|Carroll, Jeffery - Jeff Carroll|
|WELSH JR., TOM|
Submitted to: Joint Abstracts of the American Dairy Science and Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/18/2009
Publication Date: 10/18/2009
Citation: Hulbert, L.E., Carroll, J.A., Ballou, M., Dailey, J.W., Caldwell, L., Loyd, A., Burdick, N., Vann, R., Welsh Jr., T., Randel, R. 2009. A comparison of measures of stress following administration of either lipopolysaccharide (LPS) or corticotropin-releasing hormone (CRH) to Brahman bulls and heifers [abstract]. Annual meeting of the American Dairy Science Association, July 12-16, 2009, Montreal, Canada. Journal of Animal Science 87(E-Supplement 2):#22.
Technical Abstract: A better understanding of cattle responses to various stressors is needed for production and health improvement, yet it is often difficult to decipher if stressor-specific physiological effects are neuroendocrinological, immunological, or both. The objective of this study was to compare and contrast the temporal aspects of rectal temperature (RT), heart rate (HR), white blood cell (WBC) counts, and WBC differentials following either a LPS or CRH challenge. Brahman heifer (H) and bull (B) calves were fitted with indwelling jugular catheters, HR monitors, and RT devices. The following day, calves were challenged with an i.v. bolus of LPS (0.25 micrograms/kg BW; H:n=6, B:n=5) or CRH (0.5 micrograms/kg BW; H:n=6, B:n=6). Blood samples were collected at 1 h intervals from 2 h prior to challenge through 8 h, and at 12 and 24 h. Blood was analyzed using a Cell Dyn for WBC (106 cells/mL) and differentials. HR (beats per min, bpm) and RT (°C) data were continuously collected from 10 h before to 24 h following challenge and were averaged into 10-min intervals prior to analysis. Data were analyzed using ANOVA specific for repeated measures. Baseline measures were defined as data collected prior to the challenge and were averaged and used as a covariate. The first increase in RT from baseline (P less than or equal to 0.01) was at 1 h and 7 h for LPS and CRH, respectively. A peak in RT was observed at 4.5 and 9.3 h following LPS and CRH, respectively, returning to baseline for both treatments by 21 h (P less than or equal to 0.10). Increases (P less than or equal to 0.01) in HR above baseline were observed at 1.5 h after LPS and 2 h after CRH. Overall, HR was 26±0.1% greater (P less than or equal to 0.05) in LPS- than CRH-treated calves from 2.7 to 7.2 h, with both returning to baseline by 23 h (P greater than or equal to 0.10). After LPS, WBC and neutrophil:lymphocyte (N:L) ratio decreased from 1 to 5 h with a recovery above baseline (P less than or equal to 0.01) observed at 8 h. In contrast, WBC and N:L ratio increased 3 to 4 h post-CRH (P less than or equal to 0.01). Based upon the parameters evaluated in the current study, a CRH-simulated stress and an acute immunological stress induced by LPS elicit uniquely different physiological and immunological responses.