Inheritance of the resistance to compression property of Australian Merino wool and its genetic correlation with follicle curvature and various wool and body characters

Abstract

Resistance to compression is primarily a measure of the crimp structure of individual fibres. Fibre crimp, as distinct from staple crimp, has been shown to be an important aspect of wool quality with requirements depending on end use and processing conditions. A precise definition of its importance under various conditions must await further evidence.The consequences of these findings for Merino breeders depend upon the heritability of resistance to compression and its genetic and phenotypic correlation with other important wool characters. Estimates of such parameters are presented and used to formulate breeding plans for the Australian Merino. Follicle curvature was included among the characters studied because it was hypothesized that it would be as good a measure of fibre crimp as is resistance to compression. The results support this hypothesis. The most important conclusion is that, if textile requirements dictate that resistance to compression as well as fibre diameter must be controlled during Merino breeding, progress in clean wool weight will be severely restricted.

Selection for ultrafine Merino sheep in New Zealand: heritability, phenotypic and genetic correlations of live weight, fleece weight and wool characteristics in yearlings

“…The h 2 of RtC in the present trial was in close agreement with Swan et al (1995) but lower than values presented by James et al (1990) and Watson et al (1977) (0·74 to 0·80). The h 2 of bulk, a similar property to RtC, was moderate.…”

“…The h 2 of bulk, a similar property to RtC, was moderate. Watson et al (1977) also found high genetic (0·88) and phenotypic (0·64) correlations of RtC with follicle curvature, i.e. follicle curvature accounted for 77% of the genetic variation in the wool bulk property measured by RtC.…”

“…Morley (1955) estimated h 2 of SC in the range 0·24 to 0·47, Gregory (1982a) found it between 0·24 and 0·43, while Brown and Turner (1968) and Walkley et al (1987) have shown very diverse estimates for SC ranging from 0·09 to 0·78. Low RtC in Merino wools confers softness of handle (within a particular fineness range) which is ideal for luxury woollen use (Watson et al ., 1977;Wuliji et al ., 1995).…”

Genetic parameters for subjectively assessed wool and conformation traits in the Tygerhoek Merino flock

“…Previous researchers indicated WFS being moderately to highly heritable at 0.29 to 0.76, and should respond to selection if desired (Morley, 1955;Brown & Turner, 1968;Watson et al, 1977;Gregory, 1982a;Lewer et al, 1995). The highest heritability of 0.76 was estimated by Watson et al (1977) for one of the Australian Merino resource flocks whereas other estimates (0.29 to 0.38) were lower than the present estimate. Face cover score (FCS), as defined in the present study, measures the softness of wool covering the face.…”

Physical Properties and Processing of Fine Merino Lamb's Wool

“…Most of the variation in resistance to compression in Merino wools can be explained by follicle curvature, crimp, and fiber diameter, in decreasing order of importance [ 57 ] . The heritability of resistance to compression in Merinos is illustrated with a phenotypic correlation of 0.64-0.80 and a genetic correlation of 0.88 between follicle curvature and resistance to compression [ 25,54 ] .…”