January 5

Managing Drench Resistance to Barbers Pole a Must


Advice from Industry Expert Ben Foster

Industry Expert Ben Foster

Over the last 3 years, most sheep producers in NSW and Southern QLD, need no special introduction to internal parasites such as Barber’s Pole (Haemonchus Contortus).

Barber’s Pole worm is a blood sucking parasite found in the 4th stomach (Abomasum) in sheep. They thrive in warm wet climates such as the New England, Southern QLD and the North West NSW over the summer period. Barber’s pole are tremendous egg layers and can build up numbers of infective larvae on pasture extremely quickly, leading to a quick onset of disease and sudden death after grazing animals ingest these from the pasture.

However, during the last 12 months, many cases have been reported in areas that are traditionally winter rainfall, and have hot dry Summers, which do not suit barber’s pole. These areas include the central and southern tablelands, central western NSW and most parts of Victoria. This is largely due to La Niña rainfall patterns that we have experienced, providing rainfall to many of these areas over the warmer months, making conditions ideal.

The alarming threat with this parasite, is the rate to which it can build resistance to our traditional chemical methods of treatment (oral and injectable drenches). Especially if these are being overused, or not rotated. There are some areas, which have very little chemical means left to control this parasite, and therefore have to heavily rely on a range of other integrated measures.

It still surprises me how many producers still do not worm test any animals on their farms, to check if they need to drench, and also for what parasite. Most of these producers drench on demand or to a set timing. Many places can carry a mixed infection of internal parasites, and chemicals that may kill one type of parasite, may not kill the other.

Apart from doing routine worm testing, it is becoming increasingly important for farms to check all drench groups for effectiveness. Many of these drench groups have been around since the 1960’s and have been used very extensively. There are two ways this can be done. The simple way is when you are drenching a mob, take at least 10 dung samples from the animals being treated, take them to your local Pursehouse Rural store, and they can be sent away for a faecal egg count, and also a culture to identify the worms present. 14 days later take another sample for these sheep again take it for testing. The worms present at 14 days after treatment, have been left behind by the drench, and you can work out a percentage reduction. This is called a simple drench check. The second way is to see your local store and organize a full drench trial (Faecal egg count reduction test). This is usually done by an animal health company that services the store. Ideally these should be repeated every 2 years.

To get good worm control, you must use effective drenches, especially those that are over 95% effective, on the parasite being targeted. Regular testing and culturing allows producers to know what worm they are dealing with, and to what level they are infected, to allow more prescriptive choices in whether to treat, and what with. The less exposure to unnecessary treatments, the slower the selection for resistance.

In 2014, a vaccine specifically for barber’s pole worm was released in Australia, after approximately 30 years of research by a Scottish scientist/Vet from Moredun Research Institute. Barbervax is now produced in Albany WA in conjunction with the WA dept of Primary Industries and Regional Development. It has been widely used in the New England since, with some particularly good results. Barbervax is available and stocked by the Pursehouse Rural group.

At the end of the day. The most important take home message from this article, is to ask yourself what are you doing for your worm control? Do you test? What parasites am I dealing with? And what drenches work on my farm? And finally, what quarantine measures do I use if I am bringing sheep in from another property? Always assume they contain resistant worms, and use at least 4x drench actives on entry, and one of those actives must be a newer drench group, such as Derquantel, or Monepantel. And let them empty out in a holding yard for 2-3 days. With no new drenches on the horizon, we must do what we do better.

There is heaps of information available on the Paraboss website.  www.paraboss.com.au 


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