Alternatives needed to beat drench resistance

Former All Black and head coach of the Auckland Blues Leon MacDonald speaks to a group of farmers...
Former All Black and head coach of the Auckland Blues Leon MacDonald speaks to a group of farmers at the Tarras Community Hall last Thursday. PHOTO: SUPPLIED
Chemical-resistant worms might sound like a phrase lifted from the pages of a science fiction novel, but the conversation was very real for several Central Otago farmers last week.

More than 60 farmers from across the region gathered at the Tarras Community Hall to hear from Dr Andrew Dowling, PGG Wrightson’s technical expert for animal production, on the growing problem of drench resistance on New Zealand farms.

Drenching is the process of orally administering liquid compounds to animals in order to eliminate parasites such as worms.

Although practised on farms across the world for decades, drenching’s effectiveness at combating worms in animals such as sheep has been plummeting, PGG Wrightson technical field representative Dan Pavey said.

"There’s no R&D around the world, at the moment, on drenches.

"We can’t introduce a new chemical because there’s no chemistry coming.

"So it’s a whole mindset change for farmers."

While drench resistance "isn’t new" the lack of scientific innovation in the field often left farmers feeling as though they had few alternatives, Mr Pavey said .

The solution, he said, was to make "little changes" in animal and pasture management.

"So we’re saying to farmers now if a ewe or a lamb is nice and healthy and big and plump and looking a million dollars, don’t drench it.

"Because obviously, its immune system is working quite all right."

Other measures covered in Thursday’s talk included grazing different species on the same pasture and growing plant species that minimised the chances of lambs ingesting parasites from the dirt.

Following Dr Dowling’s presentation, the assembled farmers were treated to a Q&A session with former All Black and Auckland Blues head coach Leon MacDonald.