Dark and Medullated Fibres and Vegetable Matter

5. Contamination – Dark and Medullated Fibres and Vegetable Matter

Malcolm Fleet and Col Langford

Learning Objectives

On completion of this lecture you should be able to:

• discuss the relevance of dark and medullated fibre contamination in wool • describe some of the procedures used to detect and describe these fibres in white wool • document the main origins of dark and medullated fibres and the economic implications • justify practices implemented to prevent or control occurrences of dark and medullated fibres and the opportunities for improvement

• document the causes of Vegetable Contamination (VM) • calculate how VM is measured • describe the effect of VM on wool processing • describe the economic importance of VM • list and describe the plant species causing VM problems • illustrate your understanding of the strategies which can be employed to reduce VM • plan management strategies in a sheep management system to reduce VM problems in wool.

Key terms and concepts

• Dark and medullated fibres in wool, measurement and description, economic importance and occurrence, strategies to reduce. • Vegetable matter (VM), VM Types, Names of VM Types, VM Type categories, Economic importance, Wool processing and VM, Strategies to reduce VM, Sheep coats, Shearing, Grazing management.

Introduction

Australian wool is primarily of Merino origin (AWEX 2004a) and this together with sheep management and wool classing practices (AWEX 2004b) has assisted in generating a reputation for relative freedom from dark and medullated fibres (Satlo 1963; Cardellino 1978; Pattinson and Hanson 1993; Burbidge et al. 1991, 1993; Hansford and Swan 2005). Furthermore, this wool is primarily used for finer apparel end-uses that are more sensitive to objectionable fibres even when present in trace amounts. The type and level of objectionable fibre that can be tolerated will vary widely with the end-product application but a common threshold for dark fibre in Merino top is 100 per kg (Foulds et al. 1984; Hatcher 2002).

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Dark fibres can be a fault in white or pale dyed products while medullated fibres can be objectionable in dyed products, with such faults leading to the rejection of or costly repairs to the product. Reliance is placed on sheep breeding and management and wool classing requirements to ensure that lots (other than those appropriately labelled/identified) are likely to have low risk of dark fibre and/or objectionable medullated fibre. However, this reliance may not be entirely effective and recent developments involving crossbreeding of Merinos with coloured and/or highly medullated sire breeds has increased wool industry concerns and interests to develop an information system to assess risk and a rapid presale test for both isolated dark and objectionable medullated fibres (AWI 2002, 2003a). Should these marketing developments become established then the discounts associated with the presence of dark and medullated fibres will be more equitably passed back to individual producers as well as improving processing prediction and confidence in wool fibre in this regard.

5.1 Measurement and description of objectionable fibres

Methods used to detect isolated objectionable Fibres in white wool Historically, the measurement of isolated dark fibre or medullated fibre and other cleanliness faults in white wool slivers involved a variety of techniques that were labour intensive. ASTM (1980) states that examination surfaces consist of a dark surface illuminated from above for the nep test and a white surface illuminated from above for vegetable matter and coloured fibre tests. Alternatively, a white translucent surface with under-lighting may be used for all tests. The procedures involved can be entirely manual (Figure 5.1) with or without magnification aids or involve instruments (e.g. Top/Toenniessen Tester) that incorporate automatic delivering and opening of the sliver (Figure 5.2).

Figure 5.1 Cleanliness faults in top being detected using a black background. Image Source: Malcolm Fleet, SARDI (2004).

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Figure 5.2 Tops Tester used for counting cleanliness faults in top. Image Source: Malcolm Fleet, SARDI (2004).

In Australia, CSIRO improved the manual counting techniques and in Belgium, Centexbel developed an entirely automated instrument for testing cleanliness faults in tops sliver. The CSIRO team adapted Maggy-Lamp® equipment (Foulds et al. 1984) to develop a new instrument with balanced lighting to better reveal dark fibres (Figure 5.3), along with a reference scale (Figure 5.4) to try and overcome the arbitrary decision about which fibres were dark enough to be relevant (CSIRO DFD method). Fibres with darkness of level 4 and lower were unlikely to be of commercial importance and even those fibres at level 5 would be difficult to detect unless on the surface. Despite the apparent improvement over alternative manual methods the trials assessing the new method showed that problems of variations in observer technique and classification of dark fibre remained (Burbidge et al.1994).

Figure 5.3 CSIRO Dark Fibre Detector. Image Source: Malcolm Fleet, SARDI (2004).

The automatic method (Optalyser®) for rapid measurement of cleanliness faults in tops sliver has been accepted by IWTO (IWTO 1999). However, there is limited application of this technology due to the high cost of the instrument and so far it has not been adapted for measurement of wool structures other than top sliver. Even though the instrument cost is excessive the measurement cost is relatively low and it is much quicker and more objective in comparison to manual count methods.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Several other methods have been used to estimate relatively high levels of isolated dark or medullated fibres in white wool or mohair samples. OFDA100 is accepted by IWTO for measuring medullated fibre (IWTO 1998) but it is not capable of reliably detecting trace levels of objectionable fibres that can cause concern as contaminants in Merino wool (Fleet and Bennie 2002). The most recent development arising from the research programs funded by Australian Wool Innovation Ltd, to develop a rapid presale test for dark and medullated fibres involves improvements to the CSIRO DFD method (AWTA et al. 2004). This involves use of benzyl alcohol (similar refractive index to wool) and sample preparation innovations that allow a greater bulk of core sample wool to be effectively inspected for dark and objectionable medullated fibres (DMF). The benzyl alcohol procedure has recently been used to study the relationship between DMF contamination in Merino wool, from contacts with Damara crossbred lambs, in core sample, top and noil (Fleet et al. 2006a,b).

Figure 5.4 CSIRO Dark Fibre Reference Scale. Image Source: Malcolm Fleet, SARDI (2004).

Classifying dark and medullated fibres Dark fibres There is limited ability at present to classify the origin of dark fibres other than by manual inspection with a light microscope and this requires time consuming extraction and storage of the individual fibres. Nevertheless, the Optalyser® discriminates between vegetable matter and fibres or fibrous masses and experienced observers using the CSIRO DFD also learn to be selective about the dark contaminants of primary interest.

Although many dark contaminants are encountered in wool, the most common, other than vegetable matter, are of sheep origin, being either urine stain or melanin pigment (Burbidge et al. 1993). Other non-animal fibres (e.g. cotton and synthetics), other animal fibres (e.g. rodent hairs) or artificially coloured sheep fibres (e.g. farm branded, mill dyed, bacterial stained or damaged and discoloured, grease coloured or dirty), medullated fibres and those containing many small vacuoles may sometimes be important.

The primary dark fibres of sheep origin (urine stained and melanin-pigmented) can be distinguished after microscope examination. Melanin pigmentation is characterised by an uneven appearance and presence of discrete granules whereas urine stain is usually uniform across the section of the fibre (as if dyed) though may vary in intensity along the fibre (Figure 5.5). Presence of numerous vacuoles can be a source of confusion and medullation affects the appearance of urine stain and pigmented fibres.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Figure 5.5 Urine stained (above) and melanin-pigmented (below) wool fibres. Image Source: Malcolm Fleet, SARDI (2004).

Medullated fibres Medullation refers to the tract(s) of hollow cells that can be present in sheep fibres (Figures 5.6 and 5.7). White fibres that are sufficiently medullated may appear paler (Figure 5.6) than the wool bulk after mill dying (Trollip et al. 1987; Hunter et al. 1990; Hunter et al. 1996; IWTO 1999; Tester 2004). Medullated fibres tend to be brittle and this feature may either assist or hinder removal during processing or mending (Hatcher et al. 1999; Tester 2004).

Figure 5.6 White kemp fibre with a continuous wide lattice medulla. On the right most of the medulla cells have apparently been filled with mounting medium while on the left most remain vacant. Image Source: Malcolm Fleet, SARDI (2004).

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Figure 5.7 Pigmented kemp fibre with wide lattice medulla. Image Source: Malcolm Fleet, SARDI (2004).

Figure 5.8 Dyed Damara x Merino wool showing the white or pale kemp fibres. Image Source: Malcolm Fleet, SARDI (2004).

The term “kemp” has been defined in different ways (Lang 1950; Wildman 1954; WSR 1954; Gallagher 1969; Wood 2000; Hatcher 2002) but to the manufacturing industry it broadly means fibres that are highly medullated which are most likely to cause problems. These can be short or long and seasonally shed or continuously growing shorn fibres. Kemp fibres tend to also be coarse (Hunter et al. 1990; Hunter et al. 1996; IWTO 1998; Fleet et al. 2001) and chalky-white (Hunter et al. 1990; IWTO 1998) and can be seen in the fleece when present in high levels. Based on the ASTM test method, a “kemp” fibre is distinguished from lesser medullated fibres when the medulla width exceeds 60% of the fibre diameter (ASTM 1996 cited by Lupton and Pfeiffer 1998). The OFDA100 (Figure 5.7) method (IWTO1998) define ordinary medullated fibres as those having an Opacity of 80% or more while objectionable medullated fibres have an Opacity of 94% or more and a fibre diameter of greater than 25µm. Balasingam (2005) and Balasingam and Mahar (2005) review of the literature regarding medullation threshold levels and testing methods used to define objectionable fibres. Balasingam and Mahar (2005) also reports on the application of the benzyl alcohol DMF test (AWTA et al. 2004) in random screening of core samples from Australian wool lots.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England The degree of medullation, as viewed with a microscope, can be classified according to the relative proportion of the fibre occupied by medulla and whether or not it is continuous, interrupted or fragmented (Wildman 1954). As with dark fibres the length and diameter of objectionable medullation would also affect whether these differently dyed fibres will appear and be noticed in the product.

Figure 5.9 OFDA100. Image Source: Malcolm Fleet, SARDI (2004).

5.2 Economic importance and occurrence

Wool is a luxury fibre for which consumers pay a substantial premium (Meyer et al. 2003) above competing fibres. Australia has a reputation for producing wool (mainly of Merino origin) that is generally of low risk in relation to dark and medullated fibres (Hansford and Swan 2005) with this reputation estimated (Pattinson and Hanson 1993) to be worth in order of 10% of wool value to Australian producers.

The economic importance of isolated dark and medullated fibres varies with the stage at which the fault is identified in wool. The later in the processing chain that it is realised that excessive objectionable fibres have persisted the more expensive is the rejection or repair costs (Tester 2004). These costs usually cannot be passed back to the individual producer(s) responsible, due to blending at an early stage, so must be otherwise absorbed by processors; potentially affecting prices paid generally and the competitiveness of wool relative to other fibres. In manufacturing stages there is also little reporting of losses incurred and mending undertaken.

Greasy wool auction market Recent developments in crossbreeding of Merino ewes to coloured or highly medullated sire breeds has led to changes in the requirements for wool description to identify certain risk situations even though the dark and medullated fibre may not be evident in the greasy wool.

Based on the current (AWEX 2004b) Code of Practice, wool from Merinos that has been in specified contact with certain “exotic/shedding” breeds – Awassi, Damara, Dorper or White Dorper, Karakul, or the crossbreds (whether or not pigmented or medullated fibre is visible) is required to be branded with a qualifying letter according to the AWEX ID system (“Y” – for pigmented fibre and “P” – for kemp fibre). For other wool lines and breed exposures where contamination from pigmented or medullated fibres can be seen in the Merino wool the same requirement applies. Other types of dark fibre identified by bale brand or noted on inspection are also recorded as part of the AWEX ID (ie. urine stain – S and sheep brands – R). Presence of these wool faults is visually scaled to three levels, for example, Y1 – odd pigmented fibre present; Y2 – larger level pigmented fibre evident; Y3 – clearly prepared as a black line or mixture of pigmented and white wool. In 2001/02 the proportion of all wool sold at auction (AWEX database) identified as containing pigmented fibre was 0.405%, brands, 2.210% and dark stain, 4.495%. Table 5.1 shows the amounts of fault present in auction sold wool in 2001/02.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England The AWEX-ID V3.OS (AWEX 2006a) has a mandatory breed group Prime Identifier that attempts to separate breeds or breed contacts that may have different risk levels for dark and/or medullated fibre. A standard comments field allows identify of wool from certain dual-purpose Merino breeds (ie. South African Mutton Merino, Australian Meat Merino and Dohne) and the ‘shedding breed’ in contact (i.e. Awassi, Damara, Dorper, Karakul and Van Rooy). These comments may help the DMF wool lot survey project (Hansford and Morgan 2006) provided similar circumstances (e.g. urine stain controlled) apply for the comparisons made. Included is the R Prime Identifier that indicates the sheep have been run with other breeds that shed (objectionable) fibre. In the draft Code of Practice (AWEX 2006b), it is proposed that wool classers will apply this ‘R’ for “Run with” as a suffix after the usual white wool description (e.g. AAA M F R) where the wool has been contact with a specified ‘Shedding breed’ but pigmented or medullated fibre cannot be seen. However, in any case where pigmented fibre is visible in the white wool then the ‘Y’ suffix is to be applied, or if medullated fibre is visible then the ‘K’ suffix applied, instead of the ‘R’ if relevant.

Table 5.1 Amounts of auction sold Merino wool affected by dark fibre and white kemp in 2001/2002. Source: M. Fleet (2004 – Unpubl. data). Season Total Greasy Weight (greasy kg) and percentage of total per Scale: 2001/2002

Pigment Weight kg Y1 Y2 Y3

Merino fleece 294,241,882 453,690 (0.154%) 48,783 (0.0166%) 115,908 (0.039%) Merino pieces 59,518,040 71,022 (0.119%) 10,274 (0.017%) 26,167 (0.044%) Merino bellies 23,088,355 28,470 (0.123%) - 1,568 (0.007%) Crossbred fleece 31,843,192 533, 254 (1.675%) 61,728 (0.194%) 53, 217 (0.167%) Downs fleece 1,250,892 88,422 (7.069%) 22,672 (1.820%) 3,574 (0.300%) Brands R1 R2 R3 Merino fleece 294,241,882 8,316,650 (2.826%) 86,550 (0.029%) 112,572 (0.038%) Merino pieces 59,518,040 294,746 (0.495%) 22,817 (0.038%) 3,777 (0.006%) Merino bellies 23,088,355 21,039 (0.091%) - - Stain S1 S2 S3 Merino fleece 294,241,882 17,296 (0.006)% - 995 (0.000%) Merino pieces 59,518,040 1,154,988 (1.941%) 3,708,364 (6.231%) 1,037,137 (1.743%) Merino bellies 23,088,355 801,191 (3.470%) 1,200,430 (5.199%) 620,851 (2.689%) Kemp P1 P2 P3 Merino fleece 294,241,882 16,724 (0.006%) 154 (0.000%) - Merino pieces 59,518,040 17,949 (0.030%) 371 (0.001%) - Merino bellies 23,088,355 5,592 (0.024%) - - Crossbred fleece 31,843,192 209,660 (0.658%) 16,766 (0.053%) - Downs fleece 1,250,892 53,013 (4.238%) 843 (0.067%) 314 (0.025%)

The amount of auction wool sold that is recognised to contain pigmented or kemp fibre has increased in recent years with developments in Merino crossbreeding (Table 5.2) though remains relatively small making difficult the task of compiling discounts (Table 5.3).

