The value of animal fibre production systems to rural economies in Europe is becoming more widely recognised and a number of structural measures are being taken to stimulate activity in the wool and speciality fibre filière, particularly measures to improve fibre quality and presentation and the creation of labelling schemes to promote the market for European produced textile fibres. Moreover, fibre analysis technology has recently advanced with the development of a semi-automated system, the Optical Fibre Diameter Analyser (OFDA), that will provide higher precision at lower cost per sample. Accurate and consistent fibre measurement, coupled with the adoption of standard protocols for sampling and data recording, will enable accurate and reliable genetic data to be pooled on a European basis.

The formation of a thematic network for European speciality fibres, the European Fine Fibre Network (FAIR3 CT96 1597), started in 1997, will make a positive material contribution to improving the measurement of fibre traits in genetic improvement programmes and in the marketing of these fibres.

This volume is an account of the workshop held in Villaviciosa (Spain) on 10-11 October 1997, hosted by Dr Koldo Osoro of the Centro de Investigación Aplicada y Tecnologia Agroalimentaria. The papers presented described the new fibre measurement techniques available for fine fibres. The rest of the report presents the discussions held within the four fibre groups and the measurement of quality and quantity traits (mohair, cashmere, angora and fine wool), and the conclusions which were drawn concerning a set of common measurements for each species across Europe through the use of the OFDA method.

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At the final meeting of the EC-funded Concerted Action entitled "Co-ordination of research activities in the development of animal fibre production systems" (AIR3-CT-920380), it was identified that one of the gaps in developing the European high quality animal fibre sector and differentiating the European product from that of imported fibre was through improved methods of measuring fibre quality. In particular there was a need to develop and standardise rapid and accurate methods for the measurement of fibre diameter. A proposal was submitted to the EC to enable this objective to be furthered. The Thematic Network proposal, "Increased competitiveness of high quality European animal fibre textile fibres by improving fibre quality" (FAIR3- CT96-1597) was accepted by the EC with the emphasis of the proposal on introducing the use of the Optical Fibre Diameter Analyser (OFDA) as the standard method for measuring fibre diameter and other fibre measurements such as yield and crimp.

The objective is to establish an European network of researchers, producer organisations and textile manufacturers engaged in research and development on the production and processing of high quality animal fibres of European origin. The Network will:

1. enhance the dissemination of state-of-the-art fibre measurement technology and ensure comparability between fibre analyses in different countries, which is a key element in the future development of the European speciality fibre industry.

2. increase European collaboration in fibre quality improvement through the establishment of common protocols for measuring fibre traits in breeding programmes for different fibre types.

3. improve the competitiveness of European producers of speciality animal fibres by establishing clearly defined, market-led quality objectives, grading and presentation standards and the creation of new information channels between producers, industry and research.

These objectives were presented in the first edition of the Newsletter of the Network, which is entitled European Fine Fibre Network Newsletter. The title reflects the continuity of EC-funded activities in this area and is a well-known name to those involved in the sector. The newsletter will disseminate information about the Network.

The Thematic Network aims to achieve its objectives over the next two and a half years in the following manner:

1. Encourage the use of OFDA.

2. Establish and adopt common protocols for measuring fibre and other traits in breeding programmes for the different fibre types, e.g. fine wool, cashmere, mohair and angora and apply these on a European-wide basis through setting up a database facility which will assist individual breeding groups and allow for the potential for the exchange of genetic information and material within the EU.

3. Set up dialogue with the fibre-manufacturing sector to encourage the use of common measurements, grading and presentation standards.

To achieve these objectives there will be workshops, publications and the possibility of exchange visits. This workshop, which is the first in the series, is specifically concerned with agreeing a common set of fibre and other measurements for each of the fibres - fine wool, cashmere, mohair and angora. The second workshop is concerned specifically with the details of taking the agreed measurements of this workshop and translating them into a database structure. This workshop will be held in France on 9 and 10 March 1998, following the kind invitation of Dr Daniel Allain, INRA.

The third workshop in June 1998 will be linked to the DWI biennial workshop. A round trial of cashmere and mohair samples will be undertaken during this winter organised by Mr Ho Phan, DWI. The results will be presented at this workshop and it is proposed that proposals will be put to the Technical Committee of the International Wool Secretariat to adopt the OFDA technique for the measurement of fibre diameter of mohair and cashmere as an approved method to sit alongside the approved OFDA technique for wool. It is intended that this workshop will attract the fibre-manufacturing sector.

As well as funds for the above activities, there are also funds for the use the OFDA technique in breeding programmes in Europe. To facilitate this the Network has a structure of country representatives, relating to the fibre types which are important in each country. The names of the country representatives can be found on the Network's web page. The country representative will act as the link between myself, the Co-ordinator, and the breeding groups in each country and will advise on what payments should be made and, it is hoped, become involved in the measurements themselves. It is planned that assistance in terms of funding can be given to support in part the measurement of about 1000 samples per fibre per country, detailed in the contract with the EC, during the 3 years of the Network. Precise details of the method of funding can be obtained from Ms Claire Souchet, Macaulay Land Use Research Institute , the Administrator of the Network.

