Page 136 - Handbook of Properties of Textile and Technical Fibres

Physical, chemical, and tensile properties of cashmere, mohair, alpaca 115

Thus within any sample of animal fiber there will be a bivariate distribution in
cuticle scale frequency, which some authors have illustrated with concentric rings
based on the probability of occurrence (Phan et al., 1988; Teasdale, 1988).
As there has been no explanation provided as to why scale heights within samples
of rare animal fibers vary from z0.18 to z0.45 mm, McGregor and Liu (2017) inves-
tigated the cuticle properties of cashmere from goats subjected to controlled nutritional
manipulation. Cuticle scale frequency and scale thickness varied with nutritional man-
agement, fiber diameter, fiber growth, and size of animals. Predicted cuticle frequency
ranged from 8.2/100 mm for fine cashmere grown by goats in poor nutritional condi-
tions to 5.8/100 mm for coarser cashmere grown by goats fed high-protein diets
(Fig. 4.3). There was also a relationship between the cuticle thickness and the fiber
cross-sectional shape indicating that variation in the cross-section diameter of fibers
is related to cuticle properties. Thus, variation in nutrition management, fiber diameter,
fiber growth rate, and animal live weight need to be understood to clearly understand if
there are fundamental differences between fibers grown in different origins.
Conversely, it should be expected that fibers produced in very different production sys-
tems and environments from animals of different productivity will have varying cuticle
properties.

9.0
8.5
Cuticle scale frequency/100 µm 7.5
8.0

7.0

6.5
6.0
5.5

5.0
12 13 14 15 16 17 18 19
Mean fibre diameter (µm)
Figure 4.3 The predicted main effects of fiber diameter and nutritional treatment on the
frequency of cuticle scales in cashmere. Cuticle scale frequency values are shown following
adjustment for cashmere growth rate using the mean value for each nutritional treatment for the
summer (solid lines) and winter period (dash lines). Symbols for nutritional treatments: lowest
nutrition treatments including live-weight loss (B); highest protein intake treatment (,).
Modified from McGregor BA, Liu X: Cuticle and cortical cell morphology and the ellipticity of
cashmere are affected by nutrition of goats, J Text Inst 108:1739e1746, 2017.