NSW WormBoss Worm Control Programs
NSW WormBoss Drench Decision Guides
Unfortunately, with many of the LLS vets being away at their annual conference, we have fewer contributions this month.
Bill Johnson's contribution is very thorough and will apply to many districts in southern and central NSW.
Conditions remain very dry around Coonamble and worm burdens remain low. Sheep producers are reminded to worm test into autumn, especially if we receive rain.
Cattle producers are encouraged to drench weaners and adult cattle, particularly if on poor pasture quality or quantity. It is a good idea to rotate drench families to delay the development of drench resistance in cattle worms so talk to your district veterinarian for help with drench selection.
Editor’s note: some cattle drenches are now available as combination (page 5) products.
It's been pretty quiet in the Dubbo patch this month in comparison to last month from a worm point of view. Best advice I can give to sheep producers is, instead of reaching for your normal two summer drench, check your sheep mobs with a worm test to see whether drenching is actually warranted.
With the ongoing dry conditions around the Forbes area, worm tests have been few, however producers should be doing a pre-lambing worm test to determine whether a pre-lambing drench is required.
There haven’t been any faecal worm egg counts (WormTests) submitted to the Elizabeth Macarthur Agricultural Institute (EMAI) from the Nyngan District over the last month. Local private veterinarians and agricultural supply stores that perform faecal egg counts have done very few and counts are very low as would be expected due to the hot and dry conditions at the start of the year.
Barber's pole eggs can only survive for 5 days waiting for suitable hatching conditions. They require a high soil moisture profile or more than 10-15mm of rainfall. If we (hopefully) get some rain soon, eggs will hatch, but the resultant infective larvae can survive temperatures of between 35-40 degrees centigrade for around 4-6 weeks depending on the humidity, and, combined with the reducing ground cover and feed height by the day, the level of new infections could rise quickly.
However, it takes at least 18 days for the larvae to grow into an adult worms and start laying eggs. Keep that in mind when determining the timing of worm counts to get the most accurate picture of the level of infections in your flock. Barber's pole is the focus for most producers in the area and it is so important that producers use drenches in combination as part of their overall drench strategy.
If you are looking to offload some stock due to the dry conditions, remember to include resistance to worms and flystrike susceptibility in your classing decisions.
WormTest submissions have steadied over the past month. Aside from some sporadic downpours of rain experienced throughout the East of the region during the last week of February, conditions have been hot and dry.
Just prior to the rain event in late February, a set of WormTest submissions from a property near Holbrook showed a predominantly barber’s pole worm burden in mobs of crossbred ewes. No deaths were reported.
In one complex outbreak of lamb deaths, Mycoplasma ovis, the bacteria that causes Eperythrozoonosis (“Epi”), was implicated. M. ovis affects red blood cells and results in anaemia and death. It can be spread by mosquitoes and other insects which may be present in higher numbers during a wet summer. Epi can look very similar to barber’s pole worm infestation – often presenting as anaemia and deaths.
There have been no WormTest submissions this past month for the West of the region. The current lack of lush feed coverage and moisture provide a great opportunity for producers to create and utilize low risk paddocks. The stress associated with being heavily pregnant means that many ewes will have reduced immunity and are more susceptible to worms, so it is important to keep a close eye on lambing ewes and young lambs for signs of worm infestation.
Worm egg counts rose following widespread rain in late February and, as expected, barber's pole worm was the main component. Counts of several thousands were common in sheep of all ages, especially those that were last drenched in November or early December. But some properties have seen more striking evidence of barber's pole worm, including weak, pale sheep, 'swollen heads' (fluid swelling of lips, muzzle and under bottom jaw), and deaths of fat sheep.
Sheep also died from exposure on a number of properties, and many alpacas died on another, following the heavy February rainfall. You might expect weak and bare-shorn animals to succumb to a 24-hour spell of wet and windy weather. But several well-conditioned animals on good feed also died on this occasion, including seven fat white dorper ewes on one property. Barber's pole worm burdens helped make these animals more susceptible to the blizzard-like conditions.
Drench resistance is being diagnosed more frequently, and is making barber's pole worm even harder to control. In one case seen this month, sheep were showing signs of barber’s pole worms at the time they were drenched with a popular broad-spectrum 'ML' drench. Two weeks later, the sheep were still affected, and a couple had died. They were drenched again, this time with a more expensive combination drench, which was expected to control barber’s pole worms for four weeks ('ML' plus Closantel). But a worm egg count two weeks after the drench reached 23,600 eggs per gram (that’s a lot!), indicating that the worms were also resistant to that more expensive drench.
Barber’s pole worm is now the predominant worm on many sheep, goat and alpaca farms in our region. Worm control programs we have relied on to deal with mainly winter scour worms, such as the “double summer drench” program, don’t cut it with barber’s pole. We are rapidly tracking the experience of sheep properties on the New England, where barber’s pole worm is resistant to most drenches, particulary MLs. More producers there use pasture rotation to help break the reinfection cycle, and vaccination (Barbervax).
We know, for example, that barber’s pole larvae on pasture survive for only about 2 months during a hot, dry summer, but remain viable for about six months during winter. Grazing management aims to avoid rapid reinfection of sheep during summer, and reduce contamination of autumn pastures with worm larvae.
Barbervax® is the first successful use of a vaccine to control a worm in sheep. It is a clever bit of technology, designed in such a way that this highly adapted worm is unlikely to develop resistance. This comes with a down-side, which means that three doses of the vaccine are required to prime the sheep’s immune system at first, with further boosters given every six weeks until the barber’s pole worm risk is over for the year. Sounds like a lot of work and expense (at about 68 cents a dose), but some producers have no alternative. And it works, but grazing management options are still advised to be used with it..
One Far South Coast sheep producer has been using the vaccine this season, with remarkable results. Last year, despite frequent drenching, worm egg counts remained in the thousands, and the productivity of the sheep suffered. This year, under the influence of the vaccine, worm egg counts are negligible, and the sheep reportedly look great.
Barbervax® has been trialled in goats in Northern NSW, with mixed success; the vaccine was very effective in one trial, ineffective in another, and moderately successful on a third goat property. Talk to your veterinarian before using Barbervax®.
Be alert to outbreaks of Nematodirus (thin-necked intestinal worm). This is often the first worm to appear when rain falls after a prolonged dry spell, causing explosive scouring in weaner sheep. The immature worm does much of the damage, meaning that worm egg counts underestimate the problem.
Some worm egg counts currently have a significant proportion of scour worms, mainly black scour worms. You don't need to see scouring for these worms to be having an impact; they affect growth and wool production especially of young sheep and contaminate paddocks you plan to use for winter lambing.
Blowfly strike has affected young sheep, mostly those with dags. In many cases, a fly prevention chemical was applied at weaning, but that protection has now worn off. Any further scouring, either because of worms or green feed, will attract flies. Crutching will be more effective than chemicals in this case.
As this will probably be my last contribution to ParaBoss News, I wish to congratulate AWI, MLA and the Sheep CRC on developing this resource, and to thank Arthur, Deb, Maxine and the ParaBoss team for keeping it going.
[Bill, a great thanks to you for being such a regular and thorough contributor. I am sure livestock producers in and beyond your district will miss these contributions and your extensive skills, knowledge and experience. Enjoy your new adventures. Deb Maxwell]
There have been no worm tests reported for this month. It is VERY dry out this way, however some areas have received some rain - very patchy.