The Network has a small Steering Group, consisting of Mr Ho Phan, DWI, Germany, Dr Daniel Allain, INRA, France and myself. This Group has developed the programme for this workshop on "The development of European standards for the objective measurement of genetic selection parameters, based on quantity and quality fibre traits" and , with feed-back from participants in this workshop, will develop the programmes for future workshops.

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• Summary
• Introduction
• Criteria for quality assessment of cashmere
• OFDA methodology

SUMMARY

The criteria for assessing the quality of cashmere are described. The problems associated with the measurements of quality are described and the need for research identified. The methods for determining fibre diameter are outlined and the need for a rapid and accurate method for measuring fibre diameter is outlined. The Optical Fibre Diameter Analyser (OFDA) methodology is described and proposals are made for testing the reliability of the OFDA methodology for measuring fibre diameter of cashmere fibres in order to obtain acceptance as an IWTO standard.

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INTRODUCTION

It is important to have background information about speciality animal fibre, to understand why the Optical Fibre Diameter Analyser (OFDA) technique should be used for the quality assessment of these fibre types.

The total annual world production of speciality fibres (cashmere, mohair, angora rabbit, llama/alpaca, vicuna, yak, cashgora) is presented in Table 1. Whilst wool is numerically the most important fibre, angora, mohair and cashmere are significant specialised fibres with cashmere having the highest value. China is the largest cashmere producer and is developing its own cashmere processing facilities to meet an increasing internal demand. This is causing problems of supply of high-quality cashmere to European manufacturers.

Table 1: Estimated world production of luxury fibres

Notes: _a fibre currently unavailable, _b exact quantity unknown, but estimated to be well under 1000 tons, c clean weight.

Source: Textile Outlook International, November 1986, The Economist Publications Ltd.

Note: Some amendments have been made to bring this table up to date.

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CRITERIA FOR QUALITY ASSESSMENT OF CASHMERE

The criteria which are important for assessing cashmere quality are:

• mean fibre diameter (microns)
• staple length
• colour
• amount of residual coarse hair
• touch (cashmere from New Zealand is different from that from Asia)

Although these criteria are quite straightforward, some problems may arise while assessing quality of cashmere fibres. The most common problems which occur are:

• recycled material: some fibre manufacturers use some cashmere fibres which contain some elements of previously used cashmere fibres.
• dandruff.
• 60% of textile samples containing speciality fibres are wrongly labelled. Wool and less expensive speciality fibre (yak, camel hair, angora rabbit) have been used until now for cashmere substitution. In the worst case, nylon has been found in supposedly pure cashmere.
• lack of a standardised definition for cashmere. In Germany, the coarse fibres are also defined as cashmere, while in China, only the fine down of cashmere goat is considered as cashmere.

The problem of mis-labelling of cashmere samples is illustrated in Table 2, which describes the proportion of samples submitted to DWI as cases of mis-labelling.

Table 2: Cashmere analyses at DWI (1990-1996). Number of analyses

Following the problems identified above, some long-term research regarding the protection of cashmere and mohair breeders and processors in Europe is essential. Topics which require to be tackled are:

• Setting up accurate methods for identifying substitutes of speciality fibres.
• Standardisation of the method of analysis.
• Definition of cashmere.
• Definition of methods for measuring the quality of speciality fibres, namely the mean fibre diameter.

The methods for determining the mean fibre diameter are:

1. Microscope projection: the standard method since 1966 has been IWTO-8-89.

2. cross-section: developed by Dr Rasmussen and Dr Allain (described in the next paper).

3. Laserscan

4. OFDA

The disadvantages of the first two methods are the limited number of fibres that can be investigated, the manual or semi-automatic nature of the method, the fact that the measurement can be subjective (for one and the same fibre sample, different mean fibre diameter values can be found between laboratories) and there is no differentiation between very similar fibre samples.

The German Wool Research Institute (DWI) was founded in 1952 on the initiative of members of the German Wool Association, who wanted their interest represented at the International Wool Textile Organisation (IWTO). The DWI today is closely engaged in the use of IWTO methods and is involved in its standards committee. Their fibre metrologists have contributed greatly to the standardisation of methods for the objective measurement of the characteristics of speciality fibres. The main characteristics on which work has been done are:

• mean fibre diameter
• fibre length
• fibre identification
• quantitative analysis of blends of wool with speciality fibres by scanning electron microscopy
• microscopic analysis of wool/cashmere blends

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OFDA METHODOLOGY

Research on the standardisation of fibre measurement methods has showed that the OFDA technique allows a better differentiation between very similar samples. Principally the OFDA is an automatic image analysis system : moving fibres of a sample (in form of snippets) are magnified by a microscope set above the sample holder. The images are captured by a video camera and then identified and measured by a computer system. After measurement, a histogram printout is produced, showing the fibre diameter distribution. The mean fibre diameter, the standard deviation (SD) and the coefficient of variation (CV) are included in OFDA's histogram. Within two minutes, more than four thousand fibre snippets can be identified and measured. The accuracy of the OFDA method is, therefore, higher compared to the traditional one.

