NSW WormBoss Worm Control Programs
NSW WormBoss Drench Decision Guides
Over the last 3 months, rainfall for much of NSW, certainly coastal and nearby regions and much of northern NSW, has been below average. For the same period—and the last 12 months in fact—temperatures have been above average. But you know that.
None of this augurs well for sheep worms—or grass—but remember that L3 infective larvae on pasture are relatively resilient and don’t fall over at the drop of a hat, even though death rates increase as temperatures go up.
Eyeballing summary worm egg counting results for December from the Armidale laboratory (vhr.com.au)—mostly covering northern NSW, but also farther afield—average egg counts for sheep are lower than we expected (back in Spring), but there are still some ‘hotspots’, as always.
One mob of ewes at Armidale had an average egg count of 5,700 eggs per gram (epg), with one sheep having a count of 12,400 epg. The one that took the cake was a mob at Narrabri where the counts (they were barber’s pole worm) ranged from 2,500 epg up to almost 20,000 epg. Some of those sheep had very watery blood.
Why these hotspots? Well, I guess some people get lucky with storms. There might also be some management factors. A ‘biggy’ in most cases is lack of WormTesting: doing insufficient worm egg counting to get a handle on worm burdens, and drench efficacy. Yep, more often than not, unwittingly using infective drenches is one of the factors.
Harvest, heat and holidays have taken over and there are few worm counts from the Coonamble area going through to the EMAI laboratories, and therefore few results are coming through my inbox. I wonder if producers are using commercial laboratories and we are just not seeing the results? There have been reported issues with the changes to Australia Post as wormtest kits are taking 5+ days to reach the laboratory, and ruining the samples during transit.
From the few WormTests that I have seen, egg counts are rising, with counts in the thousands of eggs per gram, common. Once again, I observe that the better managed flocks that have good nutrition year round and have frequent faecal worm egg count monitoring, seem to have the lowest burdens. We have had four consecutive days now of 40°C+ heat, which will be doing a good job of destroying worm larvae on pastures.
Several producers have reported that sheep treated with Cyromazine for fly prevention were struck badly this year, and they experienced considerable losses associated with this. I have distributed maggot resistance test kits to these producers to try to identify if resistance to fly strike prevention chemicals is an issue on these properties.
We are still seeing worms in the Dubbo and surrounding areas including Wellington, Peak Hill, Gilgandra, Merrygoen and Dunedoo areas. Sheep worm egg counts have varied from 500 eggs per gram (epg) up to 1,800 epg. The predominant worm type has been mostly barber's pole worm. However, on some farms where barber's pole worm-only drenches have been administered, the black scour worm has taken over. This is why it is important to not only ask the laboratory for worm egg counts but also a larval culture so you know what worm type you're dealing with in your sheep and goat mobs.
We don't seem to be getting slammed as much as we did back in November and December when a number of on-farm investigations involved severe production losses in sheep and goats. Perhaps more people are checking their mobs with a WormTest and drenching when needed. The only worm mortality investigations seen this month have been on farms where ineffective drenches were used.
Alert: Please be aware there is widespread barber's pole worm drench resistance to mectins: ivermectin, abamectin and moxidectin, as well as other drench classes. A WormTest before drenching and a follow up WormTest 14 days post-drenching will give you a good indication as to whether your drench worked.
Some average to high worm egg count results have been observed from sheep mobs, in particular lambs. This is not overly surprising considering the common ages of tested lambs (post weaning–finishing), and previous environmental conditions (prolonged wet weather, without frosts). The cases observed this season act as a reminder that many sheep mobs may have significant underlying worm burdens (from egg count results), but not yet show any signs.
Alert: Without assessing worm egg counts many producers will be enduring 5–15% production losses unknowingly.
Most producers are considering a summer drench now (or have already performed a summer drench). I encourage producers to assess sheep worm egg counts first, and then make the decision to drench or not (LLS DVs may be contacted for advice).
Editor’s note: Check the NSW Non-seasonal Drench Decision Guide (see link at top of page).
An autumn break is likely to bring benefits on most farms, however, following such a wet winter we may see excellent conditions for barber's pole worm (BPW). This parasite is a big concern because in many cases the first signs observed are deaths. BPW infection will also usually cause a tail to form in the mob, however, scouring is quite rare—unless other worm species are also present. I encourage producers to consider BPW infection in sheep mobs over the next 3–4 months. If we start to experience some favourable rain (over a few days), a follow-up worm egg count in 2 weeks can help to provide some insight into potential, occult worm burdens.
Seasonal conditions and rainfall remain similar to my last report for the Inverell area. Hot weather, but regular storms continue to provide the opportunity for barber’s pole worm eggs to hatch and progress to larvae.
Alert: Monitoring is critical this month.
There was a case last week where a local sheep producer, following a Worm Egg Count Resistance Test (WECRT) on closantel, reintroduced it into his program. Only 2 weeks after drenching with closantel the Worm Egg Count (WEC) was 1000 eggs per gram (epg)
Alert: The idea of reversion of resistant actives to effectiveness is nice, but needs to be monitored closely.