The market penalty for pigmented fibre is on average greater than for stain and stain greater than for brands (Table 5.3). This trend could reflect the expectations of the buyer and processor about the relative darkness of these fibre types, that approved sheep brands should be scourable, and the likelihood of the darkened fibre being recognisable as faults in the end product. The flexibility of end-use of black wool is very limited while wool with lighter stain or

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England persisting brands could be used for a wider range of the darker dyed applications. Processing of coloured wool lots could also lead to the need for expensive cleaning of processing equipment to avoid subsequent contamination. In general the penalties were higher for the finer wool and this reflects differences in end-use (eg. white and pale dyed) and higher risk of appearance of dark fibre in fine yarn applications (Fleet et al. 2002b).

Table 5.2 Percentage of auction sold wool appraised as containing pigmented or kemp fibre. Source: Fleet et al. (2002b). Region Fault 1999/2000 2000/2001 2001/2002 Western Pigment 0.60 % 1.07 % 1.00 % Kemp 0.02 % 0.17 % 0.42 % Northern Pigment 0.08 % 0.18 % 0.34 % Kemp 0.01 % 0.02 % 0.07 % Southern Pigment 0.06 % 0.11 % 0.21 % Kemp 0.02 % 0.02 % 0.03 % Total Pigment 0.19 % 0.33 % 0.41 % Kemp 0.02 % 0.05 % 0.12 %

Table 5.3 Clean price reductions in auction sold wool lots arising from presence of various types of dark fibre in 2000/01 and 2001/02. Source: Fleet et al. (2002b); Fleet (2002b). Diameter (um) Year Clean price c/kg reduction and number of lots (brackets*) Merino fleece Pigment – Y1 Pigment – Y2 Pigment – Y3 17.1 – 20.0 um 2000/01 - 143 (6) - - 576 (2) 17.1 – 20.0 um 2001/02 - 67 (71) - 288 (1) - 359 (19) 20.1 – 23.0 um 2000/01 - 66 (62) - 172 (7) - 190 (19) 20.1 – 23.0 um 2001/02 - 92 (159) - 210 (4) - 281 (13) Merino fleece Brands – R1 Brands – R2 Brands – R3 17.1 – 20.0 um 2000/01 - 32 (1,134) - 73 (51) - 177 (15) 17.1 – 20.0 um 2001/02 - 18 (2,527) - 101 (78) - 142 (93) 20.1 – 23.0 um 2000/01 - 3 (2,522) - 15 (20) - 76 (3) 20.1 – 23.0 um 2001/02 - 2 (4,078) - 28 (20) - 77 (31) Merino pieces and bellies Stain – S1 Stain – S2 Stain – S3 17.1 – 20.0 um 2000/01 - 54 (1,262) - 183 (2,542) - 195 (458) 17.1 – 20.0 um 2001/02 - 39 (1,543) - 173 (3,219) - 178 (623) 20.1 – 23.0 um 2000/01 - 28 (591) - 99 (2,032) - 107 (815) 20.1 – 23.0 um 2001/02 - 33 (265) - 141 (960) - 154 (440)

*The number of lots (in brackets) is not the total number affected but those tested lots that were eligible.

Understanding occurrence on the farm Dark and medullated fibre contaminants are either acquired by: • physical transfer of the fibre • exposure to an external darkening agent • produced by the sheep.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Medullation Medullation does occur among the fibres produced by Merino sheep though the extent appears to be negligible relative to other breeds (Lang 1950). A survey (Gallagher 1969; Gallagher 1970) revealed an average incidence of medullated fibres of 1.1% though most of these fibres were of the fragmental type. Merino lambs were found to have a greater number of medullated fibres, as did the breech compared to the midside and neck sites, and this declined rapidly in the first month after birth (Gallagher 1969). It is not clear at this stage if any importance should be attached to birthcoat halo-hairs (Figure 5.10) and long coarse hair seen on some older sheep (Figure 5.11) in relation to occurrence of trace levels of inherent objectionable medullated fibres in Merino wool. The evidence available (Lang 1950; Gallagher 1969) suggests these fibres are usually not highly medullated though may contain such fragments. Balasingam and Mahar (2005) report on the application of the benzyl alcohol test to a random sample (1%) of Australian greasy wool lots in 2004. Merino fleece lots had an average of 5.8 medullated fibres per 10 g core sample (with a range of 0 – 452); skirtings or pieces lines an average of 30 (range 0 – 396); bellies lines an average of 55 (range 0 – 433); locks an average of 35 (range 1 – 406); and lines of lambs wool had an average of 133 medullated fibres per 10g of core wool (with range 1 – 572). Whereas, all samples from crossbred lines had an average of 137 medullated fibres/10g (range 0 – 576). Fleet et al. (2005) assessed wool from Merino lambs and compared it with that of wool from Damara crossbreds. Halo-hair score on newborn Merino lambs was not related to objectionable medullated fibre content as defined by OFDA100, in the subsequent shorn lamb fleece, but is positively correlated with flat fibre content and the diameter of medullated fibres overall. Merino lamb wool had little objectionable medullated fibre compared to Damara crossbreds ( ie. about ≤1 v. 100 objectionable per 10,000 fibre snippets) Figure 5.10 Merino lamb showing high coverage of halo-hairs. Image Source: Malcolm Fleet, SARDI (2004).

Figure 5.11 Adult Merino wool with coarse hairs protruding from the staple tips. Image Source: Malcolm Fleet, SARDI (2004).

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England There are a large number of sheep breeds present in Australia ranging from hair and Downs types that shed their fleece (e.g. Damara, Dorper), double-coated sheep with long and short kemp fibre that need to be shorn (e.g. Awassi), other carpet wool breeds, traditional longwool crossbred and Downs types, to Merino types (Hatcher 2002; AWEX 2004b). To some extent classifications of fibres (hair, wool, heterotype) can be associated with follicular type – primary follicles, original and derived secondary follicles (Ryder and Stephenson 1968 cited by Hatcher 2002) and differences in occurrence of objectionable medullated fibres can be related to ratios of these follicle types (Lyne and Hollis 1968) and with fibre diameter characteristics (Hunter et al. 1990; Hunter et al. 1996). While breeds producing wools with high fibre diameter tend also to have more medullated fibres (Lang 1950) these traits are not necessarily dependent (Scobie et al. 1998; Fleet and Bennie 2002). Table 5.4 shows the percentage of medullated fibres, determined using OFDA100, in lambs’ wool of various breeds.

Table 5.4 Percentage of medullated fibres in 14 week old lamb wool of various breeds. Source: Holst et al. (1997). Percentage of medullated fibres in 14-week lamb wool of various breeds (Holst et al. 1997) Merino x Merino = 0.1% Texel x Merino = 1.6% Border Leicester x Merino = 0.4% Poll Dorset x Border Leicester Merino = 0.5% Poll Dorset x Merino = 0.2% Texel x Border Leicester Merino = 5.8% Percentage of medullated and (objectionable medullated) fibres in 7-month lambs wool (Fleet and Bennie 2002) Merino x Merino = 0.37% (0.001%) Damara x Merino = 3.05% (0.78%) Merino x Merino = 0.43% (0.000%) Damara x Merino = 4.16% (1.36%)

Pigmentation The inherited colour that darkens wool, hair and skin involves melanin pigment, which is packaged in granules or melanosomes within specialised cells called melanocytes. The melanosomes move from the main body of the cell to extensions of the cell (dendrites) and are then forced into other surrounding cells (keratinocytes). These take-up the granules and ultimately form the exposed skin, wool and hair (Forrest et al. 1985; Fleet 2002a; Fleet et al. 2004).

In recessive black Merino foetal wool-developing skin, it has been found that about 57 days after artificial insemination precursor melanocytes (melanoblasts) reach the epidermis (outer) layer of the skin which then becomes heavily populated and the developing primary and original secondary follicles incorporate the melanoblasts. In a white Merino foetal sheep, the melanoblasts are apparently prevented from reaching the skin during the critical periods of wool follicle initiation or may reach the skin at this time but are prevented from colonising the epidermis. In the latter case, isolated pigmented fibres may develop (Fleet et al. 2004).

In contrast to medullated fibres, the occurrence of dark fibres in Merino sheep is of greater recognised importance and has attracted more investigation. Processing surveys reveal that fibres darkened by urine stain are most common though pigmented fibres can be just as important arising from inherent sources (Burbidge et al. 1991,1993; Mendoza and Maggiolo 1999) or as contaminants from external sources (e.g. rearing of coloured crossbred lambs – Fleet 1999b). The occurrence of pigmented fibres in white Merinos can take several macroscopic forms (Fleet 1998), including:

1. Recessive black patterns (each with variations in white spotting). • Badgerface (black ventrum and tan, light or white dorsum) • Reverse badgerface (tan, light or white belly to neck and under tail with black dorsum) • Self-colour (black often with white or grey patches but not sharply divided in dorsal/ventral manner) • Other patterns

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3. Diffuse and symmetrical located pigmented fibre remnants (present from early life and associated with the occurrence of isolated pigmented wool fibres in the fleece). • Halo-hair – especially back of neck • Spots, Speckling or patches of fibres on legs and/or face • Horn site fibres • Eye lash and ear fibres

4. Old-age black skin spots – developing pigmented fibre.

Recessive black: The occasional occurrence of black lambs in white Merino flocks is attributed to a single gene located on sheep chromosome 13 that is assumed to be Agouti (Furumura et al. 1996; Sponenberg et al. 1996; Parsons et al. 1999a,b; Beraldi et al. 2006). AWI and CSIRO/Sheep CRC are undertaking research that may characterise the genetic variation responsible for recessive black patterns enabling a specific diagnostic test that ram breeders could then use to eliminate carrier sheep. Carrier sheep are not more likely to produce isolated pigmented fibres (Fleet et al. 1989) so the problems arising primarily relate to client dissatisfaction after purchasing a ram that produced coloured lambs, the risk of transfer contamination and reduced values for coloured lambs and wool.

Random spots: Unlike recessive black, this type of pigmentation is not simply inherited or highly heritable. Fleet (1996, 1997) reported a heritability of 0.08 for random spot in a Merino flock and Enns and Nicoll (2002) report heritabilities between 0.00 – 0.07 for Romney sheep. While the reported heritabilities for the trait itself are low, occurrence has been shown to be associated with other pigmentation (Fleet and Stafford 1989; Fleet 1999a), which may be highly heritable. Table 5.5 shows the relationship between occurrence of random spot and the highly heritable (0.44, lamb; 0.82, hogget) leg fibre pigmentation on Merinos, which also increases other visible pigmentation, isolated pigmented fibres in the fleece (Fleet 1997;Fleet et al. 1995a) and wool-bearing skin melanocytes (Fleet et al. 1993; Fleet et al. 2004).

Table 5.5 Number of random spot progeny in grades for degree of pigmented leg hairs. Source: M. Fleet (1999a). Degree No leg hairs Few leg hairs Many spots / Patches Large Random spot pigmented Pigmented leg hairs area Absent 195 35 39 30 67 Present 7 4 3 10 21

Among “usual” Merinos (i.e. without pigmented leg fibres) those with a random spot usually do not have isolated pigmented fibres in the white wool. Risks from affected sheep are possible transfer contamination and the spot(s) being missed partly or completely at shearing. Also, the spots sometimes “grey” beyond visible recognition but still contain large numbers of pigmented fibres. Therefore, affected sheep should be culled as soon as practical and their fleeces kept separate from other lines (Fleet and Smith 1990).

Diffuse and Symmetrical Located Remnants Present from Early Life: Merino breeders have traditionally selected against pigmentation remnants – especially fibre pigmentation – occurring on white sheep. In doing so there have also been impacts on hidden isolated pigmented fibres in the fleece (Fleet 1996,1997). However, as there are many different types of remnant fibre, skin and hoof pigmentation, attention to all types and degrees can severely impact on the numbers of sheep selected on production traits. Therefore, it is important to know which types of pigmentation are most important to select against to reduce the occurrence of isolated pigmented fibres. Most types of remnant pigmentation on Merinos have a high heritability but for isolated pigmented fibres it appears low (Table 5.6).

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England A genetic correlation exists between two characters if affected by the same genes to some degree. The general positive genetic correlations among the various types of pigmentation (Table 5.7) mean that selecting against one or more types will affect other types not being considered. Indirect selection can lead to a response that is greater than direct selection provided the two characters are highly genetically correlated and the heritability of the correlated character is sufficiently greater than that of the character of primary interest (Turner and Young 1970). This outcome is especially important where the character of primary interest is difficult or expensive to measure as is the case with isolated pigmented fibres.