The OFDA method has been accepted by the IWTO (International Wool Textile Organisation) as a standard test method for the measurement of the mean and distribution of fibre diameter of sheep's wool (IWTO-47-95). For calibration of this image analysis system, INTERWOOLLABS standard tops have been used, whereby the lowest threshold of the mean fibre diameter of the wool standard lies at 17 microns. The average mean fibre diameter of these standard tops had been determined in projection microscope round trials previously.

There is still a lack of fine fibre samples as standards when using the OFDA as a tool for measuring small mean fibre diameters, such as dehaired fine cashmere down, whose fibre diameter ranges from approximately 13-18 microns. The same applies to mohair fibres. A round trial, which is proposed to be undertaken by this Thematic Network, will overcome this current deficiency.

The main aim of the round trial will be to test the reliability of the OFDA method for measurement of mean diameter and distribution of mohair and of fine cashmere down. Due to the fact that there is no standard for the diameter range among 13-17 microns for calibrating OFDA, the conventional projection microscope method will also be used in the round trial as a comparison for testing fibre diameter. A comparison between the values gained by the OFDA and by the micro-projection technique will be made. If the OFDA method exhibits a high precision in the trial, it is proposed to recommend it to the IWTO to be a standard method for cashmere down and mohair.

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• Summary
• Introduction
• Methods
• Results and discussion
• Conclusion
• References

SUMMARY

Many different methods for measuring fibre diameter and medullation have been developed. Most of these measurements are made by observing fibre snippets in profile, and some differences may arise due to the influence of fibre morphology, method and animal source. Measurements of cross-section characteristics are not widely used, as the method is time consuming and expensive. This presentation describes a rapid method for measuring cross-section characteristics using a new histological method, combined with microscopic image analysis and computer techniques, and an evaluation of this cross-section (CS) method.

Combed fibres are embedded in a setting medium (nail varnish and glue) and introduced into a sheath of plastic material. Cross-sections are immediately made, using a razor blade and a fibre microtome, and mounted on a glass microscope slide. Up to 5,000 different fibres can be observed on each sheath section, depending upon the animal source and fibre fineness. With a light microscope connected to a computer, images of sections are then captured and processed with a software package (Visilog, Noesys, France). Stand-alone image processing modules for mohair and angora wool have been developed. Up to 300 different fibres can be automatically identified and measured on each image, depending upon the animal source, fibre fineness and magnification of the microscope. Fibres are sorted in different groups according to fineness and medullation. The following measurements are recorded : area, perimeter, the largest, the smallest and mean diameter of each fibre cross-section, total fibre number per bundle section and the fraction of each fibre group. Measurements are saved into a file for later analysis and mean parameters are displayed. Quality of the image processing and some manual modifications can be controlled at any time by the user. It is concluded that with this rapid method for measurement of fibre cross section parameters (area, circumference, diameters, shape, type of fibre), whatever the animal source, there will be good possibilities to further extend research knowledge in biology, metrology and processing of speciality animal fibres and wool.

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INTRODUCTION

Most of the speciality animal fibres (mohair, angora cashmere, fine wool and fibres derived from the South American camelids and the Bovidae) are commercially produced in China and the southern hemisphere. However, under the pressure of agricultural diversification, there is a promising future for production of fine fibres in Europe. Fibre quality, the major criterion in determining price, and the level of fibre production per animal are the chief components of profitability for speciality animal fibre production. However, the high cost of testing fibre quality, in particular fibre diameter, and the content and characteristics of the different desirable and undesirable fibre types found in the animal's fleece, has often limited attempts at genetic improvement.

In the textile industry, a range of different methods for measuring fineness and fibre diameter distribution are employed by producers, manufacturers and merchants, The methods utilise different physical principles, and, therefore, sometimes give different but equally valid results. Most of these measurements, which have been developed mainly for wool and mohair fibres, are made by observing fibre snippets in profile. Inconsistencies may arise due to the influence of fibre type, diameter distribution or test method. The type of animal fibre is an important source of variation, especially when some or all fibres are medullated, when the cross-sectional shape is not circular and when the fleece is a mixture of different fibre types, as in angora, for example. Thus, up to now, there is no widely-used method for measuring fibre diameter in angora or quantifying the proportions of the different fibres in an animal fleece, such as medullation in Angora goats, or coarse fibre content in Angora rabbits and cashmere goats. Measurements of cross-sectional characteristics appear to be most appropriate methodology to determine fibre quality, but such methods have, to date, been developed only for research purposes in fur-bearing animals (e.g. Rasmussen, 1989), as they are time-consuming and expensive.

This presentation describes a rapid new method for measuring fibre cross-section characteristics and the proportions of different fibres of the fleece of the Angora rabbit and the Angora goat, by using a histological technique combined with microscopic image analysis and computer technology. The performance of this Cross-Section Measurement (CSM) method for determining fibre diameter is compared with results obtained using an Optical Fibre Diameter Analyser (OFDA) (Baxter et al., 1991).

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METHODS

Angora fibre sampling

A total of 206 fleece samples from 75 French Angora rabbits born in 1991 were collected. For each animal, samples were taken immediately prior to fibre harvesting from the fourth harvest (about 1 year of age) and for 2 to 6 successive harvests. At each sampling time, a well-structured lock, taken from the midside by shaving with a razor blade was divided into 2 parts: the first of which was stored intact, while the second, a bristle sample was taken.

