Interactions between stress and immune responses in cattle

Authors: Carroll, Jeffery - Jeff Carroll; Sanchez, Nicole; Broadway, Paul

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/20/2015
Publication Date: 5/5/2015
Citation: Carroll, J.A., Sanchez, N.C., Broadway, P.R. 2015. Interactions between stress and immune responses in cattle. Meeting Abstract. Phibro Animal Health and MiXscience OmniGen Day abstract book.

Interpretive Summary:

Technical Abstract: Cattle are frequently exposed to a variety of stressors at various magnitudes throughout production that may be potentially detrimental to overall health and productivity. The most commonly encountered stressors include social stressors (e.g., isolation, commingling with a novel herd), psychological stressors such as novel surroundings or interactions with unfamiliar humans or animals (e.g., barking dog), nutritional stressors (e.g., inadequate diets or contaminated feed), physical stressors such as frequent movement through facilities and/or inappropriate animal handling techniques, and immunological stressors such as pathogen exposure or wounds. Ideally, elimination of all stressful stimuli would enhance overall health and productivity; however, the creation of a "nirvana" production environment is unrealistic. Fortunately, the biological system is designed to allow animals to survive and flourish in an imperfect and dynamic environment where stressors are present. For instance, researchers have demonstrated that the combined immunological effects of glucocorticoids and catecholamines, the two most prominent stress mediators in cattle, result in a well-orchestrated biological event. This intricate bi-direction communication pathway is designed to prevent over-stimulation of the innate immune response and pro-inflammatory cytokine production while simultaneously priming the humoral immune response in an effort to provide adequate immunological protection. In a recent study, our team evaluated this complex relationship between the stress axis and immune system in weaned beef steers exposed to two dexamethasone-challenge models designed to mimic acute and chronic exposure to a stressor to evaluate the impact on the immune response after vaccination. The results, based on some aspects of the immunological parameters measured in the acute stress model, indicate that the immune system may have indeed been primed, thereby preparing the steers for subsequent immunological insults. In the chronic stress model, it appeared that some aspects of the immune response were hyper-activated, while other aspects of the immune response, such as neutrophil activity and function, were clearly suppressed. Interestingly, in both the acute and chronic stress models, antibody titers to the vaccination were either greater than or not different from control steers. These data suggest that either both the acute and chronic stress models caused immunosuppression that allowed enhanced viral replication resulting in increased antibody titer responses, or the chronic stress model elicited more of a priming effect similar to the acute stress in response to vaccination which enhanced antibody titer response. Alternatively, the acute stress model may have primed, while the chronic stress model suppressed, the humoral immune response, resulting in enhanced antibody titer responses via two very different modes of action. Data from this study highlight the importance associated with the interwoven physiological mechanisms responsible for propagation, regulation, and the attempt to maintain homeostatic balance associated with stress and immunity in cattle. These data also demonstrate how this symbiotic relationship can play an important role with regard to health and ultimate productivity in cattle. Continued research efforts to elucidate these complex interactions may allow for the conception and implementation of alternative management practices, improved selection programs, and/or implementation of various nutritional strategies to prevent or minimize significant production losses and animal health care costs for livestock producers, thus enhancing overall animal health and profitability.