Sunday, August 30, 2009

how does GIFT reports look at across fibre SD to eliminate the environmental effects.

Paul Vallely answers this question on a recent forum

Firstly, the issue of Across Fibre SD (AFSD). AFSD does not tell us what part of the AFD is influenced by environment. If we test a sample and it comes back with an average fiber diameter of 20 microns, AFSD does not tell me how much of the 20 microns is genetically influenced, and how much is environmentally influenced. AFSD, however, tells me how much of the overall SD or CV in the test report is influenced by genetics and how much is influenced by environment.

It does this quite simply. In a sample, there are two forms of variation in diameter that make up SD or CV. Firstly, there is the change in diameter along each fiber. This change in diameter is determined by variation in nutritional intake by the follicles. This ‘along fiber’ variation is therefore environmentally influenced. Secondly, there is variation in the average diameter of each of the fibers in a fiber/follicle group or bundle. This variation in the diameter of each of the fibers in the group is largely determined by the follicle make-up in the follicle group. This degree of variation is repeatable over the fleece (although the overall average will change). The difference in the average of each of the fibers in the sample is therefore largely genetically influenced.

With new technology, we can measure the variation both along the fibers and between the fibers, thereby separating the environmental influence from the genetic influence upon the overall SD or CV.

This has tremendous benefits in identifying alpacas that are genetically capable of lowering the incidence of coarse fibers over the fleece (which is one of the major problems in processing alpaca fiber).

The other thing Raelene has mentioned is the cost benefits of growing fine micron fleeces. In Australia, we have tapped into a lucrative ‘top end’ fashion market. When I was in Italy earlier this year, I saw a suit made with wool/alpaca blend. The suit had a price tag of $AUS 37,000. The fabric was absolutely magic. Tapping into this market has enabled us to pay $60 per kilo for under 19 microns, whereas 23 micorn was selling for only $4.00. This price premium is also reflected in the ultrafine wool market where 4 microns is the difference between $150 per kilo and $10 per kilo.

My business is now conducting workshops aimed at showing alpaca breeders how to breed for ‘Premium Fleeces’. In fact I have always believed the intrinsic properties of alpaca fiber combined with the enviro/welfare nature of its production and the luxurious image associated with ‘alpaca’ ensure that the top end fashion industry is the rightful place of alpaca fiber.

Raelene also mentioned SRS. On this point, I should mention that we also operate a sheep wool testing laboratory as well as breed merino sheep. SRS has largely lost popularity in the Australian wool industry. This is mainly due to a lack of understanding of the concept of soft rolling skin (a concept that actually pre-dates Jim Watts) and a mass of misinformation being paddled by ‘professional consultants’. The misuse of follicle testing is a prime example. In fact the University of Adelaide who used to do a lot of skin testing for American alpaca breeders, has now closed this service, partly because they were concerned at how the practice was being used.

A classic example is that secondary to primary ratios is only moderately heritable and is unlikely to show significant improvement in trait selection. In fact pre/post natal nutrition will probably have a greater impact on sec/pri ratios than what you can achieve through breeding. To put a further point on this, it is not the ratio that is important in fiber production, but the incidence of coarse fibers that is more crucial – and this is achieved through AFSD which is about twice as heritable as sec/pri ratios.

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