Victoria worms, flies and lice update - September 2017

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

Livestock Logic recommends that:

  • now is the time to monitor lambs every 3 weeks and ewes every 5 weeks

Livestock Logic advises that:

  • they investigated numerous cases of mortality from worms in the last few weeks predominantly in ewes in mid-late lactation, and 2017 drop lambs
  • egg counts in the district have risen in the last 4 weeks and are at their highest level for the year to date
  • while feed is great, worms will still affect production at this time of the year

Seasonal conditions in the south west of Victoria continue to be fantastic. We had a wonderful wet start to spring, but the last few weeks have brought some much needed sun and warmer temperatures to finally get the pastures to take off, and to also provide some dry ground for sheep.

We investigated a number of cases of mortality due to worms in the last few weeks, particularly due to the black scour worm. Instances have included lambs, 6 weeks post weaning and drenching, and ewes, 4–8 weeks post lambing. In most of these cases feed had been reasonable. Mortalities were due to 3 main factors:

  • the long season, the autumn break came in late March and it has been green ever since, so pastures are generally contaminated
  • the weather in August and early September was wet, cold and windy and reduced sheep grazing time, suppressed their immune systems and allowed worms to take the advantage
  • complacency amongst producers with respect to worm egg count monitoring coming into the spring

With mortality events occurring from worms there will also be many sheep that have undetected subclinical worm burdens. At this time of the year, to take advantage of the grass that is growing and convert it into meat and wool, stock need to be healthy and free of intestinal parasites. If you have not worm egg counted your lambs in last 3 weeks or mature sheep in the past 5, then it is time.

The chart below shows how worm egg counts rose higher in September, a timely reminder to monitor stock, as worm levels are now high.


Figure 1. Percentage of sheep requiring drenching in the last four months based on WormTests – Livestock Logic Laboratory