Checking worm burdens with a WormTest is essential for correct and timely drenching decisions.
The result is healthy sheep without unnecessary drenching. WormTests are the best basis for drenching decisions. Weight loss, scouring, a tail in the mob and deaths may mean that your sheep need drenching. If so, these signs occur well after substantial production losses (reduced weight gain and wool growth) from worms have already occurred in the mob. WormTests give early warning before there are significant production losses.
Checking worm burdens throughout the year using WormTests is a critical part of the WormBoss worm control program.
Most WormTests are done through a laboratory. However, worm egg counts (but usually not larval cultures) can be done by producers if they have the equipment and skills. Ideally, producers should have their preparation and counting technique reviewed by an accredited laboratory and perform ongoing quality control checks, just like an accredited laboratory to ensure their results are correct.
In this South Australian winter rainfall region all mobs should be WormTested separately, rather than using one mob to represent another. Paddock differences here will have a significant effect on resulting worm burdens, even if the sheep are a similar class.
Note: Long-acting drenches are rarely required in South Australia. Unless professionally advised, use an effective short-acting drench when treating for worms. Where treatment for barber’s pole worm is also required, broad spectrum drenches are generally effective as drench resistance in barber’s pole worm is as yet uncommon in South Australia. However, this may be changing in areas where sheep have been introduced from interstate, locations where barber’s pole worm is more common.
WormTests can be done at any time; however there are certain routine times to WormTest, shown below. Use the results with the Drench Decision Guide to decide whether to drench and when other WormTests should be done.
A larval culture (larval differentiation) with the WormTest is particularly useful in areas or seasons in which summer rainfall occurs and barber’s pole worm is a risk.
Note: Ram breeders should be aware that young rams under 2 years are highly susceptible to worms and should be regularly monitored as per weaners.
The timing of WormTests and drenches will vary between farms and seasons. Use the Drench Decision Guide (see below) to weigh up important factors when deciding when to drench or WormTest on your property. These factors include signs of worms, time since last drench, WormTest results, time of the year, and condition of sheep and pastures.
If drenching is done for other reasons (such as an early drench before holidays or harvesting), use the Drench Decision Guide to decide when to drench or WormTest again.
Sheep do not need to be yarded for a WormTest. Collect warm fresh dung from the paddock (but make sure that ewe and lamb samples are not mixed).
To conduct a WormTest obtain sandwich bags (not ziplock) for individual animal samples and then follow the instructions provided by your testing laboratory or advisor. As a guide, collect 20 individual samples from mobs up to 400 sheep, and 20–40 samples from larger mobs. The laboratory will then ‘bulk’ these samples using an identical amount of dung from each sample.
Avoid delays in transit (when worm eggs can hatch) by collecting and posting early in the week.
Also ensure samples are kept cool (refrigerate but do not freeze) before sending, include an ice brick in transit in very hot weather and exclude as much air from the sample bags as possible.
If you do your own worm egg counts, a ‘bulk’ test is easier than counting individual samples. Fewer bags or trays are needed and more sheep in the mob can be sampled.
The Drench Decision Guide helps to simplify decisions on whether and when to drench. There is a version of the Drench Decision Guide for each WormBoss region.
The Drench Decision Guide will recommend:
You can use the Drench Decision Guide at any time, whether you are contemplating drenching a mob now or in coming weeks. Not all situations require a WormTest: the Drench Decision Guide will recommend when these should be done.
See the Drench Decision Guide.