EFFECTS OF CORTISOL ON IN-VITRO INTERFERON-GAMMA PRODUCTION, ACUTE-PHASE PROTEINS, GROWTH, AND FEED-INTAKE IN A CALF CASTRATION MODEL

The objective of this study was to determine the effects of castration , with its presumed pain and inflammatory effects, including increased cortisol, and elevated cortisol per se on in vitro interferon-gamma ( IFN-gamma) production, ADG, ADFI, and plasma haptoglobin and fibrinoge n. Thirty Friesian bull calves (174 +/- 3.8 kg) were assigned to three treatments (given on d 0): 1) control(CON); 2) i.v. cortisol administ ration to mimic castration-induced increases in cortisol(CORT); and 3) surgical castration (SURG). Blood samples were collected for 12 h on d 0 and at 24 and 72 h after treatment for cortisol determination. Key hole limpet hemocyanin (KLH)- and concanavalin A (Con Al-induced in vi tro IFN-gamma production in blood, and plasma haptoglobin and fibrinog en were measured in blood samples taken before treatment on d 0 and on d 1 and 3. On d 0, CORT and SURG animals had higher peak cortisol (P < .001) and area under the cortisol curve (P < .001) than CON animals. There were no differences (P > .05) between CON, CORT, and SURG anima ls in cortisol at 24 and 72 h. There were no differences (P > .05) bet ween CON and CORT animals in IFN-gamma production, haptoglobin, fibrin ogen, ADG, and ADFI. Compared with CON animals, SURG animals had lower (P < .05) KLH-induced IFN-gamma on d 1 and CON A-induced IFN-gamma on d 1 and 3. Haptoglobin concentrations were greater (P < .05) for SURG than for CON animals on d 1 and 3. Fibrinogen concentrations were gre ater (P < .001) for SURG than for CON animals on d 3. The SURG animals had lower (P < .01) ADG and ADFI during d 0 to 7 than CON;animals. In conclusion, castration decreased IFN-gamma production, ADG, and ADFI and increased haptoglobin and fibrinogen, and these effects seemed to be independent of plasma cortisol concentrations.