Good parasite control underscores healthy stock

Boehringer Ingelheim Animal Health NZ technical veterinarian Richard Sides.

With beef prices remaining strong and lamb making record returns, farmers are heading in to a busy spring and new farming year.

And this means the marginal return on good animal health has never been greater for getting stock off on a foundation to deliver them in premium health and weight, for future breeding or slaughter.

Boehringer Ingelheim Animal Health NZ technical veterinarian Richard Sides says most farmers appreciate that to achieve this includes giving their young stock “a good drench”. 

But it’s also a good time to give the practice some close scrutiny. This season he’s urging farmers to take time to develop a comprehensive animal parasite control programme with their vet to get a clear profile on resistance and effectiveness issues they may not know about in their herd or flock.

“There has been some talk about triple resistance developing in recent years. That has always been on the cards, the minute you put any drench product into an animal you’re applying selection pressure on the parasite population within.”

Faecal Egg Count

But Richard maintains there is no need to panic, particularly if farmers are not even clear on what their own property’s status is.

“You don’t know what you don’t know – so the most proactive approach is to work with your vet to find out, starting with Faecal Egg Count testing.”

“Really this should be done as a proper, planned reduction test – an FECRT – seeing what the populations are before and after a drench programme. Just doing a one-off post-drench check means there are simply too many possibilities you get the wrong information, use the wrong product and possibly make any resistance issues worse.”

A vet skilled in parasite management will establish what the efficacy of particular drenches are on the property. They’ll also help work out methods to maintain a refugia population on the property.

At its simplest it will be determining a proportion of the flock or herd that is not drenched, to ensure resistant parasites are well diluted within the worm population. A key factor is ensuring drenched animals, in particular lambs, don’t go straight onto ‘clean’, parasite-larva-free, pasture.

“It’s important to also ensure the refugia (undrenched) animals are mixed around the farm and across mobs to disperse that population of refugia parasites,” says Richard.

“Because of this, it’s essential the resistance status of those parasites is known – hence the need for proper reduction tests. These are easier and cheaper to do than most people realise.”

Richard has also worked with farmers on other management practices that ultimately result in lower parasite populations in young stock.

Time and investment in good dam health prior to calving and lambing will reduce young stock’s vulnerability to parasite levels, and the need to drench more than necessary.

“Having your ewes or cows in top notch condition means less stress in spring time, better milk production, faster growth rates and getting youngstock away quicker, reducing parasite exposure in the process.”

Avoiding risky management practices, like putting freshly-drenched young stock onto brand new pasture where there is no refugia parasite population, is essential.

And effective quarantine drenching is also vital for bought-in stock – again requiring knowledge of drench-status.

“Overall, the ‘big picture’ is important for farmers to see,” says Richard.

“Issues like parasite resistance, and the arrival of M. bovis, are all about biosecurity, risk management, and having quality information available to make the best decisions possible.”

Richard says investment in a sound parasite control plan will deliver returns within the season, through maximising growth of young stock, and beyond, as the risk of perpetuating resistant worm populations are delayed on-farm.

“There’s no need to panic – with some good planning and communication the options remain viable and effective.”


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