Influence of temperament and transportation on physiological and endocrinological parameters in bulls

Authors: Sanchez, Nicole; Carroll, Jeffery - Jeff Carroll; RANDEL, RON - Texas Agrilife Research; WILLARD, SCOTT - Mississippi State University; VANN, RHONDA - Mississippi State University; Chase, Chadwick - Chad; LAWHON, SARA - Texas A&M University; Hulbert, Lindsey; WELSH JR, TOM - Texas A&M University

Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2011
Publication Date: 6/15/2011
Citation: Burdick, N.C., Carroll, J.A., Randel, R., Willard, S., Vann, R., Chase, C.C., Lawhon, S., Hulbert, L.E., Welsh Jr, T. 2011. Influence of temperament and transportation on physiological and endocrinological parameters in bulls. Livestock Science. 139:213-221.

Interpretive Summary: A collaborative effort was undertaken by scientists from the Livestock Issues Research Unit, Texas A&M University, Texas AgriLife Research-Overton, Mississippi State University, and the Subtropical Agricultural Research Station to determine the influence of temperament on the response of bulls to transportation. Transportation is a common management procedure that young beef cattle may experience. There have been conflicting reports on whether transportation increases stress hormones. Therefore, we utilized automatic sampling devices to monitor rectal temperature and heart rate, and collect blood samples during transportation. These automated sampling devices allowed for the collection of samples in the absence of humans and during transportation when samples normally cannot be obtained. The results from this study demonstrate that although some responses could be attributed to handling or temperament, transportation did not result in similar responses between temperament groups. Rectal temperature and heart rate were not affected by transportation, but the heart rate of temperamental bulls fluctuated throughout the study. Concentrations of the stress hormones cortisol and epinephrine were greater in temperamental bulls. Additionally, cortisol concentrations increased in response to transportation only in calm bulls. Temperament did not influence peripheral blood mononuclear cell function or gene expression, and there were limited effects of transportation on immune function. While transportation has purported to be a stressor in cattle, our data indicates that the process of loading and unloading may be more stressful than the transportation event itself. Future studies need to elucidate the potential influence of temperament on stress responses to loading, transporting, and unloading beef cattle. This data will be of interest to scientists working in the fields of stress physiology and immune function as well as cattle producers, and can be used to modify protocols for transporting cattle.

Technical Abstract: This study measured physiological, immunological, and endocrinological responses to transportation. Based on temperament score (TS), the 7 most calm (TS = 0.84 +/- 0.03) and 8 most temperamental (TS = 3.37 +/- 0.18) Brahman bulls were selected from our research herd. Prior to transportation, bulls were fitted with heart rate monitors, indwelling jugular vein catheters, and rectal temperature recording devices that enabled continuous collection of data and samples during transport. Bulls were loaded into individual stalls in a trailer, and each catheter extension was attached to an IceSampler device that was programmed to collect blood samples at 15- and 30-min intervals. The trailer remained stationary for 120 min prior to the initiation of transportation to acclimate bulls to the stalls. The bulls were then transported for 4 h (390 km roundtrip; average of 91 km/h). Collected blood samples were analyzed for cortisol, epinephrine, and norepinephrine. Additional blood samples were collected for isolation of peripheral blood mononuclear cells (PBMCs) to determine proliferation, IgM production, and gene expression. Rectal temperature increased over time (P < 0.01) but was not affected by temperament (P > 0.05). Change in rectal temperature may be partially attributable to the change in ambient temperature as the two were highly correlated (r = 0.73 and 0.72 for calm and temperamental bulls, respectively; P < 0.001). Heart rate fluctuated in temperamental (P < 0.01) but not in calm bulls (P > 0.05) throughout the study. Cortisol concentrations increased in calm (P < 0.05) but not temperamental bulls (P > 0.05) in response to transportation. Epinephrine concentrations were unchanged in calm (P > 0.05) but decreased in temperamental bulls (P < 0.05) throughout the study. Norepinephrine concentrations were not affected by transportation (P > 0.05) or temperament (P > 0.05). The production of IgM by PBMCs was not affected by temperament (P > 0.05) or transportation (P > 0.05). Proliferation of PBMCs was not affected by temperament (P > 0.05), but tended to be greater post-transportation (P = 0.06). The expression of the glucocorticoid receptor (P = 0.02) and toll-like receptor 4 (P = 0.08) mRNAs decreased in response to transportation. In summary, these data indicate that transportation only affected cortisol concentrations in calm bulls. Additionally, temperament influenced cortisol and epinephrine concentrations as well as heart rate. However, there was no influence of temperament, and limited influence of transportation, on PBMC functions. While transportation has been purported to be a stressor in cattle, our data indicate that the process of loading and unloading cattle may be more stressful than the transportation event itself.