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Queensland worms, flies and lice update - May 2020

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

The milder temperatures over the last few weeks would have favoured worm egg hatch and larval survival even though pastures are still dry. The heavy dews typical of this time of the year could provide enough moisture to compensate for the lack of rainfall and promote worm development. Temperatures during the day are somewhat ideal for barber’s pole although the cool evenings would be slowing them down. The tablelands and regions around Stanthorpe are significantly colder, and the worm cycle will grind to a halt if temperatures fall to 18°C or lower for a few days or more. In general, conditions that promote the growth of grasses also encourage the development of the barber’s pole cycle.

At this time of the year, and given the lack of rain, average worm egg counts in all classes of sheep should be low—but have you checked? WormTest some mobs; particularly weaners and late pregnant ewes. Winter lambing ewes can be worm tested up to 2–3 weeks before the start of lambing. Some mobs could be carrying counts higher than expected if drenches given to mobs after the January/ February rains did not give a 98% or higher kill. In past years, good falls of rain have occurred in June, followed by outbreaks of barber’s pole in stock crowded onto any higher ground. The weather forecast does not indicate lots of rain next month, but it may be prudent to WormTest about four weeks after any showers that do happen. 

For winter lambing ewes, it’s time to make decisions about the need for a pre-lamb drench. This drench is often given as a routine to prevent contamination of pastures with worm eggs, and to reduce the risk of high worm burdens in lambs before weaning. The drench should also be a combination of active ingredients and without any persistence, unless worm burdens are high and pastures significantly infective.

Toowoomba: Peter Lynch, Veterinary Consultant, Livestock Veterinary Services (peterlynch@shwds.com.au)

The season in Queensland has been very interesting.  The break in the season was late in most areas.  A few areas received good rain, although most of Queensland received patchy rain. 

Very little worm egg counting is being done with most graziers assuming that the season has been too hot and dry for worm survival.  This is playing with fire as paddocks can have small areas that are more favourable to grass growth and worm larval survival.  The higher humidity under the green shoots will allow the worm eggs to hatch and the larvae to climb up the sward where they will be eaten by hungry sheep. 

Weaners will be especially susceptible to worm infections as they may not have had a chance to develop any immunity.  We recommend that you conduct a worm egg count four weeks after rain, and if the count is low, repeat it every 4–6 weeks so you can drench before your sheep are affected if paddock recontamination does occur.

If you need to drench, remember to use a drench with at least two active ingredients.