NSW WormBoss Worm Control Programs
NSW WormBoss Drench Decision Guides
NEW SOUTH WALES
We are seeing some extreme worm egg counts in the VHR laboratory at the moment following good rain throughout January over a large part of the New England region. Haemonchus is the worm species of concern at this time for the majority of sheep producers.
Drench failure due to resistance is a common occurrence, however immediate and rapid re-infection of stock is also a major problem at this time. The latter can be minimized by incorporating a grazing plan within the farm system, enabling paddocks to be “spelled” for sufficient time periods in order to reduce the larval load. Summer “rest” periods ideally should be 3 months in order to prepare a “low worm paddock”, however a 4-6 week break will be much better than remaining “set stocked”.
It is under extreme worm challenge that the ineffectiveness of drenches will be revealed most obviously to the grazier. Many submissions this month refer to the fact that sheep are visually “wormy” (or worse) within a week of drenching. In some cases a drench has been used that was never likely to work given the nature of drench resistance within this region, in others a genuine combination of “actives” has failed to give any meaningful worm control, let alone achieve efficacy in excess of 95%. It is imperative that graziers establish which drenches work (and which don’t) on their property before they can hope to put in place an effective drenching strategy. This can be achieved by performing a drench resistance test (testing multiple drench groups/combinations at the same time point) or by assessing individual drenches pre and post mob treatment (a DrenchCheck-Day10).
Editor’s note: The old benchmark of effectiveness was 95%. Now, advisors generally believe that drenches should be 98% effective or better to be considered “effective”.
Watch out for barber's pole worm (and black scour worm).
Many parts of NSW got excellent rain in January, with some locations getting more than two times their monthly average.
This is good news for grass, so it's good news for worms, not least barber's pole worm (BPW, Haemonchus). But the 'quiet achiever', black scour worm (BSW, Trichostrongylus spp), could be building up as well and causing problems for sheep.
Mostly importantly, producers need to keep on the ball by doing WormTesting over the next several weeks, especially if there is follow-up rain. Lagging, evident during mustering, might also give early warning signs of looming issues with the bloodsucker, BPW.
The good rain in January will also make liver fluke happy so, don't forget liver fluke if you have it.
When you come to drench, what will you use? The first question to answer is not whether you use a long or short acting drench, or a drench from a particular family or a certain brand. The first question is: what is effective on my farm?
If you are not sure, i.e. you haven't tested the drenches you use, a multi-active broad-spectrum combination or one of the new drenches (Zolvix® or Startect®) will generally be best bets, but get good local advice. And take the opportunity to do a DrenchCheck-Day10, i.e. a worm egg count on the day of drenching and again 10 days later. It's money well spent.
The patchy rain we experienced in January has been followed by dry 40°C weather and there have been no clinical cases of barber’s pole worm across the Coonamble and Nyngan districts. However, in some flocks that have been worm tested, worm egg counts have risen and mobs have required a drench. All producers are encouraged to WormTest now—sheep can carry a barber’s pole burden and show no obvious clinical signs, yet are experiencing a production loss because of their burden.
The only way to detect this is to WormTest!
Barber's pole worm is on the rise this month. I diagnosed four separate sheep mortality investigations due to barber's pole in lambs across the district. In all these cases, lambs did not show signs of bottle jaw.
When you see these signs, it's too late.
On one property, there were up to 80 deaths. These were in four-month old Merino lambs grazing lush native pastures. Lambs had not been drenched because it was so dry prior to the flush of green feed. On another property, up to 30 Merino lambs had died over several weeks and the lamb mob in general were failing to thrive despite multiple drenches being administered. Turns out, the worms were drench resistant and responded to another chemical class. In a drier part of the Central West region, ten lambs died shortly after weaning. The lambs had not been drenched because it had been such a dry summer.
Let this be a reminder to all, no matter what your conditions are in your area, perform regular worm egg counts on your lamb mobs. This is a great monitoring tool to catch problems before they become disasters.
There have been a few worm tests conducted in our local area recently, and these have shown moderate to low worm burdens of predominately black scour worm. Worm testing, and drenching if necessary, when timed to coincide with hot, dry weather conditions, minimises pasture contamination, and further larval build up before the autumn break arrives.
Worm count results have been moderately high ranging from 30–800 epg.
The few disease investigations conducted have concluded that brown stomach worm (Teladorsagia previously called Ostertagia) and black scour worm (Trichostrongylus) were responsible for the mortalities and morbidities seen. The incidence of Nematodirus species is also increasing on some properties.
With the 3.5 inches (about 9 cm) of rain that has fallen in our area from January until now, worm activity has also increased, but will likely fall again, as temperatures for this week and the next are predicted to be hovering close to and above 40°C.
In the Wagga area worm issues have been few this month, which is not surprising given the heat.
February–March is the time to be considering a second summer drench, but only if required (worm egg count or consult your veterinary adviser). I have seen several farms returning very low egg counts, even in weaner sheep, which I have been able to attribute to a combination of paddock management, effective drenching (including lack of resistance), and dry summer weather.
