Is it time for compulsory drench resistance tests?

New England sheep producers undertake pilot project to better manage worms

Sheep on the property of John Anderson, Brookside, Armidale, whom underwent a pilot project to overcome worm burdens.

Sheep on the property of John Anderson, Brookside, Armidale, whom underwent a pilot project to overcome worm burdens.


Focus turns to high worm burden areas.


NEW England sheep producers are undertaking a pilot project testing their flock's drench resistance in a bid to better manage worms in the high burden area.

Featuring 15 landholders from Uralla, Aberfoyle, Guyra, Armidale and Bundarra, each property underwent Faecal Egg Count Reduction Testing (FECRT) using producer selected products which were then independently analysed by Invetus Parasitology.

The tests were part of the Target Sheep program, a three pronged approach to optimise the health and performance of sheep at pre-joining, pre-lambing and marking through drench management, nutrition and vaccination.

Worm related illnesses can cost the industry $430 million each year, which in a high rainfall area averages $28.29/head in loss of production.

While some leading project participants had four or five drenches with high levels efficacy, many had just two options that weren't resistant or at the onset of resistance.

Organiser and Virbac New England area manager Will Hiscox delivered some of the findings during a recent event in Armidale and said attendees were most surprised to learn of the varying levels of drench resistance even between closely located properties.

John Anderson, Brookside, Armidale, and Virbac New England area manager Will Hiscox.

John Anderson, Brookside, Armidale, and Virbac New England area manager Will Hiscox.

"I had some farms that were five fences apart and one was showing low levels of resistance and one was the opposite," he said.

"They could have been really good managers and at one point bought in sheep that were full of resistant worms and bought resistance on. The best managers can have the worst resistance, it varies a lot."

It is recommended that drench resistance tests are undertaken every two to three years.

Mr Hiscox said resistance levels in the New England may have escalated due to a lack of successful quarantine drenching and visual rather than technical assessments.

"There were some (producers) that believed they were fine, and following the testing we didscovered some of the drenches they were using in their program were showing high levels of resistance," he said.

"They weren't seeing a lot of sheep dying, they may have had the odd few, but say that drench was working at 80 per cent, following a drench the sheep would have looked healthy enough but in five years time that drench may completely break down and the farmers could incur some significant stock losses."

With many new drenches already showing signs of resistance and much of the New England relying on combination drenches, Mr Hiscox said it was important that producers looked after the products that were currently available.

"Quarantine drenching especially at the end of the current drought is going to be important," he said.

"Everyone is going to be trying to buy stock in from all over the place. There will be the potential for a lot of drench resistant parasites to be shifted from farm to farm right across NSW.

"It is important to know your resistance status. You have got to know what the worm population is doing on your farm and then if certain actives are breaking down on your farm, you will need to either prime that drench with another active or mix it into another combination to protect it.

"Animal pharmaceutical companies aren't overly willing to invest in new sheep drenches now because the financial forecasting on making a new sheep drench is quite negative because they are seeing newer drenches breaking down quite quickly, so you have got to look after what you have got."

The producers' perspective

Among the producers who took part in the program was John Anderson, Brookside, Armidale, who currently runs about 7000 sheep alongside a cattle herd on 9000 acres.

John Anderson, Brookside, Armidale.

John Anderson, Brookside, Armidale.

Brookside were one of the top performers in the pilot project with at least four drenches registering excellent efficacy, while only one had fallen to a strong resistance level.

While they aim to undertake regular drench tests, Mr Anderson said being a closed flock and implementing rotational grazing practices had benefited their worm burden.

He has split sheep into groups of 1000 head each which are rotated each week across the property.

"Since we started rotational grazing our sheep losses are very minimal compared to when we had them set stocked," he said.

"We are trying to get smaller and smaller paddocks. We are trying to fence our paddocks so we can move sheep off the camps and get them grazing the whole paddock.

"When you do get decent rainfall Barber's Pole can hit sheep very quickly. If you can be testing them well in advance of a rainfall event and no what level of worm burden they are carrying, you can plan for your next drench.

"It's also important to do another follow up test following the drench to see if it worked."

Fellow participant Phil Carlon, Queenlee, Uralla, also had positive results from the tests with four to five drenches still performing well on his 8000 acreproperty which only tested positive to Barber's Pole.

Virbac New England area manager Will Hiscox and Phil Carlon, Queenlee, Uralla.

Virbac New England area manager Will Hiscox and Phil Carlon, Queenlee, Uralla.

Shearing 14,000 Merinos this year, Mr Carlon undertakes drench testing as much as he can and knows the importance of worm control after battling problems through the summer.

In 2000, Mr Carlon expanded his holdings and purchased a property nearby. Noting the differing worm burden and drench resistance he implemented quarantine drenching within his own operation.

"Anything that comes from there back on to the property I tend to dose them, lock them up in the yards for a couple of days and empty them out," he said.

"I have been running the wether lambs out there a fair bit so they go from there straight to the abattoir so they are not coming back onto this (cleaner) country."

Is it time to provide drench resistance test information to buyers?

Both men agreed sheep producers needed to be undertaking drench resistance tests, but more importantly, disclosing the information when selling their livestock.

While both producers operated a closed flock, excluding ram purchases, they agreed online auctions or even Sheep Health Declarations should include the resistance information.

"After seeing the results presented at the Virbac Target Sheep lunch the other day it would be useful to know the drench resistance status of the farm you were purchasing sheep from. So if you are going to give a quarantine drench for bought in sheep, you know it's going to work," Mr Anderson said.

"You can buy sheep online and you will see that they have been drenched and vaccinated but you don't know if that drench has worked so it's important to quarantine drench all stock entering your property," Mr Hiscox said.

"You should use four actives, at least, when quarantine drenching."

While Mr Carlon focused on breeding sheep with resistance, he argued perhaps the industry was missing a critical aspect to overcoming worms.

"We are only breeding for resistance and we haven't got a test for resilience," he said.

"So those ewes that are out there with a belly full of Barber's Pole and it doesn't bother them, they just power on and we are not testing for those ewes.

"Are we going to go through a process where we have selected for all of this but we have culled out all our resilient ones which could have been the way to go?"

"Drench resistance information on an animal health statement would be invaluable."


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