Key points:

• Capsules provide long term-control but have drawbacks; drench resistance can develop faster.
• Regular worm egg counts are the basis for drenching decisions.

Wayne's  Story

Drench capsules and more regular egg counting is helping Wayne Lewis of the Esperance Poll Merino stud, Fleming Grove, stay on top of parasites in his 6,000-strong flock.

With a 450mm rainfall, Wayne has traditionally had significant issues with barber’s pole worms on his 4000-hectare property. “In the past we used to just drench and drench and drench and then, same as everyone else, we got the resistance problems that everyone else got”, says Wayne.

“Then we started with capsules, when they first came out 10–15 years ago.” Because the capsules were expensive, Wayne used them in a two-year rotation with traditional drenching methods.

“Then we had a really bad worm year and that’s when we discovered how good a job the capsules were doing.”

Wayne now uses capsules, which release drugs over one hundred days, annually, rotating between mectin and non-mectin drench types.

“And 80–90 percent of the time that’s all we have to do for the whole year for all our livestock.”

The rest of Wayne’s drenching decisions depend on faecal egg count results.

Lambs are monitored every six weeks, and, where previously they were drenched at weaning time, this is often no longer necessary. While ewes are also monitored, worm burdens are rarely found.

Wayne also rotates his flock onto grazing cereals, which he says keeps worm numbers low. “Worms are not as prolific in those types of paddocks.”

He says the lower worm burden has also had a flow on effect, with fewer dags and, as a result, fewer fly problems.

Wayne designed his worm management solution based on advice from private veterinary consultant, Dr Bruce Farquharson.

Nicole Swan, of Swans Veterinary Services in Esperance, also has regular contact with Wayne. She says the capsules seem to be working well in his case, but that they do have their drawbacks.

“If you’ve got resistance to that drench, it can make that resistance worse.” She also says for some farmers, the cost is prohibitive.

She recommends farmers try them on a sample mob first, and do resistance testing before going ahead.

Wayne is about to carry out another drench resistance test, but says his current regime is working so well it is actually difficult to find enough worms to carry it out.

Nicole also says breeding strategies will play a greater role, particularly as drench options are reduced.

There will be no one answer to worm control, according to Nicole. “For sheep to be a viable option, people are going to have to use multiple practices to improve production and to justify having sheep as part of their farming operation.” Worm control will fit within this.

She’s also expecting to see tailor made program for each farm, which takes advantage of new developments as they occur.

This is a direction that worm management advice is already taking. “It’s gone from being a situation where you make a blanket recommendation to where you really need a program specifically for each farmer because of resistance issues.”

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