Wednesday, April 24, 2024

Wrong turn on parasite road

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Industry experts are adamant there is still time to avoid a potential disaster, provided farmers are prepared to act now, writes Craig Page.
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The drench resistance “time bomb” is ticking for New Zealand’s beef and dairy industry. The question is, who is prepared to help defuse it?

In December last year, AgResearch parasitologist Dave Leathwick and colleagues released a research paper that identified triple resistance in cattle on four farms that were part of their study.

Drench effectiveness on some of those farms had dropped to be only 40-70% for levamisole, a previously effective treatment against cooperia. 

Fifteen years earlier, levamisole was touted as the most effective means of control against the worm in cattle. The news shocked many, but Leathwick admitted the only real surprise was that triple drench resistance had taken so long to surface. 

In this week’s edition of Farmers Weekly we dig deeper into the issue of drench resistance, and how it might be addressed.

Industry experts are adamant there is still time to avoid a potential disaster, provided farmers are prepared to act now. They must learn from the sheep industry, which has already suffered the consequences of drench resistance at a significant financial cost.

Since releasing his work, Leathwick has seen more resistance issues. 

“One farm we visited only the other day had taken a faecal egg count only 10 days post-drenching and it was already up at 650 eggs per gram. The drench simply had not worked,” he said

It is telling that those behind Wormwise, a national worm management strategy established in 2005, concede the programme has failed to stop the growth of drench resistance.

Wormwise was set up by Beef + Lamb New Zealand, DairyNZ, Deer Industry NZ, Animal & Plant Health NZ and the NZ Veterinary Association and funded by beef + Lamb NZ.

Wormwise manager Ginny Dodunski said for 20 years it was known drench resistance was a looming problem. That was reinforced by a 2021 review.

The bottom line is farming systems relying too heavily on drench to control parasites. Rather than lament its arrival, Dodunski sees the drench crisis as chance for farmers to address and reinvent their farming systems to offer more natural protection from parasites.

“Drench resistance is not the question. The question is ‘How do I set up my farm system so worms are not a cost to me?’” she said.

All those spoken to during our series are adamant farmers need to do more to help themselves rather than just relying on drench to solve their problems.

Dr Ian Scott, Massey University’s senior lecturer in parasitology, believes research into pastoral parasite control stopped as some animal health companies put their focus into the money-making companion animal markets. The number of companies willing to invest in the research and development of livestock drenches quickly dwindled.

Vets spoken to say cattle farmers can learn plenty from sheep farmers who have already had to deal with the perils of worm resistance. Larval challenges need to be reduced and could be done using crops, different grazing rotations or reducing the monoculture of cattle by mixing livestock types. 

It is clear the answers to toppling drench resistance are out there. Farmers need to be ready to take them on board.

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