Cowra Local Livestock Health Update - Barber's Pole Worm

This summer many producers have battled to stay on top of barber’s pole worm in their sheep. The warm, wet conditions over summer and autumn have been ideal for barber’s pole worm eggs to hatch. Given a single adult worm can lay 10,000 eggs per day it is not surprising that worm burdens have exploded in very short periods of time. A common misconception is that the first frost signals the end of our barber’s pole worm worries but unfortunately this is not the case.

Whilst the barber’s pole worm eggs will stop hatching when daily maximum temperatures drop below 180C, the worm larvae which have hatched already and are sitting on our pasture waiting to be eaten can easily survive cold, frost and even snow.

More concerningly they can survive for many months. Barber’s pole worm larvae survive until they use up their energy stores. At higher temperatures in summer this happens fasters, but in colder weather they use less energy and can survive longer.

A conservative rule in our area is that it takes 3 months in our hottest months and 6 months in our coldest months for 90% of the larvae on our paddock to die and a paddock to be considered “clean”.

In the Cowra district, daily maximum temperatures have still been hovering around the 180C required for barber’s pole worm eggs to hatch. While this is unlikely to continue for much longer, we need to assume that any worm eggs deposited onto our pastures in recent weeks have developed into the tough larval stage.

Historical weather records suggest by September, only 4 months away, we will be back up at these same temperatures. This means our heavily contaminated paddocks could easily harbour enough larvae over winter to cause an explosion again in spring, assuming we also have the moisture required for eggs to hatch. It is important that producers keep records of which paddocks wormy sheep have been running on and using a “traffic light” system can be helpful. For example a paddock that has had a mob of wormy weaned lambs on it is designated a “red” or “high risk” paddock. After a few months it may be downgraded to an “amber” or “moderate risk” paddock, progressing to a “green” or “low risk” paddock. This helps us allocate “low risk” paddocks to more susceptible classes of sheep – such as lambing ewes and weaned lambs.

Remember – worm testing is key.

Do a worm test on your sheep and get an idea of the worm burden. I’d also encourage producers to spend the extra money on a larval culture to find out what species of worms are present. Scour worm numbers usually peak for us in late winter, so it’s important we know what worms we are battling so we can best target them with appropriate drench choices and management strategies.

Worm test kits are available at the Local Land Services Office at 30 Lynch St, Cowra.

Given the grim situation I’ve just outlined, many producers have found themselves with no clean paddocks to lamb down on. This means if they drench with a short-acting “knockdown” product only and put them into “dirty” paddocks, they will be immediately picking up larvae which can develop into a fatal worm burden in a matter of weeks, often before lamb marking. While we always advise avoiding long-acting drenches if possible, when we are faced with limited paddock choices, long-acting drenches may need to be considered.

If reserved for these times and used correctly with a priming and tail cutter drench, the risk of developing resistant worms can be reduced. Please seek advice from your vet or livestock advisor before using any long-acting products.

If you would like further information or to chat about any animal health issues, please feel free to contact your local district veterinarians: Em Johnstone (0419 334 077) Or call 1300 795 299

• Topics:
• Agriculture / Farming
• Animal Health