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Beyond the Bale : September 2010
September 2010 BEYOND THE BALE WOOL PRODUCTION 19 Commitment is the key to worm control Amicroscope in the home office and simple worm tests have made the monitoring and management of parasites a lot easier for Greg and Kathie Tighe, who run a flock of 3000 Merino ewes on 'Kelso', near Inverell, NSW. The lack of a single drench to control worms, particularly in ewes which face the added challenge of sustaining a lamb, prompted the Tighes to implement a number of strategies to fine-tune control of the parasites. Five years ago, Kathie Tighe completed a two-day course in the use of a microscope to analyse faecal samples for worms, which has enabled her to anticipate potential outbreaks. Worm egg counts are regularly monitored before deciding when to drench, and the same science is used to determine how effective the drench is by collecting and testing faecal samples 10 to 14 days afterwards. Knockdown drenches such as Nilverm® are preferred over long-acting products, which the Tighes have found tend to have a 'tail' that can encourage resistance in the region's prevalent Barbers Pole worm. Kathie Tighe also receives the monthly WormBoss emails, containing updates on worm activity in NSW, with local information contributed by Armidale vet, Rad Nielsen. It was Dr Nielsen, from Veterinary Health Research in Armidale, who assisted the Tighes with their latest drench resistance test, and he admires their commitment to managing for worms -- a problem he says is the biggest issue for graziers in the region. "There is a perception amongst a lot of graziers that strategies like drench resistance tests are time-consuming and finicky," Dr Nielsen says. "It's incredible, though, what can be achieved through a combination of monitoring, using the right drench and the spelling of pasture or rotational grazing to lower the worm burden." A large part of Veterinary Health Research's work is testing new products for pharmaceutical companies, and Dr Nielsen says while there are new drenches in the pipeline, it is not as if they are 'rolling off the presses'. "We are running into a big headwind in terms of the chemicals we can rely on," he says. "The new ones offer a bit of a reprieve, but if we maintain the same practices of drenching on gut feeling or just every four weeks under set stocking rates, we'll come unstuck." Greg Tighe is taking another factor into account in the war against worms: breeding for worm resistance. He holds a production sale on Kelso every March, selling all his wether weaners, four-and-a-half-year-old ewes and a third of his 18-month-old ewes. For three years he has been measuring FAST FACTS l New England graziers Greg and Kathie Tighe have committed to controlling worms and avoiding drench resistance through a combination of regular testing, rotational grazing and breeding stronger sheep. l The aim of WormBoss is to reduce drenching and minimise the onset of drench resistance while increasing animal productivity and profitability. l WormBoss offers free monthly email alerts about worms in your region. his sheep for worm resistance as part of the Nemesis program, but says that has its own challenges. "You can single-trait select and make rapid progress, but perhaps at the cost of other traits like production or wool quality," he says. "Running all ewes also makes it much more of a challenge because there's very little time in the year when you can sacrifice the animal's performance." The use of grazing strategies such as spelling pasture for longer has helped, but the season also plays a major part, especially in outbreaks of Barbers Pole. "This year we had such a dry summer that we only drenched every two or three months," said Mr Tighe. That's also where the testing comes in. Kathie Tighe says the science enabled them to 'hold their nerve' when normally they would have thought it necessary to drench. She says monitoring for Barbers Pole worms has become more efficient with the advent of Dipstick, a simple procedure that allows her to test faecal samples from 20 to 25 sheep at one time. "It's more of a guide to how the whole mob is going and it'll tell you when immature worms are present prior to an outbreak," Mrs Tighe says. More information: www.wool.com/wormboss New England woolgrowers Greg and Kathie Tighe.