Mohair fibre sampling

Two types of mohair fibre samples were collected. Firstly, from 44 adult Angora goats from different French farms, a fleece sample, in form of a well-structured lock was removed from the midside by shaving. Animals were sampled during summer by the assessment committee of Caprigène (Poitiers, France) under the framework of the genetic improvement programme for French Angora goats. In addition, 8 calibrated mohair tops from the International Mohair Association (IMA) were supplied by the Institut Textile de France (ITF-Sud, Mazamet, France).

Cross section measurements

• Sample preparation and fibre histology

Small, representative fibre bundles were extracted for the analysis from each fibre sample by mixing three smaller sub-samples, taken from different locations in the lock. care was taken not to modify either the structure or the composition of the lock.

The method of Kassenbeck et al. (1965) was adapted for the histological preparation of the fibres. A small bundle of parallel fibres is drawn into a plastic sheath, about 10 to 15 mm long, with a nylon thread. Before insertion, the fibres are embedded in an appropriate medium, such as nail varnish or polyvinyl resin paper glue, which both harden rapidly, allowing rapid sample preparation. With the aid of a fibre microtome (ITF-Fibrotome, Instrument S.A, Division Adanel-Lhomargy, 15 Avenue Jean Jaures, BP238, 94203 Ivry/Seine, France), cross-sections of about 50 to 80 microns thickness are made immediately using a razor blade and mounted on a glass microscope slide. In preparing angora, it is important to obtain sections from the proximal end of the fibre, about 2-3 cm from the base of the lock, where the diameter is near constant along the fibre. In the distal section the fibres are swollen, with a larger and variable diameter. Up to 5,000 different fibres can be observed on each sheath section, depending upon the type and diameter of fibres. For mohair preparation, the same methodology is used. It is not necessary to wash the fibres. Up to 1,500 fibres can be observed inside a fibre bundle.

• Fibre microscopy, image analysis and measurements

Using a light microscope, images of a good section are captured with a video camera to feed into a computer (PC/DOS), equipped with a frame grabber (MVP/AT, Matrox), and processed with a software package (Visilog version 3.6, Noesys, France). Using Visilog library routines, three stand-alone image processing modules, written in "C" language, have been developed: one for measuring mohair fibre characteristics and two for measuring angora. One of these is the whole fleece lock and the other for the bristle lock.

Each stand-alone image processing module is subdivided into four major components:

1. Image acquisition. 256-grey levels image with a CDDmonochrome video camera and a digitiser with a typical resolution of 256*256 on 8 bits.
2. Image processing. Image filtering and thresholding techniques, such as convolution, edge extraction and point operations based on pixel information are used. Then mathematical morphology techniques and their generic functions, such as erosion, dilatation, opening, closing and thickening or thinning, based on the structure and the texture of the different objects (fibres) of an image are applied. And, at last, restoration of a binary image, in which each object (fibre) inside the image is well-labelled.
3. Image analysis. Characteristics of each labelled fibre, area, perimeter and the "Feret" diameters in several directions, are measured.
4. User-interface. It registers co-ordinates of the fleece sample and assists the computer to control the quality of the image processing. In the module for total lock analysis, the user is asked for the total number of medullated fibres (gare and kemp) in mohair or bristles in angora contained inside the fibre bundle, which can be easily determined on a bundle of about 1,500 fibres and angora bristle content on a bundle of 4,000 to 5,000 fibres. In the modules for angora, fibres are sorted automatically under the operator's control into 3 different groups: bristles, awns and downs, according to size and the number of medullae per fibre.

Up to 300 different fibres can be automatically and individually identified and measured on each image, depending upon the magnification of the microscope and the quality of the image. Two or three different images from the same bundle section are analysed.

Measurements of the area, the perimeter, the largest, the smallest and mean diameter of each fibre cross section are recorded. The different diameter measurements are calculated from each Ferets diameter (or diametrical variations) in 9 different axes with a 20o increment angle. The total number of fibres in the bundle section and the proportion of each fibre group are also calculated. All these measurements are saved into an ASCII file for later uses, and mean parameters are displayed on screen.

• OFDA measurements

An additional study compared analyses of fibre diameter by CSM, as described above, with the Optical Fibre Diameter Analyser (OFDA). This comparison was performed on 8 mohair tops, 44 mohair fleece samples and 18 angora fleece samples. OFDA measurements were performed at "Institut Textile de France Sud" (Aussillon, Bd du Thoré, 81204 Mazamet, France). Measurements were taken from 50-100 mg fibre snippets (2 mm long) which were obtained at random from 2-3 cm from the base of the whole lock. Average fibre diameter and fibre diameter distribution were determined by measuring rapidly 4,000 different fibres per fleece sample.

• Statistical analysis

The repeatability and accuracy of the method were calculated using analysis of variance methods with GLM procedures of the SAS software package (1992). Relationships between OFDA and CSM methods for measuring fibre diameter were accomplished with MEANS, CORR and REG procedures of SAS (1992).

