Can along and between fibre diameter variation make a contribution in Merino breeding programmes

The Optical Fibre Diameter Analyser 2000 (OFDA2000) model allows coefficient of variation of fibre diameter (CVFD) to be separated into a between fibre diameter variation component and an along fibre diameter variation component. Both traits are heritable (0.4 and 0.20, respectively) but not as heritable as CVFD on a minicored sample (0.67). Only CVFD between fibres is genetically strongly (-0.7) correlated with SS to nearly the same extend as CVFD (-0.65). It is more effective to use CVFD of wool samples as an indirect selection criterion to improve SS. In addition this will also result in a reduction in the propensity of FD to blowout along the staple.