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Woolcheque uses a combination of objective and subjective wool measurements and characteristics to price wool.
Objective measurements include diameter (micron), length, strength, position of break, vegetable matter and colour. AWEX-ID covers subjective characteristics.
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.
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).
Staple length generally determines the end use of wool, that is, whether it will be used in weaving or knitting.
Longer wools are processed in the worsted system (weaving). These combing types are generally around 50 millimetres (mm) and longer. The worsted system produces fine, even, smooth yarns mostly for apparel, but also for upholstery fabrics requiring a smooth finish.
The worsted system consists of two main processes, topmaking and spinning. Topmaking leaves the fibres lying in parallel after carding, gilling and combing. Wool tops are then spun into yarn.
In contrast, the woollen system converts scoured wool into yarn in two steps - woollen carding and woollen spinning.
Wool types used in the woollen system are called carding types, and usually have a much shorter fibre length (below 40 mm) than combing wools. These include types such as locks, crutchings, bellies and lambs wool. Woollen spun fabrics are used for jackets, coats, skirts, upholstery fabrics, rugs and blankets.
Wool length - management tips
Woolgrowers can manage frequency of shearing, breeding and nutrition to control staple length. Staple length is unlikely to be altered in isolation of fleece weight, unless targeting a market with a specific length requirement that differs from average.
On exception is lamb shearing. Avoid discounts for short wool by leaving lambs unshorn. Wait until the second main shearing after lambing, or if this is more 14-15 months later, have an intermediate hogget shearing before bringing them into line with the main shearing.
An issue for certain sections of the industry has been over length fine wools. Buyers of fine wools generally prefer a relatively short staple. As breeders increase fleece weights of finer micron sheep, staple length increases, introducing the possibility of discounting.
Some research indicates that processors may achieve greater efficiencies using longer wools than they presently buy, and recent market trends indicate that the discount for longer wools is narrowing. If the trade maintains its preference for shorter staple fine wools, breeding programs may have to address ways of increasing follicle density independent of length to achieve fleece weight gains.
Staple strength is a measure of the force is required to break a wool staple of a given thickness (kilotex), recorded as Newtons per kilotex (Nkt).
Staple strength relates to the efficiency of wool processing, particularly the amount of fibre breakage and wastage during combing.
Recent changes in the textile market increased processor preference for longer tops (increased hauteur) of slightly reduced average fibre diameter, with low short fibre content. Spinners can spin fine yarns faster from these tops, with fewer yarn breakages and with increased evenness and bundle tenacity. Weavers using these finer yarns of increased tenacity and evenness can increase weaving speed and produce lighter cloth with fewer fabric faults.
Woolgrowers can expect increasing trade recognition and preference for wool of high staple strength and low mid-break. Strength and mid-break percentage are determine the combing performance of wool. Many mills specify a minimum strength and a maximum mid-break percentage for their deliveries, increasing price pressure on low mid-break types, and reducing competition for wools with a high mid-break percentage.Auction data show that prices improve as staple strength increases. Compared to a baseline 35 Nkt type, penalties are large for tender wools (14-21 Nkt), with discounts declining as strength increases. Wools testing above 40 Nkt attract premiums, particularly at the finer end where discounts or premiums are magnified. Stylish 50 Nkt types at 16 micron can trade 200-500 cents above 35 Nkt types. This trend strengthened recently with the super-sound types outperforming lower strength types.
Wool strength - management tips
The key to sustainably improving staple strength and reducing the likelihood of mid-breaks in a flock is to manage the diameter profile along fibres. The strength of any fibre is the strength of its weakest (generally thinnest) point. Variation in diameter along fibres throughout the year accounts for around 40% of the variation in staple strength. Strength is maximised by making the diameter profile as smooth and level as possible along the length of the fibre.
Supplementary feeding during times of nutritional stress can help to maintain a constant level of nutrition to wool follicles throughout the year, helping to offset the effects of seasonal breaks.
