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Queensland worms, flies and lice update - October 2020

QLD WormBoss Worm Control Programs

QLD WormBoss Drench Decision Guides

Sheep

Goats

Sheep

Goats

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

While other states have had good rain in recent months, Queensland is still pretty dry and without significant rainfall since the beginning of the year*. Widespread areas of the state are relying on the accuracy of the predicted summer rainfall to replenish soil moisture levels, improve pastures and to support stock rebuild. In the interim, it might be the time to do some forward planning in terms of deciding on the summer drenches you will use, what paddocks are most suitable for lamb marking, weaning, and whether you are going to do any testing — just monitoring, or monitoring and drench resistance testing.

(Editor’s note: there appear to have been some decent falls in places since this report was submitted by Maxine.)

Ewes on a low plane of nutrition have poor immunity making them less able to fend off an establishing worm burden and signs of infection can then develop at a much lower worm egg count (WEC). Lambs and weaners are already very worm-susceptible, without the overlay of poor nutrition, until they have had sufficient exposure to worms to trigger development of immunity, usually by end of the year for early-dropped lambs, and often into the next year for late winter-dropped lambs.

The danger time for worms is after the first few falls of rain when sheep graze around any available green pick along areas of runoff. The resultant high local stocking rates enable parasites to quickly move between hosts. Improved moisture levels facilitate greater egg and larval survival. Barber’s pole under these conditions can quickly escalate. Lethargy, pale gums and in some cases bottle jaw (a swelling below the jaw) can quickly progress to sudden death if worm burdens are high enough.

WEC (or WormTest) monitoring therefore, plays a crucial role in the lead up to, and 3–4 weeks after the first rains, for determining the timing of the drench. Continued monitoring at 4–6 weekly intervals is recommended over summer depending on rainfall totals and stocking density.

Checks on drench efficacy (i.e. DrenchTest) are best done when sheep are at-hand. The results of this test will provide a guide as to how well the drench killed the worms. The Drench Resistance Test is a more in-depth test and will provide greater and more accurate information about a number of drenches. In any case the post-drench counts need to be close to zero. While sheep are at-hand, don’t forget to also physically check the ‘poor doers’ for anaemia using the FAMACHA card, if at all possible, of both sheep and goats.

November is traditionally the time when all sheep on the property are drenched in many areas of Queensland. If the rain falls later this year drenching may have to be delayed until December. But keep monitoring. Drench lambs at 12–14 weeks of age, or at weaning if these dates don’t coincide with the summer drench. What drench to use? This is where a DrenchCheck and ideally drench resistance testing trumps guessing or using what the neighbours are using!

After drenching, move young sheep out of the lambing paddock, as these paddocks will be the most heavily worm-contaminated on the farm. After weaning ewes will regain their normal level of immunity especially if nutrition levels increase.

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