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New South Wales worm update - April 2012

Rad Nielsen, Veterinary Health Research, Armidale (

High faecal worm egg counts (both Haemonchus and Trich species) continue to be seen at the VHR laboratory, reflective of the levels of pasture contamination which has occurred over the preceding months. Some individual submissions have been extreme (up to 6000epg mean), despite having received effective drenches only a few weeks prior. Such results highlight the need for grazing management in a worm control program.

The lack of rainfall over March/early April will have brought a halt to egg hatching and larval development, however it is still warm enough for a late burst of activity following rain this week.

Autumn is an important time for liver fluke monitoring and treatment. Producers who have encountered this parasite on their properties (or suspect that they do) are advised to assess their current infection status via faecal egg counts (or blood testing). A significant percentage of New England properties are testing positive for liver fluke (both sheep and cattle) at this time.


Lachlan LHPA

Eliz Braddon, Young. (

In the eastern section of the Lachlan LHPA, average worm egg counts for all ages averaged 900epg. This was varied from 4epg to 3360epg and one goat flock with a count of 23800epg! The worm populations were predominantly Barber’s Pole worm (Haemonchus) and Black Scour worm (Trichostrongylus). Barber’s Pole populations are catching producers by surprise for the most part and the problem is only recognised when deaths are occurring. The other complicating factor is that we are seeing about 43% of properties here in the Lachlan with Mectin resistant Barber’s Pole worms… so a reliance on pure Mectin based drenches is providing false security at times. It is highly recommended that you do a worm test and larval culture before you reach for the drench gun.

If you find yourself in a bit of a bother, drench with a Mectin combination (Mectin, Benzimidazole & Levamisole) or a combination drench with Barber’s Pole activity specifically (e.g. Closantel or Naphthalophos in combination)

If you have used a single active drench or a white/clear combination – do a follow up WormTest 10-14 days later to ensure that it has worked.

Pasture contamination is a real problem. You will have to think about how you can “clean” up some pastures especially for lambing ewes and young stock.

Belinda Edmonstone, Forbes (

In the central area of the Lachlan LHPA average faecal egg counts for the month of March have ranged from 0-9208epg with individual counts ranging from 0-13800epg. Losses have increased across the area with Barber’s Pole worm and Scour worms both causing problems, particularly in weaners. Larvae numbers have been building up over the mild wet summer particularly in paddocks that have had lambs circulating through them. Despite the abundant feed some of these paddocks are proving to be real death traps. FEC monitoring and planning ‘low risk’ paddocks is very important to reduce production loss in the current conditions.

Katherine Marsh, Condoblin (

Worm issues are still plaguing some producers. WormTests this month had an average count of 1680epg (range 0-26000epg). The lower counts have tended to be in older sheep or those that have already been drenched early in summer; however, counts over 1000epg are still being seen in mobs that have already received a summer drench. Whilst some properties, particularly north of Condobolin, are seeing predominantly Barber’s Pole worm, Scour worms are still appearing in abundance in some tests. Over the coming months worms will continue to be problematic, so monitoring for worms and careful consideration when choosing what drench to use cannot be stressed enough in the coming months.

North-West LHPA

Derek Lunau, Moree (

Barber’s Pole worms have continued to be problematic. Some properties have lost several head of weaners. Large numbers of mostly (pure) Barber’s Pole infection have been coming through on worm tests (anywhere from 0-10,000epg). This is despite routine drenching on most properties. There has been a problem with drench resistance (to long acting products-especially Closantel products but also some indication of ML resistance) but also some suspect cases of user error. Conditions have continued to remain moist and fairly warm. Advising SA combination drenches at this stage and onto clean pasture for winter. Drench testing 10 days after use. Hopefully the cold kicks in to settle worm movements down.

Tablelands LHPA

Bill Johnson, Goulburn, (

Worm egg counts are re-building more quickly after each drench, indicating the high level of worm contamination in most paddocks. Barber’s Pole worm is causing deaths and typical weakness, and is becoming particularly difficult to control in lambs being finished on crops or Lucerne. In this situation, drench choice is limited by withholding period and export slaughter interval, and re-infection after drenching is guaranteed to be rapid. Scour worms predominate in other flocks, and are responsible for some sheep and lambs under-performing amidst magnificent pasture.

Thoughts are now turning to lambing management, and avoiding lambing in those paddocks which carried older lambs through autumn should be a high priority. A few minutes spent going through paddock records and notebooks could save a lot of grief during lambing.

