Making and measuring genetic progress in merinos

The lamb industry has clearly experienced large productivity improvements. These are illustrated by the genetic trends in growth rates, muscle and fat depth that have been driven by the adoption of genetic improvement programs (such as LambPlan), resulting in bigger, leaner carcases.

Productivity improvements in the wool industry (represented by merinos) have been smaller, and there has been a much slower uptake of genetic improvement technology, although this is improving. This is, perhaps, because the wool industry has not had the same sort of consistent single direction as the lamb industry; instead, there have been changing emphases on wool weight, wool quality, fibre diameter and other traits.

The push for lower fibre diameter to deliver more wool suitable for next-to-skin wear has been a longstanding market objective, and the industry has significantly reduced the average fibre diameter of the merino wool clip. However, until recently, the effect of drought has masked the genetic improvement.

Demonstrating genetic improvement can be difficult when breeding objectives change, and when industry does not widely measure improvement. The national genetic improvement program (MerinoSelect) provides breeders with tools for selecting sheep with particular traits, based on their genetic merit. This is particularly useful for traits that are difficult to see, such as worm resistance, fat depth and eye muscle.

Widespread use of a genetic improvement program means that animals with specific traits can be easily identified and accessed, and industry can better evaluate genetic gain. For example, would the industry have needed to import South African genetics if the desired traits could easily be identified in Australia?

Whether or not you see breeding values as a tool to improve selection of animals that are superior for the traits you want, there is also value for industry in being able to identify sheep with a range of traits and more clearly show productivity improvements.

Genetic change in Merinos

In a paper reviewing genetic changes in the merino industry, Rob Banks and Daniel Brown of UNE considered the diverse gene pool available for different markets.

As well as identifying the large diversity in merinos available, they suggested an evolution of two types: one with high-quality apparel wool of less than 19 micron, and a dual-purpose type with a wool:meat income ratio of about 1:1. In both types, they also considered selection for disease resistance, easier care and reproductive traits.

An illustration of their view, is provided in sire evaluation trials underway in Victoria, which evaluate merino sires for a range of traits that are measured consistently across sires, sites and years, and assess the sires for genetic breeding values. The Northeast Victoria and Balmoral sites have included historical sires to give across-year linkages and illustrate how sires that were widely used in the past perform today.

Obviously, this is just an illustration of some of the changes, and the diversity of traits that are being assessed and changed — it uses individual sires, rather than reflecting a stud or industry trend.

In the Northeast trials, the historical sire has been a Toland 1996 drop ram. Compared with this ram, a 2014 Toland sire had progeny that were considerably finer, had long and stronger staples, had a slight reduction in fleece weight (3%), were less wormy, and had less body and breech wrinkle and cover.

At the Balmoral site, the historical sire was a Nerstane 1986 drop sire. Progeny from a 2010 Nerstane sire were bigger, had a small drop in fleece weight but with finer wool, were less wormy, and had less wrinkle and breech cover.

To illustrate the more dual-purpose type sheep, two Leahcim sires entered at Balmoral (although not entered as historical sires), but were 4 years apart – 2009 and 2012. The more recent ram had progeny that had similar fleece traits (but a longer and stronger staple), but the progeny were bigger, with more fat and muscle.

None of these examples (reflecting Banks's and Brown's industry observations) showed an increase in wool production, but illustrated significant changes in other traits, such as reduced fibre diameter, less worms and body wrinkle, and increased size, with more fat and muscle.

If these examples are a reflection of Banks's and Brown's observations and industry breeding changes, it is clear that monitoring wool production over time will not indicate productivity increases.

All these traits of interest — worms, wrinkle and carcase traits — have been successfully improved using genetic performance recording (MerinoSelect), along with the more traditional visual selection. Because of this, producers should have the confidence to use breeding values to make the changes required, and to show others (clients, breeders and other industries) that such progress can be, and is being, made.


  • Breeding objectives for merino sheep have changed in the past and continue to change.
  • Fleece weight may not be relevant as a key measure of productivity change if merinos are being selected for finer wool, freedom from disease, easy care, carcase and reproduction traits.
  • As a result, identifying productivity changes is more complex than in the lamb industry and is made more difficult by the slower adoption of genetic improvement technology across industry.
  • The wide diversity of traits available in merinos, and changing views about key (or priority?) traits, should increase the value for breeders of using genetic performance — as provided through MerinoSelect — to find what they want more easily, and to illustrate more widely the progress and diversity of the breed.

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Page last updated: 03 Jul 2020