August seasonal focus
Goats- using regional worm control programs for healthy goats and sustainable properties Goat producers have a lot of tools to manage worm burden in their herds. However, the treatment tools […]
Rain across eastern states prolongs the worm season
Widespread heavy rain across most of the eastern seaboard this autumn has increased soil moisture and pasture growth. It has also created ideal conditions for hatching of gastrointestinal nematodes including barber’s pole worm eggs, which require the equivalent of two days’ rain and mild temperatures (above 10ºC, optimum about 27ºC) to hatch and develop into infective larvae.
Bureau of Meteorology maps show heavy rainfall distribution across eastern Australia, from tropical North Queensland to Tasmania. The take-home message from this rainfall is that summer drenching programs to reduce paddock larval contamination may not be effective due to the wet warm conditions in autumn.
Worm larvae that develop at this time of the year (autumn) will have a longer survival time than those dropped in dry or hot conditions and a higher percentage is likely to survive through until springtime in most areas of eastern Australia.
This will be a problem not just for sheep and goats, but also for cattle producers as worm egg counts of just 100 eggs per gram (epg) have been shown to decrease average daily gain (ADG) of growing cattle by about 20%. As discussed last month, worm egg counts of just 20 eggs per gram in autumn of brown stomach worm (Ostertagia) can indicate that younger cattle (up to second calf heifers) are in danger of production losses or ill-health from this worm.
Producers are encouraged to weigh animals to check growth rate targets, look for signs of worms and monitor worm egg counts to ensure that worms do not cause economic damage to their herds.
Monthly worm egg counts slow drench resistance
In Sao Paulo State, Brazil, recent research from 27 sheep properties with barber’s pole worm (Haemonchus contortus) problems attempted to show patterns of farm management that helped determine whether drench resistance is a major problem.
The farm area, number of head and number of dams were found to be significant, reflecting the fact that properties with higher stocking rates are more likely to have resistance than those with low stocking density. Type of pasture was also found as a major predictor of resistance, consistent with previous research showing how properties of different forage species can greatly influence parasite larval survival.
The final factor able to predict resistance was monthly worm egg counts. This is associated with several management factors, including selective drenching only when animals need it, as well as the ability to choose the type of drench based on both worm numbers and species present.
This research serves as a reminder to sheep producers to test each mob regularly. Find a ParaBoss accredited WEC provider in your region and learn more about worm egg count testing.
Goats – DON’T use pour-on drenches
A study involving a meta-analysis of all research conducted across the world on the efficacy of worm drenches (anthelmintics) in goats has concluded that none work very well, but the pour-on drenches work worst of all. The research was conducted at the University of Adelaide in South Australia and published in the journal ‘Veterinary Parasitology’
More recent studies in France have confirmed that pour-on products such as eprinomectin which have been registered for dairy goats in that country are no longer effective against common worms. The researchers recommend that goat producers use alternative means to control worms, based on the principle of ‘Integrated Pest Management’ or IPM. For more details on this topic, watch the ParaBoss ‘Next Level Healthy Goats’ webinar. Learn more about zero grazing and management tools for healthy goat herds.
Back in Australia, a report on goat worm control commissioned by Meat & Livestock Australia has revealed that there is little prospect of getting more drenches registered for goats. The authors warn against goat producers trying unproven remedies and instead use Integrated Pest Management methods and ask their veterinarian for help with diagnostics as well as off-label use of drenches.
These research findings are a timely reminder that just about all uses of drenches (anthelmintics) in goats are ‘off-label’ and so should only be used on advice from your veterinarian. Your local vet will also be able to diagnose not just worms but all types of disease.
Use the WormBoss drench efficacy test instructions to check if your drench is working, before resistant worms start to colonise your paddocks and impact the health of your goats.
Cattle tick (Rhipicephalus australis) strategic control
The warm wet conditions across northern Australia have also prolonged the tick and buffalo fly season. Each female tick that matures and drops off cattle onto pasture can lay up to 3,000 eggs, causing massive pasture contamination in subsequent seasons. Cattle ticks on pasture in southern Queensland slow down and stop developing from about mid-April to June, so numbers seen on cattle during the June-October period are low. Cleaning up remaining cattle ticks in a herd in early autumn will help to suppress the numbers of ticks seen in the spring rise.
Sheep blowfly strike prevention – care with chemical rotation!
Late season rain has increased the susceptibility of sheep to flystrike. The risk is compounded by the fact that some of the most popular preventive chemicals have had their duration of protection slashed by resistance. In particular dicyclanil, which in 65g/L products has a label claim for up to 29 weeks protection, has been found to have a much shorter effective protection period in the field.
A paper has been published in Veterinary Parasitology in March 2024 (lead author Dr. Andrew Kotze of CSIRO) detailing resistance in Australian sheep blowflies. In particular, the rotation of chemicals between dicyclanil and imidacloprid has been highlighted as a risk for selection for resistance.
