Speaker Notes

Written by: Dr. Brad Crook, The University of New England. 

Source: Schlink, T. (1998). Follicle shutdown and staple strength. CRC for Premium Quality Wool, Wool Biology lecture series.

Primitive sheep have a photoperiod driven follicle cycle that leads to an annual shedding of the fleece. However, Merino shedding appears to be driven by nutrition rather than photoperiod, but this should not be ignored. It is important to be aware of follicle shutdown as it results in increased length variation within the staple and consequently, lower staple strength.

These scanning electron micrographs show the difference between fibres that have been broken and fibres that have been shed from the follicle. The magnification of the photos are different and both fibres actually have the same fibre diameter at the point of break. When examining staples and fleeces for shed fibres the staples are washed in a solvent and then hot water and stained with picric acid (yellow) and eosin (pink). The fibres are then examined with a microscope and the proportion of fibres with IRS (stains pink) still attached to the fibre is estimated. These fibres have been shed from follicles which have shutdown and look like the fibre in the right hand photo.