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The Australian Alpaca Association Ltd.

Victorian Eastern Region of the Australian Alpaca Association Ltd.


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Fleece Processors

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Reading Fibre Test Results

Paul Vallely - Australian Alpaca Fibre Testing 

Introduction

In recent years, the world's Alpaca industry has made significant progress towards establishing itself as a supplier of raw fibre to the textile and craft markets. Although commodities have suffered under the weight of global economic hardship, alpaca fibre is witnessing potential as an emerging luxury fibre within the luxury garment and environmental/welfare conscious markets.

At the 2008 National Alpaca Fibre Seminar held in Australia, presenters from processing and garment manufacturing firms revealed a growing demand for quality alpaca fibre. This was further evidenced at the World Alpaca Conference held in Oxford, UK in 2012.

Alpaca breeders at both these events were told that although a range of fibre types would be required for various product ranges, growers needed to focus on ‘key market drivers’. In other words, growers needed to produce fleeces that exhibited those traits sought by the respective markets in order to secure supply opportunities and reap price premiums.

For breeders pursuing craft and/or value adding objectives, the principle of producing fleeces that meet key fibre traits still apply.

Objective fibre traits such as average fibre diameter, variation of fibre diameter, incidence of coarse fibres (comfort factor) and staple length provide clear expectations on processing performance and eventual yarn/fabric quality, and therefore, were critical in pursuing opportunities for supplying fleece.

Similarly, objective traits also play a key role in the quality of home spun products, although the degree of importance of the relevant traits may differ compared to those preferred by commercial markets.

It should be remembered that visual traits such as colour, clearly have some influence on price paid or craft outcomes, however, they are not the subject of this article.

Monitoring objective fibre traits using fibre measurement, therefore, makes a lot of sense. It allows fleece growers the opportunity to identify alpacas that are likely to produce the more valuable or preferred fleeces. More importantly, it also provides an insight into the genetic potential of breeding stock to produce progeny capable of growing these premium fleeces. 

Both science and practical experience have proven that fibre measurement is the most effective and efficient method of monitoring fibre traits. The following information is provided to alpaca breeders as a guide to embarking on or maintaining a fibre monitoring program.


How to Take a Fibre Sample

The main points to note regarding mid-side sampling are as follows:

1 Always use the same sample site. This will enable you to effectively compare results. The preferred and most commonly used site is the mid-side. The mid-side is located half way between the fore and hind leg and half way down the body mass. The left hand side of the alpaca is normally used for the mid-side as the right side is exposed to judges when showing.

2 To breed for reduction in variation of fibre diameter across the fleece, three sample sites may be used. In this case, the mid-side, the shoulder area and the pin-bone (hip) are recommended.

3 For OFDA2000 testing, the size of the fibre sample needs to be only the width of two fingers.

4 When cutting the sample from the alpaca, ensure the sample is taken as close to the skin as possible so that a complete test analysis can be conducted on the whole length of fibres.

5 Place the sample in a paper bag. If a plastic bag is used, the bag should not be sealed as condensation build-up can distort the fibre measurements. Record the alpaca’s name and/or tag/IAR number on the bag.

6 Send the samples to your preferred fibre test provider.  

Interpreting Test Results

The following is a list of commonly used terms with fibre testing.

Micron: Unit of measurement for describing diameter of fibre. 1,000 microns = one millimetre. Fibre diameter is the single most important fibre trait with regard to commercial processing. It is also one of the most heritable fibre traits

Mic Dev: (Micron Deviation) The extent to which a sample's average micron deviates from the herd’s average.

SD: (Standard Deviation) This shows how much fibre diameter variation there is within a fibre sample. Within one fibre bundle, the individual fibres will vary by about 20 to 25 microns. For instance, one fibre bundle might have individual fibres with diameter of, say, 15 microns, while it will also have fibres with diameter of, say, 35 microns. 

The range in diameter within a fibre bundle from an alpaca, will generally be repeated over that alpaca's saddle area.

In statistical terms, a standard deviation is how far from the average you need to go to capture about two thirds of total variation within the sample. In fibre testing, we use SD to show us the degree of variation in microns.

For example, a fibre sample has an average diameter of 20.0 microns with a SD of 5.0 microns. In this case, about two thirds of the fibres in the sample are between 15.0 and 25.0 microns (5 microns either side of the average of 20 microns). The lower the SD, the less variation in fibre diameter.  

SD is the preferred measurement for determining fibre diameter variation on individual animals. Alpacas with low SD generally have a softer handle, greater tensile strength, and often have less variation over the fleece area. SD is highly heritable.

