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Western Australia worm update - April 2013

Brown Besier, DAFWA, Albany ( )

It’s still early in the year for visible worm problems, except on perennial pastures, as we generally don’t see signs of worms until there has been a few weeks grazing on the new season’s pastures. However, early rains over much of the state have led to germination, and once dense pasture swards are present, sheep will start to pick up significant worm burdens. We are therefore likely to see worm problems earlier than in most years.

As recommended last month, the main worm control priority is to start winter with low worm egg counts in all classes of sheep. If summer drenches were effective, and ewes were given an effective drench sometime the last few weeks, counts should still be low. Cases submitted to the laboratory have mostly confirmed this, although serious worm problems have occurred where sheep grazed perennial or irrigated pastures.

It will pay to check worm egg counts where there is a query over the effectiveness of the drenches used, or where there has been dense green feed for a few weeks. Mobs with average counts over 200-250 eggs per gram should be drenched, as even though there will not be a great loss of production at these levels, the seeding of the pastures with worm eggs will lead to significant problems later in the year.

Barbers Pole worm: In areas prone to Barbers Pole (Haemonchus contortus), worm egg counts are even more important, as recent rains will encourage worm larvae to develop. Sheep deaths often occur with little warning, and earlier green pasture growth means that the risk could occur earlier than usual. It will usually be necessary to have the worm eggs identified (with a larval culture and differentiation test) to indicate the proportion of Barbers Pole in a sample.

Pre-lamb worm egg counts: If ewes are lambing within the next month, and an autumn (March or April) drench was given, chances are that no pre-lamb treatment is needed. If summer drenches or no treatments were given, plan to sample ewes about 3 weeks before lambing is due to start. A drench can then be given at least 2 weeks out. This also applies for mobs lambing from June onward, whether or not an autumn drench was given.

Nicole Swan, Swan’s Veterinary Services, Esperance ( :

Esperance has been wet and warm. Everything is green.

As expected we have been getting some high WECs and Barbers pole levels between 55 and 94%. I am recommending pre-lambing Barbers Pole protection for ewes in Barbers Pole risk areas.
To date we have not seen any clinical cases.

Some lambs mobs have had levels of around 300-500 epg so warrant drenching.


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