Visual and metabolic stimuli cause adrenocortical suppression in fasted chickens during refeeding

Concentrations of corticosterone were determined in the plasma of fasted domestic fowl before and at intervals after refeeding. The deprivation of food markedly increased (p less than 0.001) the level of plasma corticosterone. When refed ad libitum the corticosterone concentration declined (by 70%) within 45 min to the level in fed birds and remained at this concentration thereafter. A similar depression in the corticosterone concentration was observed when fasted birds were merely given the sight of the same diet, although the concentration returned to the fasting level within 60 min of food presentation. Refeeding diets with different metabolic energy contents demonstrated that the duration of the feeding-induced adrenocortical suppression was energy related. In fasted birds the presentation of an inert cellulose diet caused a temporary decline in the corticosterone level. In the absence of visual stimuli the administration (by force feeding) of the inert diet had no effect on the corticosterone concentration, whereas force feeding of metabolizable diets still induced adrenocortical suppression. These results demonstrate that adrenocortical suppression occurs in fasted refed birds and both visual and metabolic stimuli are involved in this response.