Home Tools Victorian Winter Rainfall

Victorian Winter Rainfall

WormBoss worm control program

Victorian winter rainfall

Program summary

The WormBoss worm control program for the Victorian winter rainfall region has five components that are most effective when used in combination.

A summary of the components is below (click on the headings below for more information):

1. Use grazing management to create low worm-risk paddocks

  • Prepare autumn and winter weaner paddocks by using ‘Smart grazing’ where possible. Give the weaners an effective drench before they enter the 'Smart grazed' paddock.
  • Choose the least contaminated lambing paddocks for the most susceptible lambing ewes (maidens, oldest ewes and earlier lambing ewes).
  • Select weaning paddocks with lower worm-risk—these could be hay paddocks, new pastures, stubbles or paddocks grazed by mature cattle.

2. Breed and feed for worm-resistant sheep

  • Use rams with better than average WEC and DAG ASBVs1 (choose the more negative values).
  • Maintain good nutrition and body condition score to enhance the sheep’s immunity to worms.

3. WormTest at recommended times

  • Weaners, 4–6 weeks after the weaning drench (the shorter period for autumn-drop lambs or wet summers)
  • During January–February for sheep showing signs of barber’s pole worm (anaemia and lethargy)—aside from known barber’s pole worm areas this can also occur in wet summers or irrigation areas.
  • All mobs in late January/early February, just prior to the second summer drench. This will usually be 6–8 weeks after the first summer drench
  • Weaners, 4–6 weeks after the autumn break and thereafter through winter. However under high risk conditions (pastures highly contaminated with worms/higher rainfall areas/wetter than normal) test as soon as 2 weeks after the break.
  • 4–6 weeks after any short-acting drench.
  • Higher risk mobs in July/August (usually youngest and oldest). Test other mobs if high worm egg counts are found. These results will give a check on peak winter egg counts.
  • Ewes pre-lambing (provided it is at least 8 weeks post-autumn break for adults and 6 weeks for maidens). This is especially important for ewe mobs that are struggling with low condition score (less than 2.5) and/or grazing pastures of less than 1200kg DM/ha (3–4 cm pasture height).
  • And at other non-routine times as described in the the Drench Decision Guide.

4. Drench2 at recommended times

  • The first summer drench in November/December.
  • Lambs at weaning.
  • Sheep going onto paddocks that are to be kept low worm-risk for weaners.
  • Quarantine drench all introduced sheep with an effective drench that provides four actives3.
  • At other times, use the Drench Decision Guide and WormTest results to make drenching decisions.

5. Manage drench resistance

  • Conduct DrenchTests each 2–3 years and use DrenchCheck-Day10s in between.
  • Avoid unnecessary drenching.
  • Use effective drenches and rotate among all effective drench groups3.
  • Use multi-active3 combinations where possible (those shown to be highly effective on your property).
  • In general, use short-acting treatments and restrict the use of long-acting products for specific purposes and high risk times of the year.
  • Calibrate your drench guns, dose to the heaviest sheep and follow label instructions.

1 ASBVs=Australian Sheep Breeding Values.
2 Drench refers to anthelmintics regardless of route of administration
3 Drench groups are the chemical family to which an ‘active’ belongs. An ‘active’ is the chemical in a drench responsible for killing worms. Some drenches contain more than one active and are called ‘multi-active’ or ‘combination’ drenches. See Drench groups and actives.

This is an up-to-date, integrated regional worm control program for sheep in the Victorian winter rainfall region. It builds upon earlier programs and accumulated knowledge (Including from the University of Melbourne’s Mackinnon Project), as well as new information from the Integrated Parasite Management in Sheep project, funded by Australian Wool Innovation.

The program aims to improve the profitability and welfare of your sheep through:

  • fewer deaths and illness from worms
  • fewer drenches, particularly long-acting drenches
  • improved productivity
  • prolonged life of drenches


Deborah Maxwell (Sheep CRC), David Hucker (Para-­Tech Veterinary Services [Vic]), John Larsen (Mackinnon Project, University of Melbourne) and Graham Lean (Graham Lean and Associates)

Sheep CRC wish to acknowledge the contribution of David Rendell. Also, that the basis of this program is from the research performed by scientists from the former CSIRO Division of Animal Health, the Victorian and South Australian Departments of Primary Industries (or their equivalent), The Mackinnon Project (University of Melbourne School of Veterinary Science) and the cumulative knowledge and experience of sheep consultants in this region (often published in Proceedings of the Australian Sheep Veterinarians, a special interest group of the Australian Veterinary  Association).

June 2012

Each regional ‘WormBoss worm control program’ has been developed from local research results and experience proven to be relevant and successful for most farms in the region. Sheep CRC acknowledge that this is not the only method of worm control in the region and more refined programs can be developed in consultation with your worm management advisor/veterinarian using information and knowledge specific to your property and sheep.

Future events cannot reliably be predicted accurately. 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 ‘WormBoss worm control program’ (‘Information’). The 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.

No part of this publication is to be reproduced without the permission of Sheep CRC Ltd.

© Sheep CRC Ltd 2012 (ABN: 12 125 726 847)