NSW WormBoss Worm Control Programs
NSW WormBoss Drench Decision Guides
Very few worm egg counts (WormTests) were conducted over the month of February in the Condobolin District. Those results reflected low worm egg counts with the highest average count of 40 eggs per gram.
WormTest results have been extremely varied in the Coonabarabran area this past month, with counts as low as 4 eggs per gram (epg) and ranging upwards to 4500 epg. If unsure about interpreting the results, producers are encouraged to seek some advice that should consider factors such as drench history, body condition, and management plans for grazing.
Very few WormTest results have been received from around the Coonamble district. The few that have been received have had low egg counts, reflective of the ongoing dry conditions.
Worm populations have been spiking in the Dubbo and surrounding areas. Barber’s pole worm infections have been diagnosed in mostly Merino lambs that have appeared ill thrifty and weak. Some of these cases have been further complicated by an underlying Mycoplamsa ovis infection, a blood parasite that attacks the red blood cells and like barber’s pole worm, also makes the lamb anaemic. Another case of deaths due to barber's pole worm resulted from ineffective drench practices (e.g. repeatedly using macrocyclic lactone (ML) drenches to treat ML resistant worms).
With the availability of easy-to-use drenches in the form of needles and the ML-pouron, producers are reminded to still use these wisely in combination with other drenches as part of a chemical drench group combination strategy.
There have been very few WormTests due to low worm activity around the Forbes area with the dry summer. Producers are reminded to perform a worm test 6 weeks before lambing to determine if the ewes require a pre-lambing drench before being put onto low risk lambing paddocks.
Worm activity has remained relatively quiet since the start of 2018 around Wagga Wagga with few producers submitting faecal samples for WormTests for our review. Low to moderate levels of worm eggs were identified in those samples, and few disease investigations identified internal parasites as significant contributors to the disease process. Many sheep producers have now performed a summer drench, and while this can be a very useful management tool, it is not always necessary. Mobs that have been well managed, and have low worm egg counts do not require this drench (just yet)—saving you significant time and money.
Obviously, if rain and humidity develop over the next few weeks there is very likely to be increased internal parasite activity—please be mindful of this, perform worm egg count testing (WormTests) on ‘suspect’ mobs and consult your veterinary adviser.
A hot dry summer has really slowed down what was developing as a thoroughly typical barber’s pole worm season on the western side of the Northern Tablelands. Scattered storms are enabling development of worm eggs to larvae on pasture so sheep producers are advised to continue monitoring (WormTests) to avoid surprises.
There has been a steady influx of WormTest submissions from the Murray district over the past month.
WormTest and worm typing results have been quite variable and are summarised below.
Figure 1. Worm egg count and culture results, Eastern Murray (for the month prior to this report)
Figure 2. Worm egg count and culture results, Western Murray (for the month prior to this report)
The summer rainfall experienced at the end of last year has led to an unseasonal spike in black scour worm numbers. This has been reflected in black scour worm continuing to be the predominant worm type seen this last month. The Eastern part of the region has seen higher overall egg counts and several cases of worm related deaths. Signs of scour worms include death, weakness, weight loss and diarrhoea.
Figure 3. Larval culture results, from four mobs on one Eastern Murray property, demonstrating the variation in cultures between mobs.
Samples from four mobs on the one property in Eastern part of the region (shown above in Figure 3) were submitted for worm typing following worm egg counts at a separate commercial laboratory. Whilst the drenching history and average worm egg count results aren’t available to us, the results of the cultures show huge variability in worm types between mobs on the one property.
Take home messages:
Contrary to optimistic weather predictions, summer has been hot and dry, with only isolated thunderstorms bringing temporary relief to very few. Farm dam levels are low, and quality feed gone. Adult dry sheep are still in pretty good condition, but young sheep are showing the effects. Despite the dry conditions, worms continue to cause problems on some farms.
Barber's pole worm is still the main concern, seen in different flocks as deaths of fat crossbred lambs, weakness and bottle jaw in ewes, and high worm egg counts in all age groups. On some properties, barber's pole issues have occurred in a single paddock, often the one with a bit of low-lying country where sheep return frequently to look for a green pick.
Sheep carrying barber's pole worm are pumping out huge numbers of worm eggs, most of which die off without rain. We've seen in the past few years that not tackling barber's pole at this time leads to rapid build-up of worm larvae on paddocks after the autumn break, which then persists right through winter. So while it stays dry, there is an opportunity to break the worm cycle. Do a worm egg count (WormTest) on each mob to identify those which require treatment—we still see some mobs where the worm egg count is extremely low, despite not having been drenched since spring.
Not surprisingly, drench resistance is increasingly tied up with barber's pole worm problems in this district. The last drench may not have worked well and sheep appear wormy soon after the drench, meaning adult worms have survived treatment and the worm egg count is still high 14 days later. Or the protection period expected from a long-acting drench has been reduced or lost altogether. Producers are frequently disappointed to discover that they've wasted money and time drenching with a product that has not worked, but it is far cheaper to find this out with a post-drenching worm egg count than to wait until sheep get crook or die a couple of weeks later.
(Editors note: While ML drenches are generally very effective against scour worms, ML-resistance in barber’s pole worm is universal in the summer rainfall areas. Therefore it should be no surprise to also find lower efficacy in other regions.)