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Victoria worms, flies and lice update - March 2017

VIC WormBoss Worm Control Programs

VIC WormBoss Drench Decision Guides





Hamilton: Andrew Whale, Livestock Logic (

Livestock Logic Recommendations

  • Worm Management over the next 4–6 weeks will be critical to minimise winter worm burdens
  • Conditions have set us up for potentially greater worm burdens this year than the last two
  • Monitoring is key to identify the need for drenching on a farm-by-farm and mob-by-mob basis

Last month I commented on how cool the summer had been, and then in the first three weeks of autumn we had hotter daily maximum temperatures for the first three weeks of March than we had had for the rest of the summer. Farm paddock conditions are highly variable in the south west; in areas that have received reasonable rain and have perennial pastures there are still considerable levels of green feed on offer while areas north of Hamilton and in particular those with annual pasture species have very little green feed available. This means we have producers who are increasing condition on ewes from paddock feed only and others that are delivering 70–80% of an animal's required energy with supplementary feed.

The worm risk for these two different situations for the 2017 winter and spring is also highly variable. Those with considerable ground cover and green feed are more likely to be seeing pasture contamination levels increase over the late summer and autumn period. This essentially increases the number of intestinal parasites on farm to infect sheep over the coming months. Those with less Food On Offer (FOO) will not be seeing the same level of worm egg survival on their pastures and therefore the risk of worms this year will be lower.

Our worm logic statistics show that worm issues this year will be more of a problem than last year. The good spring conditions of 2016 have created much higher worm burdens in sheep. The graph below shows that there have been twice as many worms in sheep over the last 3-month (2017) period compared to the same time in 2016.

As you can see, the need for drenching this year is far greater than in the previous year. However, there are still plenty of sheep that simply drenching without testing would have been a waste of time and drench.

We recommend producers be thorough in monitoring all classes of stock over the next 2–3 weeks, particularly those that haven’t been worm egg counted or drenched since the end of January. This is important for knowing which mobs need a drench to reduce pasture contamination levels.

While we hate to talk in averages, I would estimate that most producers in our region have administered 1 more drench to most classes of stock compared to none in the 6-month period from October to March the previous year. This should be a good warning: those that haven’t done egg counts or drenching and are assuming they can manage their stock over this next 12 month period the same as they did in the previous 12 month period, will be in for a rude shock in July.

Know your worm burdens now and take action on worm management for the 2017 winter and spring.

For March 2017 state outlooks, please follow the links below:
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