Introduction:
Textural greasy wool handle has been a trait of interest for wool producers for many years
(Barker 1931; Roberts 1955, 1956; Love et al. 1987; James et al. 1990; Purvis 1990; Butler et al.
1995; Lewer et al. 1995; Stevens and Mahar 1995; Dowling et al. 2007; Hatcher et al. 2010) as the wool industry believe it relates to fabric handle, which has been shown to be a primary trait influencing consumer buying attitudes (Mahar and Wang 2010). Some wool buyers include textural greasy wool handle assessment as part of their evaluation of wool prior to purchase and consider it of secondary importance compared to traits such as fibre diameter, staple strength and staple length (Mousch pers com 2011). Producers who aim to produce soft handling wool will attempt to achieve this through either the utilisation of superior genetics, via ram purchases and selection of replacement ewes or modifying their flock management practices to better match their production environment. In many instances, producers who aim to reduce the fibre diameter of their wool clip will be indirectly improving handle through favourable phenotypic and genetic correlations (Hatcher et al. 2010).
However, it has been demonstrated that greater overall genetic gain can occur when handle is included as a selection criteria with an index focused on improving clean fleece weight (Butler and Dolling 1991) or a significant increase in the 14%, 7% and the 3.5% Merino index (Mortimer et al.
2010).
One of the major problems with assessing textural greasy wool handle in breeding programs or evaluating it when creating wool lines during shearing, is that it is difficult to assess the trait in a consistent and accurate manner. Research needs to focus on developing an assessment model where there can be consistency between assessors.
Nevertheless greater confirmation is required on the value of textural greasy wool handle within the wool industry. It is important to determine if textural greasy wool handle accounts for fibre attributes that affect the handle properties of wool that is not already measured or assessed by other traits already recorded within the industry. Numerous studies have demonstrated the influence of fibre diameter, fibre diameter co-efficient of variation, crimp properties and natural grease production on textural greasy wool handle (Roberts 1956; Ali et al. 1971; Shah and Whiteley 1971; Stevens 1994).There are some studies that have documented that these traits do account for all the variation in textural greasy wool handle (Ali et al. 1971; Shah and Whiteley 1971). However, very few studies have only focussed primarily on the Merino breed and more specifically, wool types that target the next-to-skin knitwear market. Most previous research has focussed on compressional handle, and the impact of traits such as resistance to compression and various crimp properties. Previous work has quantified the relationship between compressional handle and various properties of single jersey
knitted fabric (McGregor and Postle 2008, 2009) and confirmed its value of the measurement in the wool industry.
The advantages of being able to use indicator traits such as fibre diameter and resistance to compression to predict textural handle is that these indicator traits, in most cases, have specific standards or IWTO test methods, which dictate sampling and measurement conditions to ensure the accuracy and precision of the resulting data. In the long term it makes it easy to link and relate raw wool properties to fabric handle. It will help wool buyer’s source suitable wool and develop some certainty in processing of wool with specified handle.
The following chapter investigates the ability to predict textural greasy wool handle from the Sheep CRC Information Nucleus data. This is an ideal dataset as it includes a wide variety of Merino strains, bloodlines and wool types. It also includes the measurement or assessment of a vast array of wool production and quality traits used within the wool industry. The Information Nucleus includes eight different flocks run in key sheep production sites located across Australia. It includes a multitude of assessors across a number of years with some differences in the level of experience in assessing textural greasy wool handle. The results from this study will:
1. Determine the importance of textural greasy wool handle assessment.
2. Confirm and estimate what fibre attributes influence the assessment of textural greasy wool handle.
3. Determine if the assessment of textural greasy wool handle is still important to the Australian wool industry.
4. Determine the direction of research for wool quality traits relating to fabric handle.
Ultimately, this research will determine whether, the overall objective of producing a softer raw material to the wool value chain that requires little fibre modification or input of expensive chemical softeners to achieve the required softness during processing is realistic. Results will dictate the direction and importance of the remaining work in this thesis.
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