With their job done for the year, rams are back in their paddock. We frequently see rams affected by worms over the next couple of months, forgotten when other mobs are being drenched or monitored.

Blowfly activity continues, with one owner reporting significant impact on lambing ewes which were unable to be crutched pre-lambing (he vows he won’t do that again!). While body strike has diminished and there has been a series of light frosts, breech strike is common in any scouring/daggy sheep (often associated with Scour worms), and wethers in long grass are frequently being struck on the belly.

Riverina LHPA

Gabrielle Morrice, Narrandera (

In the North-eastern Riverina LHPA, there have been mixed worm species, including Barber’s Pole worm, with variable counts in WormTests seen over the past month. Counts have been high where sheep have not been drenched since early summer or late spring indicating a reinfestation occurring over the late summer months when feed has been short but green (unusual for this area at this time of the year). Some dramatic clinical cases of deaths in weaner lambs due to Barber’s Pole worm have been observed. Producers are being advised in this unusual season to WormTest to determine their sheep’s worm burdens on a regular basis.

Dan Salmon, Deniliquin (

There are still mixed faecal egg counts, some quite high and some very low.

Most of the sheep drenched this summer seem to have low egg counts and some of the ones drenched last summer also have low egg counts.

A PM on a Dorper lamb last week: part of a mob with a percentage not doing well, scouring and bottle jaw. It had watery blood, a couple of thousand Teladorsagia, and another couple of thousand of what looked like immature Haemonchus (too big to be Teladorsagia but no sign of ovaries). They had been drenched a few weeks earlier. Dan suspects Mycoplasma was also involved.

Colin Peake, Hay (

Very few WormTest results have come through, even with the good season and media releases recommending producers to be vigilant as it is very green here at the moment. The test results that have come through are low, which looks good but due to the excellent seasonal conditions, producers need to be vigilant and WormTest so they can gain an understanding of their flock’s worm burden.


Tony Morton, Wagga Wagga (

Barber’s Pole worms have been the most common contributor to high counts and clinical disease in both sheep and goats. There have been all the usual symptoms of sudden death, anaemia and bottle jaw as well as considerable weight loss due to chronic, untreated Barber’s Pole burdens.

The highest count of the month goes to a mob of goats drenched in early February with an effective drench and now anaemic, some with bottle jaw and dying, counts averaged 9032epg.

Larval differentials are awaited but with some scouring in the same mob, it’s likely Black Scour or small Brown Stomach worms will also be present.

The enormous variation in egg counts and species between farms and even between mobs on the same farm continues. Thus advice in an unusual season like this needs to be very specific and tailored to the individual mob.

The one piece of advice that applies to all sheep owners is do egg counts at least every six weeks.

Central West LHPA

Evelyn Walker, Dubbo (

I visited a property a few weeks ago experiencing ongoing losses in newly purchased weaner lambs despite being drenched, vaccinated and moved into clean paddocks on arrival. This management practice had been working well for several years with no problems until now. Sheep received a single active potent Macrocyclic Lactone (ML) drench only two weeks prior.

In the paddock, the mob appeared depressed and moved slowly. There were no signs of “bottle jaw.” Autopsy of a dead lamb revealed numerous live Barber’s Pole worms in the abomasum. In addition, there was very little blood throughout the carcass with all organs very pale looking. Pooled dung samples from the mob also revealed numerous strongyle worm eggs. Other mobs of recently purchased sheep were also drenched and vaccinated with the same products, but were doing fine. So, what’s happening here? In this situation, the farmer purchased a mob of sheep whose Barber’s Pole worms were resistant to the potent ML drench he used.

When purchasing or introducing new sheep onto your property, one should consider them wormy and lousy until proven otherwise. You don’t want to accidently introduce drench resistant worms or lice onto your place. It’s a good idea to use a multi-active drench on all newly introduced sheep on arrival. By using a multi-active drench (e.g. a drench with 3-4 different drench classes), there’s less chance that the worms will be resistant to all the chemical groups! After drenching, keep these sheep in a holding paddock for 2-3 days. This will give them sufficient time to empty out before moving them onto a clean paddock.

This is a valuable lesson on how drench resistance not only affects local farmers on the home front, but also those who regularly buy and sell mobs of sheep. And, don’t forget to perform a post-drench WormTest 10-14 days later to make sure the drench you used actually worked.

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