Merino fibre diameter trends

Sheep Genetics is the genetics evaluation service to the Australian sheep industry (read more here). As such the breeding trends evident in its data will foretell the direction we can expect production to follow. In this instance, we are looking at the average merino fibre diameter.

Figure 1 shows the annual average fibre diameter for merino wool sold at auction in eastern and Western Australia from the mid-1990s onwards. Reporting of breed-specific wool characteristics such as fibre diameter, before the availability of AWEX data (which begins in the 1995-96 season) was not carried out. As Figure 1 shows there has been a big drop in the average merino fibre diameter during the past 30 years from around 21-21.5 to 18.5 micron. Generally, the Western Australian merino clip has been slightly broader than the Eastern clip (on par with the South African clip). The trend lower in eastern Australia has slowed during the past decade, falling by a relatively slow 0.5 micron, much slower than the fall seen in the decade from the mid-1990s onwards.

Traditionally the New England region in northern NSW (along with the Traprock region in southern Queensland) has been the major supplier of fine wool in the Australian merino clip. Times are changing. Figure 2 shows the proportion of the merino clip sold in 2023-24 for 20 Australian regions (the bars show the proportion) ranked by their average fibre diameter ranging from the finest on the left to the broadest on the right. Tasmania came in as the region with the finest merino clip (2.8% of the clip averaging 17.32 micron) followed by the Monaro (2.3% and 17.46) and then the northern tablelands of NSW (4.1% and 17.5 micron). On the other end, the western Riverina (19.59) and far northwest NSW (19.77) were the regions with the broadest merino clips.

To better see the trend in merino fibre diameter Figure 3 shows the rolling 10-year change in the average merino micron for wool sold. The merino micron before the 1990s has been calculated from available sales data. As of 1991, the merino micron was slightly broader than a decade earlier (or at least unchanged). It then begins a plunge downward, reaching a fall of 1.55 micron over the prior decade, from 2003 through to 2010. Since 2010 the rate of fall in the average merino micron has lessened and as of last season was only 0.45 micron below that of a decade ago.

Now, to peer into the future, we use the Merino Select trend for adult fibre diameter. Figure 4 shows this trend for the past decade. It refers to a fixed, base micron so it shows the average adult merino fibre diameter in the genetics database to have been trending higher (year on year). In 2014 the trend was close to 1.3 microns below the base year while in recent seasons it has been close to 1.1 micron below the base level, implying an increase in fibre diameter of close to 0.2 micron, although the AFD fell last season. This implies the shrinkage in the rolling change in micron shown in Figure 3, is very likely to continue. This has ramifications for the micron makeup of the Australian merino clip.