Re-Use of Fleece-Testing Data to Build Wool Sale Lines
Authors
Forbes Brien
Abstract
The use of hogget fleece-test data for establishing lines of wool for sale the year after the samples were collected was evaluated by comparing an OFDA2000 device to the use of conventional mid-side testing (Laboratory). Two year-old Merino ewes (n = 673; mean fibre diameter (MFD) 19.6 µm) and wethers (n = 517; MFD 18.2 µm), from the same lamb drop, were shorn and fleece-tested as hoggets and then grazed separately as two flocks during 2001. At shearing in December 2001, individual hogget MFD measurements, adjusted for age, were used as the main criterion to prepare 4 main fleece lines per sex. Greasy fleece weights were also recorded and mid-side samples collected for later testing. Repeatabilities for MFD between hogget and 2 year-old measurements were 0.59 and 0.67 from Laboratory and OFDA2000 testing, respectively. When the sheep were shorn at 2 years of age in December 2001, the MFD of sale lines created from ewe fleeces was an average of 0.5 µm higher when comparing both fleece testing and core testing results with weighted hogget MFD values from the previous year. However the values for fleece sale lines created from wether fleeces were an average of 0.3 µm and 0.4 µm finer when comparing fleece testing and core testing results, respectively, with weighted hogget MFD values. A differentiation of 2.3 and 2.0 µm between the lowest and highest of 4 sale lines for core test MFD was achieved at the December 2001 shearing for the ewe flock and the wether flock, respectively. Based on wool prices achieved in February 2002, objective classing of sale lines, using MFD determinations from the previous year, was estimated to be $0.96 per head more profitable than selling the wool as one main line. In conclusion, the use of an OFDA2000 instrument is equivalent to conventional mid-side testing for establishing lines of wool for sale from 2-year old sheep, when clip preparation is based on individual fleece measurements on samples collected from the sheep in their hogget year.
