NZ sheep industry robbed of $98 million a year due to undetected drench resistance 

19 September 2023 

Dunedin NZ: Data analysis by Techion shows the cost of undetected drench resistance has exploded to an estimated $98 million per annum.

A key contributor to the dramatic failure is that commonly used triple drenches are not effective on 27% of New Zealand sheep farms. This level of drench failure mirrors other industry reports and again highlights the increasing productivity and sustainability threat to the sheep farming sector.

In 2020 Techion, the business that developed the FECPAKG2 parasite testing platform, reported the cost of undetected drench resistance was $48 million a year. Techion Founder and CEO, Greg Mirams said building upon data collected for the past 18 years, in just the past three years, the company has seen triple drench failure increase from 15% of properties to 27% in 2023.

The data comes from Techion’s DrenchSmart service, a faecal egg count reduction test (FECRT) that independently reports to farmers which drench actives are working effectively on their farms and which are not.

Wormwise programme manager, Ginny Dodunski notes, “Farms using untested, partially effective drenches will not see visual signs until things are quite serious, and in the intervening years farms can be quickly breeding high numbers of drench resistant worms.”

“If a drench is only 70% effective, each time that drench is given it’s effectively leaving 30% of the worms behind. These then have three weeks to continue to breed and lay eggs. If you’re drenching every 28 days, it's obvious how quickly resistance can build up”.

Greg Mirams continues saying, “The days of farmers simply assuming a triple drench will work are gone. With limited effective quarantine protection in place, farmers are often unwittingly importing triple drench resistance onto their properties.  Many farmers have not tested whether their drenches are effective and as a result, are suffering production losses they are not aware of.”

“Farmers generally only become aware there is a problem when they experience poor lamb performance in late autumn, or a large tail end in hoggets or ewes through the winter,” says Mr Mirams.  

“Unfortunately, when farmers observe these production losses, the drench has likely been failing for years. With animal performance on many farms so dependent on the use of effective drenches, when they fail, production losses can be significant.”

Techion’s 2017 study undertaken with UK retailer Sainsbury’s, reported undetected drench resistance reduced carcass value by 14%. Analysis of the 2023 Ministry for Primary Industries statistics shows 17,964,138 lambs went to the works in the 2022-2023 financial year, and undetected drench resistance could be costing the New Zealand sheep sector $98 million in 2023.  At an individual farm level, for a property producing 4000 lambs annually, undetected drench resistance may reduce income by an estimated $81,200 per year.

Gavin Hodgson, Sainsbury’s Head of Livestock, who was integral in commissioning the study says, “Improving productivity and sustainability is critical for the long-term future of the lamb supply chain.”

“The increasing threat of drench resistance, the viability of the lamb sector and harsh climatic conditions for farms across the United Kingdom and New Zealand pose a significant threat to farmers, which is why it's critical for farmers to know the effectiveness of the treatments they use.  As well as controlling parasites this knowledge will help meet customer demand for transparency by reducing farming inputs.”

“Its critical farmers test the efficacy of the drenches they use and utilise alternative measures to control parasites and protect the drenches which are still working effectively,” Mr Mirams says.

Other drench options fared no better in the latest analysis, with BZ/Lev combinations failing on 50% of properties, while Lev/Aba combinations were failing on 32% of properties.

”In two cases this year the change in drench efficacy on the property was so significant that we had to go back and test again as we didn’t believe the changes could be so dramatic over three years. We’re seeing the reduction in drench effectiveness increasing significantly. This can have a devastating impact on the farmer, their mental health, their property value and the wellbeing and performance of their stock,” he said

Although cases of drench failure production loss are becoming more common, there are sustainable and cost-effective options for farmers to improve productivity and reduce cost. It begins with a whole farm approach; instead of relying solely on drenches to control parasites farmers must utilise a range of tools. These include better nutrition of breeding stock, grazing management, pasture types, stock class options, cross-grazing and genetics. For up-to-date seasonal advice on worm management, follow Wormwise on Facebook.

Key to the success of a farm system approach to worms is easy access to FEC data, which allows timely decisions and enables monitoring of the results of management changes. 

See the table with the 18 years of test results below.


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