Containment feeding

Parasite Management – 2021 Update

It took some time for me to get my head around the multitude of worm and fluke drenches on the market. It wasn’t until I sat down with my vet and developed (and documented) an annual parasite management plan that everything made sense. I thought I’d share our plan and the reasoning behind it for anyone else who might be interested.


There’s a number of considerations that go in to developing an annual parasite management plan. These include:

  • Which parasites are compromising production in your environment
  • The lifecycle of parasites
  • The impact of parasites on different classes of livestock
  • Convenience of administration (in the context of other management activities)
  • Drench resistance
  • Cost

It’s important to recognise that the plan I’m describing here is relevant to our environment and production system and may not be appropriate for yours. We are a Spring calving, self replacing herd, turning off feeder steers and bulls at 14-15 months. We are in the high rainfall zone with lots of wet areas.

I can’t emphasise enough the value of sitting down with your vet to have this discussion. I can highly recommend Dr Brad Goonan from Murray Valley Veterinary Service. Brad’s practice is focussed on equine and production animals and is happy to travel a reasonable distance from his base in Albury.

Our Plan

Let’s dive right in and look at the overview of our plan before I explain it.

Our parasite management program for young cattle


The first thing to note is that we calve in the Spring and the plan kicks of with weaning in late Summer. Weaning is a stressful time for calves and a pour-on product helps to minimise further stress at this time. We use the combination product Cydectin Platinum which combines a ML (‘mectin) class worm drench (Moxidectin) with a LEV class worm drench (Levamisole).

Post Frost

We wait for a couple of heavy frost events before we treat the weaners again. This can occur anywhere from Late May to mid-June. At this time we use an oral fluke drench which combines Triclabendazole with a BZ class worm drench (Benzimidazole). The tricla’/BZ combination works on all fluke down to 2 weeks old. Cold weather knocks out the fluke in the environment so we can be confident that the calves will be fluke free after drenching until things warm up again.

While the BZ worm drench is present in the Flukazole, we also use a ML (‘mectin) at this time because they work so well. Previously it was the long acting Cydectin Injection but we’ve moved away from this product because

  • it’s a hassle injecting behind the ear (as instructed),
  • some in the industry suggest long acting mectins may increase probability of worms becoming resistant to MLs,
  • we were not saving on a later yarding as we want to weigh the weaners at the start of spring anyway, and
  • injectables don’t control biting lice.

We use Cydectin pour-on at this time to also target biting lice and because of its persistent activity. While probably not compromising performance, biting lice have caused some surplus heifers to be less marketable e.g. rejected for export orders because they’ve rubbed off a lot of hair. Cydectin (moxidectin) is also dung beetle friendly.

Autumn dung beetle activity

First Weigh in

In the early Spring we use a Clorsulon (fluke) and ML (worm) combination product such as Baymec Gold. Other interchangeable products include Virbamec Plus and Noramectin Plus. Clorsulon products are generally cheaper than tricla’ and nitroxynil products and target tricla’ resistant fluke. As they only work on adult fluke, this the appropriate time of year to slot them into the mix.

This is the last treatment for most of the steers as they are off to the feedlot in October.


Replacement Heifers (and their bull mates) get a straight ML at joining to optimises their health for the rest of the Spring. We use Cydectin Pour-on again for ease of use, and to save putting yet another product in the shed. When purchased in a bigger volume pack size the cost is similar (or less) than injectables. The injectables may kill parasites more quickly, however the pour-on has a longer persistent activity window.


A treatment at preg testing helps to keep those heifers ticking along early in their gestation. Heifers are in the chute for scanning so an injectable product is convenient enough. We also give them a squirt of LEV (about $1.20/head) to tick off another worm drench active. Heifers also receive an annual vaccination booster at this time.


An early-winter drench for our first-calvers is typically the last worm drench our breeders receive. Occurring after the frosts, this drench is the same as the weaners get at this time: A ML pour-on and a combined oral white drench (BZ) with tricalbendazole. The products we use are Flukazole and Cydectin for the same reason as the weaners: 42 days persistent activity on osteragia and control of biting lice. The selenium is a bonus but not nearly enough of a supplement. See other posts for our thoughts on supplementing mineral deficiencies.

Preventing Drench Resistance

To prevent/limit the development of parasites resistant to a certain class of drench, we make point of using a range of available drench classes in any given 12m period.

Here’s a quick summary of the classes:

Worm Drenches

  • ML – the macrocyclic lactones or ‘mectins
  • BZ – the white drenches (mostly oral)
  • LEV – clear drenches

Fluke Drenches

  • Triclabendazole
  • Nitroxynil
  • Clorsulon

While the ML class (‘mectins) are superior to other classes of worm drench, the BZ and LEV drenches play a role in controlling parasites that are resistant to MLs. Similarly, Triclabendazole is the superior active for controlling liver fluke. Clorsulon alone only tackles adult fluke including those resistant to Tricabendazole. Interestingly, the combination of While we don’t use it, Nitroxynil with Clorsulon tackles fluke down to 2 weeks of age as well as tackling fluke resistant to Triclabendazole.

For a more detailed comparison of drench classes including example products check out Drench Chart in our Resources Section

Combination Drenches

Combination drenches have become available in recent years and are worth concidering. For example Coopers Trifecta has all three classes of worm drench but is an oral drench and it doesn’t do fluke. Eclipse (by Boehringer) is similar to Cydectin Platinum in that it covers two classes of worm drench (ML+LEV) and is a pour-on that does not do fluke. Eclipse uses abamectin while Platinum uses moxidectin. Abamectin has a long withhold and low persistent activity while moxidectin has a 14 day withhold and 35 days persistent activity on Ostertagia.

Other classes of livestock

As cows tend to be more resilient to worms, we do not routinely drench them for worms. They do however get an annual winter fluke (only) drench with Flukcare. This gives them a few months (through the winter) to be fluke free and for their livers to regenerate (its the only organ that can do this), and be in decent condition before re-infection starts to occur in the spring.

Bulls don’t have the same resilience to worms that cows have so they get combination drenches in winter and at joining.

I hope this post has been useful in helping you reflect on your program. If you liked it please share on social media and don’t forget to get some expert advice from your vet.

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