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Tasmania worms, flies and lice update - June 2014

Perth: Paul Nilon, Nilon Farm Health (

Winter has started to bite. But the bite is a bit like old Mother McKerra’s, who lost her mail-order teeth when she sneezed crossing the Harbour Bridge in 1968. While there have been a few good frosts, it has remained remarkably mild with good pasture growth and frequent showers to keep the ball rolling.

Similar to last month the WECs have remained fantastically low, except for merino weaners, which have broken out a bit. It’s likely many weaner mobs will require a drench in the next 3–4 weeks, a decision based on WECs. Most ewes should make it through to the prelambing drench.

We’ve had enough frosts to slow fluke transmission. Now is the time for the autumn fluke drench if you have not already given it. While the flukey areas may have contracted due to the dry summer and autumn, most properties that were flukey last year will be so again this year.

I’ve written previously about a risk management approach to long-acting products in the winter. In the face of rapidly emerging ML resistance the aim should be to preserve our long-acting products for the years where they are essential. Although the winter is young, and there is plenty of time for things to turn nasty, at this stage it is not shaping as a high-risk year. You should consider a long-acting product as the prelambing drench if

  • ewes are in light condition
  • WECs have been high during the autumns and early winter
  • the weather turns cold and wet: Trichs thrive when there are puddles everywhere

If you opt for a long-acting product, I urge you to use a priming drench, preferably with a multi-active drench to get a high kill.

Winter is a good time to overhaul the gas-axe preparatory to lamb marking. With or without mulesing, tail length is a critical element in good fly control. Work done in the late 1940s by Belchener and others showed lower strike rates in sheep with the “correct” length tail: long enough to cover the vulva. This is vital in 'keeper'sheep.

Yesterday, I had a trip that covered a large slice of the sheep producing areas of Tasmania. I was surprised by the number of merino sheep, and disappointed by tail length; mostly, too short by half. It’s not difficult and the recommendation has not changed in 50 years or more.


There are some additional benefits. A mob of XB ewes in a special production system had their tails docked flush (still the fashion in some meat flocks). This flock lost 7% of their number to vulval and perianal cancer for 3–6 years. Additionally, I suspect that ‘super-short’ may predispose to vaginal prolapse.

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