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Victoria worms, flies and lice update - April 2018

Hamilton: Andrew Whale, Livestock Logic (a.whale@livestocklogic.com.au)

Livestock Logic advises that

  • seasonal conditions over the last few months have been good for reducing worm contamination issues on pastures
  • the good rainfall event on the 13th April will have started worm activity for 2018
  • producers who failed to monitor for worms over the summer should expect 2018 to be a nasty year for internal parasites

Livestock Logic recommends that

  • if the worm status of your sheep is unknown, test immediately
  • if you know your egg counts are low, then mid to late May will be the next most opportune time to test for worm levels post the autumn break to determine the level of worm pickup by stock since the break

For the most part, 2018 so far has seen a reasonably hot and dry spell that would have helped reduce worm pasture contamination levels. This has been some relief given the extreme worm pressure we saw over December and January as a result of a long growing season in 2017 and extending into 2018. About 10 to 15 mm of rain in late March with a follow up of 20–30 mm on the 13–15th April, has our season underway, and with that the worms will have also started their season. These are important dates to remember as we will expect worm egg counts to start to rise from mid-late May, 4–6 weeks after the larger rain event. For those wanting to determine their post autumn worm challenge there is no point testing prior to mid-May unless you do not know the worm status of your sheep, and if that is the case, a worm egg count now is advisable.

We continue to hear stories of producers who have done their first bit of egg counting for the year and are getting a big surprise with very high worm burdens that stock have carried for months. This would have severely impacted their production. Most producers have been feeding stock 60–80% of their energy requirements with supplementary feed for some months, and this becomes expensive when sheep fail to utilise it due to internal parasites.

The chart below shows what a wonderful opportunity February and March were to reduce pasture contamination levels, but only if you took action and drenched sheep that required a drench in January (or when they needed it).


These results show that in the last two years (both had bumper springs previously) we have seen much higher levels of early summer pasture contamination. This will lead to increased worm numbers on pasture now that we have had rain, and the worm life cycle will again be able to complete. These last two years of increased worm levels will increase the pressure of worms on stock by mid-late May.

Monitoring of young stock later this month will be critical for good winter worm control.

There continues to be lots of reports of lice, conversely with little rain over summer the reports of flystrike have been minimal.