|Carroll, Jeffery - Jeff Carroll|
|Dailey, Jeffery - Jeff|
|Welsh Jr, Tom|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 12/15/2008
Publication Date: 2/2/2009
Citation: Burdick, N., Carroll, J.A., Randel, R., Vann, R., Caldwell, L., Hulbert, L.E., Dailey, J.W., Ballou, M., Welsh Jr, T. 2009. Sexually dimorphic secretion of cortisol but not catecholamines in response to an endotoxin challenge in beef cattle [abstract]. Annual meeting of the Southern Section of American Society of Animal Science in Atlanta, GA, on Jan 31 - Feb 4, 2009. Journal of Animal Science. 87(Supplement 2):21. Abstract #63.
Technical Abstract: This study was designed to determine the effect of endotoxin (lipopolysaccharide; LPS) challenge on secretion of the adrenal stress-related hormones cortisol, epinephrine, and norepinephrine in bull and heifer calves. Brahman calves (n = 12; 269 ± 11.7 kg) were randomly selected from the fall 2007 calf crop at the Texas AgriLife Research Center in Overton, TX, and transported 770 km to New Deal, TX. The following day calves were fitted with indwelling jugular catheters and allowed to rest overnight. Blood samples were collected the next day every 30 minutes beginning 4 hours prior to and continuing 8 hours after LPS administration (i.v., 0.25 micrograms/kg BW; 6 bulls and 6 heifers). Serum cortisol and plasma epinephrine and norepinephrine concentrations were determined by RIA and EIA, respectively. Data were analyzed using the ANOVA procedure of SAS specific for repeated measures as appropriate (SAS; Cary, NC). During the 4-hour period prior to LPS administration, heifers tended (P = 0.10) to have greater concentrations of cortisol than bulls. Serum concentration of cortisol was increased from time 0 through 2.5 hours after administration of LPS before declining (P < 0.01). During this time period heifers had greater concentrations of cortisol than bulls (P = 0.05). Following peak values, cortisol concentrations declined through 8 hours and were not affected by sex (P > 0.05). Epinephrine and norepinephrine concentrations were not affected by sex prior to LPS administration (P > 0.05). Following LPS administration epinephrine concentrations increased and peaked at 0.5 hours (P < 0.01) before returning to baseline values and were not affected by sex (P > 0.05). Norepinephrine concentrations increased and peaked at 1 hour in heifers and at 1.5 hours in bulls post-LPS administration. However, concentrations of norepinephrine post-LPS administration were not affected by sex (P > 0.05). These data suggest a sexually dimorphic response of the adrenal cortex, but not the medulla, to an endotoxin challenge in beef calves.