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Queensland worms, flies and lice update - December 2016

Brisbane: Maxine Murphy, Veterinary Parasitologist (maxine@paraboss.com.au)

While the hot dry weather may kill off larvae on pasture, worms will still be alive and well in sheep, and sheep will still be dropping eggs onto pasture. In this weather (temperatures over 35°C), eggs may not hatch, so be it, but worm burdens in sheep will still need to be investigated and if necessary, drenched, before productivity is impacted.

If however, summer storms bring areas of green pick, or green pick is protected by taller, dry grasses, there may be suitable amounts of humidity and moisture for eggs to hatch and larvae to lurk. This is how the build-up starts and it will not take lambs and weaners very long to multiply the contamination to critical levels in the next few weeks.

NB: worm burdens have a habit of getting out of hand very quickly over mid-summer. Worm testing is the only way to determine what is happening inside the digestive tract of sheep.

If you plan to investigate the effectiveness of your drench in the next few weeks by taking dung samples from sheep 14 days after the drench, it is recommended you take individual samples (see case study from Justine McNally, Moree NSW) rather than bulk ones. And definitely, sample young and older sheep, but keep samples separate and place in different bottles. Mixing dung from different classes of sheep (younger sheep are usually wormier than older sheep) to produce a bulk sample may give misleading results—you may have to drench all sheep in a paddock rather than just the weaners, or worse still, you may decide not to drench at all and later find that indeed the weaners were wormy.

Post-drench egg count results should be zero for maximum drench effectiveness.

Merry Christmas and Happy New Year to all.

Texas: Noel O’Dempsey, Sheep Veterinary Consultant (odempseyn@gmail.com)

The death rate of barber’s pole larvae on pasture increases as the temperature increases. Details are available in the regional Worm Control program for your area (and here) in WormBoss in an easy to understand and use, format. For instance, at a daily maximum temperature of 35°C with 60 percent relative humidity, 50% of larvae will die in less than 15 days, at 40°C and above, even quicker. So if nothing else, the recent hot weather has killed off some barber’s pole larvae.

What the recent rain will do for barber’s pole numbers depends on a number of factors (see here) including how much rain you received, how the rain fell and the barber’s pole numbers beforehand. Don’t get caught out—Worm Egg Counting will keep you ahead of the game. WormBoss is available at www.wormboss.com.au.