Dark and Medullated Fibre Contamination in Merino Fleece from Damara Crossbred Lambs; Top and Noil Products

Abstract

The benzyl alcohol test for dark and medullated fibres, developed by AWTA/AWI/CSIRO, was used to compare the levels of dark and medullated fibre between scoured cores from greasy fleeces and the resultant noil.

Samples used in this study were Merino fleeces contaminated through contact with Damara rams or their crossbred lambs. The pigmented and medullated fibres transferred generally had high fibre diameters, are highly medullated, relatively short and show characteristics of being shed fibres which could be broadly classified as kemp.

Both top and noil products were contaminated by dark and medullated fibre thus reducing the flexibility of end-use and downgrading their value. Based on a top:noil ratio of 95:5 (being the average result in this case study) the dark fibre content in the noil was 4.24-fold that of the core sample test with 87% of the variation explained in this case study.

The measurement of dark fibres was found to be more predictable than for medullated fibres. The poor relationships for medullated fibre measurements found in this study were heavily influenced by the results from one of the ten batches. For any regression model to be meaningful in a general sense, would require a much larger data set. 

Citation

"Dark and Medullated Fibre Contamination in Merino Fleece from Damara Crossbred Lambs; Top and Noil Products", M.R. Fleet, V.E. Fish, A.R. Alaya-ay and T.J. Mahar, Report CTF01, Commercial Technology Forum, IWTO Congress, Xi'an, November 2006