ENHANCING ANIMAL WELL-BEING, IMMUNOCOMPETENCE, AND PERFORMANCE IN SWINE AND BEEF CATTLE
Location: Livestock Issues Research
Title: Bovine acute-phase response following different doses of corticotrophin-releasing hormone (CRH) challenge
Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: February 25, 2011
Publication Date: August 11, 2011
Citation: Cooke, R.F., Carroll, J.A., Cooke, F.N., Cappellozza, B.I., Trevisanuto, C., Tabacow, V.D., Dailey, J.W., Bohnert, D.W. 2011. Bovine acute-phase response following different doses of corticotrophin-releasing hormone (CRH) challenge [abstract]. Journal of Animal Science. 89:518(E-Suppl. 1).
Fourteen weaned, halter-trained Angus steers (BW = 191 ± 2.1 kg) were fitted with indwelling jugular catheter and rectal temperature monitoring device on d -1 of the study. On d 0, steers were ranked by body weight and randomly assigned to receive 1 of 3 infusion treatments (i.v.): 1) 0.1 micrograms of bovine CRH/kg of BW (CRH1), 2) 0.5 micrograms of bovine CRH/kg of BW (CRH5), and 3) 10 mL of saline. Blood samples were collected via catheters, relative to treatment infusion (0 h), hourly from –2 to 0 h and 4 to 8 h, and every 30 min from 0 to 4 h. Rectal temperatures were recorded every 30 min from -2 to 8 h relative to infusion. Blood samples were collected via jugular venipuncture and rectal temperatures were assessed using a digital thermometer every 6 h from 12 to 72 h, and every 24 h from 96 to 168 h. Samples collected from -2 to 8 h relative to CRH infusion were analyzed for plasma concentrations of cortisol, ceruloplasmin, and haptoglobin, whereas samples collected from 12 to 168 h were analyzed for plasma concentrations of ceruloplasmin and haptoglobin only. Plasma cortisol peaked at 0.5 h for CRH1 steers (58.9 ng/mL) but returned to baseline levels at 1 h relative to infusion (time effect; P <0.01). Within CRH5 steers, plasma cortisol peaked at 0.5 h (51.3 ng/mL) and returned to baseline levels 3 h relative infusion (time effect; P < 0.01). Plasma cortisol concentrations did not change after infusion for saline steers (time effect; P = 0.42). Rectal temperatures were greater (P < 0.05) for CRH1 steers compared to CRH5 and saline steers at 36 and 42 h relative to challenge. Plasma haptoglobin concentrations in CRH1 steers increased significantly and were greater (P < 0.02) compared to CRH5 and saline steers from 48 to 96 h relative to challenge (time effect; P < 0.01). Conversely, plasma haptoglobin concentrations were similar (P > 0.23) and did not change across time for CRH5 and saline steers (time effect; P > 0.48). No treatment effects were detected on plasma ceruloplasmin concentrations. In conclusion, both CRH5 and CRH1 increased plasma cortisol concentrations, but only CRH1 elicited an acute-phase protein response in beef steers.