Variations in Stress and Innate Immune Responses of Cattle: Natural Deviations and Nutritional Influences

摘要

Stress, as it relates to bodily functions, has been defined as the sum of all biologic reactions to physical, emotional, or mental stimuli that disturb an individual's homeostasis. Therefore, a stressor can be defined as any internal or external stimuli or threat that disrupts homeostasis of the body, and elicits a coordinated physiological response in an attempt to reestablish homeostasis. Maintaining a state of homeostasis requires proper functioning of all physiological processes including thestress and immune systems which are influenced by numerous factors including environmental conditions, pathogen exposure, genetic makeup, animal temperament, and nutrient availability. Research related to stress in domestic animals continues to evolve and expand, with emergent multidisciplinary efforts leading to a greater understanding of homeostatic regulation. For the past six-to-seven decades, researchers have continued to more thoroughly explore the complex interactions between stress and production parameters such as growth, reproduction, and health. Additionally, there has been an increased effort to elucidate the interactions between stress responsiveness and immunological parameters in animals that may be either predisposed to or resistant to the detrimental effects of stress due to genetic programming and(or) prior experiences. Of particular interest are animals that demonstrate differential stress and immunological responses due to previous exposure to various managerial, environmental, nutritional, or pathogenic stressors.