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Victoria worm update - December 2013

Andrew Whale, Livestock Logic, Hamilton (

There are two things that have been obvious to me in regard to sheep parasite levels over the last few weeks in December.

  1. Adult worm burdens have varied widely with large % of sheep not requiring a 1st summer drench to date. Must WEC before not administering a 1st summer drench.
  2. 2013 drop lambs are suffering the higher worm risk consequences of an extended spring period. We are seeing significant mortality and production effects on lambs as soon as 3 weeks post drenching.

As a general rule adult sheep in the South West are in good condition and with some green feed still on offer, they are still putting on weight. This improves their immune system enabling them to better cope and eliminate worms from their gastrointestinal tract.

As mentioned, lambs and weaners under 12 months of age are struggling to handle worms. Unlike mature animals they have not developed immunity to worms. Even lambs on good quality feed are prone to worm crashes if not frequently monitored and drenched. So it is not surprising we have seen a number of cases in the past few weeks where weaners are dying from intestinal parasite burdens.

Factors leading to this include:

  • Lambs being weaned onto pastures that ewes lambed down on (highly contaminated).
  • Continued rain and overcast conditions have maintained high worm populations in pasture.
  • Lambs have no immunity to gastrointestinal parasites.
  • Pastures are losing quality (particularly annuals), weaner growth rates are slowing so susceptibility to worms increases.
  • Lack of monitoring post drenching.

Last season, many lambs got a drench at weaning and not another until after the autumn break in May/June. We are faced with a very different climate to this time last year and it is imperative that producers take steps to manage their sheep, lambs in particular, to ensure worms do not impact on production.

Steps to take to minimise worm problems include:

  • Worm Egg Count lambs 4 weeks after a drench and then every 2 weeks.
  • Remember that it takes >14 days for an egg count to be detectable after an effective drench. Fatal worm burdens can occur 21-28 days post drench.
  • Utilise clean pastures for weaners where possible.
  • Get lambs onto grain trail now as likely without access to summer crops or Lucerne that lambs will need regular grain supplementation to achieve small weight gains.

The following table from Livestock Logic’s Worm Egg Count Laboratory for December highlights how age plays such a major role in development of immunity.


Average Strong Count

%  >200 epg

Mixed age 2011 and older



2012 Drop (Hoggets)



2013 Drop (Lambs)







Happy Christmas and a great New Year from the team at Livestock Logic.

It’s good to have the Ashes back in Australia’s hands!!!

Tricia Veale, Benalla (

In North Eastern Victoria we had slightly better rainfall recently but it is still very dry underneath. The rainfall for November was 14.5 mm with 45mm so far for December. The water level in the dams has decreased but most are still reasonably full.

Most farmers are busy harvesting and sudden unseasonable severe frosts at the end of November have caused what seemed to be excellent yields to get damaged in some local areas.  So sad, after all that hard work and good prospects!

Farmers are now checking their animals for fly strike. These insects are very prolific after the recent rain.

Worm egg counts are currently at low to moderate levels in this area.

Samples from some properties have revealed the presence of Liver Fluke eggs. So if you are on a property where Fluke are present then it is a good idea to request a test for these too.

It is really important not to give sheep the first summer drench unless they need it. We note that quite a few local farmers have recently drenched sheep without first testing them to make sure it is required. These farmers are in a very real danger of creating drench resistance problems on their property.

Quite a few farmers have unwittingly introduced worms onto their properties because they fail to quarantine drench newly purchased animals straight off the truck with a combination of drench groups. It’s virtually impossible to find out the truth about the drench resistance status of the vendor’s property. Also with the rapidly increasing incidence of worms that are becoming resistant to drenches, it is vital not to import other peoples’ resistance problems.

Happy Christmas and a very positive and productive 2014 to all!

For December 2013 state outlooks, please follow the links below:
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