Friday, 18 September 2020 09:47

Long-acting drench treatments called into question – again

Written by  Staff Reporters
New research has cast even more doubt on the economic value of drenching ewes with long-acting products. New research has cast even more doubt on the economic value of drenching ewes with long-acting products.

Even more doubt has been cast on the economic value of drenching ewes with long-acting products, following a recent jointly-funded Beef + Lamb New Zealand study.

The study led by AgResearch’s Dave Leathwick and co-funded by B+LNZ and AgResearch, showed that initial benefits of drenching with these products, especially to low body condition score ewes, were short-lived. It also showed the effectiveness declined in the interval after the treatments had expired. Untreated ewes tended to catch-up to their treated equivalents.

“This has also been seen in other New Zealand studies and highlights the danger of only assessing benefits at the end of the drug’s pay-out period,” Leathwick says.

He explains that many sheep farmers treat their ewes pre-lambing with long-acting drench products (capsules or injections). 

“This is in the expectation that both their ewes and lambs will benefit, however, this study shows that any benefits seen at weaning are likely to over-estimate the true value.”

This latest published research builds on previous studies from NZ and overseas, which have shown that animals treated with long-acting drenches have reduced immunity to worms because they are not being exposed to worm antigens every day.

“The sheep’s immune system needs to ‘see’ worms every day in order to function at its best,” Leathwick says.

This means that when the drug delivery ends, the ewes tend be to be less resilient to worms than those that weren’t treated.

“The true benefit is likely to be less than expected,” he adds.

These results follow on from previous studies, which highlighted that for many farmers, pre-lamb drenching may result in a net financial loss rather than gain.

This occurs because the biggest driver of financial return is lamb survival and not extra weight added to ewes or lambs at weaning.

Lamb survival is highly variable between farms and seasons, as well as treated and untreated ewes.  “This means farmers would benefit more from focusing their efforts on lamb survival to weaning than worrying about parasites,” Leathwick concludes.

Further trial work and modelling carried out in NZ showed that treating ewes pre-lambing with long-acting products increases the risk of developing drench resistance on the farm.

“For most sheep farms today, it is almost too late because resistance is now extremely common.

“For them it is now a case of farming with resistant worms. One certainty is that drench resistance will not go away if you keep drenching all the time.”

More like this

The best job in NZ agriculture!

Newly-appointed chief executive of Beef + Lamb New Zealand, Kit Arkwright, says he has landed the best job in the agriculture sector.

Splitting the difference

Beef + Lamb NZ is calling on the Government to use the split gas approach in its recently announced climate action plan.

Beef + Lamb New Zealand reacts to Global Methane Pledge

Beef + Lamb New Zealand (B+LNZ) says it is concerned the Government’s support for the Global Methane Pledge, announced at COP26 this week, does not adequately articulate its focus on methane originating from waste and fossil fuel sources.

National

Machinery & Products

New features on Case IH Optum

The latest Case IH Optum AFS Connect range features a new cab, interior and connectivity package designed to benefit both…

Sustainable battens and outriggers

A Christchurch based business has designed, developed, manufactured and released a modern alternative to the traditional wooden fencing batten.

» The RNG Weather Report

» Latest Print Issues Online

The Hound

No bull!

OPINION: Your canine crusader has had a wee bit of feedback about the new gender and sexual identity change being…

Tainted?

OPINION: This old mutt has questioned before the objectivity of research produced by Landcare Research on regenerative agriculture (RA).

» Connect with Rural News

» eNewsletter

Subscribe to our weekly newsletter