Re fibre density
Australian research conducted in 1997 by scientists Ian Purvis and Andrew Swann found that there was only minimal correlation between fibre density and fleece weights. In fact fibre density is more correlated with fibre diameter than fleece weights.
Follicles that produce fibres of low diameter are themselves, lower in diameter. An alpaca that produces genetically fine fibres (and consequently finer follicles) will have higher follicle density on average, than alpacas that produce genetically broad fibres (broader follicles). As the follicles differ greater in diameter within the fibre bundle, we are talking about averages.
Consequently, it has been found that there is a higher density of follicles on sheep (or alpacas) that have fibre and follicles of low diameter. The thinner they are, the greater the number of follicles per square millimeter.
Furthermore, as the fibre diameter varies over the alpaca, so does the follicle density vary over the alpaca.
Because follicle density is such a complex matter, almost all wool producers in Australia weigh the sheeps’ fleeces to find out which are producing more money rather than worry about follicle density.
For those who work on follicle density, they should use GIFT to monitor progress. This is for a number of reasons:
1 To compare alpacas re follicle density, you need to take account of the fibre diameter.
2 Using follicle density will only work if fibres do not vary significantly over the respective alpaca. GIFT will reduce the variation.
In addition to this, by using the ‘across sample variation’ measurement from GIFT, you will increase follicle density because you are breeding for more finer fibres within each fibre bundle (staple).
Hope this helps.
Paul Vallely
Australian Alpaca Fibre Testing
PO Box 246
Crookwell, NSW. 2583
Australia
Ph: (61) 2 48342132
Website: www.aaft.com.au
Email: info@aaft.com.au
