Key points:

• Knowledge is essential for the right decisions.
• Drench-resistance testing and regular worm egg counts have made drenching more effective and less frequent.
• Integrating a number of control strategies has improved worm control.

John & Stewart's Story

When it comes to dealing with worms and worm resistance on the Esperance properties that John Wallace farms with his brother, Stewart, knowledge is paramount.

From participation in producer groups and local field days through to keeping up-to-date with the latest research information and expert advice, John makes sure he collects a wide range of information before deciding on a strategy for dealing with worms in his flock of 4-5000 Merino ewes.

And he’s recently discovered the WormBoss website, which he said is a handy source of reference material.

Previously, John has kept up-to-date with the latest Australian Wool Innovation research through his involvement in the local sheep production group, ASHEEP, and through the WA Farmers Meat Council, of which he is senior vice president.

He has also received valuable advice from the WA Department of Agriculture and Food’s Principal Veterinary Parasitologist, Brown Besier, and former Senior Veterinary Officer, Julian Gardner, prior to his retirement.

More locally, he has worked with Nicole Swan, of the nearby Swans Veterinary Services, who began doing faecal egg counting for their business five or six years ago. According to Nicole, it’s typical of ASHEEP group members to want to be well-informed. “They’re always looking for new ideas.”

As well as providing regular worm egg count results, Nicole advises John on worm management strategies, such as whether to drench and, if so, when and what with and how to deal with immunity problems.

Nicole says worm management is a particular challenge for farmers like John, with such large and varied operations. “Because they’re so busy, they try to fit things in when they’re handling them for something else, so that they can be time efficient and labour efficient.” This led John to coordinate his sheep monitoring with other tasks that involve handling the flock, such as scanning.

John has been in more regular contact with Nicole during the last couple of years as a result of more frequent worm counting. He now does worm egg counts twice a year, once in spring at crutching time and once pre-lambing.

“Worm egg counting is a major part of my strategy”, says John. “It means I know what’s going on and I’m not guessing.” As a result, John’s reduced the amount of drenching on the property.

Nicole agrees that worm egg counting is ‘the key’ to good worm management and, in particular, avoiding drench resistance.

According to Nicole, this needs to be backed up with regular resistance testing, to ensure the drenches are still working. This is slightly problematic, given resistance testing is even more time consuming for farmers than worm egg counts. “It’s quite labour intensive and is often done best at the time of year when they’re busy doing other things.”

But she says the results are worthwhile. “We have a lot of resistance problems here in Esperance. If farmers don’t conduct resistance testing, then they can’t drench appropriately, and eventually they will find that they no longer have any effective drench options.

John plans to carry out another resistance test with Nicole this year.

Nicole’s also been helping John identify the type of worms he has in his flock. “Most times it is scour worms”, says John. “It just depends on the stocking pressure and how long you can defer the pastures as to what sort of worm pressure you end up with.”

To combat scour worms, John has been using moxidectin and abamectin pre-lambing, but has avoided ivermectin due to resistance concerns.

Barber’s pole worms have proved a particular problem in recent years, due, at least in part, to the high number of perennials on the properties. To combat this, John now drenches his ewes at crutching time in early October with closantel, a narrow spectrum drench that is long-acting against barber’s pole worm.

He has made a conscious effort to time his drenching to coincide with the changing of the seasons. Summer drenching, meanwhile, became a thing of the past when John discovered that by drenching onto stubbles, he was adding to resistance issues.

Instead, John conducts worm egg counts on his weaner lambs by the end of October, then puts them out onto a purpose-grown standing oat crop. They are then monitored every six or seven weeks. John’s found that his crossbred weaners, which make up 15 percent of the flock, are less prone to worms and rarely need drenching.

The ewes are returned to pastures for a time, before 80% are trucked to other properties of John and Stewart’s east of Esperance. They return to the main property shortly before cropping.

John’s found the combination of cropping, beef and wool production is highly complementary, allowing him to run a high winter stocking rate, and to rotate cropping, beef and sheep to minimise worm problems and erosion.

WormBoss has been developed by Australian Wool Innovation Limited the Australian Sheep Industry CRC, with support by Animal Health Alliance (Australia) Ltd.