NSW WormBoss Worm Control Programs
NSW WormBoss Drench Decision Guides
In much of NSW in November it went dry, and sometimes hot. This followed on the heels of a few months of well above average rain for much of NSW, less so for the North Coast.
The Bureau of Meterology says that it will be hot and dry for much of NSW this summer. So, worms won’t be an issue this summer, right?
Two things to consider: the resilience of the infective stages of roundworms (L3 larvae) already on pasture, and drench resistance. You could also mention other things like less than optimal grazing management, the worst for worm control being set-stocking.
Under average summer conditions, it might take 2–3 months (3 months in cooler areas) for 90% of barber’s pole worm (BPW) third stage larvae (L3) on pasture to die off. For the sake of argument, let’s say in a relatively hot and dry summer, this time is reduced by a third. If you start with a very big number, you are still left with quite a few L3s, even without being ‘lucky’ and being under a few good storms over summer.
Given the good rain in late winter and early spring, a lot of larvae were produced when it got warm enough. For BPW, this would be around late October in Tablelands areas, and perhaps 4–6 weeks earlier elsewhere. So, assume there are still plenty of L3s on many farms in NSW, and that there will be for weeks to come.
Experience tells us that there will still be worm problems, even if less than previously expected. One property here in the New England comes to mind. For each of the three dry years prior to 2016, they had ongoing problems with barber’s pole worm, and had to do a lot more drenching than you would have thought given the dry conditions. We suspected drench resistance was a major problem—and it was. Even the mectin-based triple active they were using wasn’t doing the job. Assume nothing.
Do some worm testing.
What about liver fluke? The infective stage (metacercaria) of fluke can last up to 9 or 10 months under cool, moist conditions. However, once the mercury climbs past 25 degrees centigrade (°C), the infectivity of metacercariae falls away quickly. So, fluke is stuffed if it is hot and dry? Yes and no. You still have the fluke stages inside the intermediate host snails and these snails are very good at surviving cold as well as hot conditions, even if it means they ‘shut down’ for a while. Once good conditions (warm/moist) resume, the snails ‘come to life’ and infected snails start pumping out ‘baby’ fluke again.
In short, there will be fewer worm problems if we have a hot, dry summer, but there will still be problems, especially if you don’t do regular worm testing, if you have been using ineffective drenches, and if you don’t have a good system of pasture rotation. Have another read of the WormBoss Program for your area: time very well spent.
Spring rains, and the distraction of harvest have culminated in barber’s pole worm burdens sneaking up on unsuspecting producers. Faecal worm egg counts of up to 25,000 eggs per gram (epg) have been seen around the Gulargambone area.
There are ongoing issues with fly strike.
The Dubbo and surrounding areas including Wellington, Gilgandra, Collie, Dunedoo and Peak Hill are rife with barber's pole worm. A number of deaths in lambs at foot, weaners and even goats have been due to barber's pole worm. Interestingly, half of the farms investigated are also battling black scour worms. The anaemia caused by barber's pole worm and severe dehydration from black scour worms makes a lethal combination.
Check your sheep mobs now with a worm test to see whether a drench is warranted.
The weather in Young and its surrounds has been fluctuating much like the rest of the state. The cooler (and damp) change is bringing a halt to harvesting for the moment, with many producers putting in long hours to get as much as they can finished prior to the downpour that is predicted in the coming days.
Producers should be mindful of the impending fire season ahead and should take as many precautions as possible to prepare themselves for this. “Fires near me NSW” is a good app to have handy on your phone and recommendations by the NSW Rural Fire Service should always be heeded.
On the parasite front, worms have been causing mixed issues in weaner lambs in the district. Counts during field activities have ranged from 400–10,000 eggs per gram (epg) in clinically affected animals. Regular motoring activities by producers have shown results of 0–220 epg on average. Barber's pole worm has been found on clinical examination on a few properties in the district in the last few weeks. In all instances, these were in sheep that were either brought into the district in the last 6 months, or had only been drenched on their originating property, or had not been drenched in a long while. Producers should take appropriate precautions and undertake worm egg count tests on young stock, especially if they are seeing apparent signs of weight loss and excessive scouring. When in doubt, seek advice from your local district veterinarian. With the hot temperatures predicted for January, it would be an appropriate time to clean up paddocks and adopt strategies such as smart grazing where deemed appropriate.
