Characterization and Identification of Circulating Stress Biomarkers Associated with the Holstein Stress and Tolerance Response to Bacterial Lipopolysaccharide
Genetic selection of dairy cattle for improved stressed resiliency is one strategy for mitigating the harmful effects of stressors. With global temperatures increasing, there has been greater survival and distribution of pathogens within the environment. The hypothalamic-pituitary-adrenal (HPA) axis is responsible for regulating the host immune response, to ensure efficient pathogen clearance with minimal tissue damage, and for restoring homeostasis after stress event, which includes tissue repair. The purpose of this thesis was to develop an in-vivo bovine model of stress involving bacterial lipopolysaccharide (LPS) and to evaluate a comprehensive panel of stress biomarkers. Additionally, we sought to investigate the presence of an innate immune tolerance response in dairy heifers after repeated LPS challenges. Assessing the dynamic changes of stress biomarkers in response to an initial and repeated LPS challenge will help to characterize the kinetics of the stress response and identify biomarkers for genetic selection of stress resilient animals.