Table 5.6 Heritability and (standard errors) for pigmentation types in white Merinos. Source: M. Fleet (1996, 1997). Pigmentation type Age Heritability (s.e.) Percentage Phenotypic affected correlation with IPF Halo-hair Lamb 0.61 (0.16) 23 0.33 Random spots Lamb 0.08 (0.07) 3 0.08 Ear hairs Lamb 0.23 (0.12) 8 0.13 Leg hairs Hogget 0.82 (0.21) 29 0.26 Horn site Hogget 0.71 (0.20) 29 0.27 Eye lashes Hogget 0.45 (0.22) 91 0.29 Ear hairs Hogget 0.25 (0.12) 16 0.21 Skin under Ear hair area Hogget 0.51 (0.17) 76 0.22 Face hairs Hogget 0.18 (0.11) 8 0.12 Skin under Face hair area Hogget 0.65 (0.19) 53 0.22 Nose-lips skin Hogget 0.69 (0.20) 83 0.21 Ear skin ventral Hogget 0.65 (0.20) 73 0.16 Bare skin around eyes Hogget 0.14 (0.10) 100 0.16 Under tail skin Hogget 0.49 (0.18) 93 0.18 Inside mouth skin Hogget 0.36 (0.14) 22 0.29 Hooves Hogget 0.60 (0.18) 59 0.27 Isolated pigmented fibres Hogget 0.18 (0.12) 42

Table 5.7 Genetic correlations between types of pigmentation. Source: M. Fleet (1997). Pigment HH LH HS EL ER F NL HV RS Isolated fibres in fleece 0.66 0.18 0.18 0.39 0.43 0.08 0.08 0.15 0.77

Halo-hair (HH) 0.63 0.59 0.76 0.76 0.92 0.64 0.69 Leg hairs (LH) 0.91 0.39 0.73 0.91 0.76 0.76 Horn-site hair (HS) 0.25 0.96 1.05 0.81 0.68 Eye lashes (EL) 0.47 0.60 0.26 0.33 Ear hairs (ER) 0.86 0.25 0.52 Face hairs (F) 0.74 0.46 Nose-lips skin (NL) 0.68 Hooves (HV)

Random spot (RS) Bold = significant P<0.05)

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Some types of pigmentation are only temporarily visible (tan birthcoat halo-hair, tan ear tips and some random spots). For these types of pigmentation it is important for sheep inspections to be made on lambs as soon as practical (eg. ear tagging or marking) to identify unacceptable sheep as culls. Other types of pigmentation tend to increase in extent or presence as the lamb matures (eg. leg and horn site fibres) making it important to repeat inspections at later stages (eg. crutching, sheep classing, shearing) (Fleet et al. 1995b; Fleet 1997). The crutcher and shearer can play an important role in identifying sheep that may have a fleece at risk of isolated pigmented fibres and should be culled.

As a result of assessing fleeces from the same sheep at different ages (Fleet et al. 1991a) it was found that levels of isolated pigmented fibres declined dramatically after hogget age. This is an important finding for the wool consuming industry that has been supported by CSIRO processing surveys (Burbidge et al. 1991, 1993), since the risk of isolated pigmented fibres could be reduced simply by avoiding wool from young sheep. However, it would be better if lambs were free of pigmented fibre spots and indicators of isolated pigmented fibre risk so that (based on the findings for 1.5 year old sheep) their wool should also be of low risk. Interesting, the most recent survey published (Balasingam and Mahar 2005) found dark fibre levels in 116 lots of Merino lambs wool was low (average 0.9 per 10g with range 0 – 75 per 10g) being comparable with the results for 1582 lots of adult Merino fleece wool (average 1.5 per 10g with range 0 – 430 per 10g). This may mean that selection improvements arising from SARDI advice have lead to a reduction in the pigmented fibre risk for young Merino sheep.

Old-Age Black Skin Spots: Old Merino sheep sometimes develop black skin spots in the wool–bearing areas that produce pigmented fibres (Kelley and Shaw 1942; Fleet and Forrest 1984). Based on the limited documentation available (Kelley and Shaw 1942; Fleet 2006) there can be an exponential increase in the occurrence of these age spots. Merinos appear to become most susceptible at ages of 7 - 8 years usually well after the usual culling age (Figure 5.12). Wool measurement and processing showed that old Merino sheep without the pigmented spots were generally free of pigmented fibre whereas affected sheep produced wool containing relatively high levels of dark pigmented fibre (Fleet 2006). In the Merino flock studied some sheep were shorn twice a year and after the second year these sheep had a higher number of pigmented spots. Therefore, should industry adopt multiple shearing as a practice (e.g. to avoid length penalties on fine wool, to exploit a short staple wool market opportunity or to minimise flystrike problems) then this practice could lead to an earlier onset (Fleet 2006). Also, it appears the onset may be earlier than Merino for the Corriedale breed (Cardellino 1992) perhaps indicating a more susceptible genetic background.

Figure 5.12 Percentage of sheep with black-grey pigmented skin spots bearing pigmented fibres and number of spots on affected sheep in relation to sheep age. Source: Fleet (2006b).

0 1 Spots 2 3 4 5 %Sheep 6 7 Sheep age 8 Spots Spots %Sheep

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England The development of these black skin spots is encouraged by exposure of the skin to sunlight or artificial ultraviolet light (Forrest and Fleet 1985; Forrest and Fleet 1986). In old age, the change in localised spot(s) involves a change in the type of melanocyte (dormant/phaemelanogenic to active/eumelanogenic), which become prolific, invading wool follicle bulbs and causing black-pigmented fibres to develop (Forrest and Fleet 1986).

Usual culling at 5.5 years of age likely overcomes the development of this risk in most Merino flocks. Where mobs are kept much later than this age shearers could be asked to check more carefully to identify affected fleeces for separation or the entire lot could be identified as at risk if a high proportion of affected individuals are apparent.

5.3 Strategies to reduce or identify dark and medullated fibres

Recognised practices for controlling dark and medullated fibres on farm as well as the appropriate descriptions for branding greasy wool lots are included in the Code of Practice for Preparation of Australian Wool Clips. A checklist is provided as a reminder of the tasks required in preparation for and during shearing (AWEX 2004; 2006b).

Non-sheep fibrous contaminants Simple cleanliness tasks are involved in avoiding exposure of sheep and wool to foreign fibres of non-sheep origin. Oversight on the farm to these details (e.g. leaving hay bale twine where sheep graze or are held; using fertiliser/seed bags to store or separate wool) is a continuing problem for the wool industry (Figure 5.13 and 5.14). Hay bale twine contamination found per tonne of clean wool was about 3-fold higher than found in a previous survey 10 years earlier while the amount of fertiliser/seed bag contamination had more than halved (AWI 2003b).

Previously, jute and HDPE (high density polyethylene) wool pack materials were major contaminants found in mill surveys (Heintze 1994; AWI 2003b). Wool pack material can enter wool at several points, including routine operations, where packs are penetrated and damaged; e.g. pressing and core sampling (Abbott and Blanchonette 1998). Since 1998, procedures were introduced to replace jute and HDPE with wool packs made of nylon (accepts dye similar to wool) in Australia (AWEX 1997) and continuous polyethylene film in Uruguay (Mendoza and Maggiolo 1999).

A recent mill survey (AWI 2003b) found the weight of farm pack materials (made of jute or HDPE) per tonne of wool inspected has declined by 96% and the overall frequency of non-wool contaminants in the sample declined by 52%. Farm objects were the major source of the contamination with the most common items being hay bale twine, fertilizer bags and feathers.

Figure 5.13 Black hay bale twine in top and woven fabric. Image Source: Vern Gibbs (PIRSA)

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Dark and medullated fibres of sheep origin In a wool producing flock, all sheep have the potential to produce wool darkened by urine while only some have a liability for pigmented fibre (Fleet 1996,1998). CSIRO studies have identified the on-farm factors that influence the risk of urine stain (Foulds 1989, Burbidge and McInnes 1984; Rottenbury et al. 1995). The main conclusions of this work are: • Sale lot assessment of apparent skirting quality can be a poor indicator of the likely level of stain present. • Fleece and skirtings from wethers are less likely to be contaminated by urine stain than for ewes. • Mulesing (at least in wrinkly sheep) can reduce the amount of stain to about one sixth of that produced by untreated ewes. • Fleece wool contained less stain than the pieces shed line. • If the stain is present at shearing, it is difficult to eliminate it completely. Often, modified shearing and shed procedures did reduce the amount of stain but, usually, not enough to lower the level to within acceptable limits. • Emphasis should be placed on removing stain through some form of crutching for ewes (Figure 5.15) and ringing for wethers (and rams) close to shearing. If this crutching occurs within 3-months of shearing there is low risk of contamination from this source (“Stain Free Procedure”).

Figure 5.15 Shows a) a urine-affected wool on the ewe and b) a crutched ewe. Image Source: Malcolm Fleet, SARDI (2004). a) b)

A dark fibre risk evaluation scheme was proposed as a way that the marketing industry could present to buyers, based on information supplied by wool classers and vendors, an indicator for deciding relative risk of lots in this regard (Foulds 1989). The broad information aspects influencing occurrence of both pigmented and urine stained fibre considered (Burbidge and McInnes 1994; Rottenbury et al. 1995) were:

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Trials were conducted to evaluate this approach by way of processing many individual sale lots and examining outcomes for stained and pigmented fibre against the information supplied by wool classers and vendors via wool brokers (Table 5.8).

Table 5.8 Dark fibre results for tops produced from sale lots with classified risk levels 1- 5. Source: Burbidge and McInnes (1994). Risk level* No. sale Mean dark % of lots ≤ 100 dark fibres lots fibre / kg top / kg top 1 5 43 100 2 35 72 77 3 56 112 68 4 35 254 43 5 30 802 20 *1 = fleece wool from sheep with < 3- *2 = fleece wool from wethers month from crutching. (Burbidge et al. with >3-month from crutching or 1991) skirtings with < 3-month from crutching. (Burbidge et al. 1991)

Overall the scheme performed relatively well for predicting urine stain (Table 5.8) and one aspect (“Stain Free Procedure”) was incorporated at the time as part of the elective information to be supplied in the wool classer specification. However, the CSIRO scheme was not implemented by the wool marketing industry apart from the requirement of “Stain-Free” for certain quality management schemes (e.g. Clip-Care and Dalcare). New interest in this information system (via AWTA Ltd and the Federation of Australian Wool Organisations (FAWO) developed with the concerns about other objectionable fibre threats, arising from the mating of Merinos to coloured and kempy “exotic” breeds.

The dark and medullated fibre risk (DMFR) scheme Early in 2003 a new project initiated by FAWO and funded by AWI Ltd. commenced to update the CSIRO Dark Fibre Risk Scheme to include data on the contamination risk related to “exotic” breeds. Activities were also to be undertaken to facilitate the introduction of a national vendor declaration scheme (Hansford 2003). In December 2003, IWTO approved a recommendation from FAWO that a DMFR scheme for Australian Merino wools be recognised as part of its test regulations from 1 July 2004. This acceptance by IWTO allows AWTA Ltd to include the assessed risk level (Figure 5.16) on AWTA Ltd Core Test Certificates and AWEX Ltd has been approached to facilitate inclusion in sale catalogues (Morgan 2003).

A substantial proportion of the Merino ewe flock is mated to non-Merino breeds and increases in crossbreeding are reducing the proportion of Merino wool (AWEX 2003) and Merino sheep available (Barrett 2003). Even though some of the non-Merino sire-breeds are likely to result in additional contamination by pigmented and/or objectionable medullated fibre the requirement for declaration and bale labelling (Y or P and proposed R suffix) applies only to the few specified “exotic/shedding” breeds unless the contamination can be seen in the white wool (AWEX 2004; AWEX 2006a,b). For most breeds there is currently no reliable information about Merino crossbreeding contamination effects. In the absence of breed information and specific branding options to identify the nature of the crossbreeding, an option could be to seek information and separate those entirely Merino flocks - giving three breed effect levels (self-replacing Merinos, Merinos rearing non-“exotic/shedding” crossbred lambs, Merinos rearing specific “exotic/shedding” crossbred lambs).

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Figure 5.16 Decision tree for dark and medullated fibres. Source: Morgan (2003); Hansford (2003). For the latest DMFR tree see http://www.awta.com.au/Publications/Marketing/DMF_Risk/DMFR_Scheme.htm or AWEX 2006b)

Even with the provision of a rapid, reliable and affordable presale test there will still need to be reliance on on-farm practices, descriptions and supporting information as a means of predicting the possibility of sporadic “clumpy” fibre contaminant fibres (e.g. urine stain – Burbidge and McInnes 1994, perhaps even bale twine use – AWEX 1997). The information for determining DMFR from the Wool classer's Specification or separate Woolgrower declaration form include (Hansford et al. 2003; Morgan 2003):

• WOOL TYPE (whether fleece, pieces, lambs, bellied, locks crutchings, stain etc) • QUALIFIERS IN WOOL DESCRIPTION: AWEX ID qualifiers Y (pigment), P (kemp) or S (stain) • CRUTCHING: none, Crutch/shear interval ≤ 3 months • SEX: Ewes, wethers, rams • CONTACT WITH EXOTICS: Mated, reared or run with “exotics/crosses” • AGE: ≤1 year, 1-2 years, 2-8 years and > 8 years

The introduction of the DMFR scheme involves voluntary declarations. However, where the information is not provided then “Not Declared” will be indicated against DMFR limiting its acceptability for certain buyer's requirements. As with past additional measurements buyer acceptance and demonstrated price benefits will facilitate adoption. Demonstrated price benefits for low risk wool will also enhance commitment on-farm for the breeding and management required to qualify while development of measurement and trace-back with potential penalties will encourage compliance to required standards.

Genetic improvement Observation of the many breeds of sheep reveals obvious differences in pigmentation and medullation (AWEX 2004) that must reflect genetic determinants. Single genes uniquely control some of these features while others have a more complicated genetic basis (Dolling 1970; Sponenberg et al. 1996; Dolling et al. 1996). For the most part we are not certain which genes are involved in sheep but for some features comparisons can be made with effects of characterised genes found in mice, humans and other livestock (Fleet 2002a). For example, Beraldi et al. (2006) has mapped a coat pigment dilution gene effect to sheep chromosome 2 where a likely candidate gene (tyrosinase-related protein-1) has also been mapped. This gene (TYRP1) is recognised for causing dilution of black to brown or more extreme types of hypopigmentation such as oculocutaneous albinism type 3 in humans and melanocyte death/fibre greying in mice. Interesting also, that this pigment dilution effect in the population of sheep studied is also associated with differences in body weight and survival. Fleet (1996;

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England 1997) reported significant positive genetic correlations (based on a sample of 24 to 42 sires) between residual pigmentation on white sheep and birth or hogget weights in a Merino genetic resource flock as well as the links with risk of isolated pigmented fibres (see below).

The absence/minimisation of pigmentation and medullation is most relevant to the Merino types and breeders, through selection on phenotype, have achieved much. Even though the Merino has a reputation for relative freedom from pigmented and objectionable medullated fibres there remains scope for improvement. Unwanted pigmentation remains a continual reason for culling of some sheep and for occurrences of pigmented wool fibres in certain wool lots that are excessive (Burbidge et al. 1991).