Grass seed infestations in unshorn sheep can lead to numerous animal health issues along with significant carcass condemnation occurring. Shearing any sheep that are severely affected by grass seed infestations will alleviate many of these associated problems. Producers should maintain vigilance over the coming months for fly-strike, and any animals that may be reaching the end of their protective period, would need to be monitored and brought back into the yards for a re-application of an acceptable fly-strike preventative product. At all times producers should be mindful of ESI's and WHP on all products they apply on their sheep.
Feed on many properties is drying off, but there is still plenty of metabolisable energy present in tall dry feed on offer at present. Grazing stubbles will soon become an appropriate source of energy for weaners, and producers should be mindful of the risk of grain acidosis in those paddocks where excessive seed may have fallen. Lupinosis also poses a threat in paddocks due to the wet weather forecast, and as such producers should be mindful and attentive to any changes in lupin paddocks. Lesser loosestrife (Lythrum hyssopifolia) warning has also been in place and producers should take precautions to not put hungry stock in any paddocks that contain this plant species due to its toxic nature.
Following on from my last report expecting a massive rise in barber’s pole worm (BPW) counts and worm activity, this event failed to occur. Hot dry weather limited worm activity in refugia and as a result barber’s pole worm (BPW) activity plateaued.
More patchy, storm rainfall predicted for December is likely to result in similarly patchy BPW counts.
It’s a great time to be WECing to determine worm burdens prior to paddock moves or before considering drenching.
Areas on the western side of the Northern Tablelands have had a tough start to the season with fly strike as well. Cooler weather on the tops followed by a few dry weeks have eased fly pressure for these producers.
Conditions are drying out here and getting rather hot. There is still quite a lot of dry feed about so pasture stands are good. Hopefully, the hot weather will knock the worm numbers about, and if people do the pre- and post-drench testing, they may be able to avoid some future issues if we head into milder, wetter conditions.
Testing over the last few weeks indicated that average counts ranged from 188 epg to 2,644 epg on those properties that drenched in September or October, with 8,640 epg being the highest individual worm egg count. Larval cultures reported that burdens of barber’s pole, black scour and brown stomach worm were present.
On one property the post-drench worm egg count was 848 epg, but closer examination revealed that 2 of the 10 samples had counts of 7880 epg and 600 epg respectively. This result was considered to be due to either animals being completely missed, no drench in the gun when sheep were drenched, or sheep spitting out the dose straight away. This does highlight the importance of good drench application technique so that animals aren’t missed, and are therefore prevented from reinfesting the pasture.
There was only one WEC submission to the state veterinary lab from the east of the region this month. It was from a lactating composite ewe mob that had not been drenched since December last year. Average strongyle count was 120 epg, consisting of 31% barber's pole, 12% black scour worm, 53% small brown stomach worm and 4% small intestinal worm. The nematodirus count was 20 epg.
In the west, we have seen clinical signs of diarrhoea with a worm egg count of 1,320 epg strongyle with large numbers of coccidia present. We have also had clinical cases of lungworm found in two properties lately where the lambs have been showing signs of ill-thrift and poor weight gains.
WormTest results have shown an average of 580 epg strongyle with a range of 160 epg up to 1,320 epg in the clinically affected sheep. An average of 5 epg Nematodirus was found in those tested. The two samples that were speciated showed a very high percentage of black scour worm (98% and 99% respectively) and a small number of brown stomach worm (2% and 1% respectively).
With little rain and a fair few windy days in the past month, pastures continue to dry off. Most paddocks still have a bit of green at ground level with tall dry grass above, and with greener feed in gullies and flow lines. This is creating some interesting situations. Worm larvae near the ground are being protected by the dense grass canopy overhead, prolonging their survival. But sheep are tending to avoid grazing amidst this tall grass seed, instead over-grazing short greener patches in the paddock. We know from worm egg counts that about half the flocks in the district have significant levels of Haemonchus (barber's pole worms), and any summer storms could turn these closely cropped areas into barber's pole hot-spots. The same worm egg counts show that barber's pole worms may only be a problem in one or two paddocks/mobs on the property.
