Cashmere Fibre Diameter and Curvature: Effect of Animal Age and Breedline


  • Hilary Redden
  • D Robson
  • S Rhind


Effects of selection for increased mean cashmere fleece value (V) or reduced mean cashmere diameter (F) were assessed in Scottish cashmere goats and compared with a randomly bred line (C). Cashmere samples were collected from, and live weights recorded for, animals of two cohorts (n = 10 per breedline / cohort) at 5, 17 and 29 months (Cohort 1) or 5, 17 and 21 months (Cohort 2) of age. For each cashmere sample, mean cashmere fibre diameter (MFD) and associated CV(%), mean cashmere curvature (deg/mm, MCC) and curvature s.d. (CSD) was calculated. In both cohorts animal weight increased with animal age (P>0.01). In animals of Cohort 1, overall MFD increased from 5 to 29 months of age (15.2 to 16.5 µm; P<0.01) and at 29 months, the MFD of V animals was greater than in F animals (17.8 c.f. 15.1 µm; P<0.01). Overall, MCC decreased between 5 and 29 months of age (57.0 to 52.9 deg/mm; P<0.01). At 5 months of age, the MCC of the F line (60.9) was greater than that of the C (55.8) and V (54.3) lines (P<0.05). Using the 5-month values as a covariate, at 29 months, the MCC was greater in F animals than in C (P<0.05) or V animals (P<0.01). In Cohort 2, in all breedlines, MFD increased between 5 and 21 months (15.0 to17.1 µm; P<0.01), becoming greater in V than either C or F animals (17.8, 16.7, 16.8 µm respectively; P<0.01). The overall MCC was less at 17 and at 21 months than at 5 months of age (51.4, 55.4, 58.8 deg/mm respectively; P<0.01). There was no significant effect of breedline on MCC or in the associated CSD. The overall correlation coefficient of MFD with animal age for all animals between 5 and 29 months (Cohort 1, 0.77, P<0.01) and between 5 and 21 months (Cohort 2, 0.78, P<0.01) was significant but varied with breedline. There was a significant relationship between MCC and MFD but this varied with cohort and breedline. Fibre samples taken at 5 months of age were not suitable for prediction of lifetime cashmere diameter or curvature, particularly of V line goats. It is concluded that fibre diameter and cashmere curvature changes, in response to selection, are affected by animal age, breedline and responses of individual animals; therefore these factors should be taken into account in selection of animals for lifetime performance.