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Victoria worms, flies and lice update - November 2017

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

Livestock Logic Key Recommendations

  • If worm egg counts are not too high delay the 1st summer drench until faeces become firm.
  • Make informed 1st summer drench decisions based on worm egg counts.

Have you done your summer worm egg count (WormTest) monitoring? Livestock Logic results show that those who ‘blanket’ summer drench their sheep (see Graph 1) will potentially waste a lot of chemical, time and $$ as well as increase selection pressure on drench chemicals.

Worm egg counting over summer helps to correctly time the delivery of the summer drench:

  • High egg count mobs need action immediately, 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 count mobs need a drench, but the timing of the drench is critical to achieve maximum effect and benefit. Drench too early (loose faeces and spring conditions) and you increase the need for a 2nd summer drench, as there will be larval-pickup from the pasture post drenching. Drench too late (well into summer) and you allow significant numbers of worm eggs to survive the summer in pelleted faeces.

For these reasons observing the shape of your sheep’s faeces is the key to timing the summer drench appropriately.

Once faeces firm and start to form pellets (Faecal Consistency Score of 1.5) its 1st summer drench time!

Graph 1: Percentage of mature sheep requiring drenching over the last 4 months. Results from Livestock Logic Laboratory.


The chart above indicates that less than 30% of ewes tested so far in November are in need of a summer drench. This should be a warning to producers that blanket summer drenching is not best practice nor indicated.

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 flies. The early December period will be telling as to whether or not the 2017/18 summer is a large flystrike risk season.