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Queensland worms, flies and lice update - July 2016

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

Over the last week, I had six mobs of sheep in the yards for crutching. As they were in the yards, all six mobs were tested for worms. Four of the mob worm egg counts were less than 50 eggs per gram (epg) (no eggs were seen) and two counts were 50 epg. As a result none of the sheep were drenched.

Without testing I would have been sorely tempted to drench at least one of these mobs (heavily stocked prime lambs on pasture), probably more. Worm egg counting has saved me time and labour, and helped to slow the possible development of drench resistance

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

Back in the day, the vagaries of the weather were more ‘predictable’ and drench recommendations were more prescriptive. Summer storms happened, if not in November, then in late January/early February, and good rains often fell in June and July. A short-acting drench plus closantel, was prescribed in August, November and February, and just a short-acting one in April. Worm control was relatively straight-forward.

These days, weather events are less predictable, many drenches no longer kill worms the way they used to, and overall, worm control requires a deal of planning.

As August looms, it is the time to plan strategies for the lambing period ahead, and now in particular, to decide if a pre-lambing drench should be given.

Consider:

  • Testing for worms—remember immatures don’t show up in the worm test so repeat testing might be required.
  • Barber’s pole—is it currently a threat? Actively growing green grass indicates sufficient moisture for egg hatch.
  • Drenches—if a drench is necessary, which ones, if any, will be effective? If you don’t know, at least follow up your next drench with a DrenchCheck-Day10.
  • Lambing paddocks—are they currently wormy? Were they spelled for 3 months over winter, grazed with cattle at high DSE, or grazed with sheep up to 21 days after the pay-out period of an effective drench?
  • Pre-lambing ewes—are they in condition score 3?

Winter has been a mix of useful falls of rain, cold nights and some very warm days. The infuriatingly persistent barber’s pole is probably in a start-stop egg hatch scenario, but certainly ticking over and waiting for an opportunity such as lambing, to strike.

During lambing and lactating, the ewe’s immune system temporarily fails as nutrients, normally used to build strong immunity, are directed towards supporting the growing demands of lactation.

Actions:

  • WormTest now. Collect samples from 2–3 mobs, and in particular, target any lighter condition score Merino ewes. Collecting dung from the poorer sheep cohort rather than randomly across the paddock will give better information about the worm burdens in this particular at-risk group.
  • WormTest these same sheep about 3–4 weeks before lambing commences, thus gaining a measure of the worm burden as close to lambing as possible while still leaving enough time to drench if required without unduly stressing the late-pregnant ewes.
  • Reserve the least contaminated lambing paddocks for the most susceptible lambing ewes (maidens, twin-bearers, oldest ewes and earlier lambing ewes).