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Typescript, etc.

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Thesis (Ph. D.)--University of Canterbury, 2003. / Typescript (photocopy). "December 2002." Includes bibliographical references (p. 235-244). Also available via the World Wide Web.

To improve the quality and the marketability of wool and mohair, it is important to encourage, ensure and preferable certify that the baled fibre is free of contaminants. Anything other than the fibre that is within the bale can be classified as contaminants; this may be in the form of metal and wooden objects, plastic materials, paints, and vegetable matter such as grass and seed. The internationally accepted method for detecting and classifying these contaminants are highly labour intensive and costly. The ultimate goal of the present research is to develop a non-invasive and nondestructive technique that can be used to detect contaminants, particularly plastic (polymer) materials within wool and mohair bales. Such a technique can be implemented in the wool industry and also could be applied to other fibres, such as cotton. The immediate objective of this study was to evaluate the capability and the limitation of X-rays as a technique to detect such contaminants. It was found that X-rays were suitable for detecting foreign objects, or contaminants, such as metals, but not for detecting plastic materials, such as polypropylene and polyethylene.

Diarrhoea (“scouring”) in sheep increases the risk of faecal soiling of the breech (“dag”) that in turn causes significant production losses for sheep producers and increases susceptibility of sheep to breech blowfly strike. The common causes of scouring in sheep of post-weaning age in Western Australia have not been well described. In a written questionnaire sent to sheep producers in the south west of Western Australia, about half of the respondents reported lamb, hogget and ewe flocks with moderate or severe dag. Flocks with moderate or severe dag were reported more commonly in the winter and spring months in all age groups. Young sheep and mated ewes were most susceptible to moderate or severe dag. The utilisation of professional worm control advice and parasite management tools did not reduce the risk of moderate/severe dag. A study conducted at an abattoir showed that large strongyle worm egg counts (WEC) were frequently identified in lamb lines but were much less common in adult lines. The relationship between WEC and scouring was not clear, suggesting that factors other than large strongyle infections were important, particularly in adult sheep. The low WEC and seasonal scouring pattern observed in adult sheep was consistent with the larval hypersensitivity scouring syndrome and/or factors related to green pasture as potential common causes of scouring in adult sheep. This observation was consistent with detailed investigations of flocks with “low WEC scouring” that found larval hypersensitivity scouring syndrome or factors associated with green pasture were the most likely causes of scouring in eight of the nine flocks examined. Large immature worm burdens were common and the scouring sheep had more fourth stage larvae than normal sheep. Treatment with a fully effective drench and an ivermectin controlled-release rumen capsule did not result in a reduction of faecal moisture content between three and seven weeks after treatment. The effects of dietary soluble non-starch polysaccharides were studied using carboxymethylcellulose (CMC) as a model. The CMC model was used to demonstrate that significant interactions between diet and strongyle larvae determined both faecal consistency and strongyle establishment. Sheep fed CMC had softer, looser and wetter faeces, but the factors that determined faecal consistency were complex. Establishment of T. colubriformis was significantly greater in sheep fed CMC suggesting that the environment within the gut may affect establishment of T. colubriformis in the small intestine. The findings suggested that dietary factors may interact with strongyle larvae to determine both worm establishment and severity of scouring. The results of the studies described in this thesis suggested that factors related to immature strongyle larvae, diet and the immune response interact to determine the severity of the scouring observed in sheep of post-weaning age in the south west of Western Australia.

Unlike other fibres, wool felts readily when agitated in the presence of water. For this reason, only the minimum necessary quantity of water is used when the garments are drycleaned. However, wool fibres are often deliberately felted to obtain a warm bulky handle by controlled addition of water to the solvent. This process is known as solvent milling and recently, it has become a popular alternative to the traditional milling in water alone. Although the factors which influence milling in solvent are known, the relationships between them are not well defined. A comprehensive study of the relationship between water distribution and milling shrinkage during agitation of wool in perchloroethylene has been carried out in this thesis. The Karl Fischer method of determination was used throughout to establish the distribution of water between the wool fibre and the solvent liquor. The emphasis was placed on practical production variables. The role of surfactant in affecting milling shrinkage through its effect on the transport of water to the fibre from the solvent was examined. The ability of a suitable surfactant in promoting even and rapid sorption of water by the fibre was related to the colloidal properties of the milling liquor.