- On completion of this topic you should be able to: • demonstrate an understanding of fibre diameter and the economic importance of fibre diameter • explain and calculate the difference between the standard deviation of diameter and the coefficient of variation of diameter • define the relationship between mean diameter, diameter variation and “coarse edge” or “prickle” • measure staple strength and describe its economic importance • explain the sources of variation in staple strength within a mob of sheep • describe localised vs generalised fibre weakness as determinants of staple strength • define and quantify the relationship between staple strength and each of minimum diameter, along-staple diameter variation, rate of change in diameter, fibre length variation and intrinsic fibre strength • relate raw wool style including the main component traits to economic importance • explain the influence of fibre diameter and fibre crimp on wool handle • describe fibre curvature and the value of curvature
Relationships Between Skin Follicle Characteristics and Fibre Properties of Suri and Huacaya Alpacas and Peppin Merino SheepWe aimed to quantify the number, type and arrangement of skin follicles in Huacaya and Suri alpaca skin and correlate their follicle characteristics with fibre traits of harvested fibre and compared these relationships with those of Merino sheep. Fibre and skin samples were collected from the mid-side of 12 Huacaya alpacas, 24 Suri alpacas and 10 Merino sheep. The mean fibre diameter (MFD ± s.e.) of the Huacaya and Suri were: 35.5 ± 0.9 and 28.3 ± 1.0 μm, respectively. The follicle groups found for alpacas were very different from the normal trio of primary follicles found in sheep and goats. The follicle group of the alpacas consisted of a single primary follicle surrounded by a variable number of secondary follicles. The mean ± s.e. primary follicle density was 3.1 ± 0.3 and 2.7 ± 0.1 follicles/mm2 for Huacaya and Suri, respectively. The mean ± s.e. secondary follicle density (SFD) was 13.7 ± 1.2 and 17.5 ± 0.6 follicles/mm2 for Huacaya and Suri, respectively. The mean ± s.e. ratio of secondary to primary follicles (S/P ratio) was 5.1 ± 0.5 for the Huacaya and 7.3 ± 0.2 for the Suri alpacas. The sheep had higher S/P ratios and SFD, lower MFD and produced significantly heavier fleeces. The key correlations found between traits in alpacas include a negative correlation between SFD and MFD (r = –0.71, P = 0.001) and a negative correlation between S/P ratio and MFD (r = –0.44, P = 0.003) and a positive correlation between S/P ratio and total follicle density (r = 0.38, P = 0.010). The study revealed that important relationships exist between alpaca skin follicle characteristics and fibre characteristics. It was the number of secondary follicles in a group that imparts density and a corresponding reduced MFD.
- The capability of instruments such as SIROLAN-LASERSCAN (LASERSCAN) and OFDA100 to provide measurements of fibre curvature has resulted in increased interest, within Australia among wool producers and exporters, and among overseas top-makers and spinners. However, the metrology of fibre curvature measurement by these instruments is poorly understood. Standardized conditions for preparation, and measurement procedures that stabilize the curvature of the wool fibres prior to measurement by either instrument, are yet to be defined.
- With the increased interest in the measurement of fleece samples from alpacas, a number of questions have been raised concerning the meaning of mean fibre curvature on these samples. Whilst some information has been published, there appear to be some divergent views expressed on the importance of this measurement. This bulletin is intended to impart some factual information which may be useful to growers trying to understand the measurement.
Variation in the Softness and Fibre Curvature of Cashmere, Alpaca, Mohair and Other Rare Animal FibresSoftness of apparel textiles is a major attribute sought by consumers. There is surprisingly little objective information on the softness properties of rare animal fibres, particularly cashmere, alpaca and mohair. Samples of these and other rare animal fibres from different origins of production and processors were objectively measured for fibre diameter, fibre curvature (FC, crimp) and resistance to compression (softness). While there were curvilinear responses of resistance to compression to FC and to mean fibre diameter, FC accounted for much more of the variance in resistance to compression. Fibre type was an important determinant of resistance to compression. The softest fibres were alpaca, mohair and cashgora and all of the fibres measured were softer than most Merino wool. Quivet, llama, camel, guanaco, vicuña, yak wool, bison wool, dehaired cow down and Angora rabbit were also differentiated from alpaca, mohair and cashmere. There were important differences in the softness and FC of cashmere from different origins with cashmere from newer origins of production (Australia, New Zealand and USA) having lower resistance to compression than cashmere from traditional sources of China and Iran. Cashmere from different origins was differentiated on the basis of resistance to compression, FC and fibre diameter. Cashgora was differentiated from cashmere by having a lower FC and lower resistance to compression. There were minority effects of colour and fibre diameter variation on resistance to compression of cashmere. The implications of these findings for the identification and use of softer raw materials are discussed.