Wool fibre tenacity and its relationship to staple strength

Abstract

Wool fibre tenacity and its relationship to staple strength was studied in a pen-feeding trial of 40 New Zealand Romney ewes. A method for estimating fibre tenacity is described based on normalizing fibre breaking load by cross-sectional area measured on fibre fracture-surfaces. The validity of this protocol was demonstrated by showing that (i) fibre diameter measured at the point of rupture was not significantly (P > 0.05) changed by breaking, and (ii) that the tenacity estimate was not significantly (P > 0.05) correlated with cross-sectional area variation along fibres, and (iii) showed lower fibre-to-fibre variation than other accepted measures of intrinsic material strength. The majority (83.5%) of the 1200 fibres broken in this study cleaved in smooth-planed fractures normal to the long axis of the fibre, the remaining fibres demonstrated axial-splitting following rupture. Tenacity did not differ significantly between the two break-types (P > 0.05). Tenacity demonstrated small negative correlations (P < 0.05) with fibre cross-sectional area and ellipticity. No change in tenacity (P > 0.05) occurred within fine, slow-growing 'wool-break' regions and tenacity did not vary significantly (P < 0.05) between body sites on sheep. Tenacity showed no significant variation (P > 0.05) with differential winter feeding, but significant variations (P < 0.01) of wool tenacity occurred between sheep. The sheepto-sheep differences in tenacity showed significant relationships with two indices of staple strength, work (P < 0.01) and peak-force (P < 0.01). Variability in fibre tenacity between sheep and its relationship to staple strength may provide some explanation of the origin of 'tender' and 'sound' wools.

Connexin43 Carboxyl-Terminal Peptides Reduce Scar Progenitor and Promote Regenerative Healing Following Skin Wounding

“…As we have described previously, breaking stress/tenacity and extension of a biological material stretched until failure will correlate with the mechanical properties of its weakest element [31]. For a strip of tissue of uniform material properties, this weakest element will generally correspond to its segment of narrowest cross-sectional dimension with respect to the axis of strain.…”

Wool Production and Characteristics, Physiological and Haematological Parameters and Level of some Metabolic Hormones in Barki Ewes Shorn in Autumn as Alternative of Spring Shearing

“…The almost central POB found in autumn wool may be attributed to the lower FD Av and FD SD recorded during this season (Table 2). In this way, Deng et al (2007) claimed that within staple fiber diameter variations were found to have greater prevalence to breakages, particularly where fiber diameters were at their fineness (Gourdie et al, 1992). Values of ELR increased (P<0.01) in autumn than in spring by about 6%.…”

“…Total diameter variation has a strong negative phenotypic association with staple strength (Ritchie and Ralph, 1990;Reis, 1992;Schlink et al, 1999). The majority of variations in staple strength were thought to be based on differences in intrinsic fiber strength (Gourdie et al, 1992) and fibers stretching ability (Holman and Malau-Aduli, 2012). According to Schlink et al (1999), staple strength was most highly correlated to within staple variations in fiber diameter.…”