With the drought tightening its grip in the north of the state, for many graziers worm management is not the top priority. Nevertheless, I would encourage sheep producers to maintain their worm monitoring programs in these dry times.
In the last few weeks we have seen a wide variation in worm egg counts, particularly in respect to lactating ewes. On some properties, extremely high worm burdens have been identified (up to 4500 epg mean, Haemonchus dominant), whereas on other operations moderately low WECs (sub 300 epg mean, Haemonchus dominant) have been confirmed in the majority of mobs. These differences can simply be attributed to the pre-existing pasture contamination levels in the lambing paddocks rather than genuine larval development over the lambing period, highlighting the importance of paddock preparation. By worm monitoring prior to lamb marking, these graziers have been able to modify their plans according to results—drench immediately in the ‘HIGH WEC’ cases, or withhold a lamb marking drench and continue to monitor in the ‘LOW WEC’ examples.
In both these instances the time and cost associated with worm monitoring have been more than recouped in either direct production benefits or savings in drench use. Additionally, by not drenching ewes unnecessarily at lamb marking, no further selection pressure has been applied to the worm population.
Drench resistance is the biggest threat to sheep production in the New England/SE Queensland regions—any decrease in drench use will enhance the useful life of the remaining effective ‘actives’, even more so if they would otherwise be exposed under drought conditions of low refugia.
Narrandera and Hay areas have had few Wormtests conducted in the past month. Some autopsies in adult ewes in the western areas have shown evidence of elevated scour worm burdens. Producers are advised to complete their first summer drenches or to monitor sheep that are not usually drenched.
Only a few worm tests this month, low counts off the red country and some reasonable counts off black country that has seen some rain in the last 2–3 month period. Unfortunately, paddock rotation is not an option on some properties with dwindling stock water supplies. Most tests showed 93–97% Barber's Pole.
With pastures haying off quickly, wormtest activity has been replaced by first summer drenching, usually coinciding with weaning lambs. The challenge from a worm control perspective will be how to feed those weaners to maintain and boost immunity as the clover crunches and disappears under their feet. Protein is essential, and there is still green pasture in sheltered parts of many properties that will suffice in the short term. Beyond that, start to feed supplements before they are required.
News that worms resistant to Zolvix® have been detected in a goat flock in eastern Australia should prompt a re-think of your quarantine drench strategy. Elsewhere on the WormBoss website are guidelines for drenching and managing purchased sheep on arrival on your farm. With many properties buying rams and about to replace first cross ewes, it would pay to check and implement those guidelines. The drench you use should include at least FOUR different chemicals (actives), one of which is either Zolvix® or Startect®. You can administer these drenches at the same time, but don't physically mix them in the back-pack.
As reported last month, barber's pole worms are present in about half our flocks. Some flocks have nothing but! How they impact over the next month or so will depend on rainfall. The 35 mm received by some properties last weekend will keep them ticking over. You particularly need to be careful where sheep repeatedly return to graze small, low-lying areas with short green pick, while avoiding the bulky, rank dry feed over the majority of the paddock.
That same scattered rainfall event has turned up the heat from blowflies. Poll strike in rams and breech strike in un-crutched lambs and adults are widespread. Although still registered for the purpose, diazinon gives little relief from blowfly strike.
There have not been many worm tests done on the Monaro recently. I suspect that most producers are drenching their ewes while they have the lambs in for marking, based on the season and the number of ‘daggy breeches’ in the mob.
In those tests that have been done, egg counts have ranged from 40 to 1284 epg. The predominant worm species has been Trichostrongylus (Black Scour Worm) with very low numbers of Haemonchus (Barbers Pole Worms).
Now that pastures have started to hay off in most areas, it would be a good time to conduct a Summer drench for those mobs that have not yet received one. It is recommended to use a combination drench, with at least one active ingredient from different drench group to the last drench given, before turning the sheep out onto a clean pasture.
Worm tests are few and far between; some high barber’s pole worm and other black scour worm. Most people are giving the November drench as per DrenchPlan. I have reports of suspect worm resistance to common drenches on a number of new flocks.
Very little activity in the Murray region.
A few clinical cases early in October but precious little since and few egg counts, even though we are trying to get people to get counts done so that they can drench or not as appropriate as the pasture hays off.
The season in the Northern Tablelands and NW of NSW remains hard for sheep, but fortunately, just a bit harder for worms.
But as usual, worms will always surprise us!! Had a recent case with an average WEC of 3000 epg and a high of 7000. The sheep were grazing over a large area in paddocks with predominantly rocks but due to limited availability of water true stocking pressure and potential to pick up larvae was clearly high.