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SubscribeChecking 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 even though signs such as weight loss, a tail in the mob, pale skin and eyes, bottle-jaw and deaths may be apparent, as other diseases also show these signs. Signs occur well after production losses from worms are occurring in the mob; therefore, WormTests give early warning to prevent significant production losses.
Drenching based on WormTests is also the most cost-effective ongoing option for worm control in this region, as unnecessary drenching of large mobs is expensive in both drench and labour costs. Even in remote areas WormTest results should be received within a few days, so WormTest first if you are concerned about worms.
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.
Sheep do not need to be yarded for a WormTest. Collect fresh dung from the paddock. Obtain WormTest kits or sample collection details from laboratories or resellers in your area. Follow the instructions provided in the kit.
In this region, all mobs that may need drenching should be WormTested separately, rather than using one mob to represent some or all other mobs. Paddock differences in this region have a significant effect on resulting worm burdens, even if the sheep are of a similar class. Also, mustering and giving an unnecessary drench is expensive.
In this region drenches should not be routinely given. Always conduct a WormTest before drenching sheep (except when introducing sheep and in unusual cases of predicted extensive flooding, see below). Don’t forget the rams.
Include a larval culture with the WormTest in areas or on properties with a history of barber’s pole worm, or when there is higher than normal summer rainfall, or where animals show signs of anaemia (pale inside eyelids) or bottle jaw (swelling under the jaw).
Note: A WormTest can save an unnecessary drench if signs are from another cause, however, if severe anaemia and bottle jaw are noted, an immediate drench for barber’s pole worm is usually warranted. A concurrent WormTest should also be carried out (take samples before drenching) to confirm the diagnosis, as similar signs may occur in this region from the blood parasite Mycoplasma ovis (formerly called Eperythrozoon ovis) and other causes.
Table 1. Threshold worm egg counts at and above which sheep should be drenched in the Pastoral region
Class of sheep | No culture or culture has lessthan 60% barber’s pole (i.e. mostly scour worms) | Culture has more than 60% barber’s pole |
Ewes (dry to mid-pregnancy) or wethers | 400 epg | 800 epg |
Ewes pre-lambing | 300 epg | 300 epg |
Sheep under 18 months or rams | 300 epg | 500 epg |
When choosing the drench to use, refer to the next section in this program: ‘Managing drench resistance’. For nodule worm, use a drench containing either a benzimidazole (BZ) or a macrocyclic lactone (ML) group.
The WormBoss website has a Product Search Tool where you can search on your livestock species, drench names, drench groups, or the parasite you wish to target; and a region-specific Drench Decision Guide (both below).
You can use the Drench Decision Guide at any time, whether you are contemplating drenching now or in coming weeks. Not all situations require a WormTest: the Drench Decision Guide will recommend when these should be done.
Each Drench Decision Guide is available as a separate 2-page printable version, or can be used directly online.
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