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Victoria worms, flies and lice update - November 2018

Hamilton: Andrew Whale, Livestock Logic (a.whale@livestocklogic.com.au)

Livestock Logic Key Recommendations

  • If egg counts allow, delay the first summer drench until faeces are firm.
  • Monitoring, and making informed first summer drench decisions cannot be done without worm egg counts.

Some nice recent rain events in south west Victoria have ensured a very good spring with pastures that have been grazed short, but still of exceptional quality. As a result, lamb growth rates have generally been very good and sheep producers have been able to capitalise on high lamb prices. Heading into summer the focus should be on the timing of the summer drench and considering conducting a drench resistance test (DrenchTest) for those producers that have not done one within the last 3 years.

Have you done your summer worm egg count monitoring?

Livestock Logic results (Graph 1) show that this summer, those that blanket summer drench instead of monitoring first could potentially waste a lot of chemical, time and $$ as well as put increased selection pressure on drench chemicals.

Worm egg counts allow better timing of the summer drench. High egg counts in mobs need action immediately while low egg count mobs do not need drenching as they will not have any production loss and will not be causing significant contamination of pastures over summer. Moderate egg counts need a drench, but the timing is critical to get maximum effect and benefit.

Drench too early (loose faeces and spring conditions) and you increase the need for a second summer drench, as there will be larval pickup post-drenching. Drench too late (well into summer) and you allow for significant numbers of worm eggs to hatch and larvae to survive the summer in pelleted faeces. For this reason, observing the form of your sheep’s faeces is the key to timing the summer drench appropriately. Once faeces firm up it is first summer drench time!!!

For properties north of Hamilton the need for summer drenching is fast approaching, but those south of Hamilton—with this recent rain event—could still be a month away from faeces firming up sufficiently to call it a true first summer drench.


Figure 1: Percentage of mature sheep requiring drenching from Livestock Logic Laboratory for September, October and November, 2017 and 2018.
Figure 1: Percentage of mature sheep requiring drenching from Livestock Logic Laboratory for September, October and November, 2017 and 2018.

The graph indicates that there is likely to be a reduced requirement for summer drenching this year in comparison to last year. But it is essential that you know your individual farm and mob status, and not just hope that your sheep have low worm egg counts. The graph indicates that there is a great opportunity to reduce drenching over the 2018/19 summer.

Temperatures have started to warm up in the south west, and with recent rainfall there will be increased fly activity for those who have not already taken action with chemical or mechanical treatments for fly. The early December period, if conditions stay warm, will indicate if the 2018/19 summer will become high risk for flystrike. To date there have been small levels of fly activity within flocks, but nothing devastating.