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Home Worm Control Program – QLD/NSW Summer rainfall/slopes and plains When to WormTest and when to drench or use Barbervax®

When to WormTest and when to drench or use Barbervax®

Why check worm burdens in sheep?

Checking worm burdens with a WormTest is essential for correct and timely drenching decisions. The result is healthy sheep without unnecessary drenching. WormTests are the best basis for drenching decisions. Pale skin and eyes (anaemia), bottle-jaw, weight loss, a tail in the mob, and deaths may mean that your sheep need drenching. If so, these signs occur well after production losses from worms are already occurring in the mob. WormTests give early warning of significant production losses.

How are worm burdens tested?

Checking worm burdens throughout the year using WormTests is a critical part of the WormBoss worm control program.

WormTest just before sheep are mustered for routine management events. Also, WormTest at 4–6 week (summer) or 6–8 week (winter) intervals after a drench is given or, if a drench was not required, after a suitable period, as shown by the Drench Decision Guide.

Most WormTests are done through a laboratory. However, worm egg counts (but usually not larval cultures) can be done by producers if they have the equipment and skills.

Which mobs and how many should have a WormTest?

WormTest at least one in every three mobs that are similar regarding drenching history, paddock type and class of sheep.

Testing representative mobs saves the cost of testing all mobs. But this assumes the mobs, their paddocks and drenching history are very similar. If in doubt, test additional mobs.

When should WormTests, drenches and Barbervax® vaccination be routinely done?

Use of the Barbervax® program is an optional strategy to control barber’s pole worm; it will not control other worms.

Routine drenching of lambs at weaning and routine WormTest times will still apply, however non-routine drenching will be reduced when Barbervax is used correctly. Protection against barber’s pole worms requires three initial ‘primer’ vaccinations at 3–4 week intervals. A vaccination schedule can be customised by a professional advisor.

Routine Barbervax vaccination times

Lambs or hoggets not previously vaccinated
  • V1: lambs at lamb marking; hoggets during October.
  • V2: 3–4 weeks after V1.
  • V3: 3–4 weeks after V2.
  • V4—V6: after V3, give at 6-weekly intervals while protection is required.
Hoggets vaccinated as lambs the previous year
  • V1: Give in November/December (earlier if spring is wet)
  • V2–V5: after V1, give at 6-weekly intervals while protection is required.
Breeding ewes not previously vaccinated (assumes a spring lambing)
  • V1: 8–9 weeks pre-lambing.
  • V2: 4–5 weeks pre-lambing.
  • V3: 1–2 weeks pre-lambing.
  • V4: lamb marking.
  • V5 onwards: after V4, give at 6-weekly intervals while protection is required.
Breeding ewes vaccinated the previous year
  • V1: 1–2 weeks pre-lambing.
  • V2: lamb marking.
  • V3—V6: after V2, give at 6-weekly intervals while protection is required.
Note: V=vaccination, the number (1–6) refers to first, second (and so on) vaccination in the series given in one barber’s pole worm season.

It is important to also follow the routine drench and WormTest times shown below

Routine drenching times

In October/November:

  • If the grass is green and actively growing in these months: 
    All sheep should be given an effective drench for barber’s pole worm, scour worms and nodule worm. However, if a WormTest (recommended before drenching) is greater than 500 epg, and seasonal conditions are good, your sheep may need extra protection against barber’s pole worm, such as a mid-length or long-acting drench (if effective on your property).

    If a persistent product is used, the sheep can be kept on the same pasture or moved elsewhere according to your management needs. If a short-acting drench is used, move sheep to low worm-risk pastures with good feed. WormTest in 4–6 weeks after a short-acting treatment. If mid-length or long-acting treatments are used, follow the recommendations for mid-length and long-acting treatments.
  • If the grass is brown or not actively growing in these months:
    Young sheep (less than 18 months old) will need an effective short-acting drench against barber’s pole worm, scour worms and nodule worm. WormTest in 4–6 weeks after the drench.

At weaning: This may coincide with the October/November drench – if not, always drench at weaning.

