Online Learning: Victoria—Worm Testing

Collect the number of samples per mob as recommended by your laboratory (ideally this would be from at least 20 goats—if you are doing your own worm egg count on farm, try the following ‘bulk collection’ method.

Bulk collection method:

When conducting your own worm egg counts on farm:

• Collect three pellets per adult pile (or the equivalent amount if soft or runny) or five for weaners.
• Collect from at least 20 dung piles.
• Where Haemonchus (barber’s pole worms) are an issue, and if there are over 200 goats, collect from each of 40 dung piles.
• Collect all dung into one container
• The dung then needs to be mixed extremely thoroughly.
• Conduct your worm egg count using a sub-sample from the bulk mixture.

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WormTests can be done at any time, however there are certain routine times to WormTest:
Note: a larval culture (larval differentiation) is particularly useful in areas or seasons in which summer rainfall occurs and when re-infection with scour worms or barber’s pole worm might occur.

• WormTest  weaners no more than 5–6 weeks after their first summer drench, especially in wet summers. This is usually the weaning drench for spring-drop lambs; for lambs born in autumn (often early May)WormTest 4–5 weeks after their weaning drench.
• During January–February for sheep showing signs of barber’s pole worm (anaemia and lethargy)—aside from known barber’s pole worm areas this can also occur in wet summers or irrigation areas.
• All mobs in late January/early February, just prior to a possible second summer drench. This will usually be 6–8 weeks after the first summer drench.
• Weaners, 4–6 weeks after the autumn break and thereafter through winter. However under high risk conditions (pastures highly contaminated with worms/higher rainfall areas/wetter than normal) test as soon as 2 weeks after the break.
• 4–6 weeks after any short-acting drench.
• Higher risk mobs in July/August (usually youngest and oldest). Test other mobs if high worm egg counts are found. These results will give a check on peak winter egg counts.
• Ewes pre-lambing (provided it is at least 8 weeks post-autumn break for adults and 6 weeks for maidens). This is especially important for ewe mobs that are struggling with low condition score (less than 2.5) and/or grazing pastures of less than 1200kg DM/ha (3–4 cm pasture height).
• As suggested by the Drench Decision Guide.

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A WormTest refers to a ‘Worm Egg Count Test’ or ‘WEC test’; it will identify the number of worm eggs in faeces, which is a good indication of the worm burden of the goat. Some laboratories can also perform a ‘Larval Culture’ (also called a ‘Larval Differentiation’) to identify the types of worms present and their proportion (the importance of this varies according to your location).

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1. A) When giving a quarantine drench.
2. B) When giving a strategic drench. The timing of strategic drenches depends on the region and the class of goat, as their use is closely associated with times when goats are most susceptible to worms or  when development of eggs to infective larvae on pasture is likely to be extremely low (to reduce pasture contamination) or high (to pre-empt likely immediate problems). Strategic drenches are given regardless of the average worm egg count of the herd.

There are six common strategic drenches; not all are used in every region. The WormBoss programs outline which strategic drenches to use in each region.

• Pre-lambing does
• Kids being weaned
• Winter weaners going into low worm-risk paddocks
• Smart grazing as used in sheep
• Summer drenches—temperate winter rainfall regions
• Summer-autumn drenches—Mediterranean climatic regions

Details of when/how to use strategic drenches are in Your Regional WormBoss Program.

Ideally each mob should be tested individually, as there are usually differences between paddocks in the favourability for worm survival, the number of worm eggs being deposited by different mobs, and the time since a drench was given. However, if there are a number of mobs that have the same drenching history, same class of goats and very similar paddock type (including recent level of contamination from worms) then one mob can represent two others (i.e. test one in every three similar mobs).

Testing representative mobs saves the cost of testing all mobs, but carries the risk that the result may not be representative.  If in doubt, test additional mobs. Testing individual mobs is suggested for Western Australia, South Australia, Victoria and Tasmania.

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If less than 2% of a herd are showing signs that include pale inside eyelids and gums, bottle jaw, lagging or collapse, you should treat these affected goats immediately with a drench suitable for barber’s pole worm, but also sample and test the remainder of the herd now. If these signs are not visible, but a few goats are scouring badly, test the herd now. In both cases, use the results with your Drench Decision Guide to decide whether the whole herd should be treated.

When less than 2% of a herd show signs of worms these are the possible causes:

• These goats were not drenched when the rest of the herd were (e.g. didn’t get mustered, were missed or spat out the drench in the race, strayed in from another herd). Their worm egg count may be a lot higher than the rest of the herd.
• These goats are suffering from some other illness or injury that has reduced their immunity and they have acquired a larger worm burden than the rest of the herd. Signs of another problem may be evident.
• These goats are the most susceptible in the mob because of lower worm-resistance and the herd has been tested just when these first goats are starting to show signs.
• These goats are not actually affected by worms at all. Instead, anaemia could be the result of liver fluke and scouring could be from coccidiosis or excess lush feed.

In all of the above situations, a WormTest on the remainder of the herd (don’t include these badly affected goats) to determine the worm egg count will inform your decision of whether to treat the rest of the herd.

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