The response of circulating cortisol levels in sheep to various stresses and to reserpine administration

Abstract

The effects of several stresses on circulating cortisol levels in sheep were investigated. The aim was to devise a means of assessing the effects of certain treatments on the response of cortisol to stress. Short periods of fasting proved effective stresses initially but routine applications of this stress resulted in greatly diminished cortisol responses. This change in response was shown to be to some extent reversible. Longer fasts produced very variable changes in cortisol levels, but consistently elevated free fatty acid levels, while shearing and short periods of transportation produced consistent elevations in cortisol levels but variable changes in free fatty acid concentrations. Levels of cortisol following transportation and shearing approximated to those in lambs at slaughter under commercial conditions. The daily administration of 3, 5, or 7 Ilg of reserpine per kilogram body weight for 3 days did not affect basal circulating cortisol levels or the degree of response of these levels to stress. © 1973 CSIRO.