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RESULTS AND DISCUSSION

Cross section measurements: variability, repeatability and accuracy

Table 1 shows means and standard deviation for each characteristic: area, perimeter, smallest, largest and mean diameter, and bristle content, measured on the 44 mohair fleece samples and the 206 angora fleece samples (one whole lock and one bristle lock per sample). The variabilities, expressed as components of between-sample and between-duplicate (or between-image) variance, are given in table 2 for both angora and mohair fleece samples. Repeatability of cross-section measurements, expressed as the ratio of the between-duplicate variance of the total variance, was 0.91, 0.91 and 0.95 for the area, 0.83, 0.80 and 0.96 for the perimeter, 0.92, 0.99 and 0.95 for the largest diameter, 0.93, 0.90 and 0.93 for the smallest diameter, 0.93, 0.97 and 0.96 for the mean diameter in mohair, total angora and bristle angora lock, respectively, and 0.96, 0.99 and 0.90 for mohair kemp content, mohair gare content and angora bristle content, respectively.

TABLE 1

Mean (+-standard variation) measurements of cross section fibre characteristics in mohair and angora fleece samples.

Measuring fibre characteristics, the overall precision of the CSM method (expressed as 95% confidence limit for average duplicate measurements of each fibre characteristics) was 169.9 square microns, 15.9 square microns and 86.7 square micorns for the area, 23.8 microns, 5.0 microns and 11.8 microns for the perimeter, 3.4 microns, 0.3 microns and 1.9 micorns for the largest diameter, 2.5 microns, 0.7 microns and 1.4 microns for the smallest diameter, and 2.9 microns, 0.4 microns and 1.4 microns for the mean diameter in a mohair lock, a total angora lock and a bristle angora lock respectively.

Measuring the proportion of fibre types, the overall precision of the CSM method (expressed as a 95% confidence limit for average duplicate measurements) were 0.1%, 0.1% and 0.3% for kemp content and gare content in mohair and angora bristle content, respectively. Fibre type was determined by counting 4,000-5,000 angora or 1,000-1,500 mohair fibres.

TABLE 2

Variability of cross section fibre measurements in mohair and angora fleece samples.

*kemp content, **gare content, ***bristle content

The repeatability and precision of the cross-sectional fibre measurements are adequate for most angora and mohair production research purposes, as the variation between animals is far greater than the variability between duplicates, within a fleece. This holds for cross-sectional area and the different fibre diameters, which are important characteristics in use in the textile industry. The perimeter measurement has a larger between-duplicate variation and a lower accuracy. However, this character is not widely used, except for defining fibre shape, using an area/perimeter ratio.

Kemp content in mohair, which is determined with relatively good accuracy (0.1% with a 95% confidence limit) is an important trait, as kemp and other medullated fibres are undesirable in mohair. Until now, the high cost of testing mohair, in particular fibre medullation, has limited the genetic improvement of the Angora goat. This CSM method, which allows simultaneous measurements of both cross-section parameters and medullation content (kemp and gare) in mohair, is acceptable in terms of cost, accuracy and rapidity for most mohair research purposes, including genetic selection to improve fibre quality.

Bristles are desirable fibres, which play an important role in determining angora fibre quality (Rougeot & Thébault, 1989). Bristly fleeces are valued because of their resistance to felting and their aptitude to produce a fluffy yarn used for certain luxury knit products. Bristle content is determined from 4,000-5,000 individual fibre measurements with a relatively good accuracy (0.3% with a 95% confidence limit). Usually, the proportion of bristles ranges from 0.2 to 1.8% in the Angora rabbit fleece. Bristle diameter, or more precisely, the cross-sectional area, is also an important parameter (Allain et al.,1992), which may be determined with good accuracy using this method. All these traits are taken into account in the breeding programme to improve fibre quality in the Angora rabbit, and these can now be accurately measured in one procedure.

The overall precision of the CSM method for measuring fibre diameter in angora, and in particular the largest diameter, is consistent with the commercial standards for angora, and IWTO standards for the wool trade, i.e.ñ0.20æm, for 20æm wool, (IWTO, 1969). However, as only midside fleece samples have been tested, more information about sampling methodology in a fibre lot is required.

Fibre diameter measurements: comparison between CSM and OFDA methods

The Optical Fibre Diameter Analyser is a promising new system for rapid evaluation of average fibre diameter and its distribution, and it is now under intensive evaluation for wool and mohair throughout the world. The value of the method for angora and mohair was made by comparing OFDA and CSM, though still within the range of the smallest and largest diameter. There was, however, no correlation between the two methods (Table 3). This difference could be due to the medullation in angora fibres, as ODFA was first developed for non-medullated wool. As OFDA measures the fibres in profile, the cross-sectional shape, which is ovoid in angora and near-circular in wool and mohair, will also influence the diameter measurement, depending on the orientation of each fibre snippet.

In mohair, mean fibre diameter determined by CSM was greater than by OFDA. The divergence was, however, consistent, and there was good correlation between the two methods, 0.99 and 0.93 in tops and fleece samples, respectively.