Black sheep and random spots Black lambs and random spots on lambs usually occur only at a low frequency in Merino flocks. While the occurrence of a black lamb indicates that both the sire and the ewe are carriers of the recessive gene responsible, the cause of lambs with distinct random pigmented spots is much less certain to explain (see section 5.2). For the commercial wool producer the potential for transfer contamination from these sources is usually relatively low and prevented as soon as all affected sheep are separated and culled (Fleet 1996; Fleet et al. 1995a). The major problem is inconvenience caused and loss in value of coloured lambs and wool that on a national basis is important. For the ram breeder, occurrence of black lambs could signal an important increase in a recessive gene and the need to reverse the change.

Even though there is some degree of relationship between non-wool pigmentation and occurrence of black (Fleet et al. 1989) and random spot (Fleet 1999a) lambs the degree of overlap is large and this difference cannot be relied upon to prevent the problem.. Furthermore, culling sheep for occurrence of any type of pigmentation may leave few individuals to assess on more economically important production characters (Fleet et al. 1989; Fleet 1999a). Table 5.9 shows that white sheep that are carriers of the genetic variation for recessive black (selfcolour) have slightly more black-grey pigmentation for bare-skin around the eyes, nose-lips and under- tail and in the hooves.

Brooker and Dolling (1969) report on various matings of black rams to white ewes, involving 566 white progeny (all carriers of recessive black) of which only 5 were classified has having a random/piebald spot (i.e. about 1%), 29 were black lambs (indicating about 10% of the ewes were carriers). Furthermore, from matings between white with random/piebald spot and black parents producing 2 black progeny and 111 white progeny (all carriers of recessive black) only 9 progeny (i.e. 8%) had a black random/piebald spot. These findings indicate there is little, if any, dependence of occurrences of random spots on white sheep that are carriers for recessive black. At present, the only mechanism available to ascertain a ram’s status for recessive black is by progeny testing/occurrence of a black lamb. Unfortunately, the principle of simple Mendelian genetics cannot be reliably applied for testing pre-disposition to production of random spots (Brooker and Dolling 1969; Fleet et al. 1985). However, it is practical to identify via DNA paternity testing services the ram(s) responsible for black lambs in a syndicate-mated flock. Research underway by CSIRO/Sheep CRC with support from AWI may characterise DNA variation responsible for black lambs and produce a diagnostic test that could be used to specifically eliminate this genetic variation from ram breeding flocks or sale rams.

Table 5.9 White carriers for recessive black (AWt/Aa) had a little more black-grey skin and hoof pigment. Source: Fleet et al. (1989). Type of pigment Genotype No. sheep with level of black-grey pigment Nil Minor Distinct Skin around eyes Non-carrier (AWt/AWt) 2 72 3 Carrier (AWtt/Aa) 1 68 35 Nose-lips skin Non-carrier (AWt/AWt) 40 37 0 Carrier (AWt/Aa) 38 63 3 Under-tail Non-carrier (AWt/AWtt) 55 22 0 Carrier (AWt/Aa) 42 61 1 Hooves Non-carrier (AWt/AWtt) 54 22 1 Carrier (AWt/Aa) 64 35 7

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Isolated pigmented fibres Some Merino sheep produce fleeces containing isolated pigmented wool fibres. As this fault is hidden in the fleece and difficult to measure, considerable effort was invested to find if relationships existed with visible pigmentation and to identify the most efficient indicators for selection (Fleet et al. 1989; Fleet and Smith 1990; Fleet et al. 1995a; Fleet 1996, 1997, 1998).

Using a Merino resource flock at Trangie Agricultural Centre (NSW) the heritability of various types of visible pigmentation and isolated pigmented fibres was estimated (Fleet et al. 1991b; Fleet 1996, 1997) and hypothetical culling manipulations undertaken on the data set to examine effects on isolated pigmented fibres in the hogget fleece, visible pigmentation and the main productive traits (Fleet et al. 1995a; Fleet 1996; Fleet 1997; Fleet et al. 1997). Figure 5.17 shows the levels of isolated pigmented fibres found in groups of hogget fleeces separated on the basis of 4 pigment culling criteria (Fleet et al. 1995a).

Figure 5.17 Isolated pigmented fibre concentration in culled and selected groups based on four criteria. Source: Fleet et al. (1995b).

Ø Criteria 1 = Only those with pigmented birthcoat halo-hair pigment culled Ø Criteria 2 = Only fibre pigment visible on hoggets (excluding eye lashes) Ø Criteria 3 = Fibre pigment visible on hoggets (including eye lashes) Ø Criteria 4 = 3 above plus including pigmented fibres recorded on the lambs

The results shown in figure 5.17 indicate that separating sheep with visible fibre pigmentation (when present) can effectively reduce isolated pigmented fibres in hogget fleece wool. Since these types of visible fibre pigmentation also mainly had high heritabilities (Fleet 1996, 1997) the culling of affected sheep would be expected to reduce occurrences in future generations. Furthermore, such culling was demonstrated (Fleet et al. 1997) to not affect clean fleece weight, fibre diameter and body weight in the selected sheep as phenotypic correlations were all low (Fleet 1996; 1997).

Study of the inheritance of leg fibre pigmentation from affected and unaffected Merino sheep at Turretfield Research Centre (South Australia) provided data consistent with the proposal that an identifiable gene is involved in preventing this feature (as well as reducing other pigment types) in Merino sheep (Fleet 1994; Fleet et al. 1995b; Fleet 1996). Should this leg fibre pigmentation develop in a Merino flock then after careful sheep inspection (during early life – lamb to hogget) and culling all individuals affected with any trace, this feature can potentially be almost completely removed from the flock in a single generation.

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A rationale called the Ram Classing Lattice (Dolling et al. 1993; Dolling 2002) was developed for making selection decisions about various characters that are either: • Visually appraised but not based on a selection index (e.g. wrinkle, pigmented remnants). • Known to be controlled by identifiable genes (e.g. polledness, recessive black). • Characters used as selection criteria in compiling a selection index (e.g. fleece weight), and • Non-index characters which are measured (e.g. fibre curvature).

The lattice allows emphasis to be placed on the most important selection criteria (whether based on an index or a single character) while considering all other selection criteria. It provides the ram breeder with a basis for a simple and flexible grading basis, reflecting individual merit for both the most important selection criterion as well as merit in the other criteria. Figure 5.18 provides a Flow Chart of the steps involved in using this rationale.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England New technology and novel options Even though much can be achieved through selection on phenotype it is also clear that without gene specific selection or new genetic options for preventing pigmentation and objectionable medullation, these fibres will continue to arise and cause problems at least at low levels. Identifying and characterising useful or unwanted genes in this regard has the potential for complete elimination of one or more of these inherited sources. This research, at least for pigmentation, would be facilitated by the numerous Genomic achievements in mice, humans and other livestock (Fleet 2002a). Initial molecular approaches to pigmentation problems in the Merino have concentrated on recessive black (Parsons et al. 1999a,b) and this is being continued together with investigation of the random spot problem by CSIRO/Sheep CRC and AWI. Other pigment genes have recently been studied at the molecular genetics level in primitive breeds of sheep where pigmentation and colour patterns are maintained as part of the breed description (Vage et al. 2003; Beraldi et al. 2006). Similar opportunities for pigment/medullation gene mapping could arise in Merino x terminal sire crossbreeding flock situations.

5.4 Description and measurement of vegetable matter

Vegetable fault (or vegetable matter - VM - contamination) refers to any particles of plant material present within greasy wool. When present, vegetable fault incurs a price penalty in the market place, because VM influences: • the yield of clean, usable fibre • the system by which the wool is to be processed (worsted or woollen) • fibre loss and breakage during processing • residual contaminants in the top.

The price discounts imposed depend on the amount and type of VM present. It is incorrect to assume that all VM-causing pasture species are “undesirable”, as some valuable pasture species also contribute to VM fault, such as sub-clover and medics.

Vegetable Matter is one of the most important contaminants encountered by buyers and processors of Australian wool. While many VM Types can be readily removed by machinery during processing, the overall world-wide cost of obtaining clean wool fibre products is so large that processors continue to investigate technological advances to improve the efficiency of VM removal. Both the amount present and the type of VM contribute significantly to the price that will be paid for raw wool. The amount of VM directly influences the Clean Fibre Yield which can be obtained after processing the greasy wool, whilst the amount and type of VM affect the method, speed and cost of processing.

The quantity and type of VM found in wool generally reflect the seasonal conditions, the district where the wool is grown and the farm management practices. Some types of VM are confined to limited geographical areas, whereas others are distributed across Australia and are also found in other wool growing countries. The high rainfall, cropping and pastoral areas cover a diversity of pasture management and stocking rates which can affect VM species.

Measurement of VM content VM content is measured as part of the process of pre-sale testing of wool to predict the weight of greasy sample in a sale lot. When appraising the amount of VM present within the fleece, the error in the appraisal can be almost as large as the estimated VM level. That is, for an appraisal of 5% VM, the actual amount could vary from 1% to 10% VM, due to the non-uniform distribution of VM through the fleece.

For this reason, the level of VM in wool is measured and expressed as the vegetable matter base (VMB), this being the amount of clean dry VM present as a percentage of the greasy wool sample. The determination of VMB involves immersion of a scoured wool sample in boiling sodium hydroxide (10% w/v) and stirring for 3 minutes. The wool dissolves, leaving VM and

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England other alkali-insoluble material (such as wool pack material and skin pieces) largely intact. The residual material is collected on a sieve, dried in an oven and separated into three categories, namely seed and shive (S), hard-heads and twigs (H) and burr (B). The masses of each are corrected for slight losses due to the alkali and any mineral matter present, to give the total amount, and the percentage, of VM present in the sample. Information on the H%, B% and S% is reported in the sale catalogue for “Appraisal Purposes Only” – the test certificate provided by AWTA only covers VM base.

Description of VM types Normally only a small part of a plant (usually a burr (seed-pod), a seed, a leaf, part of the stalk from a small plant, or a twig from a tree) normally attaches itself to the wool on the sheep. Therefore standard botanical descriptions are difficult and impractical to use in describing VM Types.

Historically, the market used the H, B and S Types to broadly describe VM fault. The AWEX-ID system subsequently modified and expanded this to the following 7 categories, to reflect differences in the relative importance of the types in processing:

• Burr (B) – Denotes the seed pods produced mainly by the Medicago species and subterranean clover. While some types are generally non-fibrous in shape and therefore relatively easy to remove during processing, other types may unravel into fibrous threads during processing, making them harder to remove • Seed (E) – Denotes fine grass seed material, such as Carrot Seed (Tragus australianus) and Dock (Rumex spp), and other seed material such as Saffron Thistle (Carthamus lanatus) • Shive (S) – Denotes fibre-like seed material derived from a wide range of plant species often difficult to remove • Bogan Flea (F) – Denotes the seed of Calotis hispidula, a small, flea-shaped seed with several spreading awns. It is capable of causing dense matting of the wool • Noogoora Burr (N) – Denotes a hard, spine-covered burr, capable of causing damage to processing machinery due to its hardness. The less common Ring Burr (Sida platycalyx) is also described in this category • Bathurst Burr (T) – Denotes a hard, spine-covered burr, more easily removed during processing compared to Noogoora Burr • Moit (M) – Denotes all non-burr, non-seed plant material such as leaves, twigs and bark, that is relatively easy to remove during processing.

Major vegetable matter types in Australian wool Source: AWTA 1986 Images of V.M. used with permission.

Examples of VM categories: a. Category B (burr)

Barrel Medic (Medicago truncatula)

Also known as Clover Burr and Barrel Clover.

Barrel Medic is barrel shaped with 4-6 spined coils. The spines are thick and lie flat against the coils. This burr is easily distinguished from Burr Medic and Cutleaf Medic by its hard, woody appearance

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Also known as Trefoil, Spiral Burr or Clover Burr. The burr is a flat rounded seed pod. It is typically about 4mm across but may be as small as 2mm or as large as 8mm. The pod consists of 2 to 3 spined coils, which enclose several light-brown kidney shaped seeds.

Burr Medic is very common in Australian wools and is one of the most troublesome types to processors. Not only do its protruding spines catch in the wool, making them difficult to remove, but also, if broken up during carding, its coils tend to unwind into thin ‘eyebrow’ shaped pieces which are even more difficult to remove and can persist in the finished product.

Cutleaf Medic (Medicago laciniata)

Also known as Barrel Medic, Clover Burr or Toothed Medic. The Cutleaf Medic is barrel shaped with 5-6 spined coils. The spines are shorter and stiffer than those of the common Burr Medic.

Due to natural variations within types it is often difficult to distinguish between Cutleaf Medic and Burr Medic in wool. The name derived from the plant (not the burr), as the plant has serrated leaves.

Small Burr Medic (Medicago minima)

Also known as Woolly Burr, Trefoil or Clover Burr. The Small Burr Medic is similar in appearance to the common Burr Medic, although can be distinguished by its tighter coils and thinner spines. The thin spines break off easily, but when present they give the burr a hairy, or woolly appearance.

b. Category E (seed)

Caltrop (tribulus spp)

Also known as Bindi, Cat’s Head. Caltrop is a small hard seed casing. It is divided into 5 sections and each section has a sharp spine. In the example shown here, 4 spines have been broken off. There are many other small, hard types resembling Caltrop and it is often difficult to identify them with any degree of certainty. In general, these types cause no problems during processing.

Carrot Seed (Tragus australianus)

Also known as Small Burr Grass or Marthaguy Burr. Carrot seed is a small grass seed. It is divided into 2 parts which are pointed at the tip. Each part is covered with short, thick spines. Because of its spines, Carrot Seed is difficult to remove during processing. In large numbers, it tends to form a mat of seed in the tips of the wool.

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Also known as Corkscrew, Crowfoot or Wild Geranium. Storksbill is a long, thin grass seed. Similar in appearance to Spear Grass, it has covering of fine hairs and a single twisted awn. However it is easily distinguished by its overall larger size and, in particular, its thicker awn. Because Storksbill is generally thicker and stronger than Wire Grass and Spear Grass, it is more readily removed during processing.

Dock (rumex spp)

Also known as Clustered Dock, Swamp Dock, Red Dock or Sorrel. Dock is a small seed which forms in clusters. The individual seeds break off and catch in the wool, often with their short stem remaining attached. Dock is easily removed during processing.

