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Resources >> Fleece >> New Fibre Test for Genetic Selection

New Fibre Test for Genetic Selection

by Paul Vallely - AAFT

Many breeders will testify that attempting to predict how progeny will perform based on observable traits of the sire and dam can be extremely frustrating, almost to the point where breeders start to lose their own fibre. This is in no small part due to Mother Nature’s surprise packages such as the phenomenon of genetic mutation, the effect of recessive genes with the impending ambush from relying on traits with low heritability. And that’s only the start.

The effects from environmental influences can be one of the greatest hindrances to predicting which phenotype traits of breeding stock will pass onto their progeny. It can be argued that a sire or dam’s fibre traits will be influenced by environmental factors as much as they are influenced by genetics. 

Given many breeders rely heavily on fibre testing to select breeding stock, how can we decipher which parts of the fibre test results have a chance of being passed onto a breeding animal’s progeny, and which are nothing more than a reflection of what has passed down the animal’s throat.

There is a solution. Recent advances in fibre measurement technology now mean we can isolate the genetic aspects of one of the key fibre traits – fibre diameter variability.

Firstly, the question of why is fibre diameter variability such a big deal.

To effectively compete in today’s apparel markets, natural fibres need to feel soft against the skin. Any significant evidence of coarse or prickly fibres will result in substantial discounts or may not be tolerated at all. This is particularly the case for the potentially lucrative ‘high-end’ apparel markets.

In addition to this, a high variation of fibre diameter may result in irregularities in the various stages of processing. This problem leads to eventual cost inefficiencies and inferior end-product. 

In June 2005, Francis Rainsford, President of the International Alpaca Association, reported on “Mounting concerns being expressed in Peru over the steady increase of coarser alpaca fibre (31microns+)”. Francis Rainsford also refers to a US$1m project aimed at reversing the trend towards “coarse and hairy fibre production” by developing improved breeding strategies.

A major fibre processor recently agreed to this in stating ‘it didn’t matter whether they were primary or secondary fibres, medullated fibres, kemp, guard hair or whatever else – if there was a high level of coarse fibres, the raw product could be rendered irrelevant’.

At the 2006 National Alpaca Fibre Seminar, one knitwear designer confessed her reluctance to use natural fibres that exhibited high levels of broad micron fibres.

It has been continually shown that this problem is not so much a result of fleece classing. It is mainly due to the fact that the offending fibres are found right throughout the fleeces. This has been noticed with the fleeces for the alpaca ultrafine bale scheme. Although they represent the most superior fleeces to be found in Australia and are subjected to a most fastidious classing procedure, we are still finding far too many coarse fibres in the consignments.

The message is clear – to improve our product, breed out coarse fibres.

The best method to identify fleeces with coarse fibres is to determine the extent to which the diameter of individual fibres vary on the fleece. A higher than normal variation will pinpoint fleeces with higher than normal amount of coarse fibres.

A further aspect of fibre diameter variation is that research (Vic DPI 2007) indicates animals with low variation measurements are more likely to have less variation in fibre diameter over the whole fleece. Our own experience supports this research. In other words, by breeding for low diameter variation, not only does the fibre become more valuable, there becomes more useable fleece on the respective animals. 

Anecdotal evidence also suggests these animals are less prone to ‘micron blow-out’ as they age.

Animals with low fibre diameter variation, therefore, offer immense scope for improving genetic performance for fleece production. 

How then do we identify these superior animals?

In the main, fibre testing is one of the most cost effective methods a producer can use to select stock for reducing fibre diameter variability (SD or CV). This has been shown time and time again by trials and research conducted by numerous agricultural R&D institutions. 

By the way, as fibre diameter variation is repeatable over the saddle or commercial fleece area, we need only test, say, a mid-side sample. It should be remembered, however, that the actual fibre diameter is not repeatable over this area.

I should also mention at this stage, that we use Standard Deviation (SD) as it is the true measurement of variation. Coefficient of variation (CV) increases or decreases as a result of the mean’s value. There has been many a bar-room brawl over this debate, however, after manually calculating many SD’s and CV’s while studying (enduring) statistics at university, I can assure readers that SD is the preferred measurement for determining fibre diameter variability on individual animals.

And now for some good news – in this case, we have Mother Nature working on our side. 

Fortunately, variability of fibre diameter is a highly heritable trait and therefore it is relatively easy to achieve genetic improvement. Reported at about 40% heritability on sheep, it is not as high as ‘average fibre diameter’ (reported at about 55%), but high compared to many other traits (NSW DPI 1990). 

