- The cortex of a crimped Merino wool fibre comprises two hemi-cylinders, which differ in both chemical and physical properties. The form of the crimp wave is related to alternations in the positions of the two cortical components within the fibre—the ortho- and the para-cortex1–4. The ortho-cortex tends to lie on the convex aspect of the crimp wave and the para-cortex on the concave aspect.
- Crimp and bulk, important wool fiber properties, are thought to be related to differences in the protein composition of the orthocortex and paracortex. Fiber morphological studies have demonstrated that the paracortex has a higher proportion of matrix and cysteine than the orthocortex. While there is some evidence for the differential expression of genes between these cell types in the follicle, this has not been demonstrated satisfactorily in the mature fiber. Using proteolytic digestion of wool fibers, followed by ultrasonic disruption to obtain relatively pure fractions of both cell types, the KAP3 high sulfur protein family was found to be present in higher concentrations in the paracortex. This significant finding provides an explanation for the higher cysteine content reported in the paracortex. This represents an advance in our understanding of protein expression variation in the orthocortex and paracortex, and how this relates to key physical and mechanical properties of wool fibers.
Measuring Fabric Handle to Define Luxury: An Overview of Handle Specification in Next-to-Skin Knitted Fabrics from Merino WoolAn examination is presented of the relevance of luxury to the wool textile and garment supply chain. This examination leads to a review of the concept and importance of fabric handle as a means of defining important aspects of fabric quality. Examples are given for woven fabrics of the general relationships between subjectively assessed fabric handle attributes such as fabric softness and smoothness and measured low stress, generally high deformation, fabric properties such as fabric bending rigidity and extensibility. A brief overview is presented of the development of a system for predicting a set of subjectively assessed handle attributes for next-to-skin knitted fabrics from measurable fabric properties. Seven handle attributes selected by experienced assessors as being important for defining tactile sensations associated with next-to-skin knitted fabrics were: fabric smoothness, hairiness, softness, tightness, dryness, warmth and weight. Subjective assessments on a 1–10 scale of these seven attributes, plus an assessment of overall handle, were conducted by 12 experienced assessors on 74 next-to-skin knitted fabrics. The precision of the mean assessment of the 12 assessors ranged between 0.8 and 1.1, indicating that there was sufficient consensus on key fabric handle assessments to justify development of a method for predicting them from measurements of the physical properties of fabrics. All fabrics were tested using the PhabrOmeter fabric evaluation system, which records the force exerted during insertion of a fabric into and through an orifice. Geometric parameters were derived to describe the PhabrOmeter force-displacement curve results, and statistical models were developed to predict the average handle assessments of the 12 assessors. The precision of the models in predicting the handle intensities of eight fabric attributes on an independent validation set of 22 fabrics was significantly better than the precision of an individual assessor (confidence limits = 1.4–2.6 and 2.5–3.8, for predicted and assessed ratings, respectively). A case is made that this technology has the potential to assist in the growth of new markets for Merino wool products.
Selenium Supplementation Increases Wool Growth and Reduces Faecal Egg Counts of Merino Weaners in a Selenium-Deficient AreaThis paper reports on the effects of selenium supplementation on liveweight (LW), greasy fleece weight (GFW), fibre diameter (FD), impact of parasite infection and plasma glutathione peroxidase (GSH-Px) activity in weaned Merino sheep reared in a selenium-deficient area (blood GSH-Px < 40 U/g Hb). At weaning, 208 Merino wethers were assigned to two groups: control (CTRL) and treatment (SEL). The SEL group was injected with 0.5 mL of Deposel, a slow release selenium injection. LW, blood and faecal samples were taken at 6-week intervals over a 24-week period. At the end of the trial the animals were shorn and GFW and FD measurements were taken. The SEL group had significantly higher (P < 0.01) LW compared with the CTRL group at Weeks 6, 12, 18 and 24. There was a significant difference (P < 0.05) in GFW between the SEL and CTRL group, 2.93 and 2.75 kg, respectively. There was no difference in FD between the two groups. A trend (P < 0.06) towards lower faecal egg counts in the SEL group was seen but the difference between the two groups was not significant. As expected, the SEL group had significantly (P < 0.001) higher plasma GSH-Px activity compared with the CTRL group. In conclusion, selenium supplementation in weaned Merino sheep reared in a selenium-deficient area could increase the LW and GFW of the young sheep while perhaps reducing the level of parasitic infection.
Seasonal Variation in Fibre Diameter and Length in Wool of Grazing Merino Sheep with Low or High Staple StrengthThe associations between fibre growth characteristics and wool staple strength were investigated in groups (n = 10) of Merino wethers with either low or high staple strength. Sheep grazed together on pastures based on subterranean clover and annual rye grass for about 13 months. The sheep were weighed and injected intradermally with [35 S]-cysteine at about 14-day intervals. Mid-side patches were harvested and dye bands placed in the wool at about 28-day intervals. Patch clean wool growth, pasture digestible dry matter/ha and pasture crude protein/ha had similar seasonal amplitudes of production (287, 286 and 267% of respective minimum). These were significantly higher than the seasonal amplitude in liveweight (24.5%). The seasonal amplitude in fibre diameter was significantly greater than that for rate of fibre elongation (71.4 and 41.4% respectively). This seasonality in fibre length and diameter resulted in statistically significant seasonal fluctuations in the ratio of fibre length growth to fibre diameter. Fortnightly variability in fibre diameter was not significantly related to variability in fibre length growth rate between sheep for individual time periods. However, for the pooled data over the experimental period a statistically significant relationship (R2 = 0.13, P < 0.01) was improved with the addition of parameters for sampling time and staple strength group. Staple strengths for the low and high staple strength groups were 25.6 and 32.8 N/ktex respectively (P = 0.057). There were no significant differences between the staple strength groups in seasonal change in liveweight, wool production or fibre parameters measured in this study but the low staple strength group had longer fibres. Staple strength was most highly correlated with mid-side fibre diameter coefficient of variation (R2 = 0.50) followed by seasonal amplitude in liveweight.