NB: frequent monitoring of all mobs will be needed to detect a problem early, combining worm egg counts and checking for any weak, pale sheep.
It is a good year to try "Smart Grazing". The two main enemies of worm larvae are sunlight and drying. The bulky overburden of grass on most paddocks will shade worm larvae and create a moist, favourable micro-climate. If carried through to autumn, it will also restrict germination of clover and grasses needed for winter feed. Smart Grazing involves identifying a paddock now to be available for grazing by weaner sheep after the autumn break. Crash grazing the chosen paddock for a few weeks with low WEC adult sheep at a high stocking rate, by combining mobs of adult sheep immediately after a summer drench, will help prepare the paddock for autumn grazing.
(Editor’s note: extract from “Smart grazing for weaner worm control”
Intensive grazing means using 2½–3 times the normal stocking rate for no longer than 30 days after each of the summer drenches are given. After the intensive grazing period, the paddocks are de-stocked to allow the pastures to re-grow. This means that the total stocking pressure for the 'Smart grazed' paddock will be the same as that for a paddock continuously stocked at the farms normal stocking rate. >>Read more.)
Producers have heard that liver fluke are making a comeback, and so they are. But it is important to note that just because an animal has "bottle jaw", it doesn't mean it has fluke. Do some tests or seek advice before drenching; it could save you a lot of money. Both liver fluke and barber's pole worms can cause fluid to accumulate in a doughy lump under the skin between the lower jaws, and affected animals will be anaemic (seen as pale inside eyelids). In recent weeks, producers have seen similar swellings due to photosensitization in sheep, and hardware disease and wooden tongue in cattle. In the latter case, they were all ready to fluke drench 160 cows at a cost of about $10 per head. Dung or blood samples may be tested for liver fluke.
Blowfly activity has been restricted by dry weather. Most fly strike throughout spring was in wet dags. As pastures have dried out, fewer sheep are scouring. Don't forget to check the other end—a few merino weaners have been struck on the poll, possibly after rubbing and scratching at grass seeds in ears and eyes.
Only seven WormTest results from sheep were received in November and early December this year, which is cause for some concern given that conditions have been excellent for hatching of worm eggs and survival of worm larvae on pasture.
Worm Egg Counts (WECs) have ranged from 160–1,440 eggs per gram (epg), with individual animal counts ranging from 80–3,440 epg. There has been a wide range in results from larval differentiation—some properties have had very high burdens of Trichostrongylus (black scour worm), some have had very high burdens of Haemonchus (barber’s pole worm), while others have had mixed infections. Those with mixed infections have tended to have low WECs. This finding highlights the importance of requesting a ‘type’ or larval culture when doing a WormTest.
A recent case highlights the importance of doing DrenchTests and DrenchChecks and using an integrated worm control program. A producer started losing ewes just prior to lambing. The ewes had been drenched about a month previously at shearing. They had run on the entire property with no preparation of any pasture prior to lambing. The producer had been rotating between two products that both contained a macrocyclic lactone, ML, or “mectin” as their only active against haemonchus and trichostrongylus. He reported drenching 4–5 times per year and had never done any WECs. A month into lambing and 70 out of the mob of 250 ewes had died. A heavy burden of haemonchus was diagnosed on post mortem. The deaths ceased once the ewes were drenched with a product containing a newer active. The producer has been advised that ML resistance on his property is more than likely as is heavy contamination with haemonchus larvae.
NB: Under current climatic conditions WECs every four weeks are strongly recommended. This recommendation will only change if conditions turn hot and dry.
(Editor’s note: Here is a look at a nationwide overview of drench resistance.)
Pastures have dried off substantially in the last few weeks. The number of worm tests conducted in the recent weeks has also declined. While not many reports of losses attributed to parasitic burden have been received, average eggs per gram (epg) on worm tests have varied from 0 to 1,480 eggs per gram (epg), with one property recording a 100% Haemonchus burden.
Flies and grass seeds have become a high priority, with numerous producers concerned about seed impact on feet, followed by fly activity.
Producers are reminded of the benefits from conducting WECs to appropriately manage worm burdens, and to be armed with knowledge of the worm potential for the upcoming months.