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Western Australia worm update - October 2013

Nicole Swan, Swan’s Veterinary Services, Esperance (

So far this month we have only counted a couple of mobs. Most farmers have started or are trying to start harvest. The mobs had an average of around 200 epg. One mob had counts up to 1100 epg.

Brown Besier, DAFWA, Albany (

Weaning drenches

A weaning drench should be a routine operation, as lambs are at their most worm-susceptible time of life.  Unless lambing was on pastures planned to be worm-free (ewes drenched into a clean pasture, or given slow-release capsules), worm burdens usually reach significant levels between 12 and 16 weeks, and a drench is given before signs of parasitic disease are seen.

However, there are two risks to consider:

  • This has become an exceptionally wormy year, and we are seeing high worm burdens a month or more earlier than usual.
  • Weaning is often later than the recommended (for Merinos) 12 -14 weeks, and prime lambs are often not weaned until the first draft has been turned off.

In these situations, a drench before weaning may be needed to avert problems – the options are to wean earlier than usual, or to do some worm egg counts to check the worm situation. Don’t get caught thinking that the normal worm situation will apply every year!

Drench resistance testing kit

It’s also time to think about drench resistance testing – weaning is the best time from both the convenience and worm burden viewpoints.  The resistance picture has moved on in recent years, and you can no longer assume that commonly-used drenches will still be effective.

To make the resistance testing job easier, DAFWA now has a pre-paid kit which contains the hardware needed: small amount of different drenches, sampling equipment, pre-addressed postage bags and clear instructions. 

The new kit tests for resistance to four commonly-used drenches: abamectin, moxidectin, a white-clear drench combination, and a white, clear and abamectin combination. Other drench types such as the organo-phosphate combinations can easily be added (at a small extra cost).

The cost is $440 – mostly for the laboratory work. At about the cost of a drum of a common sheep drench, it’s a small up-front cost that will far outweigh the potential losses of using ineffective drenches.

Obtaining the kits: The first step is to visit or phone a DAFWA office, to talk through the test requirements, organise pick-up or despatch of the kits, and arrange payment. Offices handling the kits are: Albany (08 9892 8444), Esperance (08 9083 1111), Katanning (08 9821 3333), Narrogin (08 9881 0222), Merredin (08 9081 3111), Moora (08 9651 0555) and Manjimup (08 9777 0000). 

It takes about 2 weeks to receive a result once the samples are sent off. We strongly recommend that you talk with a veterinarian or sheep consultant once the results are back, to ensure they are translated into the most efficient program for the particular farm.  We can’t take away the work in the yards, but using the kit will make the logistics easy.

For October 2013 state outlooks, please follow the links below:
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