Cashmere goats exhibit seasonal cycles in hair growth and moulting which are an evolutionary response to seasonal changes in temperature. The winter coat of the cashmere goat consists of two types of fibre, a coarse outer coat of guard hair produced by the primary hair follicles and a dense Insulating undercoat of cashmere (<19 microns diameter) produced by the smaller and more numerous secondary follicles. In the Spring, under the influence of Increasing daylength, both guard hairs and cashmere are shed from the follicles and a sparse coat of guard hair remains.

The efficiency of harvesting fibre from cashmere goats is limited by the season of the moult, the long duration of the moulting period and by the variability between individual animals in the timing of the moult. Lynch & Russel (1989) reported that an earlier rise in plasma prolactin was associated with an advance In the onset of the spring moult in the cashmere goat.