April seasonal focus

Liver fluke Fasciola hepatica

Livestock producers across the liver fluke regions in eastern Australia use April as a chance to get on top of liver flukes in their flocks and herds. This is because the host snails that transmit liver fluke are very sensitive to cold and/or dry conditions, so we can predict the high-risk periods for liver fluke in stock. The change of seasons in autumn enables a complete control program.

Transmission of liver fluke usually slows down as the weather cools. This means that when the first frosts occur, further pickup of liver fluke is unlikely. In coastal areas, liver fluke risk remains at a low level when the temperatures drop below 10^oC.

You can view the liver fluke life cycle – video courtesy of Ridgeway Research.

Liver fluke control tips

1. Check if your stock need treatment with a liver fluke test by taking dung samples and submitting to your vet or lab. If the lab does a sedimentation test (for liver fluke eggs) this will tell you if adult flukes are present. Since adult flukes take 12 weeks to mature and lay, immature fluke can still be present when you get a zero count. Some labs will also do a liver fluke ELISA test, which also picks up immature fluke.
2. Treat with an effective flukicide. Resistance to triclabendazole and albendazole have been confirmed recently and closantel resistance is also reported. See below for available treatments.
3. Do a 30-day post-drench fluke egg count to check that the treatment has worked. Note that this is different from worm egg count drench checks (14 days), because the fluke eggs take longer to be expelled from the bile ducts.

Liver flukes are happy to infect other grazing animals including kangaroos and will even infect humans.

More information on liver fluke

Ostertagia (brown stomach worm) in cattle

Veterinarians across southern Australia report that late summer and autumn is the peak period for outbreaks of ostertagiosis in cattle. These worms burrow into the lining of the fourth stomach (abomasum). The disease is mainly seen in yearling to three-year-old cattle but in recent years severe cases have been seen in adult cattle as well.

Cattle that survive have multiple scars in the wall of the abomasum that can affect lifetime productivity. Now is a good time to check for this worm by doing a worm egg count and larval culture. Since up to 90% of the Ostertagia worms can be ‘inhibited’ and therefore not laying eggs, even low worm egg counts (down to 20 eggs per gram) can indicate a problem.

More cases are being seen in recent years, possibly because of development of resistance to commonly-used drenches (anthelmintics). To do a drench resistance test, consult your veterinarian or see the WormBoss instructions.

Watch this webinar to find out more about this disease. Additionally, you can also visit the WormBoss page.

Cattle tick (Rhipicephalus australis) autumn strategic control

Autumn is a great time to get on top of cattle ticks. This is because the development of larvae from eggs on pasture slows down over the cooler months. Hitting the remnant adult tick population in your herd with a short-acting treatment now will minimise the number of eggs surviving and infecting cattle next spring.

For more information see the article in TickBoss.

Biting insects including buffalo flies (Haematobia irritans exigua)

Warm, wet conditions across most of northern Australia mean a prolonged season for biting insects. This means that the buffalo fly season in North Queensland and the Northern Territory continue to cause irritation and loss of production in northern herds. Treatment at this time of year should focus on short-acting treatments. See the TickBoss product search tool for more information.

The conditions are also ideal for midges and mosquitoes that spread disease such as three-day sickness, also known as bovine ephemeral fever (BEF). There is a vaccine available to protect animals from this disease because mosquito control is not practical. See your local vet or rural store for details.

More information on buffalo fly seasonal distribution.

Resistant worms in sheep

Laboratories across Australia have been kept busy over the past year diagnosing resistance in sheep worms. Patterns vary somewhat from region to region, but there are some clear trends emerging.

1. Multiple-resistant brown stomach worm (Teladorsagia circumcincta) The brown stomach worm takes advantage of the late part of summer to survive in dungpats and pellets long enough to hatch out with the autumn rains. Many locations now have brown stomach worms that survive all 3 of the chemicals usually found in the combination drenches (mectins, levamisole and benzimidazoles). This is concerning as these chemicals have been the first choice for many producers across southern Australia for this worm.
2. Barber’s pole worm (Haemonchus contortus) Because of their nutrient-rich diet; blood! these worms have very high egg-laying capacity (fecundity). Females can lay up to 10,000 eggs in a day! That means that even a single survivor after a drench can then re-populate a whole paddock with her resistant progeny under the right seasonal conditions.

Use the WormBoss drench efficacy test instructions to check if your drench is working, before those resistant worms start to colonise your paddocks.

Goat worm pressure ongoing

Use knowledge of worm life cycles to your advantage – can you utilise browse to help with some paddocks clean up? This is where grazing shrubs helps to decrease the amount of worms entering the goats. Every little bit helps. Check out this link that discusses using pasture and browse for worm control in goats.

Be sure to consult your veterinarian about your goat worm control program.

And always remember – Test – Don’t guess!