CVD: (Coefficient of Variation of Diameter) Is the standard deviation expressed as a % of the sample’s average. For example, if the average diameter is 20.0 microns with a SD of 5.0 microns, the CVD is 25.0%. (5/20 x 100) 

CF: (Comfort Factor) Percent of fibres in a sample that are equal to or less than 30 microns. Fibres greater than 30 microns are generally responsible for the prickle sensation when worn next to the skin.

CEM:  (Coarse Edge Micron) The range in microns between the average diameter and the coarsest 5% of the sample. This is a good tool for monitoring problematic primary fibres.

<15%: The percent of fibres in a sample less than 15 microns.

CRV: (Fibre curvature) expressed in degrees/millimetre. Generally, higher curvature is associated with higher crimp frequency.

SF: Spin Fineness: Calculation using micron and CVD to represent the spinning quality. 

Micron Profile: A graph showing the variation of fibre diameter along the staple. Can be used for analysing the nutritional intake over the growing season. The graph is read from left to right.

Histogram:  A bar graph depicting the distribution of fibre diameter for the sample.  On the vertical (y) axis of the graph is the micron of the fibre counts. On the horizontal (x) axis are a series of numbers which represent the frequency of distribution of those fibres counted. 

SL: Staple length expressed in millimetres. (Staple is another term for fibre bundle)

Max Mic. The broadest point along the staple, expressed in microns. 

Min Mic. The finest point along the staple, expressed in microns.

FPFT: (Finest point from the tip) Expressed as millimetres from the tip to the finest point in the staple. An indicator for the ‘point of break’.

MFE: (Mean fibre ends) The average fibre diameter of the fibre ends [tip and base] expressed in microns.

Hauteur (predicted):  The estimated length of fibres after scouring, carding and combing.

Example of two sets of results including data, histograms and micron profiles. Analysis of the results follows below the examples.

 


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

 

Animal 

 Avg diameter 

 Overall SD 

 Overall CV 

 ‘Along fibre’ SD 

 ‘Between fibre’ SD

Alpaca 1

17.27

3.53

20.4

0.86

3.14

Alpaca 2

23.1

3.76

16.27

1.4

2.87

Alpaca 3

20.81

4.12

19

1.22

3.15

Alpaca 4

21.89

4.43

20.23

1.65

3.07

Alpaca 5

23.23

4.21

18.12

0.66

4.15

Alpaca 6

21.57

3.75

17.38

0.77

3.45

Goat 1

16.17

5.1

31.5

0.47

4.74

Goat 2

17.59

5.58

31.7

0.91

5.14

Sheep 1

16.1

3.63

22.54

.73

3.54

Sheep 2

17.1

2.77

16.2

.79

2.59

Sheep 3

16.7

3.12

18.68

.97

3.05

Sheep 4

18.7

3.65

18.98

1.55

3.02

 

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 info@aaft.com.au


Analysis of Two Fibre Test Examples (Above)

Top Example (6B46)

The average fibre diameter is 15.8 micron. As can be seen on the histogram, most of the fibres are centred close to the mean diameter. Almost all fibres are between 9 microns and 28 microns, (range of 19 microns). This alpaca has very low variation of fibre diameter, and consequently has a low SD of 3.4 microns, (2/3 of fibres are between 12.4 microns and 19.2 microns). As all fibres are below 30 microns, the Comfort Factor is 100%. 

The micron profile shows a relatively flat profile indicating stable level of nutrition passing to the fibre follicles. The profile shows the average diameter of the fibre staple starting at almost 17 microns at last shearing (left side of profile), then finishing at about 16 microns when the sample was taken.

The results indicate this sample is from a superior animal, capable of producing premium ultrafine type fibre.

Bottom Example (6Y40)

The average fibre diameter is 26.3 microns. The histogram shows high variation of diameter of individual fibres, ranging from 13 microns to 48 microns, giving a range of 35 microns. For this reason the SD is 5.5 microns, (2/3 of the fibres are between 20.8 microns and 31.8 microns). Note that the CV is 20.8%, which is lower than the above alpaca at 21.4%. The reason for this is the difference in fibre diameter.

The comfort factor is 82%, meaning 18% of fibres are greater than 30 microns. The fibre from this alpaca would likely have a prickle feel if worn next to the skin.

The micron profile shows the level of nutrition falling dramatically about half way through the growing season, before rebounding to almost its initial diameter. This might be a result of worm infestation, dry conditions or ill health followed by a return to lush or healthy conditions. The fibre would likely be tender at the finest point on the profile.

This alpaca would be regarded as producing inferior fleece by commercial standards.

Micron Blowout

Many growers lose faith in their animals once they receive a test report showing a high fibre diameter result . The fact is, the animal might be capable of producing premium type fleeces, however, it may have been subject to overfeeding. 

During 2006, Australian Alpaca Fibre Testing conducted over seven thousand alpaca fibre tests. The average micron for these tests was 25.1 microns. A high percentage of these tests were on samples from first or second fleeces.

