Weaner cattle - is your drench doing its job? - Elders Rural Services

Weaner cattle – is your drench doing its job?

A recent scientific article in the Australian Cattle Veterinarians (ACV) journal highlighted the need to check that your weaner drench is effective.

Drench resistance is widespread in Australia. 6-13,16  It is recommended that combination drenches (more than one active against the same parasite) be the standard treatment of cattle.

The ACV journal article outlined valuable data from 2018-2021 on:

  • the extent of drench resistance in Australian cattle worms
  • how different drenches are working against different worm types
  • productivity responses when more effective drenches are used on-farm.

Which worms are resistant?

Effective drench programs are essential to drive good productivity in young Australian cattle. 1,2,3,4

The important worms in Australian cattle are Barber’s Pole Worm, Cooperia and Ostertagia.5 Drench resistance in these worms can lead to a decrease in productivity.1,2,3,14,16

The ACV article collated 25 trial results to show that overall mean efficacy of single active drenches in Australian cattle can be estimated at only 72 per cent (pc). Drenches need to be working at 95 pc or better.

A summary of the mean results for pour-on drenches and worm type is found in table below.

table showing summary by pour on drench formulation for Faecal Egg Count Reduction Tests (FECRTs) and Total Worm Counts (TWC) completed between 2018 and 2021 in multiple locations in Australia. All data uses arithmetic mean.
Table showing summary by pour on drench formulation for Faecal Egg Count Reduction Tests (FECRTs) and Total Worm Counts (TWC) completed between 2018 and 2021 in multiple locations in Australia. All data uses arithmetic mean.

Other key findings include:

  • The dual-active combination of moxidectin and levamisole (Cydectin Platinum) was 99 to 100 pc effective against all key worms of cattle.
  • Barber’s Pole Worm and Cooperia resistance to ‘Mectin’ drenches is common. Levamisole is generally effective against these worms.
  • Moxidectin (as in Cydectin) has an advantage against ‘Mectin’ resistant worms, especially Barber’s Pole Worm, when compared to ivermectin and doramectin 15,16
  • Mean efficacy of doramectin pour-on against Barber’s Pole Worm across eight studies was 28.9 pc while mean efficacy of moxidectin pour-on was 75 pc. In one study, doramectin 1 pc injectable had an efficacy of 8 pc ,while Cydectin injectables were 99 to 100 pc effective.
  • Mectins are performing adequately against Ostertagia on many farms but resistance has been detected. Moxidectin was still 97 to 100 pc effective in controlling Ostertagia in five scientific studies. Levamisole used on its own was not always reliable against Ostertagia and should be used in combination with another active for reliable worm control.

A nitroxynil and ivermectin combination (Nitromec) had very high efficacy (100 pc) against  mectin-resistant Barber’s Pole Worm suggesting that nitroxynil might be an undervalued active for treatment of this parasite.

The impact on cattle

The impact of drench resistance in cattle is often not severe illness or death, like in sheep; but instead, significant loss of productivity.

Over a period of eight weeks, the failure to effectively remove worm burdens in growing cattle can mean a potential loss of 8 to 12 kg.1,2 While many cattle producers can visually identify a difference of 30 to 50 kg, it is difficult to identify a productivity loss of 8 to 12 kg.

This is one reason that drench resistance may remain unidentified on some cattle properties. Which is a problem, because investment in genetics and feed may be undermined by failings in the animal health program.

In 2020-21 James Cook University (Townsville, Queensland) and New South Wales DPI (north coast, NSW) investigated cattle weight gain following treatment of weaners with different drench products. The combination drench, Cydectin Platinum, led to increased weight gain (for example 8 kg more than doramectin pour-on over two months).

Virbac senior livestock technical services manager Dr Matt Ball encourages farmers to ensure they choose the most effective cattle drench to fight parasites.

“We now recognise that single active drenches are no longer effective to control all key worms or protect productivity,” Dr Ball explained.

Cydectin Platinum

Cydectin Platinum is the next generation dual-active pour-on drench for cattle containing moxidectin and levamisole. Benefits include:

  • unrivalled worm control (99 to 100 pc)
  • highly effective against single and dual-resistant worms
  • seven day withholding period
  • only combination drench with persistency – prevents pasture contamination for up to 35 days
  • no known impact on dung beetles.

It also is the first veterinary use of DMI-SorbTM technology to keep the product concentrated to the areas where it was applied and reduce absorption variability. All in the convenience of an easy to use low volume pour-on.

Cattle producers are encouraged to work with advisors to seek improvements in their parasite management programs.  The use of combination drenches should be the default position when chemicals are needed to protect the health and productivity of cattle.

Article written by Virbac for Seasons magazine. 


Canton et al (2019) Impact on beef cattle productivity of infection with anthelmintic-resistant nematodes, New Zealand Veterinary Journal, 68: 187-192.
NSW DPI (2020) Duck Creek Endoparasite Trial – Virbac Data on File.
Virbac (2016) Weaner Productivity Trials – Virbac Data on File
Eppleston & Watt (2016) Post Weaning Growth of beef heifers drenched with long and short acting anthelmintics, Australian Veterinary Journal, 94:341-346.
The Australian Society for Parasitology (2014) Australasian Animal Parasites Inside Out. E-Textbook.
Sutherland and Leathwick (2011) Anthelmintic resistance in nematode parasites of cattle: a global issue? Trends Parasitol. 27(4):176-81.
Rendell (2010) Anthelmintic resistance in cattle nematodes on 13 south west VIC properties. Australian Veterinary Journal 88:504-509
Wonders (2016) What does anthelmintic resistance mean for worm treatment in cattle? Proceedings of the 98th District Veterinarians conference.
Rendell, Homer, Rolls, Webb-Ware, Cotton, Beall, Larsen (2014), Anthelmintic resistance in cattle nematodes on thirty-six Victorian properties, Proceedings of the 28th World Buiatrics Congress 231–244
Cotter, Van Burgel, Besier (2015), Anthelmintic resistance in nematodes of beef cattle in south-west Western Australia, Veterinary Parasitology 207, 276-284
Lyndal-Murphy et al (2010) Reduced efficacy of macrocyclic lactone treatments in controlling gastrointestinal nematode infections of weaner dairy calves in subtropical eastern Australia. Vet Parasitology. 168:146-150.
Bullen, Beggs, Mansell, Runciman, Malmo, Playford, Pyman (2016), Anthelmintic resistance in gastrointestinal nematodes of dairy cattle in the Macalister Irrigation District of Victoria, Australian Veterinary Journal 94, 35-41
Eagleson, Bowie, and Dawkins (1992). Benzimidazole resistance in Trichostrongylus axei in Australia. Veterinary Record 131, 317-318
George M, George M and Kotz A (2020) Production impacts and resistance of gastrointestinal parasites in feedlot cattle, MLA: B.FLT.3002
Pritchard and Geary (2019) Perspectives on the utility of moxidectin for the control of parasitic nematodes in the face of developing anthelmintic resistance, International Journal for Parasitology- Drugs and Drug Resistance, 10:69-83.
Ball and Gibbison (2021), Resistance Patterns to Avermectins and Milbemycins in Australian Cattle Nematodes, ACV Journal Dec 2021.

Virbac Cydectin is available for sheep and cattle at your local Elders store.

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