|Willard, Scott -|
|Vann, Rhonda -|
|Randel, Ron -|
|Welsh JR., Tom -|
Submitted to: Innate Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 28, 2010
Publication Date: August 5, 2011
Citation: Burdick, N.C., Carroll, J.A., Hulbert, L.E., Dailey, J.W., Willard, S.T., Vann, R.C., Randel, R.D., Welsh Jr., T.H. 2011. Temperament influences endotoxin-induced changes in rectal temperature, sickness behavior, and plasma epinephrine concentrations in bulls. Innate Immunity. 17(4):355-364. Interpretive Summary: A collaborative study was conducted involving scientists from the Livestock Issues Research Unit, Texas AgriLife Research and Extension Center-Overton, Texas AgriLife Research-College Station, and Mississippi State University to elucidate the stress hormone profiles in cattle with various temperaments following an intravenous challenge with an endotoxin. Due to the interaction between temperament and stress responsive hormones, we hypothesized that more temperamental bulls would have a reduced stress hormone response to the endotoxin. Therefore, this study was designed to determine the influence of temperament on the febrile response and the production of cortisol and epinephrine in response to an endotoxin challenge in young, growing Brahman bulls. Results from this study clearly demonstrated that endotoxin induces the secretion of the stress hormones cortisol and epinephrine, and increases rectal temperature. While rectal temperature and epinephrine differentially responded based on temperament of the bulls, temperament did not affect the response of the adrenal cortex to endotoxin challenge. However, it is not yet clear whether the diminished febrile response and failure to produce an epinephrine response to LPS challenge affects immune responsiveness of temperamental bulls. Future studies will be needed in order to determine if temperament affects specific parameters associated with the innate immune response to an endotoxin challenge. A clear understanding of the interrelationship between stress hormones and the immune system to early inflammation may lead to methods of early intervention to minimize the debilitating impacts of illness on growth and productivity. This information will be of interest to scientists working in the fields of innate immunity, stress regulation, and the influence of animal temperament on stress and immune responses.
Technical Abstract: This study was designed to determine the influence of temperament on endotoxin (lipopolysaccharide; LPS) induced changes in body temperature and the secretion of cortisol and epinephrine. Purebred Brahman bulls were selected based on temperament score (average of exit velocity, EV, and pen score, PS) measured 28 d prior to weaning, with the 6 most calm (1.01 ± 0.16 EV and 1.00 ± 0.00 PS), 7 most temperamental (3.51 ± 0.25 EV and 5 ± 0.00 PS), and the 8 most intermediate (1.59 ± 0.12 EV and 2.25 ± 0.16 PS) selected from a pool of 60 bulls. Bulls were fitted with rectal temperature recorders that measured at 1-min intervals and indwelling jugular catheters were placed in all bulls. Blood samples were collected and serum isolated every 30 min beginning 2 h prior to and 8 h after administration of lipopolysaccharide (0.5 ug/kg) for determination of cortisol (by RIA) and epinephrine (by EIA) concentrations. Prior to the administration of LPS, temperamental bulls had greater concentrations of cortisol than calm or intermediate bulls (P < 0.05). Cortisol concentrations increased in all bulls following LPS administration and there was no difference in the response due to temperament. Epinephrine concentrations peaked 1 h post-LPS administration in calm and intermediate bulls (P < 0.05). Concentrations of epinephrine were greater in temperamental bulls than calm and intermediate bulls prior to LPS administration and following peak epinephrine concentrations (P < 0.05). Temperamental bulls did not exhibit an epinephrine response to LPS challenge. Therefore, temperament differentially affected the response of the adrenal medulla, but not the adrenal cortex, to endotoxin challenge. These data suggest that temperament affects the degree of response to an endotoxin challenge. Future research may lead to methods of early intervention to minimize the negative impacts of illness on growth and production.