Managers are encouraged to rotate chemicals to another active ingredient (spinosad, ivermectin which both showed low levels of resistance in the flies) but to be cautious about rotating to imidacloprid, as it appears to select for dicyclanil resistance even more quickly than dicylanil itself. It is important to remember that application problems including wash-out in rain, will cause a lower residual of chemical in the fleece and therefore shorter protection periods.
Other tips for preventing blowfly chemical resistance include using a different chemical class to your lousicide on sheep, breeding sheep that are not susceptible to flies, and making sure application is effective.
Strategic Liver fluke control
Autumn is a good time to use an effective liver fluke treatment to control numbers of fluke both in the livestock and the environment. This is because transmission of liver fluke usually slows down as the weather cools. 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 10º C.
Because of widespread resistance in liver fluke in Australian livestock, check that your treatment works by doing a test on dung samples, once at the time of treatment and again 30 days later. Find a ParaBoss accredited WEC provider in your region.
The table below shows details of treatments available for sheep, cattle, and goats.
| Treatment | Formulation example (products) | Dose | Meat WHP/ESI | Comment* |
| Clorsulon+nitroxynil injection (beef cattle only) | Clorsulon 67g/L Nitroxynil 340g/L | 1.5ml/50kg | 70/140d- NOT for dairy cattle | Kills early immature fluke to 2w, immature and adult fluke |
| Triclabendazole oral (cattle or sheep) | Triclabendazole 240g/L sheep/cattle Triclabendazole 120g/L sheep/cattle | 1mL/20kg 1ml/10kg (cattle) 1mL/12kg (sheep) | 21/56d(c) 21/63d (s) 21d/56d Milk 21d before start of lactation | Kills early immature, immature and adult fluke |
| Triclabendazole + oxfendazole oral (cattle & sheep) | Triclabendazole 120g/L Oxfendazole 45.3g/L | 1ml/10kg | 21d/56d (c) 21d/63d (s) Milk 21d before start of lactation | Kills early immature (2w), immature and adult fluke, also kills other parasites susceptible to oxfendazole |
| Clorsulon+ivermectin injection (cattle only) | Clorsulon 100mg/mL Ivermectin 10mg/ml | 1mL/50kg | 28/42d Milk 0d | Adulticide Also kills other parasites susceptible to ivermectin |
| Albendazole oral (cattle, goats or sheep) | Cattle albendazole 112.5g/L Sheep or goats albendazole 19g/mL | 4ml/45kg (cattle) 1mL/4kg (sheep/goats) | 10d/10d NOT for dairy cattle | Cattle- adult liver fluke Sheep- Aids in the control of adult liver fluke Also kills other parasites susceptible to albendazole |
| Levamisole+ oxyclozanide oral (cattle or sheep) | Levamisole 75g/L Oxyclozanide 150g/L | 5mL/45kg (cattle) 1mL/10kg (sheep) | 14d Milk 0d (c) | Adulticide, also kills nematodes susceptible to levamisole, and assists in the removal of tapeworm segments in sheep and lambs. |
| Closantel oral (sheep only) | Closantel Na 37.5g/L | 1mL/5kg | 28d/60d | Immature (6w) and mature liver fluke, also kills other parasites susceptible to closantel |
| Closantel +albendazole+abamectin+ levamisole oral (sheep only) | Closantel 37.5 g/L Albendazole 25g/L Abamectin 1g/L Levamisole 40g/L | 1mL/5kg | 28d/ | Immature (6w) and mature liver fluke, also kills other parasites susceptible to closantel +albendazole+abamectin+ levamisole |
| Closantel +abamectin oral (sheep only) | Closantel Na 50g/L Abamectin 1g/L | 1mL/5kg | 49d/84d | Immature (6w) and mature liver fluke, also kills other parasites susceptible to abamectin and closantel |
Care with use of mectins in cattle
Analysis of sales figures shows that many cattle producers are using the same active ingredients (that is, mectins) for a variety of uses on their cattle.
The mectin class includes five popular molecules that are useful for cattle- ivermectin, abamectin, doramectin, eprinomectin and moxidectin. The class was released in Australia in 1986 and immediately had a major impact, as the products were safe and useful to treat a range of pests.
Cattle managers now use them to control:
- cattle lice (sucking and biting),
- a range of ticks that get on cattle (paralysis ticks, bush ticks, cattle ticks)
- buffalo flies, as well as nuisance flies
- internal parasites (gastrointestinal nematodes)
However, each time they are used they have an impact on resistance selection, not just for the pests being treated but also for ‘non-target’ parasites. This has led to internal parasites, including barber’s pole worms, brown stomach worm and Cooperia showing medium to high levels of resistance. Resistance in cattle ticks and lice has been noted in other countries, but not yet confirmed in Australia.
Producers are urged to check the class of active ingredient in the products they are using and use a different class of chemical for internal and external parasites. Using combination products gives higher efficacy and slows the onset of resistance against worms.