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Online learning: Qld/NSW Summer Rainfall / Tablelands and Slopes—Deciding when to drench and what drench to use

This strategy describes when to use strategic drenches and how to decide when tactical/therapeutic drenches are needed.

Structured reading

For those who like to see all the information and simply read through it in order. Each heading is a link to a page of information—the dot point provides a summary of the page.

Tip: Keep this page open and open the links in new tabs.

Qld/NSW Summer Rainfall / Tablelands and Slopes: When to test and when to drench
The times for routine worm testing and drenching in this region. Not all testing or drenching is routine; other times to do these are recommended by the Drench Decision Guide, according to details you provide about your mob of sheep.

Qld/NSW Summer Rainfall / Tablelands and Slopes: Drench Decision Guide
This tool recommends whether a mob should be drenched, the length of protection warranted and when to worm test again. It is your day-to-day tool on drenching decisions that should be used in conjunction with the annual program of routine testing and drenching times.

The DDG tool steers you through a series of questions about your sheep; choose the answer that applies to your mob (or make up your own scenario).

Question and answer

For those who prefer a problem based approach to learning, answer the following questions.
Each of the questions below links further down the page to the answers.

Questions:

  1. What is the purpose of a strategic drench?
  2. Which classes of sheep receive a routine (strategic) drench, and when?
  3. The online Drench Decision Guide (DDG) for Qld/NSW Summer Rainfall / Tablelands and Slopes assists you to decide whether a mob of sheep should be drenched now and when to test again. Open the DDG and answer the questions it offers based on the scenario (from below) that you are using. Try at least three of the following scenarios.
  • Ewes in mid-pregnancy are in Condition Score 3 with 500 kg/ha of green herbage mass; their last drench was a short-acting combination.  A WormTest shows an average count of 900 epg with 85% barber’s pole worm.
  • Weaners injected with long acting moxidectin in mid-February (after a short acting drench at late December weaning). It is now late-March and the weaners look good.
  • Ewes just prior to lamb marking, they were drenched with a short-acting combo into a low worm-risk lambing paddock, they have no signs of worms. A WormTest just conducted shows greater than 60% barber’s pole worm for an average count of 400 epg.
  • Ewes early September, just shorn and will soon go into their lambing paddock 3 weeks before lambing starts. The paddock has not been prepared as low worm-risk.
  • Ewes late August, just shorn and about to go into lambing paddock in 2 weeks for start of lambing. The paddock has been prepared as low worm risk.
  • Lambs before weaning in a moderately good year, drenched at marking with a short-acting drench. The weaning paddock has not been prepared as low worm risk.

Answers:

You can also click on each question below to go to WormBoss pages with related information.

1. What is the purpose of a strategic drench?

Strategic drench: a drench given at a critical time to sheep that are susceptible to worm infection (e.g. weaners and pre-lambing ewes) and also given at times to reduce worm larval contamination of a pasture grazed by the drenched sheep over the following weeks or months. The sheep themselves may have had a low worm egg count at the time of this pre-emptive treatment.

2. Which classes of sheep receive a routine (strategic) drench, and when?

In this region there are two situations where sheep should be drenched without a prior WormTest, these are:

  • Pregnant ewes just prior to lambing when they enter their lambing paddock.The worm challenge is typically about to rise at this time of year and lambing ewes, which experience a temporary loss of immunity during lactation, can contribute to a large increase in paddock contamination and a source of ongoing infection for themselves and their lambs.
  • Lambs at weaning. Weaned lambs are highly susceptible to worms, especially from the stress of weaning. Summer weaning also coincides with high worm-risk weather conditions. Drenching at weaning will help weaners to achieve the growth rates needed for survival.

In both cases use a drench known to be effective on your property. Preferably use a short-acting treatment, and where possible, use a multi-active combination. After these drenches, move the sheep into prepared low worm-risk paddocks.

3. The online Drench Decision Guide (DDG) for Western Australia assists you to decide whether a mob of sheep should be drenched now and when to test again. Open the DDG and answer the questions it offers based on the scenario (from below) that you are using. Try at least three of the following scenarios.

  • Weaners in May that received a combo drench into a prepared winter weaner paddock about a month ago, less than 5% are scouring, an egg count shows 80 epg.
  • Weaners in late January that were drenched with Monepantel at weaning in early December. There are no signs of scouring and they look healthy.
  • Ewes in November. No drench was required before lambing. About 15% are scouring.
  • Ewes received a first summer BZ/LEV/ML drench in early December, it is now mid January. Summer has been unusually wet. Sheep are not scouring but a couple of ewes were found dead in the paddock and others are lagging during mustering.
  • Late-lambing ewes in good condition just prior to being moved to their lambing paddock. A worm egg count shows 350 epg.
  • Lambs just about to be weaned, they look well-grown with no obvious signs of worms.

 


Links to the learning topics for Qld/NSW Summer Rainfall / Tablelands and Slopes

  1. Introduction
  2. Grazing management
  3. Breeding for worm resistance
  4. Worm testing
  5. Drenching (you are currently on this page)
  6. Drench resistance management
  7. Sheep worms