Shearing close to the date of a seasonal nutritional stress will put the break in the wool very close to the tip or base.
Sheep will often develop breaks in the wool during times of sickness. Maintain sheep in good health.
Breeding to reduce between fibre variation in diameter
Variation in diameter between fibres as they emerge from the skin accounts for around 40% of the variation in staple strength. Therefore, a key breeding objective to maximise staple strength is to have all fibres within staples of similar diameter. Consider carefully your source of rams, and make sensible use of measurements.
Clues to look for to identify sheep with low variation in diameter between fibres include:
|Visual clue||All fibres of similar diameter||Fibres of widely differing diameter|
|Visual||Wool brightness||Glossy, or bright lustrous wool||Dull or flat|
|Crimp Depth (fibre alignment)||Deeply crimped from staple base to tip||Flat, lazy, or indistinct crimp|
|Staple thickness||Clear-cut bundles or thin locks||Thick staples or blocks|
|Tip shape||Small, rounded tips with evident crimp||Pointy dry tips or angular blocks|
|Visible hair||No evidence of hair around breech or poll||Hairy breech, poll and harsh, kempy muzzle|
|Tactile||Texture||Smooth, silky feeling||Rough, harsh, or gritty|
|Measured||Shape of Diameter Histogram||Narrow, symmetrical||Broad, skewed|
|CV of Diameter||Less than 19% for mid-sides||More than 21% for mid-sides|
|% fibre > 30 um||< 1%|
|Staple strength||SS > 40 Nkt|
Position of Break (POB), measured in conjunction with staple strength, is a measure of the position in the staple (base, mid or tip) where it will break given enough force.
Both sections of the broken staple are weighed after the strength test, with the results converted into values indicating whether the staple was broken in the base, middle or tip region.
POB indicates to the processor where fibres are likely to break during processing and the length of the broken fibre sections.
For example, if a staple breaks at the tip, then the broken fibres are either very short (and probably lost as card waste or noil) or rather long. If the staple breaks in the middle, both fibre sections are about equal length and relatively short.
Despite higher fibre losses during processing, low mid-break wools are usually preferred by processors as they give a longer average length in the top (hauteur). Longer wool tops receive a higher price for the topmaker, so greasy wool buyers usually pay premiums for low mid-break wool.
Price differences for POB can be seen across the entire clip. In fine wools, differences of around 150 cents can often be seen between a very low mid-break of single figures, and a mid-break in the 80 to 90% range. Most mills now specify a maximum mid-break for a delivery, making POB an important measurement for both woolgrowers and buyers.
Position of break - management tips
Nutrition and time of shearing are the best ways to reduce the percentage of mid-breaks in wool.
Manage sheep nutrition throughout the year to maintain an even profile along the length of the fibre. Sudden changes in nutrition, for example the winter "break" in winter rainfall areas, can cause breaks in the wool fibre. The key is to maintain the supply of nutrients to the follicles during these stress times, particularly when midway between shearing dates.
Supplementary feeding just prior to and during these periods may reduce the impact of seasonal breaks. Identifying the most appropriate times for joining and lambing to match feed supply to peak feed demand can help maintain a more appropriate plane of nutrition for the sheep.
The second management tool involves time of shearing. If it is difficult to reduce mid-break or increase strength via nutrition management techniques, the break can be managed by altering shearing dates. While a weak point will still appear in the wool, shearing at or near the seasonal break will shift the POB towards either the tip or base.
If the break is within 10mm of either end of the staple, the Length and Strength test is less likely to break the staple at this point, increasing the overall strength measure.
Vegetable matter (VM) in wool is a disadvantage as its removal during processing can be costly. Depending on the severity and type of VM, wool may need to undergo additional processing called carbonising. Carbonising is a relatively complicated and expensive process where wool passes through sulphuric acid bowls and ovens, before rollers crush the remaining brittle VM. Carbonising is slow and usually involves higher fibre loss than other processing methods.