The average range in fibre diameter along the staple was 4.8 microns. This represents how much the fibre changed in diameter over the growing season. This variation is caused mainly by changes in nutritional intake. High nutrition causes the fibre to broaden. Overfeeding high quality hay or grain has often been the cause of much anguish when the fibre test results are revealed.

With many of the alpacas we tested, the fibre diameter blew out by more than 10 microns. In one year, an alpaca blew out by a staggering 19.2 microns – starting at 18.1, and finishing with 37.3 microns at the point of shearing. 

A random selection of 100 test results from 2006 showed about 20% of fleeces to be under 20 microns at one point, but finished with an average fibre diameter of over 26 microns. 

Obviously, feeding regimes for pregnant females or developing crias might require high nutrition irrespective of impact on fibre diameter. Furthermore, I’m not suggesting you keep your alpacas just one step away from needing life-support systems to survive. The message is to find the right balance. 


Should alpaca breeders use ‘SD’ or ‘CV’ or both when evaluating fibre traits?

Over the years I have operated AAFT, the question of whether to use Standard Deviation (SD) or Co-efficient of variation (CV) when evaluating fibre traits is undoubtedly one of the most frequently questions asked. It also happens to be one of the issues most plagued by misunderstanding, and consequently, carries the potential to de-rail breeding strategies aimed at improving the quality of fleeces. 

One of the most useful aspects of fibre testing, is the ability to measure the degree of variation in fibre diameter. Variation in fibre diameter is correlated with processing performance of fleeces, ‘handle’ of fleeces, micron blow-out, tensile strength, variation in diameter over the fleece and incidence of coarse fibres. The major benefit in using fibre diameter variation, however, is its high level of heritability, meaning breeders are able to achieve substantial genetic gains using this trait. 

The two statistics used when measuring variation of fibre diameter are Standard Deviation (SD) and Co-efficient of variation (CV). In saying this, however, it might also be noted that fibre test histograms provide a graphical representation of fibre diameter variation. 

To determine whether to use SD or CV for the purposes of selecting breeding stock, it is appropriate to calculate SD and CV for two imaginary samples of fibers. 

While we obviously use software programs to calculate these statistics, I will do it manually. For ease of calculation, the samples will have a ridiculously small number of fibers. 

The first sample has 5 fibers, each with the following average diameter in microns: 18, 19, 19, 20 & 21. The AFD of this sample is therefore 19.4 microns

We calculate the SD as follows =

1/ obtain the sum of the squares for each of the data values (eg 324 + 361 + 361 + 400 + 441 = 1887)

2/ square the sum of the data values and divide by the number of values (eg 18 + 19 + 19 + 20 + 21 = 97, thence 97 x 97 divided by 5 = 1881.8)

3/ subtract 2/ from 1/, then divide the answer by the number of values less 1 (eg 1887 - 1881.8 = 5.2, thence 5.2 divided by 4 = 1.3)

4/ obtain the square root of 3/ (eg, the square root of 1.3 = 1.14

The SD of the sample is therefore 1.14

Now take a second sample of fibers with exactly the same degree of variation (distribution of fibers from the mean) Lets say the microns of the five fibers are 23, 24, 24, 25 & 26. (AFD of 24.4)

The calculations for SD of this second sample are:
1/ 2982
2/ 2976.8
3/ 1.3
4/ 1.14 

The SD is also 1.14. The SD is the same because they both have precisely the same degree of fibre diameter variation.


If, on the other hand, we take a sample with a higher degree of variation in the diameter of the fibres, the SD will also be higher, for example, fiber microns of 23, 24, 24, 25 & 29. (AFD of 25.0 microns)

The calculations are:

1/ 3147
2/ 3125
3/ 5.5
4/ 2.3

The SD is 2.3. 


At this point, it should be clear that SD is the true and unbiased indicator of variation. 

This then brings us to CV. We calculate CV by dividing the SD by the AFD and then multiply by 100. In other words, because of the way we calculate CV, the higher the AFD, the lower the CV. Let me give some examples.

The first sample mentioned above will have a CV of 5.9%, (1.14/19.4 x 100). The second sample has a CV of 4.7%. 


Further, lets take two alpacas with identical variation, say, SD of 4.7. One has AFD of 22.0 microns, the other is 27.0 microns. Their CV's are therefore 21.4 and 17.4.

The problem is that when breeders are selecting low CV alpacas, the alpaca may in fact have a very high variation of fibre diameter, but also have a high AFD. Using CV, therefore, can conceal the fact that an alpaca has a high number of very coarse fibers.

The message is simple. Use SD and not CV.


POINTS TO REMEMBER  


Click on the links below to find a list of fleece buyers as provided by the Australian Alpaca Association.

 

Fleece Buyers

More detailed information on Fleece Buyers

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