CALCULATION OF THE HERITABILITY OF SPINNING FINENESS FROM PHENOTYPIC AND GENETIC-PARAMETERS OF THE MEAN AND CV OF FIBER DIAMETER

In sheep selection programmes where fibre diameter distribution measurements are available, such as when using the FDA method of assessing fibre diameter, spinning fineness (as defined by Anderson, S.L. (1976), J. Text. Inst., 67, 175-80) might be preferable to using mean fibre diameter as a sheep selection criteria. This paper uses a Taylor's expansion to obtain an approximation to the heritability of spinning fineness when the phenotypic and genetic parameters of only the mean and the coefficient of variation of fibre diameter are available. The approximation assumes that the mean and coefficient of variation of fibre diameter are both phenotypically and genetically independent. Approximations are also obtained for the genetic correlation between spinning fineness and mean fibre diameter, and between spinning fineness and coefficient of variation. Using the approximations, estimates of heritability of spinning fineness and of the two genetic correlations are calculated for published studies.