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Beyond the Bale : December 2013
FAST FACTS Using genetics to tackle flystrike: l Woolgrowers need a clear, well defined breeding goal. l Plan to cease mulesing, don’t just cease. l Have a clear focus to manage dags and reduce breech and tail wrinkle. l Manage fleece weight reduction by focusing on other important economic traits; once achieved return to improving fleece weight. l Monitor progress and get the sheep “right” first. David Thompson runs ’Moojepin’, a 2000 hectare property near Katanning in Western Australia, with his wife Sue and son Hamish. The Thompsons have a 2700 head breeding flock and produce seedstock Multi-Purpose Merino (MPM) rams. Having faced a few years of particularly bad breech and bodystrike on his property, David decided in 1994 to take a radical approach to protect both his flock and the long term profitability of his business. He decided to tackle the problem by removing the wrinkle in his sheep that make them susceptible to flystrike. Using both visual selection methods and genetic tools, and prioritising key traits, he has achieved some impressive results. THE CHALLENGE In the mid-90s David’s sheep had heavy, tight wrinkle, an average micron of 22.8, and fleece weight of 6.5kg. In addition to being at higher risk of flystrike, they were a challenge to shear. “I looked at the cost to the business in terms of flock management, labour, other inputs and the stress on both the sheep and ourselves, and made the decision to de-wrinkle the flock,” David said. “We didn’t have any objective genetic tools at our disposal at the time, so our decisions were based solely on visual selection. We culled sheep with the heaviest wrinkle. Since then we’ve had a zero-tolerance approach to wrinkle.” In 1995 the Thompsons culled heavily, selling around 50 per cent of the flock and putting in more crops to make up the difference in income. The next step was to search for the ’right’ genetics to re-build the flock. At the time this was much more difficult as there were far fewer sheep around with minimal wrinkle to choose from. Using genetics to tackle f lystrike David Thompson and son Hamish on their 2000 hectare property near Katanning in Western Australia. David uses both traditional selection methods and ASBVs to inform his decision making. DAVID’S STORY The first priority was getting the wrinkle off. However it wasn’t as simple as just selecting plainer bodied sheep. David knew there would be trade-offs, especially in fleece weight, and had to decide what to prioritise. Yet profitability in the sheep and wool business isn’t based on micron and fleece weight alone. David looked at the numbers and to maintain business profitability, would have to lift lambing and weaning rates, and retain fleece quality. David enlisted the help of a Victorian classer, Ben Duxson, and in 1995 they secured the first lot of new genetics, with the first mating in 1996. While David did notice an immediate change in the sheep, the process was pretty slow going in the first few years. “We brought in semen from a range of bloodlines across the country, and some worked for us and some didn’t. By the 2001-02 season we’d learnt a few valuable lessons. “ Focusing on very long, soft white wool and disregarding crimp as a priority for selection was probably the hardest decision for us to make. But this decision enabled us to make the breakthrough in eliminating wrinkle from the flock.” He also noted that the plainer bodied 28 28 28 ON-FARM December 2013 BEYOND THE BALE