Technical note: effect of corticotropin-releasing hormone on adrenocorticotropic hormone and cortisol in steers.

摘要: The objective of this study was to determine an appropriate exogenous dose bovine corticotropin-releasing hormone (bCRH) stimulate the physiological effects hypothalamic-pituitary-adrenal axis in steers as a method test sensitivity pituitary and adrenal gland. Twenty 14-mo-old Holstein-Friesian were blocked by weight (443.7+/-2.5 kg) randomly allotted receive either saline (control) or bCRH (0.1, 0.3, 1.0, 1.5 microg/kg BW). Animals housed slatted-floor facility (n = 5 per pen). Indwelling jugular catheters, for both administration blood collection, fitted on d -1 experiment. Saline administered i.v. at time 0. Serial samples collected -15, 0, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150, 165, 180 min relative Following 0.1 microg bCRH/kg BW, peak ACTH response not significantly different from pretreatment baseline concentrations (mean measured -15 0 before administration). Mean following BW (P 0.177) controls. Administration increased < 0.05) above concentrations, mean these treatments greater than Peak cortisol responses all those concentrations. bCRH-treated controls, but there no significant differences among treatments. ratio doses tested differed control values, indicating reactivity adrenals. In conclusion, challenge may be useful testing subjected stressful husbandry conditions, minimum 0.3 is required stressor hormones.