Tuesday, 23 April 2013 16:17

Worm risk when rain comes

Written by 

RAIN AND continued warm weather could see a surge in the worm burdens after the long dry, warns COOPERS  animal health Technical Advisor Hannah Field.

 

“Once it rains… if temperatures are still mild, worm populations can explode.” 

A high worm challenge will put pressure on young stock, so monitor the likely challenge by watching the weather and ideally faecal egg counting, she advises.

“Be ready to drench as worm burdens rise.”

While adult animals are generally more tolerant of worms, any in low body condition are already stressed so may also benefit from drenching.

Field warns against reaching for longer-acting drenches such as moxidectin without assessing which worm species are present.

“Long-acting drenches such as moxidectin are higher risk for resistance, and are often in a single active formulation, which is not recommended best practice; combination drenches are advised.

“Also, Moxidectin does not have the same long-acting activity against Teladorsagia (Ostertagia spp) and Trichostrongylus as it does against Barber’s Pole.”

If conditions are very warm – around 18 deg C - and wet, that’s when Barber’s Pole can reproduce rapidly.  A FEC and larval culture should be done to find out whether it’s prevalent.

“This will give you an idea of which worms to target. If Barber’s Pole is a good proportion of the worm population, then a long-acting drench is usually recommended.”

Fewer worms will have survived on pasture during the dry so particular care with drench use afterwards is needed to minimise the risk of selecting for resistance, stresses Field. 

Any worms surviving the drench are likely to be resistant and if worm numbers on pasture are still low because of the dry conditions there’s less competition or dilution from drench susceptible strains when the drenched stock are turned onto it. As the resistant eggs hatch, the majority of larvae ingested will be resistant. Once in the gut, they’ll mature to produce thousands more resistant eggs, resulting in a rapid rise in the resistant population on farm.

To avoid this scenario, Field recommends:

Drenching with a fully effective drench. “If you don’t know the resistance status of your farm use a triple combination drench, such as Coopers Alliance.”

If you do need to use a long-acting drench for Barber’s Pole, be sure to use an exit drench after this, such as a triple combination.

Note which parts of the farm were grazed by stock given the long-acting product and graze undrenched adult stock on them next to dilute any resistant worms that may have been shed.

More like this

Nervous wait for winter

The unknown of what winter will bring is very much on the mind of the Hawkes Bay Rural Support Trust head Mike Barham.

Rain eases drought worries

Farmers on the lower east coast of the North Island have welcomed heavy rains, which have fallen in the last week.

Rain flattens milk production

The persistent rain of the last four months is causing serious problems for dairy farmers in most regions of the North Island.

Featured

Creating a buzz on World Bee Day

The message for the 2025 World Bee Day is a call to action for sustainable practices that support bees, improve food security, and protect biosecurity in the face of mounting climate pressures.

NZ supports rules-based system

Deputy Prime Minister Winston Peters often describes NZ as a small and isolated nation situated 'just north of the penguins' but says in terms of global affairs, NZ and other small nations should be judged on the quality of their arguments and not the size of their military.

National

Machinery & Products

Iconic TPW Woolpress turns 50!

The company behind the iconic TPW Woolpress, which fundamentally changed the way wool is baled in Australia and New Zealand,…

» Latest Print Issues Online

The Hound

R.I.P. Sir Bob

OPINION: When news broke that Sir Bob Jones had died at age 85, the nightly news bulletins all led with…

Can't help itself

OPINION: Greenpeace claims that the appointment of Dr John Roche as the PM's Chief Science Advisor is handing the powers…

» Connect with Rural News

» eNewsletter

Subscribe to our weekly newsletter