Routine WormTest times

WormTests can be done at any time, however there are also set times to WormTest (preferably with a larval culture in warm/wet times to check for barber’s pole worm):

  • prior to the October–November drench
  • pre-lambing
  • late January if drenching was not done in October/November
  • late February if drenching was done in October/November (except weaners, see final point below)
  • from March to October, 4–6 weeks after significant rain (20+ mm) that also has follow-up rain (10+ mm) in the following few weeks
  • ewes prior to mustering (e.g. for crutching, joining, shearing) as directed by the Drench Decision Guide
  • weaners from weaning to shearing: every 4–6 weeks (summer) or 6–8 weeks (winter) after a drench

WormTest more often in high rainfall years and less often in very dry years. However, when sheep congregate on smaller areas due to tall thick pastures, heavy rain/flooding or bore drains WormTest more often.

Check the intestines: Nodule worm can be a problem in this area; check for signs when any sheep die or are killed for rations. Open the abdomen and find the large and small intestines. Examine the outside wall of each for firm white pimples or nodules. If these are present, you should routinely drench in May with a drench that contains either a macrocyclic lactone (ML) or a benzimidazole (BZ).

When are other WormTests done and drenches given?

The timing of WormTests and drenches will vary between farms and seasons. Use the Drench Decision Guide to weigh up important factors when deciding when to drench or WormTest on your property. These factors are signs of worms, time since last drench, the persistence of the last drench, WormTest results, recent rainfall, and condition of sheep and pastures.

If drenching is done for other reasons (such as an early drench before holidays or harvesting), recommence WormTests 4–6 weeks (summer) or 6–8 weeks (winter) after the drench was given.

Then use the Drench Decision Guide to decide when to drench or WormTest again.

What samples should be collected for WormTests?

Sheep do not need to be yarded for a WormTest. Collect fresh dung from the paddock. Obtain WormTest kits or sample collection details from laboratories or resellers in your area. Follow the instructions provided in the kit.

  • Avoid delays in transit (when worm eggs can hatch) by collecting and posting early in the week.
  • Ensure samples are kept cool, but not refrigerated, before sending.

If you do your own worm egg counts, use the ‘bulk’ sampling method where all of the dung is collected into one container.

  • Collect 3 pellets per pile of dung from at least 20 individual piles of fresh dung.
    • In barber’s pole worm areas collect from 40 piles of dung if the mob has over 200 sheep.
    • Choose pellets of equal size so that each sheep is equally represented.
    • If dung consistency is runny, use a plastic spoon. Don’t avoid runny or soft dung.
  • Collect lamb and ewe samples separately.
    • Dung should be very thoroughly mixed together before preparing your solution for counting.
    • Count 5 chambers from the sample.

See ‘Checking a mob of sheep for worms with a WormTest.

The WormBoss Drench Decision Guide

The Drench Decision Guide is reliable and helps to simplify decisions. There is a version of the Drench Decision Guide for each WormBoss region.

The guides consider:

  • whether signs of worms are present
  • the class of sheep
  • the WormTest results
  • the condition of the sheep
  • the condition of the pasture
  • the likely worm contamination of the paddock

The Drench Decision Guide will recommend:

  • whether to drench now
  • whether to use a persistent drench
  • when to WormTest again

Results from the Drench Decision Guide can be applied to mobs without a WormTest if other mobs (same class, and similar drenching and paddock histories) have been tested. If in doubt, WormTest the mob.

How to use the Drench Decision Guide

You can use the Drench Decision Guide at any time, whether you are contemplating drenching now or in coming weeks. Not all situations require a WormTest: the Drench Decision Guide will recommend when these should be done.

Each Drench Decision Guide is available as a separate 2-page printable version, or can be used directly online. Both are available at the link below.

Using the print version:

  1. Start on the page that shows the ‘Drench Decision Guide Questions’.
  2. Read Question 1.
  3. Follow the ‘go to’ information on the right for the answer that applies to your sheep.
  4. Only go to the question or recommendation to which you are directed by your answer.
  5. When you are directed to a letter, this is the final recommendation, and is shown on the next ‘Recommendations’ page.
  6. Also, read the important information in the green boxes.

Using the web version:

  1. Agree to the terms of use and press ‘Start’
  2. Select an answer for the first question and you will automatically be taken to the next appropriate question.
  3. Select an answer for each question and you will automatically be taken to the Recommendation, where your choices and Recommended Actions will be shown, as well as other important information.

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