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Victoria worms, flies and lice update - April 2016

VIC WormBoss Worm Control Programs

VIC WormBoss Drench Decision Guides

Hamilton: Andrew Whale, Livestock Logic (

Livestock Logic

Weaner worm egg counts are starting to increase, particularly in districts south of Hamilton, and are also expected to increase from early May in areas north of Hamilton.

Minimising worm contamination of pastures in May is a key to healthier and better performing stock and weaner survival throughout the winter

Key Recommendations:

  • Worm egg count any weaner mobs not tested for 3 weeks
  • Worm egg count any mature mobs not tested for 6 weeks
  • Worm egg count any animals not drenched in the last 6 weeks.
    Any worm eggs passed in faeces in May will lead to worm larvae on pasture and a much higher worm pressure during winter. 

As predicted last month, rain events in mid- and late-March did occur in most regions of south west Victoria and promoted small quantities of green feed in most paddocks. This rain combined with cooler weather will now encourage worm larvae to survive longer on pastures and complete their lifecycles.

Livestock Logic set up some drench tests during the week of the 21st and already there is evidence of increasing worm burdens in weaners. Very few drench tests were conducted in the preceding 3 months due to the dry weather conditions and consequent low worm egg counts.

The chart below shows that the percentage of high (>250 epg) weaner worm egg counts increased more sharply during the latter half of April after reaching their lowest level in March.

Graph 1: Percentage of sheep requiring drenching from Livestock Logic Laboratory over the last 3 months.

Most properties in the south west have very low worm levels as a result of the previous dry spring and summer period. Producers who know that their worm status is low from the judicious use of effective drenches combined with monitoring over the late summer/early autumn period, will have confidence that production losses from worms will not be an issue over the winter. In a low worm pressure situation such as this, producers are encouraged to rethink the use of long acting drenches and capsule products and instead use short acting drenches for lambing in late autumn and early winter. Persistent products put added selection pressure on drenches normally reserved for use during periods of high worm pressure. Worm pressure is expected to remain reasonably low in this region over the coming 2-3 months, but keep monitoring.

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