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Queensland worms, flies and lice update - March 2016

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

Weather conditions across the sheep raising regions of Queensland have continued to be demanding with sheep numbers in some regions falling to very low levels.

Exhausting, hot, dry conditions slowed the expected barber's pole build-up over the summer, as eggs and larvae on pasture were unable to withstand overheating and desiccation. But the adult worms in sheep would have been somewhat protected, and despite being quite short lived (a few months), many will still be dumping worm eggs out onto pasture, but to no avail. Under inhospitable conditions, no further development will take place and reinfection will be minimal, except of course if sheep are grazing green pick along open bore drains.

Sheep on poor feed for an extended period will be malnourished, and even a few worms will exacerbate the issue and be a cause for a drench treatment.

Despite the TV coverage of flooding rains in the west, rainfall across the region and into the Maranoa was actually quite patchy. Currently, temperatures are still hovering above 35°C.  Larval numbers on pasture are expected to be remain low until temperatures fall, which should occur during April. If paddocks had a reasonable amount of grassy coverage that lasted 3-4 weeks, worm burdens could now start to increase, even if the pasture has now died back.  If rain was poor and germination only lasted for about 2 weeks, then there is unlikely to be much increase in the worm risk.

Worm egg count testing is recommended to be conducted in April and sheep drenched if counts are elevated.  Every drench needs to be followed with a worm test 10-14 days later as the assumption that every drench can kill at the required level is false.

Autumn is the time to prepare for lambing.  Decisions need to be made on how to achieve a low worm pasture and what would be an efficient drench for the lambing ewes.  For winter lambing, preparation of the lambing paddock by spelling over summer will take about 3 months. For spring lambing, spelling paddocks over the cooler period of winter will take longer, i.e. up to 6 months.

March and early April sheep should be monitored for flystrike.