Considering there was an unseasonal incidence of barber's pole worm issues in mid-late December, and then rainfall in late January, I have been concerned that the worm was going to rear its ugly head again—however, not as yet (from disease surveillance and WEC monitoring).
Producers do need to keep this in mind, particularly if there is a good autumn break this year (i.e. WormTest (WEC) all young stock!).
The season remains excellent for barber’s pole worm.
WEC results have been variable, but there has also been a constant flow of investigations and enquiries indicating the presence of barber’s pole worm.
There were a few cases of Haemonchus infections in the last month. Now, as the weather is HOT, pasture contamination is expected to ease, but there might be another spike in barer’s pole worm cases if rain falls in autumn.
In the west of the district this month we had a large number of worm egg counts conducted as farmers looked to see if summer drenching should be part of their worm management plan.
The combined average worm count for the district was 205 epg strongyle type and 13 epg Nematodirus. There was a bit of variation between individual test results with 72 epg strongyle and 0 epg Nematodirus being the lowest figures and 356 epg strongyle and 84 epg Nematodirus being the highest numbers found.
Three samples were submitted for culture and worm identification. Black scour worm was found to be the most prevalent (63%, 92% and 100%) with brown stomach worm being the second most prevalent (31%, 7%) and barber’s pole worm present in only one sample (6%). Most of the samples submitted were from sheep that had received a Macrocyclic Lactone drench last year, the adult sheep having received the drench as last year’s summer drench early in the year, and younger stock having been given a drench in spring.
In the east the average worm counts were 384 epg strongyle type and 18 epg Nematodirus. These ranged between an average of 0 epg and 1700 epg strongyle and 0 to 80 epg Nematodirus. The most prevalent worm species was barber’s pole by a long way (77–96% of the sample) with brown stomach worm and black scour worm jostling for second place (1–9% and 1–14% respectively and large bowel worm and small intestinal worm coming in very small amounts if present at all (1%). A number of properties are drenching for barber’s pole worm for the first time for a number of years.
With the monthly rainfall for January more than twice our long-term average, and distributed pretty evenly over the month, the optimists were spruiking an early autumn break. It was certainly enough to tickle up some barber's pole worms. Egg counts rose dramatically from near nothing to tens of thousands in the space of a few weeks, mainly in younger-aged mobs on properties that tested younger and older age groups separately. But even at this level, producers said the sheep with the high egg counts were "jumping out of their skins", or had "travelled a couple of k's to the yards without knocking up". At the same time, though, we've seen some producers caught out by barber's pole worms, with several weaners on one property and older ewes on another dying after a fatal encounter. Another example of the valuable early warning provided by regular worm testing.
Part of the challenge with barber's pole in our district is its unpredictability. Not only is it not found on every property, but only certain paddocks on affected properties appear to cause trouble. Most of us select the paddock with the most "green" to run our weaners during summer and autumn. This is also the environment that best suits barber's pole. So the weaner mob is usually the best one to sample to see if barber's pole is present on your property. Barber's pole worms thrive with set-stocking too, and rams are at high risk on most farms as they tend to be shut in a little secure paddock out of the way, where barber's pole can go unnoticed.
But not all worms in sheep at present are barber's pole. In a couple of mobs of weaners, a number of the lighter lambs started scouring due to thin-necked intestinal worm (Nematodirus). This worm responds quickly to rain after a dry spell, especially where the same weaner paddock is used each year. Egg counts on several properties are also showing an increase in black scour and brown stomach worms, not to the point of causing scouring, but at levels that mean a second summer drench will be needed.
Blowfly strike has been confined mainly to breech strike of sheep with wet dags.
The Bega Valley is continuing to look fantastic as we enjoy an excellent season. The ongoing warmth and moisture has seen the pastures thrive, and also the worms! Worm counts have ranged from an average of 200 epg up to an average of 3000 epg (range 400–7320). While the dominant worm species in most mobs has been barber's pole, the occasional property has had a high percentage of black scour worms—a good reminder not to rely on assumptions.
After similar weather conditions last year, most producers are far more alert to the destructive potential of high barber’s pole counts this time around, and are using WECs to give them a warning before they find dead sheep. There is also more awareness of the importance of using combination drenches and rotating the mix of actives as much as possible.
We are continuing to encourage people to do WECs regularly, along the lines of every 3–4 weeks in the current conditions. The biggest problem people are having is the grass getting too long for sheep feed—not usually an issue we have in February—and we're not complaining!
Worm egg counts have varied across the Yass district with some sheep flocks demonstrating low worm burdens and others having moderate to high burdens. Barber's pole worm is proving to be the most common contender at the moment, although one producer had a fairly significant parasitic burden involving four worm species (barber's pole, black scour worm, brown stomach worm and large intestinal worm).
Producers are encouraged to test the efficacy of the drench they elect to use by conducting 10–14 day post drench WEC (also called a DrenchCheck-Day10). Again this month a few producers have been caught out using a single active product with some dire consequences.
The common story is that sheep (especially weaners) that were returned to paddocks post-drench, but prior to the recent rains, are now requiring a second drench, 4 weeks later. It is important to remember, while weaners are benefiting from the developing green pick, so are the worms!!