WormBoss worm control program


Program Summary

The WormBoss worm control program for Tasmania 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 autumn and winter weaner 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.
  • Select weaning paddocks with lower worm-risk—these could be hay paddocks, new pastures, stubbles or paddocks grazed by mature cattle, but do not compromise nutrition to provide safe grazing.

2. Breed and feed for worm-resistant sheep

  • Use rams with better than average worm egg count (WEC ASBVs1) and, if applicable to your area, less dagginess (DAG ASBVs); choose the more negative values for both.
  • Maintain good nutrition to enhance the sheep’s immunity to worms.

3. WormTest at recommended times

  • Before the second summer drench (January) to ensure it is required.
  • Weaners 3–4 weeks and ewes 6–8 weeks after all short-acting drenches.
  • After a WormTest shows drenching is not required, test again in a further 3–4 weeks for weaners or 6–8 weeks for ewes.
  • Ewes going onto crop that is to be kept low worm-risk for weaners, as well as the weaners before they use the paddock.
  • Sheep showing apparent signs of barber’s pole worm (especially during January in the summer rainfall region and on irrigation summer pastures).
  • Wethers prior to mustering for routine management activities.
  • And at other non-routine times as described in the Drench Decision Guide.

4. Drench2 at recommended times

  • Breeding ewes pre-lambing.
  • Lambs at weaning.
  • Give the first summer drench at lamb marking time (low rainfall) or at weaning time (medium to high rainfall region and summer rainfall). Consult your adviser.
  • Sheep going onto paddocks that are to be kept low worm-risk for weaners.
  • Weaners going onto highly contaminated short-rotation ryegrass pastures (i.e. in the pasture’s second or third year). Consider a long-acting product.
  • Drench all introduced sheep with a combination of no less than 4 unrelated drench actives with at least one of these being the newest drench actives: monepantel (Zolvix®) or derquantel (with abamectin—Startect®)3.
  • At other times, use the Drench Decision Guide to make drenching decisions.

5. Manage drench resistance

  • Conduct DrenchTests every 2–3 years. Use DrenchCheck-Day10s between DrenchTests.
  • Avoid unnecessary drenching.
  • Use effective drenches and 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 only for specific purposes or high worm-risk times.
  • Calibrate your drench guns, dose to the heaviest sheep and follow label instructions.

1ASBVs=Australian Sheep Breeding Values.
2Drench 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 Tasmania. It builds upon earlier programs and accumulated knowledge, 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), Paul Nilon (Nilon Farm Health).

Sheep CRC wishes to acknowledge that the basis of this program is from research performed in Victoria by the former CSIRO Division of Animal Health, the Victorian Department of Primary Industries and The Mackinnon Project (University of Melbourne School of Veterinary Science) and the cumulative knowledge and experience of sheep consultants in the region, in particular, Dr Paul Nilon.

September 2015

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)

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