Galvanised Burr (Bassia birchii)

Also known as Roly Poly, Bind-eye or Stick. Galvanised Burr is a hardened plant stem with spines protruding in clusters at intervals along its length. The stem resembles a small stick or twig and, apart from the spines, has a smooth surface.

Saffron Thistle (Cathamus lanatus)

Also known as Thistle. Saffron thistle has a small, hard seed. It can be recognised by its flat, spreading bristles which are usually found intact. In wool, the seeds are often associated with the sharp spiked leaves which surround the seed pod. It is common in wheat growing areas. Saffron thistle is easily removed from wool during processing.

Spiny Burr Grass (Cenchrus incertus)

Also known as Bayonet Grass or Gentle Annie. Spiny Burr Grass is a small seed-pod. It consists of 2 outer sections which are covered with long, stiff spines and are joined at the base to partly enclose a third central section. Each section contains one small seed. Spiny Burr Grass is a less common type and does not cause problems during processing.

Subterranean Clover (Trifolium subterraneum)

Also known as Sub-Clover, Basket Burr or Barrel Burr. Subterranean Clover has a small spherical seed-pod. It is typically about 4mm in diameter, but may be as small as 2mm or as large as 8mm. The pod holds up to 5 smooth black seeds and is usually found intact. Although Subterranean Clover is classified as Burr for testing purposes, its processing characteristics are not like those of the other Burr types. It tends to remain loose in the wool and is easily removed by carding. If damaged during processing, it breaks up into short pieces rather than unwinding into long ‘eyebrows’ like other Clover Burr and Medic types. c. Category S (shive)

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Barley Grass (Hordeum leporinum) Also known as Oats or Shive. Barley Grass consist of 3 similar spikelets joined at a spoon-shaped tip. Each spikelet has 3 long slender bristles that often break at some point along their length. Barley Grass is one of the most common VM Types in Australian wool and is also one of the most troublesome to processors. This seed penetrates deep into the fleece and sometimes through the skin, causing injury to the sheep.

Spear Grass (stipa spp)

Also known as Corkscrew Grass, Shive or Plains Grass. Spear Grass is a long thin grass seed. The head is covered with fine hairs and has fine barbs at the tip. It has a single awn, which is usually twisted for part of its length. The corkscrew effect enables this grass to penetrate deep into the fleece. Because of its similarity, Spear Grass causes the same types of problems as Wire Grass during processing.

Wire Grass (aristida spp)

Also known as Shive, Spear Grass or Feathertop Wire Grass. Wire Grass is a long thin grass seed. The head has a narrow groove and very fine barbs at the tip. It can be identified by its awns, which no other major type has. The awns may be twisted into a long column rather than being separate as in the examples shown here. Wire Grass is one of the most troublesome VM types to processors. Its long, slender awns easily break off and, because of their fineness, are very difficult to remove during processing.

Wild Oat (avena spp)

Also known as Black Oat or Shive. Wild oat is a hard, thick grass seed. It is covered with fine hairs and has a twisted awn protruding at an angle from its centre. The hairs and awns break off easily leaving a smooth seed.

d. Category N (Noogoora/ring burr)

Noogoora Burr (Xanthium occidentale)

Also known as Nog or Nogs. Noogoora Burr has a hard, bean-shaped seed casing. Similar to Bathurst Burr in appearance, although longer, it can be identified by 2 enlarged spines at its tip. Overall, its spines are stronger and more difficult to break off. Noogoora causes problems in processing, due to its hardness and size rather than causing any fibre loss. In carbonising, it is difficult to crush because it does not readily absorb acid like other vegetable matter. In carding, it can catch in the card teeth, blocking and sometimes damaging them.

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Also known as Monkey’s Ring or Lifesaver Burr. Ring Burr is a large distinctive seed-pod. It consists of many hard, flat segments joined to form a continuous ring. Each segment has several stiff spines and contains one small kidney-shaped seed. Ring Burr is not a common type, being normally found in wool from certain areas of Queensland only. However, due to its hardness it causes problems similar to Noogoora Burr in carbonising. e. Category T (Bathurst burr)

Bathurst Burr (Xanthium spinosum)

Also known as Beans or Cockle Burr. Bathurst Burr has a hard bean- shaped seed casing. It is covered with numerous hooked spines, which are slender and break off easily once the burr is dry. The burr holds 2 seeds. The hooked spines strongly attach the Bathurst Burr to the wool. However, the burr is easily removed during processing because the spines break off. In many cases these burrs float off in the scouring process.

f. Category F (Bogan flea) Bogan Flea (Calotis hispidula)

Also known as New England Crusher or Marthaguy Burr. Bogan Flea is a small flea-shaped seed. It has a woody appearance with several spreading awns. Bogan Flea initially forms as a spherical cluster of many seeds, about 5 mm in diameter. Once on the sheep the cluster usually breaks up causing dense matting of the wool.

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5.5 VM effects on wool processing

Manufacturers are not only interested in the amount of vegetable matter but also the type. Some types are inexpensive to remove from the wool, while others cause damage by breakages in machinery. Thin seeds such as shive may manage to go through the combing machine. This requires recombing and sometimes not even this prevents vegetable matter showing up in the finished cloth. In all cases VM causes some degree of entanglement and causes fibres to be broken during processing (Dawes 1973).

VM in greasy wool is costly to remove and if it remains in the product it may lead to the product being downgraded. This can be seen in the descriptions and photographs of the VM types in the previous section. And obviously the VM type and quantity of determines the effect that this has on the processing ability of a line of wool. Processors will often not comb wool with VM greater than 3%. Research has led to a better understanding of the mechanisms by which VM attaches to the wool and shown that the removal can be enhanced by employing a 3 stage scouring process developed by the CSIRO which causes the VM to swell and detach from the wool fibre.

The card and comb in processing are specially designed to remove VM and between them remove about 99.5 percent of the VM. However this very small remaining fraction can add significantly to the cost of processing the wool, because each piece of VM that persists through into the woven or knitted fabric has to be removed carefully by hand (Teasdale 1991, Plate 1988). Even with a Free or Nearly Free (F/NF) wool it would be normal to have something like five large pieces of VM per kilogram of yarn.

Moderate amounts of VM are removed by the carding and combing processes, but the only satisfactory method of removing excess VM is by the carbonisation process which destroys it with sulphuric acid. Carbonising is the process for removing VM from raw wool – especially very short, burry wools such as lambs, crutchings and locks.

5.6 Economic importance of VM

Freedom from moderate VM only brings a substantial price premium for spinners and they avoid any losses by only buying wools which are Free or Nearly Free (F/NF). Wools which contain a large amount of VM require chemical treatment (carbonising) but many processors do not have this equipment and the wool also deteriorates especially in tensile strength. Topmakers can deal efficiently with VM in the early stages of carding. However they end up with a high proportion of short fibres (noils) with heavy burr content. Because these noils need carbonising and are of low value, topmakers make an appropriate allowance in wool price (Dawes 1973).

Table 5.10 Percentage discounts for VM fault in a range of fleece wool microns sold at auction, December 2003 to February 2004 using a combination of the Southern and Northern Region Premium and discount reports. Source: AWEX (2004b).

VM% 18 19 20 21 23

0 0 0 0 0 0

1 0 0 0 0 0

2 -1.2 -0.7 -0.6 -0.6 -0.6

3 -3.5 -2.5 -1.9 -1.9 -1.9 4 -5.5 -4.8 -4.3 -4.0 -4.2

5 -7.7 -6.7 -6.2 -5.9 -6.4 6 -11.1 -9.5 -8.2 -8.6 -8.5

8 na na -10.2 -10.4 na

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Students can familiarise themselves with the stages and types of wool processing if they study wool marketing or processing units, to assist them to understand the effect of VM content and type on the processing ability of wool. Discounts vary over time and when prices are high, discounts would normally be higher than in the Tables 5.10 and 5.11 and these discounts are also additive. For example, for a 20 micron wool with 5% VM of Moit and Burr would have a discount of 7.8% for VM.

Table 5.11 Percent discounts for VM type of fleece wool microns sold at auction, December 2003 to February 2004 using a combination of the Southern and Northern Region Premium and Discount Reports. Source: AWEX (2004b). VM Type 18 19 20 21 23 Seed E 0 0 0 0 0 Burr B -0.5 -0.4 -0.6 -0.4 -0.3 Shive S -0.7 -0.5 -0.5 -0.5 -0.5 Moit M -1.0 -1.1 -1.0 na -0.4 Bogan Flea F na na na na na Noog/Bath N/T na -1.5 -0.9 -0.6 -0.4

5.7 Strategies to reduce VM fault

The amount and type of VM found in wool reflects the seasonal conditions and the district in which the wool was grown, as well as management practices on individual properties. Some VM types are confined to limited wool-growing areas, while other types are distributed throughout much of the sheep production zone of Australia.

VM problems are more common in wool from mixed farming and pastoral areas as these areas have a greater capacity to sustain plant species causing problems in wool. The high rainfall areas have less VM problems due to greater ground cover, more reliable and higher rainfall and higher stocking rates which tend to limit growth of some of the more problematic species.

For example, the study of Warr et al. (1979) of VM contamination across NSW showed that the major seed contaminant in all districts except the Western Division was Barley Grass, the latter region having Wire Grass and Spear Grass as the major seed types. The major burr types in the NW and CW slopes and plains were from Medicago species with the NW and CW slopes and plains having higher VM than the Tablelands and Southern areas of NSW. Burr contamination was the major VM component in NW and CW slopes and plains, whereas seed was the major component contributing to VM in Tablelands and Southern slopes environments while hard heads were a major component in the Riverina district only.

As the level of VM contamination and the main species causing this contamination vary from district to district, the opportunities for controlling VM contamination will therefore vary between districts. In some areas opportunities to reduce VM levels or types may be low due to the degree of VM contamination and VM type compared to the cost to reduce this contamination to low levels. In addition to the strategies discussed below, opportunities may also exist to manipulate VM fault via chemical control of problematic species and utilisation of crop residues for grazing during seeding periods.

Shearing time Time of shearing has a major effect on the amount and type of vegetable fault present in the fleece, by influencing the length of wool carried during periods when these plants are a problem which is normally when they are seeding. In evaluating the options, a distinction must be made between annual and perennial pasture systems, given the differences between the two in pasture dynamics and time of seed set.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England In a study conducted in Central NSW, Warr and Thompson (1976) demonstrated that shearing lambs in October reduced VM accumulation in the fleece compared to unshorn lambs, for all three species contributing to VM contamination (Table 5.12). The shorn lambs also showed less penetration of seeds into the skin compared to unshorn lambs, the latter group exhibiting an associated loss in live weight arising predominantly from reluctance to move through the mature pasture.

A larger study of Warr et al. (1979) considered 4 shearing times (summer, autumn, winter, spring) within each of the 7 main wool-growing districts of NSW. In this instance, shearing time was shown to only affect total VM fault in one of the 7 surveyed districts, this being the CW slopes and plains. A summer shearing gave lower VM compared to autumn and winter shearing times. For the other locations, the relative contribution of the burr and seed components changed at particular shearing times, but without affecting the total level of contamination. This study indicated that, at least within NSW, the benefits in terms of VM of changing shearing time, depend on the district in which the wool is grown, this being a reflection of regional differences in the dynamics of the pasture species.

Table 5.12 VM fault and seed penetration of skin in Merino and Crossbred lambs grazing seed infested pasture from October to December in Central Western NSW. Source: Warr and Thompson (1976). Merino Crossbred

Shorn Unshorn Shorn Unshorn

Barley grass (%) 0.1 0.7 0.4 0.8

Storksbill (%) 0.1 1.0 0.6 3.1

Medic Burr (%) 1.7 23.2 0.6 16.9 Skin penetration (no. per 6cm2) 0.0 5.7 0.7 7.0

This is further demonstrated in the study by Ritchie (1992) comparing autumn and spring shearing in the cereal-sheep zone of WA. On pastures dominated by annual grass species (Figure 5.19) and on pastures comprising a mix of annual grasses and medics (Figure 5.20), an autumn shearing gave rise to a higher accumulation rate of VM in the fleece compared to a spring shearing.

Figure 5.19 Accumulation of seed and shive in spring and autumn shorn Merino sheep grazing grass-dominant pastures over the spring-autumn period at Katanning, WA. Source: Ritchie (1992).

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Figure 5.20 Accumulation of seed, shive and burr in spring and autumn shorn Merino sheep grazing mixed pastures over the spring-autumn period at Katanning, WA. Source: Ritchie (1992).

Grazing management Modification of botanical composition of a pasture by grazing can be achieved through: • Heavy or light stocking densities • Continual grazing of either sheep or cattle • Changing the length and frequency of rests (for desirable species) • Strategic grazing based on the stage of growth of the plant • Hard grazing over the flowering period to reduce seed production of undesirable species • Tactical cutting (fodder conservation or slashing) • By allowing pastures to seed and regenerate.

Botanical composition is easier to manipulate by grazing management if the problematic species are annuals. The growth pattern of both the problem and desirable species need to be known to be able to determine the periods of weakness in the problem species when a desirable change in botanical composition can be obtained. This may involve the use of a herbicide to reduce the seed set of the less desirable plants (PROGRAZE®).

Stocking rate or grazing pressure in association with grazing management can also influence VM contamination by modifying the species composition of the pasture, and thus also the amount and/or type of vegetable fault present in the fleece. For example, at 2.04 wethers per hectare on natural pastures in Central West NSW (Brownlee 1973), the predominant pasture species were those associated with burr fault (Medicago spp) with the grass component (mainly Aristida and Stipa spp) being somewhat less. However, when grazed at 1.02 wethers per hectare, the contribution of Aristida to the pasture increased, whereas that associated with the Medicago spp decreased. While no results for VM fault were reported in this study, the change in botanical composition would suggest an associated change in the seed and burr components of the VM in the fleece.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Figure 5.21 The effect of short-term grazing by cattle on the height and number of seedheads of Whitespear Grass present in Mitchell Grass pasture in SW Qld. Source: Wilson and Simpson (1994).

The value of grazing pressure to modify botanical composition and possibly VM contamination does depend on the pastures species present and their relative competitiveness and responsiveness when being grazed. For example, when Whitespear Grass (a major source of seed contamination in Qld) is grazed by sheep, there is little effect on plant height and seedhead numbers. However, both attributes can be substantially reduced when grazed by cattle (Figure 5.20), such that sheep subsequently grazing on these pastures showed markedly reduced contamination arising from Whitespear Grass.

