Rams with poor feed efficiency are highly responsive to an exogenous adrenocorticotropin hormone (ACTH) challenge

Abstract

An animal's response to a stressor is to increase metabolic rate, and thus energy consumption through the activation of the hypothalamic-pituitary-adrenal axis. Changes to energy use by an animal are likely to influence the efficiency with which it is utilised. In this study, we tested the hypothesis that less efficient sheep are more responsive to exogenous administration of adrenocorticotropin hormone. This was done by firstly determining the appropriate dose (0.4, 1.6 or 6.4 μg/kg LW) and peak serum cortisol response time (45 min) to exogenous administration of adrenocorticotropin hormone in a pilot study (n = 3 sheep). Following this, adrenocorticotropin hormone (2.0 μg/kg LW) stimulated..