Managing the Risk of Dark and/or Medullated Fibre Contamination

This publication is reproduced with the permission of Australian Wool Innovation Ltd (AWI), the funder of the work described in the paper, and the Federation of Australian Wool Organisations (FAWO), the research provider.

Abstract

This project was initiated in response to on-going concern by members of the Federation of Australian Wool Organisations (FAWO) over contamination of the Australian wool clip by dark and/or medullated fibres. Funding was sought from and provided by Australian Wool Innovation (AWI) as one of its initiatives to address the contamination issue. It is anticipated that the project outcomes will be useful in countering alarm about the degree to which the Australian Merino clip is contaminated, thereby protecting its high standing.

A manual method of measuring dark and/or medullated fibre contamination in a scoured coresample is commercially available. While equipment costs are low, labour costs are high (~4 hours/test), thus it is unlikely to be commonly used. AWI is currently funding three research groups to develop improved methodologies for measuring this form of contamination. The sampling required for different sources of contamination requires clarification. Research has shown that dark and/or medullated fibres in the wool from Merinos that have been in contact with exotica sheep or have raised an exotic cross lamb can be detected using a coresample.
In contrast, core-sampling does not provide a representative sample of urine-stained and isolated pigmented fibre contamination due to its discrete nature. Thus, any test based on a core-sample will not work for dark fibre originating from these latter sources.

Woolclassers/growers are urged to declare lots that contain dark fibre by using a “Y” qualifier in the description. However, there is no method to declare the risk of dark and/or medullated fibres as negligible. To protect the Australian Merino clips’ reputation, tools are required to control/manage the risk of unwanted delivery of dark and/or medullated fibres. Equally, white wool Merino producers would like the opportunity to identify their product as such.

The prediction of dark fibre contamination was proffered by Roger Foulds of CSIRO in 1983, with its principles later utilised in wool quality schemes (eg. Clipcare, Dalcare). Thus, FAWO proposed that a voluntary vendor declaration for the risk of dark and/or medullated fibre contamination be investigated, and if viable, reported in sale catalogues and test certificates.

A dark and/or medullated fibre risk (DMFR) scheme would provide:

• an interim approach pending a low cost Pre-Sale Test: and
• on-going information on the risk of traditional urine stain
  and pigmentation.

The project updates the CSIRO Dark Fibre Risk Scheme to include data on the contamination risk related to exotic breeds. Activities to facilitate and support the introduction of a vendor declaration for dark and/or medullated fibre contamination includes:

• Practical methods that allow growers to declare information to determine a DMFR and transfer it to broker/private treaty merchant and test house.
• Submissions to the Australian Wool Exchange (AWEX) and the International Wool Textile Organisation (IWTO) proposing that the DMFR Factor is reported in Sale
  Catalogues and on Test Certificates.
• Objective tests on sale lots covering a range of Risk categories to validate the scheme and to develop a sampling regime for future testing system(s).
• Industry seminars to guide and promote the introduction of the Risk Scheme. Written material will aid communication with producers and the trade.
• An industry-working group to ensure the interests of all sectors is considered. The group will contribute to any related or subsequent projects.

Citation

"Managing the Risk of Dark and/or Medullated Fibre Contamination", Literature Review prepared by Kerry Hansford for AUSTRALIAN WOOL INNOVATION PROJECT - EC573, August 2003