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New South Wales worm update - November 2012

Stephen Love | Veterinarian/State Coordinator-Internal Parasites, NSW Department of Primary Industries (stephen.love@dpi.nsw.gov.au)

We have had two La Nina or wet years in south-eastern Australia—where a lot of our sheep are—but now in places spring has been a bit dry. In short, seasonal conditions are variable; so are worm egg counts.

Each month the NSW DPI State Vet Lab just outside Sydney, and Veterinary Health Research (Armidale, NSW), send me their summary of WormTests in sheep for the month: click here to view these reports.

During October, worm egg counts (WECs) ranged from very low to quite high, in all parts of NSW. Even within localities, or between paddocks on a single holding, WECs in sheep can be quite variable.

The Darling region (Bourke-Wanaaring) area is not usually the most hospitable place for worms, but one mob of ewes had an average WEC of 6,748, ranging up to a WEC of 32,200 eggs per gram (all barber's pole worm).

Not so surprising was the New England with average WECs in some WormTests up around 5,000 (and we are having a dry spring). In the Central Tablelands, there were average counts up around 6,500, and at Yass one mob of ewes averaged 1,196, with counts up to 7,320 epg were mostly black scour worm, not barber's pole worm, so the extra money (about $25) to get a 'worm type' (larval culture) can be well worth it.

In the Riverina, not normally worm heaven, a mob of wethers had WECs ranging up to 3,120 epg, and these were mostly black scour worm too. In 'flukey' districts, a number of fluke egg counts were positive for liver fluke eggs.

So, the rain may have eased off, but you don't want to ease off WormTesting too much just yet. Remember, a neighbour's WormTest results, or a WormTest from just one mob on your own place, may not paint an accurate picture of what is happening in most of your mobs worm-wise.

High-ish WECs are not always down to barber's pole worm. You need to get larval cultures as well as WECs done regularly, if not always. And when you do drench, seriously consider a DrenchCheck-Day10: a WormTest on or just before drenching, followed by a WormTest 10-14 days later.

LHPA DISTRICT REPORTS

Lachlan LHPA

Belinda Edmonstone, Forbes (belinda.edmonstone@lhpa.org.au)

In the central area of the Lachlan LHPA average faecal egg counts for the month of October have ranged from 0–1,408 with individual counts ranging from 0–3,040. There is an increase in the number of barber’s pole worm appearing in larval cultures. Given the right conditions these worms can very quickly contaminate a pasture. Producers need to be planning the first summer drench on to ‘low risk’ pastures. You should be using a known effective drench preferably in combination with unrelated drench group

Hume LHPA

Tony Morton, Wagga Wagga (tony.morton@lhpa.org.au)

It’s been a busy month at the Wagga office doing drench resistance trials on weaners. There have been plenty of eggs in most undrenched weaners, this has enabled us to undertake drench tests in most mobs sampled. The main species have been black scour worms, small brown stomach worms and barber’s pole worms. Our December report should have a summary of the results.

The headers are out in some areas so if it hasn’t already been given, the first summer drench should be a priority.

Tablelands LHPA

Bill Johnson, Goulburn (bill.johnson@lhpa.org.au)

The focus has shifted from worm monitoring to drenching, both for weaning and for a first summer drench. So the question most asked at present is “What drench should I use?” The first summer drench for adults and weaning drench for lambs requires a highly effective clean-out. As with the past two seasons, it needs to cater for our usual scour worms (black scour and brown stomach) as well as barber’s pole worms. An increasing number of worm tests in this area indicate resistance to ‘single actives’: drenches containing just one chemical group. There is evidence of increasing resistance of barber’s pole worms to abamectin when used alone.

The best answer is to use a drench that has been shown to work on your property, following a DrenchTest. There are sufficient worms in many young sheep to allow you to test for resistance, and a number of vets and rural merchants willing to give you help. Failing that, most experts recommend a drench that combines several actives.

Make good use of those adult sheep after the first summer drench. They produce next to no worm eggs in their dung for the first three weeks after drenching, so use them at high stocking rates during this window to ‘open up’ pastures, and expose remaining worm larvae to summer sun. Set aside these ‘smart grazed’ paddocks to be used by weaners after the autumn break.

North-West LHPA

Libby Guest, Narrabri (libby.guest@lhpa.org.au)

There have been few WormTests conducted over the last month because many producers are busy with harvest. In the western portion of the North West LHPA, barber’s pole worm activity is lower than in recent years due to lack of rainfall. This will change quickly when summer rain is received.

In the eastern portion, reasonable rainfall over the last couple of weeks will have fired up the barber’s pole worm life cycle and monitoring via WormTests is a smart move.

Riverina LHPA

Gabe Morrice, Narrandera (gabe.morrice@lhpa.org.au)

Only a small number of WormTests have been received this month and these have shown very low worm egg counts.

Colin Peake, Hay (colin.peake@lhpa.org.au)

No WormTests this last month or evidence of clinical disease.

It has been very dry.

Dan Salmon, Riverina (dan.salmon@lhpa.org.au)

A bit of a mixed bag this last month, despite relatively little monitoring or clinical disease.

One mob of Dorpers had an average egg count over 1,200 with 60% Haemonchus and 30% Trichostrongylus, the Haemonchus being very uncommon in the southern Riverina and the Trichostrongylus relatively uncommon in the southwest Riverina. They were running on a property where goats had been run for many years and had been drenched in March.

On the other hand a mob of Merino ewes had very low egg counts despite not being drenched since 2011.

Central West LHPA

Greg McCann, Dubbo (greg.mccann@lhpa.org.au)

We are seeing various levels of worm activity ranging from low to high worm egg counts this spring. The mild winters we experienced, survival of the worm larvae on pasture and contaminated paddocks have contributed to early barber’s pole worm infestations in some areas. For example, on two different sheep properties in the Dubbo area, the overall average worm egg counts were 1,100 and 1,400 epg. The predominant worm type was barber’s pole worm.

Sheep producers are strongly encouraged to start monitoring their sheep flocks now with worm egg counts. Some of the producers in our area are even participating in on-farm drench resistance testing. Of the resistance tests conducted, ML(mectin)-resistant barber’s pole worm is a common feature. However, the degree of individual drench resistance varies from farm to farm.

Although using an effective drench for your worm type is integral in worm management, other factors like good nutrition and pasture management are just as important in keeping on top of the worms. For example, one sheep producer used an effective knock down drench on his weaners; moved them to a clean paddock (a paddock that had been spelled 3+ months); supplementary fed them with grain; and 5 months later, the worm egg counts remained very low for this mob—an overall fantastic result.