TABLE 3

Comparison of average fibre diameter and standard deviation determined by OFDA and CSM in 18 angora fleece samples.

TABLE 4

Comparison of average fibre diameter (microns) and standard deviation determined by OFDA and CSM methods in mohair

A linear correction factor was calculated that enabled similar results to be obtained from both methods (Table 4). OFDA is, of course, a promising system for rapid evaluation of average fibre diameter and its distribution. This was recently demonstrated for mohair (Qi et al., 1994), and a recent modification to OFDA to differentiate medullated fibres from non-medullated fibres is under development, with a specific application for mohair (Peterson et al., 1994), but this system is not yet quite operational. The CSM method is not as rapid as OFDA, and mean fibre diameter is determined on a smaller fibre number, but, with the CSM, only one operation is necessary to determine both fibre diameter and medullated fibre (kemp and gare) content in mohair, as well as the shape parameters of the cross-section. This should provide important information on fibre quality and enable further developments in research on fibre biology.

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CONCLUSION

The CSM method now permits the simultaneous measurement of both fibre cross-sectional characteristics (area, perimeter and diameter) and the proportions of the different fibre types found in an animal fleece. This rapid new method has been demonstrated to be repeatable and accurate, and combines simple histological techniques and image processing with computer technology. This method has been described for angora and mohair measurements, though it could be easily adapted for other fine fibre measurements, such as cashmere and camelid fibres.

For angora fibres, measurements of cross-sectional characteristics appears to be the most appropriate methodology to determine quality criteria, as the fleece is a mixture of different fibre types and the fibre is medullated and has a non-circular cross-section. Evaluating the performance of the CSM against OFDA, has confirmed this hypothesis. The repeatability and precision of the method for angora is consistent with accepted commercial limits, though more information is required on sampling methodology in a fibre lot, as this study has been concerned only with fleece samples.

For most angora and mohair production research purposes, CSM method is adequate for measuring fibre type content and cross-sectional fibre characteristics (of all fibres and of each individual fibre type) of individual fleeces. Thus with the CSM method, there are good possibilities to further develop research on the biology, metrology and processing of angora, mohair and other fine fibres. This method has particular use in support of genetic research programmes to improve fleece and fibre quality in Angora rabbits and Angora goats.

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ACKNOWLEDGMENTS

The authors wish to thank the French "Ministère de l'Agriculture et de la Forêt" and the French "Ministère de la Recherche et de la Technologie" for financial support within the "Programme Agriculture Demain" framework; J. Falières and R. Mollaret for their technical contribution, and J.C. Folmer for image processing assistance. The involvement of "Institut Textile de France Sud" for OFDA measurements, and the supply of calibrated mohair tops, is also gratefully acknowledged.

REFERENCES

• Allain, D., Rochambeau, H. de, Thébault, R.G., Mollaret, R. & Vrillon, J.L. (1992). Relationship between guard hair diameter and tautness in the angora fleece. J. Appl. Rabbit Res. 15:1559-1567, Proceedings of the 5th World Rabbit Congress, Corvallis, Oregon, USA.
• Baxter, B.P., Brims, M.A. & Taylor, T.B. (1991). Description and performance of the Optical Fibre Diameter Analyser (OFDA). Report No8. IWTO Technical Committee Meeting. Nice, France.
• Kassenbeck, P., Jacquemart, J. & Monrocq, R. (1965). Méthodes de caractérisation des fibres kératiniques en microscopie optique. 3rd International Congress on Wool & Textile Research, Section 1:100-111. Peterson, A.D., Gherardi, S.G. & Brims, M.A. (1994). The measurement of medullation in mohair using the Optical Fibre Diameter Analyser. Proceedings of the Australian Society of Animal Production, 20:363.
• Qi, K., Lupton, C.J., Pfeiffer, F.A. & Minikheim, D.L. (1994). Evaluation of the Optical Fibre Diameter Analyser (OFDA) for measuring fiber diameter parameters of sheep and goats. Journal of Animal Science, 72:1675-1679.
• Rasmussen, P.V. (1989). Description of skin and hair morphology by using microscopic image analysis and computer techniques. Scientifur, 13:181-184.
• Rougeot, J. & Thébault, R.G., (1989). "Le lapin angora, sa toison, son élevage". Eds Point Vétérinaire, 4th édition, 176pp. SAS (1992).
• SAS User's guide: Statistics (version 6.03), SAS Inst. Inc., Cary, NC, USA. Visilog (1988). User and programmer guide (version 3.6), Noesys, Domaine technologique de Saclay, 4 rue R. Razel, 91892 Orsay cedex, France.

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The following summary covers the wide-ranging discussion about the importance and measurement of traits associated with the quantity and quality of cashmere production.

There is a variable but always significant differential in the price paid for cashmere with whiter, finer fibre commanding the highest price. Other parameters, such as those described by the textile trade as ‘style’ and ‘handle’, are also important in determining quality but the main traits of interest for all the breeding groups present were annual production and diameter of cashmere.

