A lambing break is a common observation in the staple of ewes when being shorn. This article puts together work carried out and published in 2009 by the Western Australian Department of Agriculture and Food on time of lambing patterns in the Australian flock and subsequent staple strength in wool sold six months later.
Seasonal conditions (the amount and quality of pasture) can be manipulated to explain around half of the variation in staple strength. This is looking at pasture from a supply perspective. On the demand side lambing is the big variable determining the surfeit or deficit of pasture within a season. In reality the two variables seasonal conditions and lambing are related, and should be considered together, grist for other articles. This article takes a simple look at the relationship between staple strength and time of lambing in various regions.
In 2009 the Western Australian DAF published the results of a survey carried out in 2005-2007 about the time of lambing in different regions around Australia. The assumption in this article is that the lambing patterns have not changed greatly.
As the wool staple provides a history of conditions in which it has been grown, to observe the effect of lambing we need to look at wool which has grown so any change in staple strength has moved up the staple so that it can be measured. The wool staple strengths shown in the schematics in this article relate to wool sold six months after the nominated month (for example for a June lambing the staple strength for December sold wool is shown).
Figure 1 shows the lambing pattern of eastern Australia (lamb survey results for different regions in the DAF report have been weighted for wool production to arrive at the regional lambing pattern) and the average staple strength for wool sold six months later, from 2005 onwards. There is a clear drop in staple strength during the lambing months (which has a wide spread) with a rebound in the staple strength for the few non-lambing months.
In Figure 2 the exercise is repeated for Western Australia, where there is a much tighter lambing window and a bigger drop in staple strength (around 3 N/ktx).
Tasmania is of interest as it has predominantly spring lambing with a high concentration in September. Staple strength from the non-lambing months does vary, while staple strength from lambing months is uniformly at the low end of the Tasmanian staple strength range.
Finally, to New England, where staple strength averages across the years at levels southern regions can reach occasionally. Lambing in the northern tablelands of NSW is spring focussed, with staple strength following a similar pattern to Tasmania. Wool from lambing months pushes the staple strength down by 4 N/ktx, from the heady average of 39-40 N/ktx in wool from the non-lambing months.
What does it mean?
While the real story behind staple strength levels will lie in the interaction between seasonal conditions and time of lambing, the time of lambing does show when the greatest risk for low staple strength (and high mid-point break) is likely to be. There is not a lot farmers can do, but for the supply chain this is handy information to understand when planning greasy wool purchases.
Key Points
- The time of lambing correlates with lower staple strength in wool sold some six months later.
- This correlation holds across all regions.
Click on figure to expand
Click on figure to expand
Click on figure to expand
Click on figure to expand
Data sources: AWEX, Western Australian DAF, ICS