Twenty-seven worm tests were submitted from this region during the last few weeks, and 13 of them had an average worm egg count of above 500 eggs per gram (epg) with the range in counts from 0 epg up to 19,160 epg. Four of these tests showed that 80% of the infecting worm burden was due to barber’s pole while a further two tests contained black scour worm populations of 52% and 92% respectively.
It will be interesting to see the worm test results over next 4 weeks following this hot weather.
It is so hot here maybe the worms will all perish, because we are!!!
In the western part of the region this month there were some clinical issues with worms, with many WormTest results gathered as part of disease investigations. From the eight samples sent to the testing laboratory, the average worm egg count was 969 eggs per gram (epg) strongyle type, and 25 epg nematodirus type, with small amounts of coccidia also present.
The range of strongyle egg counts varied from 8 epg (1½ year old merino ewes) up to 4,360 epg (dying weaner lambs). Of those tests which had speciation performed (4 of the 8), black scour worm was the most common, and present in all four samples with an average of 67%, brown stomach worm was the second most common and found in 3 samples with an average of 31%, the large intestinal worm was found in one sample with an average of 1%, and the small intestinal worm in a minority of tests and also averaged out at around 1%.
Many of the disease investigations found reasons other than worms for the deaths of sheep where only low numbers of eggs were detected.
One producer who did not need to drench last year, found that there was no need to drench this year either, as only 20 epg of strongyle type eggs were found.
Another producer drenched his weaner lambs in November with a 4-way combination drench containing Abamectin, Albendazole, Closantel and Levamisole hydrochloride, and found them to still be scouring. A worm test revealed 620 epg strongyle type and 40 epg nematodirus type eggs.
In the east, the only laboratory results available were from part of a trial, while numbers of eggs are not known, these samples showed the presence of barber’s pole worm in 3 of the 4 samples tested, as well as brown stomach worm and black scour worm.
Alert: Producers are reminded to continue to monitor for barber’s pole worm due to the recent summer rain.
Hot and mainly dry conditions recently have meant few parasite problems in the district. To remind us they are still about, anaemia and weakness due to barber's pole worms were detected during mustering of a mob of young merino wethers. They were given an "early" summer drench in late October (it was still pretty green then), and were set-stocked. Another mob of hoggets, again set-stocked since the first summer drench, had a worm egg count near a thousand eggs per gram, predominantly barber's pole worms. Set-stocking promotes barber's pole infections.
For the most part, worm egg counts show low results, and sheep are in good condition. But keep an eye on lambs. There is scant green feed in most paddocks, and grasshoppers galore to compete with weaners for any green pick. Weaner growth rates have stalled on dry pasture, and some lambs have lost weight in the last few weeks, making them more vulnerable to worms. A protein supplement like lupins could be a good investment.
Alert: Conditions are also ideal for summer storms to trigger hatching of nematodirus, which can cause explosive outbreaks of scouring a week or two later in paddocks used for weaning each year.
An increasing number of producers now use worm egg counts after drenching (DrenchCheck) to check the effectiveness of that drench. The timing is critical, though. For short-acting drenches, collect samples 14 days after drenching. Delaying collection by even a few days may make the exercise a waste of time. Timing of collection for long-acting drenches varies, with three collections recommended for those drenches active for 90–100 days. One recent DrenchCheck, sixty days after a long-acting moxidectin injection, showed a worm egg count of 260 eggs per gram. As this product protects against black scour worms for 49 days and barber's pole and brown stomach worms for at least 90 days, a culture for worm type present was important. The presence of barber's pole worms in this DrenchCheck indicated loss of efficiency against this parasite.
Blowfly activity has been pretty much confined to poll strike after fighting in rams. There is very little wool to retain blowfly chemical around the base of horns, so rams need more frequent applications.
Unfortunately, a number of properties have had significant losses due to barber's pole worm in the past month. Conditions in spring were ideal for the hatching and survival of barber's pole larvae on pasture, but for many producers the effects of burdens acquired during or after this time are only now being felt. In some cases, drench resistance was a factor. Drench resistance can be a very serious problem for producers who are attempting to deal with a developing barber's pole outbreak, since disease can develop rapidly. Some have found that, by the time they discover the drench has failed, significant losses have already occurred.
Scour worms can also be a contributing factor in weaner ill-thrift and diarrhoea over summer. Other causes of diarrhoea in weaner sheep should also be considered. These include bacterial enteritis or coccidiosis.
Sophie and I have had no WormTests submitted this month.
I have just received the final report on some faeces submitted from a mob of Kalahari Red X rangeland goats. A number of these goats died just prior to Christmas. The faecal worm egg count (WEC) came back at 3,680 eggs per gram (epg) with 38% barber’s pole, 61% black scour and 1 % brown stomach worm - so a good mix.
Other than that, all is quiet on the worm front and with temperatures over 40 degrees for weeks at a time and only the odd thunderstorm I suspect larval survival will be minimal throughout January and February in the Upper Western area.