Annual production of cashmere can be measured at harvest in early spring when the kids are approximately 8 - 12 months of age, but in many cases, depending on the husbandry system, selection and culling of animals is necessary before this time. For example in Spain there is a strong market for young kid meat which can be exploited if selection is based on samples taken at around 3 months of age. Prior to harvesting, annual production can be determined from the weight (W) of cashmere on a measured area of skin (usually 10 cm2 at the mid-side position), body surface area (determined as a function of live weight (fL)) and a knowledge of the proportion (P) of the growing period reached at the sampling date, such as:

Estimated annual production = W x fL x 1 / P.

The group considered whether a single mid-side sample was representative of the fleece as a whole and concluded that it was currently the best option. The relationship between live weight and body surface area was discussed and whether different relationships were required for the different sexes and ages of goat. It was concluded that the use of a single relationship (Couchman and McGregor, 1983) was acceptable since its use would not affect within-flock ranking, but members of the group agreed to distribute any new information linking live weight and productive surface area as soon as it became available.

A problem was identified in the consistency of sample timing between the different countries and systems of management which could prevent direct comparison of the different data sets. Skin follicles must reach a certain level of maturity before they can respond to the long-day moulting signal. Secondary cashmere bearing follicles mature later than primary follicles and this determines the pattern of moulting in the kid coat e.g. kids born before April tend to moult cashmere and guard hair from the kid coat, so that kids born in January, and sampled at 5 months of age, may in fact have moulted and have no cashmere present in the coat. Kids born from April onwards tend to moult guard hair only, and a sample taken at 5 months of age has a high yield of cashmere. It was concluded that each group should sample their kids at a time to suit their individual system of management but would make the necessary measurements to derive the relationship between the kid sample and the first annual harvest for their particular system.

The group discussed the use of OFDA for the measurement of diameter and yield using the method of Hermann and Wortmann (1997). The patch sample size adopted (< 1 gm) is too small to be subsampled using the standard minicore which is needed to provide a length-biased sample of snippets for the determination of cashmere yield. It was concluded that this issue should be examined by the various testing laboratories involved and should be included in the next round trial. Fibre samples taken for estimation of yield should in the meantime cover at least 20 cm2 . The diameter at which fibres were split into guard hair or cashmere was also discussed and it was concluded that while 30 um was the current standard, setting the level at 27 æm would reduce the proportion of intermediate fibres classified as cashmere.

Diameter is the main criterion of quality in cashmere and, although the group discussed a range of other parameters, no attempt was made at this point to determine the most important. Since most of them could be measured concurrently on the same sample presented to the OFDA machine, it was decided that this should be done. They included variability in cashmere diameter and the use of different statistical parameters to describe the frequently skewed distribution. They also included medullation in cashmere fibres (<30 æm) and the measurement of crimp, although some development work is required to relate the output from OFDA to crimp in cashmere. The diameter of guard hair and its distribution should also be recorded since it affects the commercial dehairing process.

Measurement of cashmere length was discussed and the group concluded that ‘drawn length’ measurements should be adopted since this gave minimum and maximum values and an estimation of the distribution of fibre length. Finally measurement of lustre and colour were discussed. There is currently no objective method for the measurement of lustre in raw fleece samples and it was agreed that this should be determined (preferably at harvest) using a scoring system for which a set of standards would be required. Colour was to be determined in the whole animal or fleece and for guard hair as well as cashmere since coloured guard hairs which are missed in the dehairing process are a serious contaminant of pastel-coloured products.

The group finished with a discussion about the sampling and testing of whole groups or subsets of animals for inclusion in the data base. The database was seen to have at least 2 functions : 1) for commercial use - to promote the sale or exchange of better quality animals, and 2) as a research tool - to store data on whole populations of animals to give unbiased estimates of the various genetic parameters. It was concluded that the two uses are not incompatible ; all animals within a breeding group should be tested and their data entered into the database without any pre-testing selection. The owner of the data could then grant access to all or part of their own information on request from another party. Participants of the cashmere group agreed to this.

References

• Couchman, R.C. and McGregor, B.A. (1983) A note on the assessment of down production in Australian goats. Animal Production, 36, 317-320.
• Herrmann, S. and Wortmann,F.J. (1997) Opportunities for the simultaneous estimation of essential fleece parameters in raw cashmere fleeces. Livestock Production Science, 48, 1-12.

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Among the five producers groups who were present (UK, Portugal, Denmark, France and Spain), three had already a selection scheme or an organisation.

The UK producers group has a buck register book, which contains:

• pedigree information
• fleece assessment at 18 months
• fibre test at 18 months
• information about animal conformation

In Denmark, a national selection scheme is already in place. Aspects which are recorded are:

• pedigree
• reproductive information
• fleece assessment at 18 months
• fibre test at 18 months
• body conformation

A national database does exist and the breeding value is estimated.

In France, a national selection scheme is also put into place. Information which are collected are:

• pedigree and reproductive value
• fleece assessment at 18 months
• fibre test at 18 months
• buck testing (30 per year) at 18 months

A central database allows a breeding value estimation.

