Barber's pole worm advice
31 Jan 2022
By Coonamble District Vet, Jillian Kelly
We are seeing massive faecal egg counts and clinically unwell sheep from Barber's Pole Worm (BPW) at the moment. The conditions are warm and wet, meaning they are ideal for egg hatching, larval survival on the paddocks and reinfection of sheep. A single adult BPW can lay 10,000 eggs per day so burdens can go from “low” to “woah” in a very short space of time.
This does not necessarily mean rush out and drench! There are some things to consider first and it's worth understanding a bit about how Barbers Pole Worm operates to combat it effectively. A good summary of BPW can be found here - it's easy to understand and has been written especially for our area, so is a must read!
Worm testing is key
The most important thing is to do a worm test on your sheep and get an idea of their worm burden. To give you a rough example of some test parameters, anything about 500 eggs per gram requires a drench, most sheep start to look clinically unwell above a few thousand eggs per gram, start to die at around 5,000-10,000 eggs per gram and I saw an egg count recently of 26,000 eggs per gram!!! My point is that there is a huge gap between needing a drench based on an egg count vs the point where you can see the sheep are clinically sick. Don't wait for the clinical disease – the sheep will be doing poorly and the larval contamination onto the paddocks is enormous. You can pick up a worm test kit from any Local Land Services office, just give us a ring first on 1300 795 299 to arrange collection.
Beware of larvae survival
Another important point to consider is that BPW larvae can survive on paddocks for many months. They are killed more quickly in a hot dry summer; however, this year the weather has rarely gotten above 35C, there has been regular rainfall and there is a thick grass canopy on the ground which insulates eggs and larvae from environmental desiccation. This means that anywhere you have had sheep grazing with a BPW burden in recent months will be contaminated and many of these larvae will probably survive and “overwinter”, becoming active again next spring and summer, ready to again cause clinical disease. If you have BPW now, your management strategy needs to be a long term one, not just a “drench and forget”.
Keep records
It is a good idea to keep records of not only which mobs of sheep are wormy, but what paddocks they've been running on. You can keep a spreadsheet, or just a note in your notebook is fine too. It's important, considering the burdens we are seeing, to try to allocate "clean" (or at least "lower risk") paddocks for your 2022 lambing and weaning and keeping good records can help with this.
Black scour worms
Interestingly, we are also seeing some residual black scour worm activity. Usually, black scour worms don't like our summer weather - but this year it has been wet and mild and they are persisting. For this reason, when doing a worm test it is worth spending the extra money on a larval culture to find out what species of worms are present. You can then target them with your drench selection and understand better how best to manage burdens as we move into autumn and winter.
Understandably, if you have high worm burdens and the animals are clinically unwell, you may not have the luxury of waiting 10 days to get the results back on the larval culture. So, I guess in this case, if you must drench in a hurry, it is worth choosing a combination drench that targets both species. To give you an example, active constituents such as levamisole and closantal are useful for Barbers Pole Worm but won't work so well for Black Scour Worm so single actives using these products are not advisable this time.
Which drench to use?
So which drench should you choose? This is not a simple question and the answer will probably be different for each enterprise based on type of sheep, plans for lambing, weaning or sale and paddock rotations.
For example, the prolonged survival of BPW larvae on the pasture means that if you drench sheep with an effective short acting (knock down) product and put them back onto a "dirty" paddock (one where there have been sheep in the last 4-6 months), they will be immediately picking up larvae and have an adult worm burden three weeks later.
A long acting drench may be useful in some instances; however producers are advised to check the Withholding Periods and Export Slaughter Intervals on these products to ensure they fit with any plans for sale of their sheep.
Trials conducted by central west Local Land Services throughout 2012, and again in 2021 have found significant drench resistance to many of the commonly used drench active ingredients. A summary of these results can be found here.
A drench trial (or faecal egg count reduction trial) is an excellent on-farm investment to establish which drenches are working on your enterprise. The results are usually relevant for the next 3-5 years and can help make the best drench choices for optimal results. Central west Local Land Services are currently helping producers conduct these trials. To do so we require a mob of around 100 un-drenched weaner aged sheep with a faecal egg count of >200 eggs per gram. If you are interested, give your local district vet a call.
This summer has been very comparable, in terms of weather, to the 2010-2011 summer and interestingly, producers who, this year, have worm tested regularly, understood their property's drench resistance status, used effective drenches only when necessary and utilised the environment to kill larvae have had low egg counts all summer and haven't had to drench, in stark comparison to 2010-2011 when they were losing sheep. Good work, if this is you! If you’d like this to be you, give us a ring!