Relative economic value of wool processing parameters for New Zealand strong wool between 2003 and 2007
Price trends for a total of 147,416 lots of wool in the strong wool segment of the New Zealand clip sold at auction between 1 July 2003 and 30 June 2007 were analysed by multiple regression analysis to determine the effect on price of five key characteristics known to affect wool processing performance. Changes in exchange rate were allowed for by covariance against the exchange rate of the US dollar on the day of the auction. The residual standard deviation within the data set was 20.4 c/kg clean. Mean values of the slope of the regression, or relative economic value, were 0.4 ± 0.2 c/ kg clean/mm change in barbe length, -1.9 ± 0.9 c/kg clean/μm change in mean fibre diameter, 2.5 ± 0.5 c/kg clean/CIE Y value change in brightness, -5.0 ± 0.6 c/kg clean/CIE Y-Z value change in intensity of yellowness and -16.8 ± 3.0 c/kg clean/% change in vegetable matter contamination. These estimated values align closely with values estimated in 1991 for the New Zealand clip as a whole confirming that despite the significant changes that have occurred within the wool processing industry the economic significance of individual wool characteristics to wool processors have not changed.
A review of wool fibre variation across the body of sheep and the effects on wool processing
Abstract Variations in wool characteristics due to location on the body of sheep are reviewed and compared with variation from other sources. The biological basis for variation and the relevance of this source of variation to industry are also discussed. For many traits, variation between sites on the body was trivial in comparison with variation between individual fibres within those sites and variation between sheep. To set the context within which wool variation could have an economic impact, fleece skirting and other wool processing steps that are influenced by fibre variation, or might increase or decrease the impact of variation are initially discussed. Processing intimately blends wool from numerous sources and distributes variation from individual fleeces and positions within fleeces among larger processing batches. Variation within fleeces and flocks is thus of limited concern in breeds with a history of selection for wool for industrially manufactured wool products. Variations in dye uptake caused by highly pigmented or medullated fibres are two exceptions that cannot be effectively hidden by blending. The balance of evidence suggests that reducing the variation in most fibre characteristics across the body of wool-producing breeds is not economically justified for conventional manufacture of apparel, interior textiles or lower value products on an industrial scale, though further research may be justified for high value uses or in breeds not selected for uniform wool production.
Mathematical Concepts and Methods in the Industrial Utilization of the New Zealand Wool Clip
This paper outlines various mathematical concepts, such as vector spaces, Boolena algebra, and linear programming, that have been found helpful in developing computer software for use by various groups involved with marketing and using New Zealand wools. Considerable raw data concerning the New Zealand wool clip are now available in the form of computer records covering the production and prices received at auctions over several seasons. These data can be transformed by mathematical methods to yield more specific management tools of value to sheep breeders, wool exporters, wool-marketing bodies, and wool processors. The methods used could be of general application to other natural-fibre industries.