Some plants (especially annuals) only shed seed for a limited period and problems can be reduced by either deferring grazing these paddocks or creating some cleaner paddocks that can be grazed when seed is a problem. If possible do not graze paddocks with a high population of problem plant species but do not graze with sheep with a higher wool value such as hoggets or lambs.

Sheep coats The use of coats or rugs on sheep is another potential strategy for reducing VM fault in the fleece. The value of this strategy does depend on the pasture species present, the total level of VM normally accumulated when rugs are not used and the improvements in wool value relative to the cost of using coats. The improvement in wool value will depend on fibre diameter, as there is more to gain if coats are used with fine wool rather than broader wool types. However, the “convention” is for medium and broader wool types to be run in those environments subject to higher levels of VM fault.

A trial conducted in Central West NSW (Hatcher et al. 2003) to consider the feasibility of running fine wool sheep in this environment found that sheep coats slightly reduced the VM content and increased the style on fine wool sheep. Table 5.13 shows the VM fault and VM particles in coated and uncoated sheep in a number of locations in South Eastern Australia (Abbott 1979).

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Table 5.13 VM fault (%) and residual VM particles in wool top for rugged and unrugged sheep run together in a number of wool-growing regions. Source: Abbott (1979).

Location Rugged VM% VM particles per 100gm top Birchip, Vic Yes 0.4 4 No 0.9 2 Wanbi, SA Yes 4.1 90 No 4.7 160 Sandalwood, SA Yes 4.4 16 No 9.7 45 Deniliquin, NSW Yes 0.7 6 No 2.5 20

Agronomic opportunities Another potential field of research for addressing VM contamination is the development of less problematic cultivars of valuable pasture species. For example, Barrel medic is a valuable pasture species in many wool-growing areas, but it is also a problematic species in terms of VM contamination. There are, however, spineless cultivars of this pasture species. Brownlee and Denney (1985) demonstrated marked differences between cultivars of Barrel medic in their persistency under grazing, pod productivity and contribution to VM in the fleece (Table 5.14). This study included two spined cultivars - Akbar and Hannaford - and two spineless cultivars - Cyfield and Tornafield. Cyfield was similar to Hannaford in terms of persistency and productivity, but without contributing to VM contamination. Tornafield likewise did not contribute to VM contamination, but was not as productive or persistent as other cultivars.

These results suggest that there may be opportunity for developing cultivars of pasture species with a reduced capacity for being acquired in the fleece, while retaining their contribution to the feed base. Limited research appears to have been conducted in this field.

Table 5.14 The persistency, productivity and contribution to VM fault of barrel medic cultivars after 3 years of continuous grazing at 4 sheep per hectare at Condobolin, central NSW. These results refer to the last year of the experiment. Source: Brownlee and Denney (1985).

Cultivar Medic % Total pod Medic burr fault in (kg/ha) (gm per gm greasy) paddock Skirtings Bellies Akbar 33 1580 10.1 11.1 Hannaford 52 2497 7.2 13.5 Cyfield 60 2900 0.0 0.0 Tornafield 30 1113 0.0 0.0

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Readings The following readings are available on CD: 1. Brownlee, H. 1973, ‘Wool production, ground cover and botanical composition of pastures grazed by merino wethers in central western New South Wales. I. natural pasture’, Australian Journal of Experimental Agriculture; Animal Husbandry, vol. 13, pp. 502-509. 2. Brownlee, H. and Denney, G.D. 1985, ‘Evaluation of medics under continuous grazing with sheep in central western New South Wales’, Australian Journal of Experimental Agriculture, vol. 25, pp. 311-319. 3. Dolling C.H.S. 2002, Sheep classing and selection – a genetic basis, Lecture notes. 4. Fleet M.R. 1998, Dark fibre control in sheep and wool, PIRSA/SARDI Fact sheet Agdex 437/30. Available on Prime Notes CD-Rom (QDPI) and web home of SARDI (www.sardi.sa.gov.au) retrieved Aug 2003 and AWTA Ltd (www.awta.com.au) retrieved Aug 2003. 5. Fleet M.R. 1999, Wool contamination – pigmented and highly medullated fibres, PIRSA/SARDI Fact sheet Agdex 437/85. Available on Prime Notes CD-Rom (QDPI) and world wide web pages of SARDI (www.sardi.sa.gov.au) retrieved Aug 2003, AWTA Ltd (www.awta.com.au) retrieved Aug 2003 and AWEX Ltd (www.awex.com.au) retrieved Aug 2003. 6. Fleet, M.R. and Bennie, M.J. 2002, ‘A comparison of Damara crossbred and Merino lambs wool’, Animal Production in Australia, vol. 24, pp. 69-72. 7. Hatcher, S., Atkins, K.D. and Thornberry, K.J. 2003, ‘Sheep coats can economically improve the style of western fine wools’, Australian Journal of Experimental Agriculture, vol. 43(1), pp. 53-59. 8. Warr, G.J., Gilmour, A.R. and Wilson, N.K. 1979, ‘Effect of shearing time and location on vegetable matter components in the New South Wales woolclip’, Australian Journal of Experimental Agriculture; Animal Husbandry, vol. 19, pp. 684-688.

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Summary Summary Slides are available on CD

Dark and medullated fibres in Merino wool can arise from a number of sources including contact with exotic breeds of sheep, brands applied to sheep, urine stain and pigmentation from the sheep itself, with these sources of contamination able to be reduced through careful management practices and genetic improvement. Dark and medullated fibres of both sheep and non-sheep origin are common faults in wool products, given their different dying characteristics, and the cost of such faults is currently absorbed by the manufacturing sector, due to blending at an early stage of processing. Currently there is no presale test for identification of dark and medullated fibre risks and thus reliance is placed on producers and woolclassers to declare wool lots of known risk. In recent times, the crossing of Merinos with dark or kempy exotic breeds has led to increased problems for the Australian Wool Industry. A new dark and medullated fibre risk scheme, developed from an existing risk prediction scheme for urine stain, will assist the wool marketing industry to better recognise lots at risk of DMF contamination and help encourage producers and classers to play their role in reducing this problem.

Vegetable matter is also a common fault in Australian wools that can be minimised through careful sheep and grazing management. VM exists in numerous forms each causing different problems during processing. The key to minimising VM problems is knowing the species causing the problem, and its growth pattern and implementing management procedures to avoid long wool sheep from coming into contact with that species during seed set.

