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Queensland worms, flies and lice update - July 2019

Brisbane: Maxine Murphy, Veterinary Parasitologist (maxine@paraboss.com.au)

The sheep areas of southern and south western Queensland are still very dry. In contrast, the coastal strip, where many goats and some sheep are raised, has received showers throughout the winter albeit less than the monthly averages. It used to be that during the dry season we could expect barber’s pole eggs and larvae on the ground to die off while black scour numbers increased due to their greater tolerance of drier conditions. But that may not have been the case this year.

Rule of thumb: worm testing and larval cultures need to be commenced if there has been significant rain of about 20+ mm that is followed by 10+ mm of rain in the following few weeks.

Maximum daily temperatures are warming—if they ever dropped consistently below the magical 18°C—so rain is the limiting factor both for worm development and pasture growth. Once barber’s pole is in full swing, and because they are such heavy egg layers, they predominate in worm tests, despite black scour being present.  For instance, black scour worm is a very poor egg layer, each female worm lays just 200 eggs per day for black scour worm contrasted by 5000–10000 for barber’s pole.

Sheep and goats, when forced to graze close to the ground, will actively pick up worm burdens. One solution is to give goats lots of browse that is free of larval contamination. SImilarly, sheep do best when they graze pastures above 10cm high.

Any discussion of worms should include plans for ensuring low worm-risk kidding and weaning paddocks are ready for these events. If the paddocks are not low-worm, then follow the testing regimen on page 2 of the drench decision guide (DDG) for the East Coast.

It would be wise to use DrenchCheck at each drench so that you know how well the drench worked. Worm egg counts are taken at drenching and again 2 weeks later from the same animal or groups of animals. This allows for comparison of before- and after-drenching egg count and calculation of the percentage reduction.