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Queensland worms, flies and lice update - April 2018

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

It has been an endless and unpleasant summer and for many, maximum temperatures are still over 30°C. Unless temperatures drop to below 18°C for a number of months, barber’s pole will remain a threat—especially if it rains.

Barber’s pole worm eggs will die in about 5 days if temperatures are too cold for hatching (below 18°C), but to kill infective larvae already on pasture, about 3 months at temperatures of less than 18°C are required. In other words, it’s just not cold enough in Queensland to stop barber’s pole activity at any time of the year—the Stanthorpe region may be the exception. But it can be too dry!

The moisture requirements of worms can be met by about 4–5 days of rainy and over cast weather. So if it’s been stormy and overcast for a few days, and especially if you have had follow-up rains it’s time to WormTest.

WormTest a couple of mobs of different age groups as WormTests from a single mob do not necessarily reflect the worm burden in different mobs across your property. You may find the results surprising! The dry and very hot conditions over the last few months may cause you to think that worms are not an issue, whereas monitoring may change your mind. Most of the damage due to low or moderate worm burdens will go unnoticed and leave you blaming lack of adequate nutrition as the cause of less than expected productivity when pastures dry off.

At this time of the year black scour could also be present, albeit in low numbers, and nodule worm may be hiding in older sheep. In any sheep that are killed for rations, look for signs of nodules that are easily seen through the wall of the large intestine and perhaps further up in the small intestine.

When planning a drench, consider faecal sampling 10–20 sheep for a worm test about 7-10 days before drenching the mob, and then resampling the same 10­–20 sheep 14 days after drenching for another worm egg count. If the post drench counts are zero, then the drench worked. Yay!