References

Dark and medullated fibre Abbott, G.M. and Blanchonette, I. 1998, ‘Wool packaging and contamination’, Wool Technology and Sheep Breeding, vol. 46, pp. 198-212. Abbott, G.M. 1979, ‘Rugging of sheep with polyolefin fabrics: the benefits and economics’, Wool Technology and Sheep Breeding, vol. 27, pp. 29-33. ASTM 1980, ‘Standard Test Method for Neps, vegetable matter and coloured fibre in wool top (D1770’, Part 33 – Textiles in Annual Book of ASTM Standards. American Society for Testing and Materials, Philadelphia, USA. ASTM 1996, ‘Test method D2968. Med and kemp fibres in wool and other animal fibres by microprojection’, Section 7 in Annual Book of ASTM Standards. American Society for Testing and Materials, Philadelphia, USA. AWEX 1997, Report of the contamination working party, Australian Wool Exchange Ltd, Sydney, pp. 22. AWEX 2002, Australian Wool Statistics Yearbook, Australian Wool Exchange Market Reporting Service. AWEX 2004a Australian Wool Statistics Yearbook. Australian Wool Exchange Market Reporting Service. AWEX 2004b. Code of Practice for the AWEX Quality System. Preparation of Australian Wool Clips. The Woolclasser (Australian Wool Exchange Limited; Sydney). http://www.awex.com.au/ AWEX 2006a. AWEX-ID V3.OS Released. BOARDtalk, Australian Woolclassing Journal, August, p2.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England AWEX 2006b. Draft Version 3.0 Code of Practice, Preparation of Australian Wool Clips, The Woolclasser 2007-2009. (http://www.awex.com.au/AWEXMAIN.524866:STANDARD:1935475545:pc=PC_15). AWI 2002, $1 million investment to address dark and medullated fibre issue. Media release, 13 September 2002, Australian Wool Innovation Ltd. AWI 2003a, ‘Four-pronged attack on costly issue’, in: Beyond the Bale. Issue No. 5, June 2003. AWI 2003b, The AWI 2003 non-wool contamination survey, Australian Wool Innovation Ltd, Sydney, pp 29. AWTA Ltd, CSIRO and AWI 2004, Development of an improved test for detection of dark and medullated fibres in presale core samples. International Wool Textile Organisation, Technology and Standards Committee, Shanghai Meeting Report No. RWG 5. Available at www.awta.com.au/Publications/Research_Papers/Wool_Contamination.htm. Balasingam A. 2005. The definitions of medullation threshold values used by different testing methods to define an objectionable medullated fibre in Merino wool. Milestone TMS01 report, AWI project EC651 (AWTA Ltd; e-mail: [email protected]). Balasingam A. and Mahar T.J. 2005. Status report on the dark and medullated fibre testing of presale core samples and review of the detection threshold for contaminant medullation. International Wool Textile Organisation, Raw Wool Group, Hobart Meeting Report No. RWG 4. (www.awta.com.au/Publications/Research_Papers/Wool_Contamination.htm) Barrett, D. 2003, ‘Australian sheep flock – breed and age composition’, in: Australian Farm Surveys Report 2003, Australian Bureau of Agricultural and Resource Economics, Canberra. Beraldi D., McRae A.F., Gratten J., Slate J., Visscher P.M. and Pemberton J.M. 2006. Development of a linkage map and mapping the phenotypic polymorphisms in a free-living population of Soay sheep (Ovis airies). Genetics Society of America Vol 173: pp 1521-1537. Brooker M.G. and Dolling C.H.S. 1969. Pigmentation of sheep III Piebald patterns in Merinos. Australian Journal of Agricultural Research Vol 40: pp 445-455. Brownlee, H. and Denney, G.D. 1985, ‘Evaluation of medics under continuous grazing with sheep in central western New South Wales’, Australian Journal of Experimental Agriculture, vol. 25, pp. 311-319. Burbidge, A., McInnes, C.B. and Foulds, R.A. 1991, Development and preliminary evaluation of the CSIRO dark fibre risk scheme for individual sale lots of Australian wool, International Wool Textile Committee, Technical Committee, Lisbon, Portugal Meeting, Report No. 12. Burbidge, A., Rottenbury, R.A. and Sunderland, R.F. 1993, Dark fibre contamination in wool tops from consignments of Australian wool. International Wool Textile Committee, Technical Committee, Nice Meeting, Report No. 11. Burbidge, A., McInnes, C.B., Brown, G.H., Foulds, R.A. and Stephens, L. 1994, Inter-laboratory trial to evaluate IWTO(E)-13-88(E). International Wool Textile Committee, Technical Committee, New Delhi Meeting, Report No. 22. Burbidge, A. and McInnes, C.B. 1994, ‘Dark fibre risk and prediction’, in WOOLSPEC94, Paper N, CSIRO, Sydney IWS. Cardellino, I.R.A. 1978, ‘Incidence of pigmented fibres in Uruguayan wools’. Boletin Technico No. 3. Secretariado Uruguayo de la Lana pp. 43-45. Cardellino, I.R.A. 1992, ‘Herencia de las fibras coloreadas’, in: Seminario Sobre Mejoramiento Genetico en Lanas, Secretariado Uruguayo de la Lana, Piriapolis, Uruguay pp. 99-115. Chapman, D. and Crean, D. 2000, Woolclasser Development Program. Western Institute of TAFE, NSW. Dolling, C.H.S 1970, Breeding Merinos, Rigby Ltd, Adelaide. Dolling, C.H.S., Anderson, L.J. and Castle, G.T. 1993, ‘A ram-classing lattice for a ram breeding flock’, Wool Technology and Sheep Breeding, vol. 41, pp. 269-280. Dolling, C.H.S., Rae, A.L., Denis, B., and Renieri, C. 1996, ‘Loci for visible traits’, in Mendelian inheritance in sheep 1996 (MIS96), (eds. J.J. Lauvergne, C.H.S. Dolling and C. Renieri), Committee on Genetic Nomenclature of Sheep and Goats, France, University of Camerino, Italy. Dolling, C.H.S. 2002, Sheep classing and selection – a genetic basis, Lecture notes. Enns, R.M. and Nicoll, G.B. 2002, ‘Incidence and heritability of black wool spots in Romney sheep’, New Zealand Journal of Agricultural Research, vol. 45, pp. 67-70.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Fleet, M.R. 1994, ‘Recently identified genes that control pigmentation in sheep’, in Proceedings 5th World Congress on Genetics Applied to Livestock Production, University of Guelph, Ontario, Canada, vol. 19, pp. 428-429 Fleet, M.R. 1996, ‘Pigmentation types – understanding the heritability and importance’, Wool Technology and Sheep Breeding, vol. 44, pp. 264-280. Fleet, M.R. 1997, The inheritance and control of isolated pigmented wool fibres in Merino sheep, Master of Agricultural Science (Animal Science) thesis. Department of Animal Science, University of Adelaide. pp. 257. Fleet, M.R. 1998, Dark fibre control in sheep and wool, Fact sheet Agdex 437/30, PIRSA/SARDI. Fleet, M.R. 1999a, ‘Random spot and relationship with other pigmentation in Merinos’, Association for the Advancement of Animal Breeding and Genetics, vol. 13, pp. 290-293. Fleet, M.R. 1999b, Wool contamination – pigmented and highly medullated fibres. Fact sheet Agdex 437/85, PIRSA/SARDI. Fleet, M.R. 2002a, ‘Pigment prevention in sheep: Complex or simple?’, Wool Technology and Sheep Breeding, vol. 50, pp. 410-416. Fleet, M.R. 2002b, ‘Comparison of dark fibre discounts’, BOARDtalk the Australian Woolclassing Journal, November 2002, Australian Wool Exchange, Sydney, pp. 3. Fleet, M.R., Alaya-ay, A. and Mahar, T.J. 2006a. Relationship between greasy and processed dark fibre contamination from Damara crossbred lambs in Merino wool. International Wool Textile Organisation, Technology and Standards Committee, Cairo Meeting Report CTF 2. pp 1-12. (http://www.awta.com.au/ Publications/ Research_Papers/Wool_Contamination/ IWTO_2006_05_CTF02.pdf) Fleet, M.R. and Bennie, M.J. 2002, ‘A comparison of Damara crossbred and Merino lambs wool’, Animal Production in Australia, vol. 24, pp. 69-72. CSIRO Publishing, original publishers. Fleet M.R., Brien F.D., Smith D.H., Chenoweth K.A Grimson R.J., Jaensch K.S. and Kemper K.E. 2005 Relationship between birthcoat halo-hair and medullated fibres in Merino and Damara crossbred lambs. International Journal of Sheep and Wool Science 53: 66-75. Fleet M.R., Fish V.E., Alaya-ay A.R. and Mahar T.J. 2006b. Dark and medullated fibre contamination in Merino fleece from Damara crossbred lambs: Top and Noil products. International Wool Textile Organisation, Technology and Standards Committee, Xi’an Meeting Report CTF 1. pp 1-9 Fleet, M.R., Flavel, P.F., Stafford, J.E., Smith, D.H. and Dolling, C.H.S. 1985, ‘The incidence of pigmented lambs among the progeny of pigmented rams and Merino ewes which have a high frequency of individuals with spots of pigmented fibres’, Agricultural Record South Australian Department Agriculture, vol. 12, pp. 5, 23-26. Fleet, M.R. and Forrest, J.W. 1984, ‘The occurrence of spots of pigmented skin and pigmented wool fibres in adult Merino sheep’, Wool Technology Sheep Breeding, vol. 32, pp. 83-90. Fleet M.R., Forrest J.W., Walker S.K. and Rogers G.E. 2004. Foetal development of melanocyte populations in Merino wool-bearing skin. Wool Technology and Sheep Breeding Vol 52: pp 101-123. Fleet, M.R., Foulds, R.A., Pourbeik, T., McInnes, C.B., Smith, D.H. and Burbidge, A. 1995b, ‘Pigmentation relationships among young Merino sheep and their processed wool’, Australian Journal of Experimental Agriculture, vol. 35, pp. 343-351. Fleet, M.R., Lush, B.J. and Hynd, P.I. 1993, ‘Age-related changes in white wool-bearing skin melanocytes’, Wool Technology and Sheep Breeding, vol. 41, pp. 83-90. Fleet, M.R., Mahar, T.J. and Turk, J.A. 2002b, ‘Merino crossbreeding and objectionable sheep fibres: the problem and potential solution’, Wool Technology and Sheep Breeding, vol. 50, pp. 650-656. Fleet, M.R., Mortimer, S.I. and Gallagher, J.R. 1997, ‘Culling visible fibre pigmentation in Merino hogget sheep: Effects on production and other pigmentation traits’, Association for Advancement of Animal Breeding and Genetics, vol. 12, pp. 172-175. Fleet, M.R., Mortimer, S.I., Hynd, P.I., Gallagher, J.R. 1995a, ‘Pigmented fibre concentration in the skirted hogget Merino fleece after culling on visible pigmentation’, Australian Association of Animal Breeding and Genetics, vol. 11, pp. 318-322.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Fleet, M.R., Pourbeik, T., Mortimer, S.I., Ponzoni, R.W. and Rogan, I.M. 1991b, ‘Heritabilities and phenotypic correlations for pigment traits in Peppin Merino sheep’, Proceedings Australian Association Animal Breeding Genetics, vol. 9, pp. 400-403. Fleet, M.R., Smith, D.H. and Stafford, J.E. 1989, ‘Comparison between Merino sheep homozygous (WW) or heterozygous (Ww) for white fleece on the incidence of isolated pigmented wool fibres and types of non-fleece pigmentation’, Australian Journal Agricultural Research, vol. 40, pp. 445-455. CSIRO Publishing, original publishers. Fleet, M.R. and Smith, D.H.S. 1990, ‘Pigmented fibres in white-skirted fleece wool from piebald Merino sheep’, Australian Journal of Agricultural Research, vol. 41, pp. 155-156. Fleet, M.R., Smith, D.H. and Pourbeik, T. 1991a, ‘Age-related changes in pigmentation traits in Merino sheep’, Wool Technology Sheep Breeding, vol. 39, pp. 26-36. Fleet, M.R. and Stafford, J.E. 1989, ‘The association between non-fleece pigmentation and fleece pigmentation in Corriedale sheep’, Animal Production, vol. 49, pp. 241-247. Fleet, M.R., Turk, J.A., Cottell, M.A. and Keynes, G.N. 2001, ‘Merino wool contamination from rearing of Damara crossbred lambs’, Australian Journal of Experimental Agriculture, vol. 41, pp. 725-731. Forrest, J.W. and Fleet, M.R. 1985, ‘Lack of tanning in white Merino sheep following exposure to ultraviolet light’, Australian Veterinary Journal, vol. 62, pp. 244-246. Forrest, J.W., Fleet, M.R. and Rogers, G.E. 1985, ‘Characterisation of melanocytes in wool- bearing skin of Merino sheep’, Australian journal of Biological Science, vol. 38, pp. 245-257. Forrest, J.W. and Fleet, M.R. 1986, ‘Pigmented spots in the wool-bearing skin of white Merino sheep induced by ultraviolet light’, Australian Journal Biological Science, vol. 39, pp. 125-136. Foulds, R.A., Wong, P. and Andrews, M.W. 1984, ‘Dark fibres and their economic importance’, Wool Technology and Sheep Breeding, vol. 33, pp. 91-99. Foulds, R.A. 1989, ‘Dark fibre contamination in wool: Its prediction and ramifications’, Wool Technology and Sheep Breeding, vol. 37, pp. 33-37. Furumura, M., Sakai, C., Abdel-Malek, Z., Barsh, G.S. and Hearing, V.J. 1996, ‘The interaction of Agouti signal protein and melanocyte stimulating hormone to regulate melanin formation in mammals’, Pigment Cell Research, vol. 9, pp. 191-203. Gallagher, J.R. 1969, A metrological and histological evaluation of Merino wool quality. PhD thesis of the Dept. Livestock Husbandry, University of New England. Gallagher, J.R. 1970, ‘An evaluation of Merino wool quality II An estimate of the incidence of coarse fibres in Australian Merino wool’, Journal of Agricultural Science, Cambridge, vol. 74, pp. 99-102. Hancock, B. and Schuster H. (eds), 2004. Winning against seeds - management tools for your sheep enterprise (Meat and Livestock, Australia) ISBN 1 74036 578 Hansford, K. 2003, Managing the risk of dark and/or medullated fibre contamination – Literature Review. Australian Wool Innovation Project EC573. August 2003. Available at: www.awta.com.au/Publications/Research_Papers/Contamination.htm. Hansford K.A. and Swan P.G. 2005. Australian Wool Innovation 2004 Global Survey of Dark and Medullated fibres. International Wool Textile Organisation – Technology and Standards Committee. Commercial Technology Forum. Report CTF 02. Biella Meeting, November 2005. (www.awta.com.au/Publications/Research_Papers/Wool_Contamination.htm). Hansford K.A. and Morgan P. 2006. All breeds trial for management of dark and medullated fibre risk. BOARDtalk, Australian Woolclassing Journal, January, p3. Hatcher, S., Foulds, R.A., Lightfoot, R.J. and Purvis, I.W. 1999, ‘The relative wool contamination potential of Awassi and black Merino sheep when penned together with white Merinos’, Australian Journal of Experimental Agriculture, vol. 39, pp. 519-528. Hatcher, S. 2002, ‘Fibre medullation, micron, marketing and management’, in Proceedings of a Symposium on African and Middle East meat sheep breeds. Cowra Show Society, Cowra NSW (accessible from: http://www.awta.com.au/Publications/Research_Papers/Research_ Index.htm. Heintze, G.N. 1994, ‘Comparison of non-wool contaminants found at two Australian carbonisers’, Wool Technology and Sheep Breeding, vol. 42, pp. 279-292. Holst, P.J.< Hall, D.G. and Stanley, D.F. 1996, 'Barley grass seed and shearing effects on summer lamb growth and pelt quality. Australian Journal of Experimental Agriculture, vol 36, pp 777-780.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Holst, P.J., Hegarty, R.S., Fogarty, N.M. and Hopkins, D.L. 1997, ‘Fibre metrology and physical characteristics of lambskins from large Merino and crossbred lambs’, Australian journal of Experimental Agriculture, vol. 37, pp. 509-514. Hunter, L., Frazer, W. and Smuts, S. 1990, ‘The measurement of kemp in mohair’, Proceedings of the 8th International Wool Textile Research Conference, vol. 2, pp. 299-3111. Hunter, L., Smuts, S. and Dorfing, L. 1996, ‘The characterisation and measurement of objectionable medullated fibres in wool and mohair using image analysis’, International Wool Textile Organisation, Special topics Group, Cape Town Meeting. IWTO 1998, Specifications of test methods. IWTO-57-98. Determination of medullated fibre content of wool and mohair samples by opacity measurements using OFDA, International Wool Textile Organisation, Woolmark Co. Ilkley, UK. IWTO 1999, Specifications of test methods. IWTO-55-99. Method for automatic counting and classifying cleanliness faults in tops using the Optalyser instrument, International Wool Textile Organisation, Woolmark Co. Ilkley, UK. Kelley, R.B. and Shaw, H.E.B. 1942, ‘A note on the occurrence and inheritance of pigmented wool’, Journal of the Council of Scientific and Industrial Research, vol. 15, pp. 1-3. Lang, W.R. 1950, ‘Non-kempy medullated fibres in Australian Merino wool’, Journal of the Textile Institute, vol. 41, pp. T309-T320. Little, D.L., Carter, E.D. and Ewers, A.L. 1993, 'Live weight change, wool production and wool quality of Merino lambs grazing barley grass pastures sprayed to control grass or unsprayed. Wool Technology and Sheep Breeding vol 41, pp 369-378. Lupton, C.J. and Pfeiffer, F.A. 1998, ‘Measurement of medullation in wool and mohair using the Optical Fibre Diameter Analyser’, Journal of Animal Science, vol. 76, pp. 1261-1266. Lyne, A.G. and Hollis, D.E. 1968, ‘The skin of sheep: A comparison of body regions’, Australian Journal of Biological Science, vol. 21, pp. 499-527. Morgan, P. 2003, ‘Update of progress in dark and medullated fibre risk project’, December 2003, Australian Wool Testing Authority, Available at: www.awta.com.au/Publications/ Research_Papers/Contamination.htm. Mendoza, J. and Maggiolo, J. 1999, ‘Cuanto importa la calidad en la lana’, Lana Noticias No. 122, Secretariado Uruugayo de la Lana, pp. 37-41. Meyer, L., MacDonald, S. and Skinner, S. 2003, Cotton and Wool Outlook. United States Department of Agriculture. Available at: http://jan.mannlib.cornell.edu/reports/erssor/field/ cws-bb/. Parsons, Y.M., Fleet, M.R. and Cooper, D.W. 1999a, ‘The Agouti gene: a positional candidate for recessive self-colour pigmentation in Australian Merino sheep’, Australian Journal of Agricultural Research, vol. 50, pp. 1099-1103. Parsons, Y.M., Fleet, M.R. and Cooper, D.W. 1999b, ‘Isolation of the ovine Agouti coding sequence’, Pigment Cell Research, vol. 12, pp. 394-397. Pattinson, R. and Hanson, P. 1993, An assessment of risk factors associated with dark fibre within the Australian wool clip. Report prepared by the Australian Wool Corporation for the Awassi Seminar. DPIE Canberra, Woolmark Co. Melbourne, September pp 1-12. Rottenbury, R.A., Burbidge, A. and McInnes, C.B. 1995, ‘Predicting the risk of dark fibre contamination in sale lots’, Wool Technology and Sheep Breeding, vol. 43, pp. 328-337. Ryder, M.L. and Stephenson, S.K. 1968, Wool Growth, Academic Press, London. Satlo, I.G. 1963, ‚Anteil dunkler haare in wollkammzugen’, Melliand Texttilberitche, vol. 44, pp. 441-442. Scobie, D.R., Bray, A.R. and Merrick, N.C. 1998, ‘Medullation and average fibre diameter vary independently in the wool of Romney sheep’, New Zealand Journal of Agricultural Science, vol. 41, pp. 101-110. Sponenberg, D.P., Dolling, C.H.S, Lundie, R.S., Rae, A.L., Renieri, C. and Lauvergne, J.J. 1996, ‘Coat colour loci’, in Mendelian inheritance in sheep 1996 (MIS96), (eds. J.J. Lauvergne, C.H.S. Dolling and C. Renieri), Committee on Genetic Nomenclature of Sheep and Goats, France, Univerity of Camerino, Italy.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Tester, D. 2004, ‘The impact of coloured and medullated fibres on spinners and weavers’, BOARDtalk the Australian Woolclassing Journal, Australian Wool Exchange, Sydney, January 2004, pp. 1. Trollip, N.G., Heinrich, A. and Rensburg, N.J.J. 1987, ‚A comparison of the uptake of a pre- metallised dye by mohair and kemp’, Proceedings of the Electron Microscope Society of South Africa, vol. 17, pp. 157-160. Turner, H.N. and Young, S.S.Y. 1970, Quantitative Genetics in Sheep Breeding, MacMillan, Melbourne. Vage D.I., Fleet M.R., Ponz R., Olsen R.T. Monteagudo L.V., Tejedor M.T., Arruga M.V., Gagliardi R., Postiglioni A., Nattrass G.S. and Klungland H. 2003. Mapping and characterisation of the dominant black colour locus in sheep. Pigment Cell Research 16: 693- 697. Wood, E. 2000, ‘Tangling with wool series: 5. Hollow wool’, Wool Technology and Sheep Breeding, vol. 48, pp. 253-258. WSR 1954, ‘The measurement of medullation or hairiness in wool’, Wool Science Review, The International Wool Secretariat, London, UK, Issue No. 13. Wildman, A.B. 1954, The Microscopy of Animal Textile Fibres, Wool Industries Research Association, UK. Vegetable matter Abbott, G.M. 1979, "Rugging of sheep with polyolefin fabrics: the benefits and economics" in Wool Technology and Sheep Breeding, Vol 27 Issue 2, pp 29-33. Australian Wool Testing Authority, in Testing the Woolclip. Australian Wool Testing Authority 1986, in Vegetable Matter in Australian Wool. pp 1-60. Brownlee, H. 1973, "Wool production, ground cover and botanical composition of pastures grazed by Merino wethers in Central Western New South Wales. I. Natural Pasture." in Australian Journal of Experimental Agriculture. Animal Husbandry, vol. 13 (64) pp. 502-509. Brownlee, H. 1973, "Wool production, ground cover and botanical composition of pastures grazed by Merino wethers in Central Western New South Wales. I. Barrel medic pasture." In Australian Journal of Experimental Agriculture. Animal Husbandry, vol 13 (64) pp 510-515. Brownlee, H. and Denney, G.D. 1985, "Evaluation of medics under continuous grazing with sheep in Central Western New South Wales." in Australian Journal of Experimental Agriculture, vol. 25 (2), pp 311-319. Dawes, K. 1973, Objective Measurement of Wool. New South Wales University Press. Hancock B. and Schuster H. (editors) 2004. Winning against seeds - management tools for your sheep enterprise (Meat and Livestock, Australia) ISBN 1 74036 578. Hatcher, S., Atkins, K.D. and Thornberry, K.J. 2003, ‘Sheep coats can economically improve the style of western fine wools’, Australian Journal of Experimental Agriculture, vol. 43(1), pp. 53- 59. Holst P.J., Hall D.G. and Stanley D.F. 1996. Barley grass seed and shearing effects on summer lamb growth and pelt quality. Australian Journal of Experimental Agriculture 36: 777-780 Little D.L., Carter E.D. and Ewers A.L. 1993. Live weight change, wool production and wool quality of Merino lambs grazing barley grass pastures sprayed to control grass or unsprayed. Wool Technology and Sheep Breeding 41: 369-378. NSW Agriculture 2000, PROGRAZE® Manual. Plate, D.E. 1988, ‘Processing Developments: New Ways to make it Work, in The Australian Bicentenary Wool Conference: Proceedings of an International Symposium, Sydney NSW 17- 20 July 1988. Ritchie, A.J.M. 1992, in Management for Wool Quality in Mediterranean Environments, (eds. P.T. Doyle, J.A. Fortine and N.R. Adams), Department of Agriculture WA, pp. 125-131. Ryder, M.L. and Stephenson, S.K. 1968, Wool Growth, Academic Press, pp. 805. Teasdale, D. 1991, ‘Wool Preparation, Marketing and Processing’, in Australian Sheep and Wool Handbook (Ed. Cottle, D.), Inkata Press. Warr, G.J., Gilmour, A.R. and Wilson, N.K. 1979, "Effect of shearing time and location on vegetable matter components in the New South Wales wool clip" in Australian Journal of Experimental Agriculture: Animal Husbandry, vol. 19, (101) pp. 684-688.

