Selection-strategy study shows growers the way to go
A 10-year project using demonstration flocks has provided a wealth of information for improving productivity
The South Australian Selection Demonstration Flock (SDF) project is now considered a landmark study, with many woolgrowers finding that the 10-year project has given them a clear direction for improving on-farm productivity.
Funded by AWI and the South Australian Research and Development Institute (SARDI), with support from Meat and Livestock Australia, the University of Adelaide and the South Australian Stud Merino Sheepbreeders Association, the project was established to evaluate and demonstrate the strengths and weaknesses of the various selection strategies typically used in the Merino industry.
It found that while all breeding methods made good genetic progress and a combination of strategies can be used in any flock, a strategy based on objective estimates of genetic performance achieved the highest dollar return.
As the project progressed, six demonstration flocks developed: control, performance index, classer-assessed, elite wool, dual-purpose and fine wool.
Stud Merino producer Geoff Davidson participated in the classer-assessed flock, which involved selecting sheep using largely visual and tactile assessment to reduce ewe flock micron to 22 micron, increase fleece weight, improve skin quality, wool softness and handle, maintain body size and maintain or improve structural soundness in sheep.
The key points of the classer-assessed flock were:
- selection based on visual and tactile assessment by professional classers, with occasional and non-systematic use of objective measurement data, resulted in even progress and consistent conformation;
- fibre diameter was reduced, fleece weight slightly increased, staple strength maintained, staple length increased and body weight substantially increased;
- progress was slower than some other breeding methods; and
- low operating costs were a notable feature.
Mr Davidson, of ‘Moorundie Park Poll Merino Stud’, north of Clare, approached the SDF project believing sheep classers have a clear role in further improving the performance of the Australian Merino, and he saw the project as a unique opportunity.
"Visual appraisal is essential to maintaining the conformation standards of the national flock," he says. "I wanted to improve my understanding of the use of objective measurement in sheep selection, and contribute to a valuable industry endeavour.
"While many commercial farmers focus on productivity and achieving their goals, I believe stud breeders are obliged to be fully aware of selection system developments."
Mr Davidson runs 4000 stud ewes on his 2000-hectare property, with the aim of increasing grower profitability through improving fertility, worm resistance, growth rate and quality wool production.
The aims of the classer-assessed group were to decrease fibre diameter to 22 micron, maintain good body weight and improve conformation from the starting flock of 24 to 25 micron sheep.
"The dilemma facing South Australian Merino producers at the time [1996] was strong micron in an era of premiums for fineness," he says. "So our selection committee looked at ways of reducing micron without compromising other production traits.
"We had to be mindful of fleece rot and selection for white wools, and as the project unfolded, the committee decided to decrease micron further – which was achieved."
Fleeces went from 24 to 25 micron down to an average of 21 micron over the 10 years of the project, while all other necessary production traits were maintained.
Mr Davidson believes the classer-assessed method demonstrates that setting a breeding objective is the first step to achieving production goals: "And the selection method also proved that a good classer can achieve good results at low cost, though after watching what happened at Turretfield over 10 years, perhaps we could have improved our outcome if we had used more measurement data. In particular, progeny-testing data would have been good to assess the progress towards the breeding objective."
Mr Davidson notes that it is difficult to achieve classing consistency from year to year because it depends on who is available on classing day to make the decisions. "I think the traditional classer-based selection system as a method on its own might become more applicable to commercial flocks, while at stud level we’ll move towards using a combination of selection systems," he says.
Mr Davidson regards the use of outside sires as a way to make a large initial impact. "But one has to be careful not to introduce unwanted traits – and that’s where being able to measure and monitor progress is very useful."
In his own enterprise, Mr Davidson is using some of the key SDF outcomes. "I am working to a breeding objective and gathering more information on my flock, especially on fertility, body weight, micron, fleece weight, muscle and worm resistance – though I’m not using an index at this stage.
"I think it’s vital to recognise that client demand is the key driver for breeders. The industry has become commercially focused, and we need to keep this in mind when producing the seed-stock sought by clients."
Further grower insights into alternative selection systems are now available in a brochure, Merino breeding for profit, which outlines the SDF findings.
More information: Merino breeding for profit is available by contacting the AWI Helpline, 1800 070 099, and can be downloaded from the AWI website, www.wool.com.au/publications
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