How then do we differentiate between the genetic component of fibre diameter SD from the environmental component so we can rely on the fibre test results when selecting breeding stock.

This fact is best explained by looking at the two forms of variation in a fibre sample.

Firstly, there is the variation along the fibre. This variation is created by the ever changing levels of nutrition reaching the follicles. High nutrition such as flush spring feed will increase diameter while drought or heavy worm burden will result in a decrease in diameter. This variation along the fibre is therefore created by environmental influences. The variation in diameter along individual fibres is normally 2 to 6 microns.

The second form of variation is between the individual fibres in a fibre bundle or staple. Depending upon the breed of animal, some fibres might be 20 microns finer than the coarser fibres in the one staple. The variation between the fibres in the one bundle or staple is primarily the result of variation in the follicle traits of the animal. While the eventual follicle traits will be influenced by pre and post natal nutrition, the foundation upon which these follicle traits are determined is genetically influenced. It is this form of variation that holds an important key to selecting breeding stock for fibre production.

The SD (or CV) measurements normally found in fibre test results is the amalgamation of both forms of variation. These results, therefore, are a cocktail of both ‘along’ and ‘between’ fibre variation. The noise created by the environmentally influenced ‘along fibre variation’ reduces the effectiveness with which we could use this trait in selecting breeding stock.

Fibre testing, however, has just got a lot better.

Using a recently developed fibre measurement program that was initially designed to support research projects, we are now able to differentiate between ‘along fibre variation’ from ‘between fibre variation’. The data generated by the program is therefore able to isolate fibre diameter variation that is influenced by environmental factors from that influenced by genetic factors.

To illustrate this form of testing, 6 alpacas, 4 sheep and two goats were tested using the new program. The results are contained in table 1. 

As with all measurements of SD, the higher the value, the greater the degree of variation. It should also be mentioned that this breeder has successfully bred for low SD and therefore, the figures are lower than average.

Table 1



 Avg diameter 

 Overall SD 

 Overall CV 

 ‘Along fibre’ SD 

 ‘Between fibre’ SD

Alpaca 1






Alpaca 2






Alpaca 3






Alpaca 4






Alpaca 5






Alpaca 6






Goat 1






Goat 2






Sheep 1






Sheep 2






Sheep 3






Sheep 4







From table 1 above, we can see that alpacas 2, 3 &4 experienced greater variation in nutritional intake owing to their ‘along fibre’ SD. Alpacas 5 & 6 have greater variation between fibres and probably, greater variation across the fleece. Compared to other alpacas of relatively similar micron, these two would have more coarse fibres and consequently, inferior fleeces.

For the purpose of this example, alpaca 4 is of interest to us. This alpaca had the highest overall SD reading (& second highest CV reading). Normally, we would have discounted this alpaca for high variation based on these results. The information from this new program, however, reveals a different story.

Alpaca 4 had a high overall SD because of the abnormally high variation in nutrition it was exposed to. The ‘along fibre’ variation was a mighty 1.65 microns – clearly above the average. The variation between the fibres, however, was a very respectable 3.07 microns. In other words, this alpaca is genetically sound in so far as it’s fibre diameter variation. It would have little variation over the fleece, genetically capable of producing superior fleeces, but above all, likely to breed progeny that are capable of producing superior fleeces.

The true breeding potential of this animal would have been camouflaged using the existing method of fibre testing. I might add that this is not an uncommon event.

In terms of the sheep results, we find sheep 4 had a similar predicament to alpaca 4. The nutritional variation created a high overall SD measurement, even though the sheep appears to possess superior genetics regarding fleece quality.

There is nothing particular to note with the goats’ test data.

With the use of this technology, we are identifying many superior animals that might have otherwise been culled.

I should also stress that interpreting any fibre test results requires experience as the issue of fibre metrology is far from being a case of ‘black and white’.

Although still in its infancy stage, the use of this new technology is forecast to play a significant role in ‘fine tuning’ selection strategies for breeding stock.

For this reason, the Australian Wool Innovation Ltd and the NSW Stud Merino Breeders Association have invested $100,000 into evaluating the commercial adoption of testing for ‘between fibre’ variation.

Furthermore, a number of alpaca studs in Australia and the UK are now using this testing as part of their alpaca sire selection criteria.

In the future, in may be the case that ‘between fibre’ variation is routinely used by breeders. In the mean-time, some of our best breeding stock may be going unnoticed.

For further information, contact Paul Vallely, email