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Warr, G.J. and Thompson, J.M. 1976, "Liveweight change and intake of lambs as affected by seed infestation" in Proceedings of the Australian Society of Animal Production, vol. 11, pp. 173-176. Wilson, A.D. and Simpson, R.J. 1994, in Pasture Management: technology for the 21st century, (eds. D.R. Kemp and D.L. Michalk), CSIRO pp. 1-25. Rudwick, V. and Turnbull, D. 1993, The Australian Sheep Flock: 1992 Demographics, ABARE Research Report 93.3, Canberra. Sackett, D. and McEachern, S. 2003, AgInsights 2003, Holmes Sackett and Associates Pty. Ltd. Shafron, W., Martin, P. and Ashton, D. 2002, Profile of Australian Wool Producers, 1997-98 to 2000-01, ABARE Research Report 02.7, Canberra. Wool International 1998, Australian Wool Compendium. Glossary of Terms

Agouti the Agouti gene influences via the tissue environment whether melanocytes produce mainly eumelanin or phaeomelanin so influencing the colour of pigmentation. This switch involves the production of Agouti Signal Protein (ASP) that binds to a receptor (MC1-R encoded by the Extension gene) for Melanocyte Stimulating Hormone (MSH). This competitive binding of ASP reduces signalling for eumelanin synthesis by MSH and encourages phaeomelanin synthesis as well as other pigment inhibiting effects. In white Merino sheep most of the potential for production of phaeomelanin in wool and hair follicles has, however, been prevented in foetal development by associated effects of white spotting gene(s) AWEX Code of the Code of Practice for the Preparation of Australian Wool Clips is a national Practice - quality system developed by the Australian Wool Exchange Ltd. It provides clear Woolclasser guidance on how to prepare a wool clip that is free of contamination, clearly described and well presented AWEX-ID a system developed by the Australian Wool Exchange Ltd for the appraisal and grading of the non-measured characteristics of greasy wool. Content of pigmented fibres (Y) and kemp fibres (P) are scaled to three levels (1= odd fibre; 2 = greater amount visible and 3 = clearly greatly affected) Carbonising wools, typically short-stapled, with vegetable matter content so high that it cannot wools be removed economically by mechanical treatment; for such wools, the first treatment is usually carbonising Carbonise to treat wool with sulphuric acid, followed by baking, which embrittles burrs present so that they can be easily broken up, crushed and removed Carding after wool is scoured and dried it is fed into a carding machine which opens up the wool into an even layer, removing as much vegetable matter as possible, and draws the fibres parallel to each other to some degree, to form a single continuous strand of fibres called a sliver Card sliver a continuous strand of opened and loosely assembled scoured wool fibres, together with variable amounts of vegetable matter. Its linear density is approximately constant and it is without twist Chromosome the structures supporting the cell nucleus genetic material inherited by an individual. In sheep the fertilised egg supports 27 pairs of chromosomes (one of each pair derived from each parent) Combing a process performed after carding and gilling to remove most of the short fibres (noils), neps, vegetable matter and foreign matter, leaving the longer fibres lying parallel to the direction of the sliver. After two more gillings, this product is called a top Combing wool wool suitable for conversion to yarn on the worsted system. Generally it is merino wool having a staple length of about 40 mm or greater, or crossbred wool having a staple length of about 75 mm or greater Cotted wool wool that has become partially felted on the sheep’s back; wool with a matted appearance

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England CSIRO (DFD) CSIRO DFD is a manual instrument developed by CSIRO, Australia, for the Dark Fibre counting of dark fibres in wool top but can also be used for scoured staple wool or Detector other semi-processed forms. It can include an attachment to automate the CSIRO Dark delivery and opening of top sliver for inspection. Other contaminants (e.g. vegetable matter) can also be counted and medullated fibres can be revealed and Fibre Reference distinguished as objectionable to some degree. The instrument is supported by Scale the CSIRO Dark Fibre Reference Scale which consists of photometrically graded CSIRO dyed fibres, representing variations in darkness from level 4 (light brown) below Microphotometer the threshold of commercial relevance (level 5) to black (level 8). The CSIRO Microphotometer is an attachment to a light microscope for measurement of the amount of light transmitted through the fibre at a selected point and is used for objective basis classification of darkness Diffuse pigmented fibres that typically diffuse, symmetrically located and clearly visible pigmented fibre (e.g. specked, roan) or hidden (e.g. isolated pigmented wool fibres) and usually remnants present from birth or developing in early life Eumelanin comprise of black or brown pigments produced within melanocytes “Exotic” sheep in the context of this lecture the term “exotic” is used in reference to AWEX specified sheep breeds (Damara, Dorper, Awassi and Karakul) that because of colouration and/or objectionable medullation and limited documentation are classified in the highest risk category Fault contamination, especially Vegetable Matter, in greasy and in semi-processed wool Fibre diameter the thickness of individual fibres; it is customary to quote an average value (Mean Fibre Diameter or MFD) in micrometres. (Also see fibre diameter distribution and micron) Genetic a genetic correlation exists between two characters if affected by the same genes correlation to some degree Gilling the process which mixes fibres thoroughly along the length of a sliver, and increases their alignment during the production of the top Greasy wool wool from the sheep’s back or sheep skins which has not been scoured, solvent degreased or carbonised or otherwise processed. It contains grease and suint extruded from the follicles in the skin and dirt and Vegetable Matter picked up from grazing Hair in this context of this lecture “hair” used generally to separate coarse fibres, that may be medullated or part medullated, but are distinctly different from wool or heterotypes. These fibres may be continuously growing or shedding types Heterotype in the context of this lecture a fibre that is partly distinctly coarse and may be medullated to some degree (hair-like) and partly finer and usually non-medullated (wool-like) Heritability heritability estimates the proportion of the observed (phenotype) variation in a trait that can be explained by genetic effects or breeding values Kemp in the context of this lecture a kemp is defined as a fibre with a medulla occupying the majority of the fibre diameter/volume Medullated medullation in fibres take the usual form of a tract of hollow cells in the centre of the fibre though there are varying degrees from a wide unbroken lattice occupying most of the fibre diameter/volume, other unbroken medullation occupying lesser amounts of the fibre diameter/volume, interrupted where the medullation is broken by non-medullated areas, fragmental where only small fragments of medulla occur or as even smaller vacuoles Medullometer a photo-electric device developed by WRONZ, New Zealand, that measures the amount of light scattered by medullation when the wool is immersed in a liquid with a similar refractive index to wool

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Melanin natural pigments produced by special cells (melanocytes) that in animals produce visible darkening and different colours of skin and hair or wool Melanocyte specialised mature cell that produces melanin pigments in the form of granules called melanosomes. These granules are forced via finger-like extensions (dendrites) of the melanocytes into adjoining cells (keratinocytes) that ultimately form the outer skin (epidermis), wool or hair Melanoblast immature melanocyte Micron commonly used name for the unit of measurement of fibre diameter, correctly termed a micrometre (µm) Near infrared involves a special photometric (spectrophotometer) instrument that measures reflectance reflectance or transmission of light (especially wavelengths in the infrared range) analysis by the sample material Neps small balls (or aggregations) of entangled fibres ranging in size from pin points to approximately 2mm in diameter which are created during processing. These are mostly removed from the top in the combing process Neural crest the neural crest is embryonic tissue in which groups of melanoblasts are formed and then migrate to and colonise skin regions in coloured animals. Several genetic mechanisms in white sheep are likely to be involved in preventing the formation and migration of melanoblasts, timing of migration, maturation and colonisation by melanocytes and survival. These gene effects produce the general lack of wool, hair and skin pigment to a greater or lesser degree as reflected in various breeds Noil the short fibres removed during the combing process; it comprises second cuts, pieces of broken fibres, neps, and is contaminated by small pieces of vegetable matter OFDA100® an image analysis system designed for the rapid assessment of fibre diameter, fibre curvature and medullation in wool and mohair Optalyser® an automatic instrument developed by Centexbel, Belgium, for rapid counting of cleanliness faults (dark v. very dark fibre, vegetable matter – burr v. straw/shive and fibrous wool masses (slubs and neps). It subdivides each type by size Phaeomelanin phaeomelanin is produced within melanocytes by a separated biochemical pathway from eumelanin and comprises pigments with colours ranging from yellow to reddish-brown Phenotype the observable characteristics of an individual Primary wool primary follicles originate first in foetal development, bud from the epidermis and follicles develop a sudoriferous (sweat) gland and arrector pili muscle in addition to a sebaceous gland Projection a light microscope incorporating a projection screen and scale from which fibres microscope or fibre snippets can be inspected and manual measurements made (e.g. fibre diameter) Old-age spots white Merino sheep – especially in very old-age, sometimes develop black-grey skin spots in wool bearing areas that can produced black pigmented wool fibres Random spot distinct black or tan–coloured pigmented fibres spots, usually evident at birth and showing a typical singular or asymmetric (random) distribution on the coat. This form of partial coat colouration is not simply inherited and has a low heritability Recessive black simply inherited coat colour determined by a completely recessive gene (presumed to be within Agouti) on sheep chromosome 13. In order for this phenotype to be seen the individual must be homozygous (have a pair of alleles that produce recessive black). The alternative phenotype (produced by the most dominant allele) is white and tan and in Merinos the expression of tan fibre is usually completely or almost completely prevented by white spotting genes

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©2009 The Australian Wool Education Trust licensee for educational activities University of New England Secondary wool original secondary wool follicles begin development in the foetal lambs after follicles initiation of primary follicles and also bud from the epidermis but do not develop a sudoriferous (sweat) gland or arrector pili muscle. Secondary derived follicles develop similarly though budding starts from the upper part of the original secondary follicles instead of the epidermis Simply inherited inherited in a predictable manner in accord with expectations for a single gene Siroclear automatic equipment designed by CSIRO, Australia, that uses an optical sensor to detect cleanliness faults (vegetable matter, dark fibres and fibrous masses) in yarns, removes these faults and mends the yarn. However, very high levels of such faults could reduce the speed of running yarn to commercially unacceptable levels. The equipment is commercialised by Loepfe Bros. in the Yarnmaster® range Sliver a continuous band of carded, or carded and combed wool in an untwisted condition Slubs see neps – relatively larger masses of more or less tightly packed wool fibres TOP sliver that forms part of the starting material for the worsted and certain other drawing systems, usually obtained by the process of combing, and characterised by the following properties:

(a) a substantially parallel formation of the fibres, essentially free of vegetable matter. (b) the absence of fibres so short as to be uncontrolled in the preferred system of drawing. (c) a substantially homogeneous distribution throughout the sliver of fibres from each length group present TOP/Toenniessen a manual system for the counting of cleanliness faults in wool top (dark fibres, Tester vegetable matter and other contaminants and fibrous wool masses (slubs and neps) that incorporates automated delivery and opening of the sliver for inspection Vegetable matter burrs (including hard heads), twigs, seeds, leaves and grasses present in wool (VM) Vegetable Matter the oven-dry mass of ash-free, ethanol-extractives-free burrs (including hard Base (VMB%) heads), twigs, seeds, leaves and grasses present, expressed as a percentage of the mass of the sample Woollen Yarn the wool used in the woollen system generally has a shorter mean fibre length (eg System approximately 400 or less) than that used in the worsted yarn system. Fibres within woollen yarns are less parallel, whereas they tend to be in a parallel array in worsted spun yarns. The cloth produced is comparatively bulky, with many fibres extending from the surface. Woollen fabrics include tweeds, felt, flannel, blankets and knitwear Worsted Yarn the yarn is made from top, and undergoes more stages of processing, (i.e. gilling, System combing and drawing) than the woollen yarn system. In worsted yarn the fibres are more parallel and tighter spun, resulting in smoother, stronger yarn than the woollen system. The fabric produced is smooth, dense and retains its shape well. Products from the worsted system include suitings and some knitwear

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