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Biological worm control for livestock stands up to scrutiny

A NEWLY commercialised biological parasite control for livestock has been tried and tested in Australia, writes STUART BARBER.

NEMATODE parasites, commonly known as internal worms or roundworms, are a major cause of disease in livestock.

According to Meat and Livestock Australia, they cost the sheep industry more than $400 million a year and the beef industry more than $90 million a year. In the goat industry, they are by far the biggest cause of loss at $2.5 million a year.

Anthelmintic drugs are a common treatment used to kill nematodes.

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While anthelmintics will most probably remain the mainstay of livestock parasite control, they should make up just part of an overall parasite-management program because parasites start to develop resistance to new classes of anthelmintics within five to 10 years of first exposure. Constant investment in developing novel anthelmintic drugs that are as good as, or better than, previous classes is necessary to combat resistance.

Other control mechanisms include genetic selection of livestock, nutrition, vaccination, paddock rotation, bioactive forages (plants that help reduce nematode numbers), multi-species grazing rotation and parasite predators.

The last of those — parasite predators — has been commercialised in Australia.

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When larval and adult roundworms are present in an animal’s body, the immune system attacks. However, there are parasite stages that occur outside the animal’s body — thousands of eggs and larvae pass out in dung and end up on pasture, where they reinfect animals.

Over the past few decades, research has examined predators that prey on parasite eggs and larvae on pasture, reducing the number of nematode larvae that animals eat, helping to stop the life cycle.

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Microscopic nematode predators were tested for their ability to cut parasite numbers, and the best commercialised predator so far is a fungus called Duddingtonia flagrans. A lot of research has been performed on this fungus in Australia and a product is available to enhance worm control on properties.

This product is available in two formulations — a feed additive called BioWorma, used by feed companies, and Livamol with BioWorma, which can be used by individual property owners as a mix in feed. This fungi is naturally occurring, but is fed at a higher ratio than would normally be found on pasture. The products need to be fed regularly, ideally daily, to ensure adequate levels of the fungus are passed into the dung to kill nematode larvae soon after they hatch.

It needs to be used as part of an overall parasite-control program and may be useful on properties that struggle with anthelmintic-resistant nematodes.

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On goat properties, resistance to drench is likely to develop early, given goats metabolise most drenches faster than sheep and are often treated more frequently, and this fungus may be particularly helpful. Using a fungus that kills larvae on the ground is never 100 per cent effective, but trials suggest significant reductions of 50 to 90 per cent.

This reduces the number of larvae that survive to be picked up by livestock and limits egg numbers. So, while change won’t happen overnight, it will happen with regular use over time.

If stock are drenched, moved on to pasture that hasn’t been grazed recently and fed this type of product, then control of roundworms is likely to be improved.

This has the potential to significantly reduce the need for chemical control. Your vet assess ways to combine chemical and non-chemical control mechanisms.

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Dr Stuart Barber is a lecturer in veterinary science at the University of Melbourne.

Original URL: https://www.weeklytimesnow.com.au/agribusiness/farm-magazine/biological-worm-control-for-livestock-stands-up-to-scrutiny/news-story/fcbc31f0606639f119414f8a2f0c7424