Influence of the Adrenal Cortex on Wool Growth and its Relation to ‘Break’ and ‘Tenderness’ of the Fleece

Abstract

WE were interested to know whether the adrenal cortex exerted a depressant action on wool growth in sheep. Such a mechanism might underlie the decline in wool growth observed in winter¹ and during pregnancy², since cold and gestation are known to increase adrenocortical activity in other species³. The marked increase in the number of active follicles which begins about ten days after birth in the lamb (Ferguson, K. A., Schinckel, P. G., Carter, H. B., and Clarke, W. H., in preparation) may possibly be due to release from adrenocortical inhibition. Field-observations link the occurrence of ‘break’ or ‘tenderness’ of the fleece⁴ with disease, advanced pregnancy or environmental stresses which may be expected to stimulate secretion of adrenocorticotrophic hormone.