SRS® breeding (see www.srsalpaca.com) is a proven way of improving the overall quality of alpacas. It has been applied successfully to Merino flocks and Angora herds around the world.

The breeding objective is to maximise the density and length of fibres grown by the alpaca. If there are more fibres and longer fibres on the animal's body, fleece weights will increase. And as density increases, the wool becomes sustainably finer in diameter.

The selection methods utilise both visual fleece indicators of density and length as well as measurements of density and length.

The concept is based on the pre-papilla cell research of Moore et al (1998), Pattern and morphogenesis in skin, Journal of Theoretical Biology, 191:87-94, and later unpublished data. This work has shown that the density and fineness of fibres is controlled by the size of the pre-papilla cell clusters (Figure 1) formed in the foetal skin.

High follicle density and fine fibres require small clusters to form from a large starting population of pre-papilla cells. Large clusters produce low follicle density and coarse fibres.

The alpaca originates from two-coated ancestors with an outer coat of course and medulated primary fibres ('guard hair') of about 80 microns diameter and an inner coat of very fine secondary fibres ('down'), about 16 microns in diameter.

The vicuna and guanaco are examples of camelids which still retain this primitive coat.

By selection for fleece quality, the alpaca has moved noticeably toward a single coated animal.However, the two-coated characteristics have been reduced, not eliminated. For example, the primary fibres in many alpacas are still 5 to 10 microns stronger than the secondary fibres.

This indicates to us that our breeding program has to focus on reducing the diameter of the primary fibres to be finer than the secondary fibres, which must also be fine.


At the same time the fibres should be as long as possible.

Fibre length is thought to be regulated by the 'single strength' of mitogen(s) produced by the pre-papilla cells (Figure 2). Strong signals are thought to increase fibre growth rate, and vice versa.

In SRS® sheep breeding, fleece length has already been doubled in 10 years. We anticipate the same may happen with our alpacas.

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Crimp and Fibers

	'High density leads to highly aligned, fine fibres of even size and shape that produce a deep crimping pattern'.
	'High density leads to cylindrical fibres (circular cross-sectional areas) with bilateral segments of ortho-cortex (dark staining) and para-cortex (unstained).
	'High density leads to low scale height. The faster the fibres grow, the further apart are the scale ridges.'
	'Low density leads to entangled fibres of uneven size and shape that produce a poorly defined crimp'.
	'Low density leads to irregularly shaped fibres with uneven distributions of ortho-cortex (dark staining) and para-cortex (unstained).'
	'Low density leads to high scale height. The slower the fibres grow, the closer these 'prickly' scale ridges are.

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