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South Australian Winter Rainfall

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Drench Decision Guide

South Australian winter rainfall

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Future events cannot reliably be predicted accurately. ParaBoss, UNE and Sheep CRC makes no statement, representations or warranties about the accuracy or completeness of, and you should not rely on any information relating to the Drench Decision Guide ('Information'). ParaBoss, UNE and Sheep CRC disclaims all responsibility for the Information and all liability (including without limitation liability and negligence) for all expenses, costs, losses and damages you may incur as a result of the Information being inaccurate or incomplete in any way for any reason.
Are these sheep showing signs[1] suggesting a worm infection?
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1Signs of worms

Scour worms (black scour worm [Trichostrongylus species]; brown stomach worm [Teladorsagia circumcincta]; and others [incl. Nematodirus]): dark scours; weight loss; death.

Barber's pole worm: anaemia (pale inside eyelids and gums); 'bottle jaw' (swelling under the jaw); lethargy, lagging or collapse when mustered; death.

NOTE: Other diseases can cause similar signs. Seek veterinary advice if WormTests do not indicate worms.

What class of sheep are these?
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Which stage applies to these young sheep?
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Are these rams in the month before joining?
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Which stage or zone[1] and time of year apply to these ewes, rams or wethers? (choose the first applicable option)
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1South Australian winter rainfall region

South Australian Zones

WormBoss Drench Decision Guide Report

Region: South Australian winter rainfall

Date: %21 %Dec %2024

Your Selections

History of selection will appear here

Your Recommended Action

If these are lambs, seek veterinary advice immediately, otherwise WormTest now. Treat with an effective short-acting drench[1] if egg count exceeds 250 epg. WormTest again in 6 weeks[2]. If results show scour worms are not the likely cause of the scouring/weight loss seek veterinary advice.

Treat now with a drench[1] effective against barber's pole worm, and at the same time collect samples and submit for a WormTest with a larval culture. If signs do not improve in 4-7 days seek veterinary advice.

No treatment is required now. Treat or WormTest at weaning depending on your zone.

  • South-East and Higher Rainfall Mediterranean[1]: Treat with an effective short-acting drench[2] at weaning.
  • Lower Rainfall Mediterranean[1] (there are 3 options):
    1. WormTest just prior to weaning (collect only lamb dung). Treat with an effective short-acting drench[1] if egg count exceeds 150 epg.
    2. WormTest at weaning (collect when the lambs are separated and hold nearby till results are received). Treat with an effective short-acting drench[1] if egg count exceeds 200 epg.
    3. Or treat all lambs at weaning with an effective short-acting drench[1] (least-preferred option as many mobs will not need drenching).

Region zones are provided in the map below.

  • South-East and Higher Rainfall Mediterranean[1]: WormTest each 4 weeks[2] from 12 weeks[2] till turnoff.
  • Lower Rainfall Mediterranean[1]: WormTest at 12 weeks old. Treat with an effective short-acting drench[3] if egg count exceeds 200 epg (further testing should not be required unless signs of worms become evident).

Region zones are provided in the map below.

  • South-East and Higher Rainfall Mediterranean[1]: WormTest 4 weeks post-weaning then 4—6 weekly[2]. Treat with an effective short-acting drench[3] if egg count exceeds 200—300 epg (use 200 if last drench was within a month and 300 if last drench near 2 months ago).
  • Lower Rainfall Mediterranean[1]: WormTest 6 weeks post-weaning then 6 weekly[2] on green pasture, or 8 weekly[2] on dry pasture, or 10 weekly[2] on crop stubbles. Treat with an effective short-acting drench[3] if egg count exceeds 250 epg (post-weaning WormTest) or 300 epg for later WormTests.

Region zones are provided in the map below.

Treat rams with an effective short-acting drench[1].

