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Tasmania worms, flies and lice update - February 2018

WormBoss Worm Control Programs

WormBoss Drench Decision Guides





Perth: Paul Nilon, Nilon Farm Health (

The weather has been mostly dry and hot by our Tasmanian standards, with only sporadic relief via a few showers. Pasture conditions are like those of western Victoria.  In essence, it’s a state of two parts: dustbowl perennial pastures for many, while those with water are madly keeping finishing paddocks going.

Consequently, the worm situation is also in two parts. Dry perennial pastures are very safe, just waiting for the benefit of a second summer drench (unless you live in the Gobi Desert south of Ross). Irrigated legumes and perennial pastures are starting to build contamination and so finishing lambs are at high risk unless you keep on top of it all with regular monitoring (WormTests). More on this further on.

So, as the current state of worms is as boring as Darwin’s dry season weather, I thought I might pen a paragraph about Essendon’s cup hopes; except for two niggles (and the fact that the Bomber’s chances are not great).

Firstly, I received my annual reminder about tapeworms. A client rang to ask about their importance and was happy to accept the advice that they are inconsequential. [Many people are not so sanguine. All I can say is that one humiliating moment at University in 1982 (before most of you were born) the great Hugh Gordon gave me a bollicking for suggesting they may be of importance]. This is not just my opinion: a large body of work and the opinion of many credentialed parasitologists is that tapeworms are of no importance. If you must treat them, go ahead, but my advice is to buy your partner a bunch of roses and then use the good will generated to have a weekend away on what you saved. 

Now, what I am about to write goes against everything I’ve written for the last 8 years, and mostly what you will find on the WormBoss website.  I may be shot. It concerns monitoring; specifically, monitoring of prime lambs on irrigated legumes, grasses and perennials. Do not extrapolate to merino lambs on dry summer pastures.

Advisors exhort people to monitor (WormTest) diligently for 3 good reasons:

  • Firstly, it reduces unnecessary drenching with the side benefits of slowing resistance development.
  • Secondly, and more importantly, it alerts you to the need to drench before suffering production losses. Moreover, you can use your monitoring data to get some idea of how contaminated a paddock might be.
  • Finally, it can be a source of diagnosis: “shitting-to-death” (scouring) lambs with a zero worm egg count probably do not have worms and will not respond to a drench! Where as, lambs with an egg count of 2000 eggs per gram (epg) and no scouring probably have Haemonchus (barber’s pole worm).

To realise these benefits you need monitor relentlessly and record results: I routinely suggest every 3 weeks.

While some people have heeded this message, many have not, or monitor insufficiently to get the benefit.

If this is you, and there is a fair chance it is (although “you” may not read this column), I am going to recommend an alternative approach

  • Either, divide the lambs into heavy and light, and put the light lambs under the protection of a Long Acting (white capsule or Moxidectin injectible, depending on the projected time to finishing and ESI considerations).  You can treat the heavies every 4 weeks with a short acting drench, again depending on the expected finishing time and ESI.

(Editor’s note: this is consistent with WormBoss’s advice to use long-acting products when there is a special need)

  • Or, treat everything every 4 weeks with a short acting.

Again, I emphasise, this advice is for prime lambs on green tucker, and that it is second best practice.

Why do I recommend it?

  • Well resistance is still likely to worsen, but because pasture is likely to be very heavily contaminated in these situations, which provides refugia, the effect will be more moderate.
  • Importantly, this will give you better parasite control.
  • However, if “you” do not know your farm’s drench-resistance status (and I bet “you” don’t), it is still possible for you to make it worse!! 
  • Hence why it is second best practice. Regular monitoring and treating according to need will still provide a much better outcome.

So, there you have it: I feel like the parent of a teenager suggesting they carry condoms: is it an invitation for less than desirable behaviour, or just making the best of a less than perfect situation, in this less than perfect world?

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