wool fibre micron diameter



Mean fibre diameter is a measurement in micrometres (microns) of the average diameter of wool fibres in a sale lot. Fibre diameter is responsible for 70-80 per cent of the greasy wool price over the long term.

Fine and superfine wool production has increased as a percentage of the Australian wool clip. Australia dominates the supply of fine wool to the international trade, accounting for over 90 per cent of global production of Merino wool of 19.5 micron and finer.

Global demand for finer wool has increased. Manufacturers and processors must source more fine wool to satisfy the global consumers' demand for lightweight garments with next-to-skin comfort, particularly in women's wear.

Micron premiums

The chart below shows the relationship between micron and price. The finer the wool, the higher the price received, with the micron premium increasing as fibre diameter reduces.

Between 17.0 and 20.0 microns, there is over 100 cents difference for each full micron. This falls to less than 50 cents between 21.0 and 22.0 microns. Finer than 17.0 microns, the premium for each micron can be 200 to 400 cents. Lower styles and lower strength types tend to display a much flatter micron/price curve.

Wool diameter management tips

The most important decision for woolgrowers with respect to the price received for wool, is the fibre diameter produced. This decision should be based first and foremost on market requirements in the medium to long term.

Failing this, long term historical price relativities are a better guide than recent, short term price margins.

Breeding is the critical determinant of fibre diameter. While environment plays some role in determining the type of sheep run, fine wool sheep are successfully run in pastoral areas and do not necessarily cut less wool.

Compare several ram sources to before changing bloodlines. Review wether trial and sire evaluation information to identify the most productive sheep.

Variation in fibre diameter (CVFD) is also of some importance, as high CVFD is usually associated with low staple strength. CVFD is controlled by genetics and influenced by fluctuations in nutrition.

Ways to influence diameter

Set breeding objectives for the flock, and design a breeding program to meet those objectives. Choose a ram source with similar objectives that provides objective information on its sires to clarify buying decisions.

'Fining up' the flock through breeding is a long-term process but need not compromise wool cut or other traits.

In higher rainfall areas, sheep can be run at a high stocking rate to maximise wool cut per hectare. Understocked sheep cut more wool per head but less per hectare, and the wool has a higher fibre diameter. Consider lambing in spring rather than autumn to match feed demand with supply.

Apply grazing management techniques to maintain a reasonably constant plane of nutrition, minimising fluctuations in diameter along the fibres.

Tools such as rapid in-shed micron testing with Laserscan or OFDA can help achieve breeding objectives and prepare premium, finer fleece lines during classing.

As a rule of thumb, keep all the wool from similar sheep together. A fine line strategy is only likely to give a net benefit if you have individual measurements for each fleece (visual classing is not precise enough), and where premiums increase steeply for decreasing fibre diameter (that is, the clip should average below 21um as a guide only).

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