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Victoria worms, flies and lice update - February 2020

Hamilton: Andrew Whale, Livestock Logic (a.whale@livestocklogic.com.au) and Lexie Leonard, Livestock Logic (l.leonard@livestocklogic.com.au)

Key recommendations:

  • Frequent monitoring of all stock on pasture
  • Frequent monitoring of ewes and rams to be joined
  • Consider a Drench Resistance Trial if you haven’t had one in the past 3 years

It currently feels like autumn in south-west Victoria, and the warm days are few and far between the mostly cool weather and rain! Since the start of February, Hamilton Airport has recorded 44 mm of rain, with some areas around Hamilton recording as much as 80 mm. Following a mild January when there was plenty of dry standing feed in paddocks, conditions have been perfect for worm survival on pastures. Rain events in late January and during February have knocked the quality of dry feed right down, and by now, it will not be useful as a feed source for sheep. Green pick following the rain will increase worm pickup from the pastures. Weaners on pasture, both cattle and sheep, are the highest risk, class of stock and require the most frequent monitoring.

For areas that have had more than 25 mm rain in the past 2 weeks, faeces will begin to soften and allow the worm lifecycle to begin again on pastures. Take care when putting stock onto pasture with fresh green pick, as we expect worm uptake to be significant and immediate. This, combined with expected higher than usual pasture larvae burdens will place greater significance of monitoring of worm egg counts and flock health to ensure worm issues are dealt with promptly.

Due to these weather conditions, we recommend all classes of stock are regularly monitored via worm egg counting (WEC), and drenching done when WEC results are high enough. Calendar-based drenching programs have proved particularly ineffective this year, and if you have drenched stock without WEC monitoring, we strongly recommend you to WEC soon.

Areas with known barber’s pole worm burdens should pay particular attention to WEC monitoring and stock health, as conditions have been ideal for these worms. Immature barber’s pole worms can kill young stock if burdens are high enough, even with a WEC of zero eggs per gram. Immature worms do not lay eggs, but do suck blood and can produce severe anaemia if the larval pickup from the pastures is heavy enough.

Fly issues have remained relatively localised due to the cooler weather, and, to date, we haven’t seen severe outbreaks or issues with flystrike.

Figure 1: Percentage of sheep requiring drenching this year compared to last year
Figure 1: Percentage of sheep requiring drenching this year compared to last year