Physiological, Behavioral, and Biochemical Responses to Restraint Stress in Cattle

Stress has a significant impact on animal health and productivity and public perception of animal stress can influence industry practices. Understanding stress responses in livestock may help reduce stressful management procedures and facilitate the selection of stress-tolerant animals. In this study, behavioral responses (chute entry order, chute behavior, and exit velocity), physiological responses (serum cortisol and neutrophil to lymphocyte (N/L) ratios), and biochemical responses (global patterns of kinase-mediated phosphorylation) were evaluated in cattle (n = 20) subjected to three 5-minute restraint periods, with one week intervals. Correlations among stress responses were assessed across all animals as well as for two sub-groups (n = 4/group) selected on the basis of either high or low serum cortisol levels. Across all animals, both entry order and exit velocity were positively correlated with serum cortisol levels. However, these correlations were not consistently reproducible for the sub-groups of high and low serum cortisol responders. Kinome profiles of peripheral blood mononuclear cells (PBMCs) revealed distinct signaling events in high and low cortisol responders and these pathways were independently validated, confirming changes in glycogen metabolism and apoptosis. Levels of serum glucose, as suggested by kinome data, provided a reliable and inexpensive indicator of serum cortisol levels in healthy calves and was significantly (p < 0.05) correlated with other physiological and behavioral responses to restraint. Habituation or sensitization of stress responses during replicate restraint events was also evaluated across all 20 animals as well as within the high and low serum cortisol sub-groups. Serum cortisol levels displayed a pattern consistent with sensitization, while no habituation or sensitization pattern was observed for serum glucose levels, N/L ratios, or behavioral responses. Collectively, this investigation provides insight into correlations among physiological, behavioral, and biochemical responses of cattle subjected to a brief restraint. These responses may provide biomarkers for the selection of stress tolerant animals