和生产。

Dairy cattle are routinely subjected to a variety of stressors that negatively impact health and fertility, welfare and production. Health and climate experts predict that exposure to stressors (i.e. pathogens, fungal mycotoxins and extreme temperature events) will increase as climate conditions continue to destabilize. Since antimicrobials are now less available for preventing and treating livestock disease, there is a need to explore alternative strategies, such as genetic selection for increased stress resilience, to enhance animal health; it is anticipated that stress resilient animals will be healthier, live longer, and be more productive. In the proposed study, we plan to develop an immune stress challenge for dairy calves using microbial-associated molecular patterns (MAMPs) so that dairy cattle populations can be stress-phenotyped, which is not currently possible. This novel health phenotype will then be used to calculate heritability estimates, explore associations with other measured health and production traits, and carry out a genome-wide association study (GWAS) to identify genetic markers associated with stress responsiveness. Lastly, resilience of stress-phenotyped animals to climate-associated stressors will be assessed. Given the wide-ranging impacts of stress on animal health and production, it is anticipated that development of this stress model will allow Canadian breeding companies such as the SEMEX Alliance to carry out genomic selection to improve dairy cattle health and production well into the future.