Friday, February 10, 2012

Alpaca Fleece- Fibre density

Fibre density is one of the most misunderstood traits of alpacas. High fibre density is strongly correlated with low average fibre diameter. Conversely, low density is strongly correlated with high fibre diameter. By the way, science to date has shown us there is little causal relationship between the two traits - in other words, there is something deeper occurring that influences their relationship. The problem is that broad fibre will feel denser than finer fibre because of its greater mass. In other words, a broad fleece will feel denser because of its diameter, than a finer fleece, even though the finer fleece is likely to be more dense.

Performance trials with sheep and alpacas have shown that comparing fleeces using an index on fleece weight with AFD is the most effective way to increase fleece value and will have a positive effect on density.

The most effective traits to breed for are fibre diameter and standard deviation because they are the most important traits in terms of processing performance. The positive coincidence is that these two traits are the two most heritable fibre traits.  Heritability scores of about .55 and .40 respectively. Fibre density is about .30.

Paul Valleley

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