WormTest. Treat with an effective short-acting drench[1] if the egg count exceeds:

  • South-East[1]: 75 epg.
  • Higher Rainfall Mediterranean[1]: 100 epg.
  • Lower Rainfall Mediterranean[1]: 250 epg for early lambing ewes and 150 epg for late lambing ewes.

Region zones are provided in the map below.

WormTest just prior to lamb marking. Treat with an effective short-acting drench[1] if the egg count exceeds:

  • South-East[1]: 200 epg (winter) or 300 epg (spring).
  • Higher Rainfall Mediterranean[1]: 200 epg.

In the Lower Rainfall Mediterranean[1] sheep do not require testing or drenching at this time if there are no signs of worms.

Region zones are provided in the map below.

  • South-East and Higher Rainfall Mediterranean[1]: WormTest just prior to weaning (or about 6—8 weeks after marking). Treat with an effective short-acting drench[2] if the egg count exceeds 200 epg for early lambing ewes and 300 epg for late lambing ewes.
  • Lower Rainfall Mediterranean[1]: WormTest only if more than 10% sheep are scouring. Treat with an effective short-acting drench[2] if the egg count exceeds 250 epg.

Region zones are provided in the map below.

Treat with a summer drench 2—3 weeks after the feed has dried off, but before Christmas. This should be a highly effective short-acting drench[1].

WormTest 6—8 weeks after the summer drench was given. Treat with an effective short-acting drench[1] if egg count exceeds 80—100 epg. Continue to WormTest at 8 weekly[2] intervals and treat with an effective short-acting drench[1] if egg count exceeds 100 epg.

WormTest each 8 weeks from when the feed is drying off until pre-lambing. Treat with an effective short-acting drench[1] if egg count exceeds 100 epg (or up to 200 epg only during late summer and providing ewes are in good condition).

WormTest prior to harvesting. Treat sheep staying on pasture with an effective short-acting drench[1] if egg count exceeds 250 epg. For sheep that will later go on stubble, drench if egg count exceeds 400 epg.

WormTest again 10 weeks after the pre-harvest test or when they are coming off stubble (after at least 6 weeks). Treat with an effective short-acting drench[1] if egg count exceeds 250 epg.

This recommendation should be read with the information provided below.

Review available drenches with the WormBoss drench search

1Guidelines for worm control treatments to slow drench resistance

When giving all treatments

Follow the product labels. Dose to the heaviest sheep in the mob or groups. Calibrate equipment to ensure the right dose is delivered with the right procedures. Do not mix drenches unless the label states they are compatible. Check withholding periods and export slaughter intervals.

Choosing treatment options on your property

Use these 4 principles together, where possible:

  1. Use drenches most effective on your property; ideally those shown to reduce worm egg count by at least 98%. If drench effectiveness is unknown, conduct a DrenchCheck-Day10 after drenching.
  2. Use a combination of 2 or more drench groups.
  3. Rotate drench groups each time a mob is drenched and for each paddock.
  4. Use short-acting treatments.

For more details read the drench resistance section in the WormBoss worm control program, South Australia.

Long-acting treatments

These are rarely required in South Australia. Also, resistance to long-acting treatments has been reported on properties in South Australia. To be safe, you should seek expert advice before incorporating them into your worm control program.

2Signs of worms

Scour worms (black scour worm [Trichostrongylus species]; brown stomach worm [Teladorsagia circumcincta]; and others [incl. Nematodirus]): dark scours; weight loss; death.

Barber's pole worm: anaemia (pale inside eyelids and gums); 'bottle jaw' (swelling under the jaw); lethargy, lagging or collapse when mustered; death.

NOTE: Other diseases can cause similar signs. Seek veterinary advice if WormTests do not indicate worms.

3High risk worm conditions

Sheep can sometimes be rapidly re-infected with worms, causing illness and death within 3 weeks of a drench when WECs will still be low or zero. If the onset of scouring, weight loss or deaths is sudden, urgently seek veterinary advice.

4South Australian winter rainfall region

South Australian Zones
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