2 IDENTIFICATION OF CONTAMINANT SALE LOTS
SUMMARY A trial incorporating the testing of commercial core samples has provided further evidence of wool contamination arising from crossbreeding Merinos with Damara fat tail rams. The trial has also highlighted limitations of the CSIRO Dark Fibre Detector for this purpose in terms of both its subjectivity and the operator time required for a test. Core samples from bales of fleece wool from Merino ewes known to have reared Merino lambs (5 lots), or to have reared Damara crossbred lambs (14 lots), or to have been mated to Damara rams but failed to rear a lamb (6 lots), were tested for pigmented and for medullated fibres by 3 laboratory methods. The tests were performed at AWTA Ltd and SARDI. The wool from the 3 different farm management practices had significantly different (P<0.005) concentrations of pigmented and medullated fibre. The ewes rearing the Merino lambs showed the lowest contamination, those rearing the Damara crossbred lambs showed the greatest contamination, and the remaining 6 lots showed intermediate concentrations of pigmented and medullated fibre. The 2 laboratories were not significantly different (P≥0.05) in their reported concentrations of medullated fibres and of the darkest (CSIRO darkness levels 6 to 8) pigmented fibres. However, for the pale-pigmented fibres (CSIRO darkness levels 4 and 5) and the total pigmented fibre concentration there were differences between the laboratories.
Merino wool contamination from rearing of Damara crossbred lambs
Recent importations and promotion of Damara sheep has raised concerns and debate about potential for Merino wool contamination. This project examined Merino ewe wool contamination arising from the mating of Damara rams and rearing of Damara crossbred lambs. Shirley-blended core samples from 3 commercial greasy wool sale lots known to involve Merino ewes shorn with Damara crossbred lambs at foot (2 lots), or shorn 3 weeks after weaning, were assessed. Contaminant fibres were above commercial expectations for Merino wool and present in every core sample measured. There was no significant difference found between these sale lots. From an experimental flock, composites of fleece samples were carded and the effects of mating or rearing alone assessed. No detectable increase of pigmented or heavily medullated fibres, above very low background levels, were detected among the Merino ewes mated to Damara rams (1 ram per 65 ewes). However, high concentrations of contaminant fibres were found in the Merino ewe wool at weaning of their Damara crossbred lambs and also 3.5 months after weaning; with reduced levels post-weaning. The management strategy of restricting wool exposure to mating effects alone may offer advantage but delaying shearing of ewes after weaning to reduce the contaminant fibre burden was, in this case, not sufficient to overcome potential concerns for wool processing. However, in view of the many potential contributing factors, actual contamination may vary widely between cases and require the advancement of presale measurement to gain buyer confidence and accurate appraisals.
Economics of General-Purpose Assembly Robots
Summary A study of the comparative economics of various automatic assembly systems using general-purpose assembly robots is described. In the study, use is made of a “typical” candidate assembly whose profile is obtained from statistical analysis of actual products submitted by interested companies. It is shown that the choice of assembly system and the various parts presentation methods depends on three main factors, namely: the annual production volume per shift, the number of parts in the product and the equipment payback period.