Hair fibre represents an important biological process to many feral and domesticated animals, both for environmental protection and as an aid to thermoregulation. Mohair which is the fine fibre produced by secondary hair follicles of the Angora goat grows essentially independent of season, with typical growth rates of 0.5-1 .0mm/day and annual yields typically 2-3kg. In contrast, down production from secondary hair follicles of double coated goats, classified as cashmere, is dependent on season. Fibre grows from around the summer to the winter solstice or later, with growth rates in this period of 0.3-0.7mm/day and annual yields maximally 600g but typically less than 100g. Questions arise as to how the seasonal stimuli affect fibre growth, and what determines the differences in fibre production between the two genotypes at the follicle level.

In the work described here, based on the in vitro isolation and culture technique developed for the Angora and Cashmere goats by Ibraheem et al (1993, 1992 repectively) we have compared fibre volume produced in vivo and in vitro, examined the DNA concentration and protein depositional capacities of mohair and cashmere secondary follicles. In addition the effects of the hormones prolactin and melatonin as mediators of photoperiod in vivo, on in vitro protein deposition in mohair and cashmere secondary hair follicles are also examined.