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Victoria worms, flies and lice update - July 2019

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

Across the region,

  • Worm issues are now being seen in mobs from rapid larval pickup
  • Hoggets, lambing ewes and spring calves are at considerable risk of worm issues
  • Assess pasture risk as well as stock risk when making drenching decisions

Hamilton and surrounding districts have been lucky over the past 4 weeks, receiving plenty of rain for the start of winter. Coupled with continuing mild weather into July, we have seen continued good pasture growth that has been a blessing for winter lambing ewes. These weather conditions have also been productive for worm growth; over the past 3 weeks, we have seen a sharp increase in worm burdens in all classes of stock. Clinically these have been appearing as acutely scouring stock, which may look like Coccidia; however, we are finding that very few of the samples tested are positive for Coccidia and are purely due to large, rapid worm-pickup. If you are finding worm issues now, then these paddocks will remain high-risk until pasture growth picks up in late August. Worm egg count (WEC) monitoring will help to develop a plan for mob rotations until spring. Paddocks with good feed wedges and that have been ‘testing’ with low WECs should remain low-risk for the rest of winter.

WEC testing prior to lamb marking is necessary to check whether mobs need drenching and to assess the need to drench lambs. We often find lambs at marking are drenched unnecessarily, adding another job and cost onto marking. WEC results of ewes combined with lamb age and pasture assessment give a very good indication of worm-risk in lambs. Pre-lambing WECs for spring ewe mobs are advisable as mobs may not require drenching, especially if they have a body condition score of greater than 2.8 (>CS 2.8) and have well-prepared lambing paddocks.

Hoggets and spring calves are still at high-risk of worm-related issues over July and August. Continued frequent monitoring is vital as worm burdens can rapidly increase over 3 weeks given the current weather conditions, and combined with nutritional and cold stress, this can lead to production loss and death in young stock very quickly.

If you are finding high worm burdens in your stock now it is not too late to develop a plan for the rest of winter; being proactive about strategic drenching and paddock selection will help keep production levels of stock high and deaths at a minimum.

Blanket drenching mobs is very rarely the best option, especially at this time of year, and poor drenching decisions will often cause mobs to be re-drenched in a month’s time.

Average rainfall for Hamilton for the first 15 days of July
Average rainfall for Hamilton for the first 15 days of July