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Beyond the Bale : March 2017
Deb Maxwell and Cameron Peardon know only too well how quickly and easily barber’s pole worms can take their toll. Despite Deb being a sheep extension officer for years, control of these worms was hit and miss on the Guyra property in the New England district of NSW that she manages with her husband, Cameron Peardon. In 2011, while working for the Sheep CRC, Deb joined a team to add Programs and Drench Decision Guides to the WormBoss website. At this time she started working with Lewis Kahn who had recently completed an AWI-funded project to develop an integrated parasite management program for the New England region. “The concepts of worm control were already well known, but Lewis’s research put it all together into a simple and clear program of what to do and when to do it, and proved on commercial properties that it was highly effective,” Deb said. “We were already well ahead on breeding for worm-resistance with our stud flock and we did drench resistance tests and regular monitoring, but the Guyra climate is so suitable for barber’s pole worms that paddocks became heavily contaminated in spring and summer, and the challenge in autumn was particularly high. “The very first year we prepared and used a low worm-risk weaner paddock, we went six months without drenching them. We’d never gone more than six weeks after weaning before. This last year the 2015-drop ewes have gone over 13 months [at the time this article was written] since their short-acting weaning drench. “Preparing low worm-risk paddocks has had a phenomenal impact on worm control here, and we have found it very easy to do. We prepare both lambing paddocks and weaning paddocks. “I also wonder if drenching somehow interferes at times with natural immunity to barber’s pole worm. It’s a possibility demonstrated by the late Ian Barger working at Chiswick Research Station, Armidale, but not fully confirmed or understood. But it is known that immunity to barber’s pole worms is short-lived compared to scour worms. “We’ve found that by limiting exposure to worms – particularly weaners who are only starting to build their own immunity – that they get a chance for it to develop strongly with continued and gradually increasing exposure to worm larvae. “As a result we don’t see any yo-yo effect where worm levels go up and down dramatically – getting cleaned out with a drench, then rapidly re-infected. “We simply follow the strategies in the WormBoss program for this region. We breed for worm-resistance and prepare low worm-risk lambing and weaning paddocks. Drenches now are always used as combinations and are known to be effective based on our three-yearly DrenchTests. Monthly WormTests let us know exactly what is happening with each mob, allowing drench intervention in plenty of time if needed. “It’s cheaper and less work than our previous management and it gets far better results. To top it off we don’t worry that we’ll find sick sheep anymore.” DEB MAXWELL AND CAMERON PEARDON ‘MANNUM PARK’, GUYRA, NEW ENGLAND, NSW MERINO STUD FLOCK OF 350 EWES PLUS FOLLOWERS CASE STUDY in WormBoss), graze in the 2–4 weeks after the drench, then remove the stock: • 2 weeks for goats • 3 weeks for sheep in barber’s pole worm areas • 4 weeks for sheep in scour worm areas If a long-acting product is used, grazing can be longer in line with the actual length of persistence the product provides on your property (long-acting drenches may have a shortened length of protection if worms are resistant to that product; WormTest at 30, 60 and 90 days). When the paddock is ready to be used, drench all sheep into the paddock with the most effective drench combination you have. Ideally, prepare enough paddocks so that the susceptible stock using them will have enough feed for at least three months, to get them past their most susceptible phase. If a number of paddocks are required to achieve this, they can be prepared on a staggered timeframe to match when they will be used. MANAGING DRENCH RESISTANCE FROM CLEAN PADDOCKS Preparing and using clean paddocks does have a downside that needs to be managed. By removing most larvae and drenching sheep in, almost the only larvae on the paddock that will develop and reinfect the sheep will be from worms resistant to the drench group used on introduction to the paddock. There may be very few of them, but with hardly any other worms to dilute them, they will be dominant in that population. In managing this, it is one of the few times when drench rotation is really useful. When the sheep leave the paddock (or the whole group of paddocks prepared for and used by that mob) do the following things: • Drench the sheep with a different drench group/s known to be effective on your farm. Using the same group again won’t clear these resistant worms. • Next graze these paddock/s with a mob that has at least a moderate worm burden and whose last treatment was a different drench group/s to that given to the first mob using the low worm-risk paddock. This will bring in some worms that are more susceptible to the original drench, which will dilute any resistant worms. In combination with other WormBoss strategies, low worm-risk paddocks have a major beneficial impact on worm control. MORE INFORMATION WormBoss provides the latest information about worms and management tools including Drench Decision Guides and Regional Worm Control Programs. WormBoss is available at www.wormboss.com.au ON FARM 37
In the Shops - March 2017