After discussion, general breeding objectives were identified. These were:

1. to increase the fleece weight
2. to decrease the fibre diameter and the variability of the fibre diameter all along the body.
3. to have no medullation in fibre
4. to test the fibre at 18 months
5. to assess the fleece with 1 or 3 samples (the French use only one midside sample, compared to the British who take 3 samples).
6. to record some general husbandry aspects such as the pedigree, the reproduction value and the bodyweight (conformation).
7. to have a database, in order to allow some genetic evaluation.

Proposal programme for standardisation of fibre test and fleece assessment:

1. assessment of the fleece weight

2. fleece sampling at 18 months of age on three locations: shoulder, britch and mid-side fibre testing : measurement of the mean fibre diameter, assessment of the fibre distribution and assessment of medullation

Both fibre test and fleece sampling should allow data evaluation. Two methods could be used, either the OFDA methodology or the cross-section methodology. The round trial undertaken should allow a decision about which method is the best.

3. body weight and staple length should also be recorded.

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Two types of angora rabbits were considered, the French and the Scandinavian (Finland and Norway). The methods of classifying the fleece were quite different according to the country; the grades used do not designate the same quality.

Despite these differences in fleece assessment, parameters recorded were identified during the discussions as:

• bristle diameter (microns)
• down diameter (microns)
• percentage of bristle within the total fibres

The cross-section method was proposed to measure these parameters. The OFDA methodology could be also used, once it has been proved it is reliable for such fibres.

The sampling method proposed was the following:

• sample taken at mid-patch
• sample cut with a razor
• area of 1 cm2
• taken at the first harvest, after one year

Future objectives to be developed:

One major one is to design a common registration card. So far, the three systems represented were very different from each other.

The second objective is to establish the reliability of the OFDA method for measuring bristle and down fibres. It is very important for angora fibre to have information about bristle rate because this type of fibre is used by manufacturers.

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Three main topics were identified and discussed in this group. These were:

• important characteristics of wool
• recommended selection criteria
• procedures to follow for sampling.

A database structure was difficult to identify because no such database exists at the moment in Europe, and the breeding and selection priorities vary among the European countries. Some more work on the subject will be carried out and investigated in more detail at the next workshop.

The economic characteristics identified were, in order of priority:

1. fibre diameter: it should ideally be between 18-23 microns.
2. fibre/staple length >60 mm, and with a low variability.
3. colour: the fleece should not be pigmented, or miscoloured (no yellowing). If there is a coloration, it should be well defined (black, brown, grey, shades).
4. high yield (clean/greasy %).
5. high wool quantity per animal.
6. no medullation.
7. no fault in fibre characteristics (crimp, uniformity, tensile strength, handle), homogeneity.

The group developed a set of selection criteria from identified economic characteristics. A ranking was difficult to carry out because the objectives and priorities in breeding are different according to breed and country. The ranking given below was not agreed by everyone but it reflected the general consensus.

The selection criteria should be on:

1. fibre diameter (microns, + CV%)
2. staple length
3. greasy weight
4. medullation
5. pigmentation and colour

There should also be an attempt to minimise fibre faults (in term of crimp and uniformity within the staple and the fleece). These criteria should be assessed using visual characteristics (handle, tactile feeling, elasticity of the wool)

The proposed measurement procedures were :

1. Fineness

The OFDA method, with assessment of mean and CV% was recommended.

• sample size: 3 cm2 on 3 sites (shoulder, mid-side, britch) or 4.5 cm2 on 1 site (mid-side)
• time of sampling: for a first selection, samples should be taken at 150 days (male) for a second selection, samples should be taken at 16 months (male and female).

2. Staple length

• measured with a caliper (ruler) on the live animal
• samples taken on 3 sites (shoulder, midside and britch)

3. Medullation

The OFDA new methodology should be able to measure the medullation of fibres. This technique is under investigation by Dr Ho Phan.

4. Pigmentation

The use of visual assessment was proposed, as well as using the light reflection method.

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The main outcomes of the workshop are contained in the reports of each of the rapporteurs on the specialist fibre groups and the objective of this summary is to identify the actions that are required to enable databases of fibre quality and quantity measurements to be set up in relation to breeding programmes.

Cashmere. The quality and quantity traits have been identified and the measurement techniques to be used have also been selected. There are still some technical issues to be resolved concerning the size of patch samples and the prediction of fibre quantity from patch samples and the surface area of the animal, and the measurement of lustre and crimp as additional quality measures. The database, developed by the Macaulay Land Use Research Institute, would act as a useful starting-off point for the Network's cashmere database.

Fine Wool. The quality and quantity traits have been predominantly identified. There are still some issues to be resolved about how some of the measurements would be made on the animal, for example colour. The discussion at the second workshop would require to focus on genetic parameters before final decisions on what should be included on the database could be made. Since there was no suitable database being used by European groups, one would have to be designed or one identified that was being used elsewhere in the world.

Mohair. The relevant traits had been identified. There was a need to develop a uniform classification system across Europe and a meeting was planned prior to the second workshop to action this. Similar databases had been developed in France and Denmark which could be extended for use in other countries.

Angora. It was identified that (a) there was a need to design a common animal registration method, (b) a unified fleece classification system was required, (c) a standard method of taking fibre samples was needed and (d) the most appropriate time to take fibre samples had to be identified. Further discussions would take place prior to the second workshop.

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