VM testing is a standard pre-sale procedure. The figure published in wool-sale catalogues is the percentage of VM found in the greasy wool core-sample.
VM is allocated into seven main types in the AWEX-ID typing system:
- B - Burr (barrel medic, burr medic).
- E - Seed (sub clover, carrot seed, scotch thistle).
- S - Shive (barley grass, wild oats).
- N - Noogoora burr.
- T - Bathurst burr.
- M - Moit.
- F - Bogan Flea.
In combing wool, the fibrous types (S) of VM are the most difficult for processors to remove. S types align with the fibre during combing and can pass through to the final fabric resulting in the largest discounts. Burry VM types (B) such as those belonging to the medic group generally sit on top of the staple and are considered easier to remove during processing. Higher percentages of Burr are usually acceptable by processors for this reason.
VM discounts are relatively minor in the market place for types testing less than 1.5%. Penalties apply when fleece wool approaches the 2% level and rapidly increase when VM measures over 2%, reflecting the higher processing costs and lower throughput for the processor.
Vegetable matter tips
There are a number of ways to reduce VM levels in wool clips.
The conditions in which sheep graze can have a large effect on the amount of VM in the fleece. Location in Australia will play a large part in both the levels and types of VM in wool, however a number of strategies exist to reduce VM.
Pasture management tools include herbicide spraying or slashing at key times of the year, and changing pasture types, although this may have other long-term management implications.
Grazing tools include matching stocking rate to carrying capacity during the year, and strategic grazing techniques such as cell grazing
Shearing can be timed so that sheep are in short wool at the time of greatest exposure to seeds, burrs and other contaminants. Shear sheep before seeds mature.
Frequency of shearing can also have an impact on the levels of seed and burr in the wool, although more regular shearing (more than once per year) is uncommon and generally seen as uneconomical.
While it can be tempting to skirt heavily at shearing time to reduce high levels of VM in fleece wool, studies have shown that this practice is not economically efficient.
An AWI study of 1200 sheep in Western Australian found that VM can be significantly reduced by using sheep coats.
Fleece from non-coated animals had an average VM of 2.0%. Fleece from coated sheep had an average of 0.7% VM. The coats also improved yield and reduced fleece rot.
Sheep coats improved the value of the wool sold by an average of $3.40 per head but in some cases was up to $8.51 per head. Click to download the Economic Viability of Sheep Coats for Wool Production Final Report (PDF 350Kb).
Greasy colour is important to processors as only white product can be dyed to pastel shades, whereas off-coloured wool is restricted to darker colours.
Wool colour is appraised as being either scourable or unscourable.
Scourable colour is a discolouration that will wash out during processing. It is visible in the wool as a creamy colour or a very light yellow and is common in 'old' wool that may have been stored for some time.
Scourable colour will wash out in early stage processing (scouring) to give a creamy-white product. Scourable colour is appraised in the AWEX-ID type structure using the Qualifier 'M'.
Greasy wool with unscourable colour will result in an end product that will come out off-white or yellow, even after washing. Unscourable colour is usually visible as brighter yellow shades in greasy wool.
Unscourable colour in wool can be influenced by climate (high rainfall and humidity levels), diet, animal health and external parasites. Unscourable colour is appraised in the AWEX-ID type structure using the Qualifiers H1 (Light/Odd colour), H2 (Medium colour), or H3 (Heavy colour).
Brighter wools have a wider range of uses and often receive a higher price. Discounts for unscourable colour depend on the severity, with larger discounts for brighter yellow colours. As with most faults, the finer the wool, the greater the discount.
Wool colour management tips
Breeding and the environment influence the average whiteness and brightness of wool. Select sheep specifically for these attributes, but balance this against other breeding objectives with greater economic importance.
Fleece rot can result in unscourable colour and predispose the sheep to flystrike. Cull sheep with signs of fleece rot.
Over ten years or so, it is possible to greatly reduce the incidence of fleece rot and body strike with this approach, if your ram breeder is doing the same.