Cattle Drench Options
There are a variety of drench options available for cattle. Understanding how and when we use them is important.
Oral
Oral drenches are a good option for a variety of reasons. They are generally cost-effective, they come in the greatest number of combinations of active ingredients (single, double and triple) and are easy to give in small animals. Orals are designed to be absorbed from the rumen, and some contact with the worms also improves efficacy. In a trial of different moxidectin (an ML) formulations, the most effective route to control Cooperia was the oral1. However, regardless of administration method, Levamisole is the most effective active ingredient to control Cooperia. No oral drench controls lice, and they all have meat, milk and bobby calf withholdings making them less suitable for older (dairy) stock.
Injectable
Some people prefer the more reliable dose accuracy of injectable drenches, as there is no risk of a dose being spat out or risk of inefficacy if using a pour-on due to dirty coats or rain.
Recent trial work has demonstrated that injected ivermectin attained higher concentrations in resistant Ostertagia parasites and in the abomasal mucosa where they are located, than when it was given orally2. However, the same trial also showed that the highest levels were attained in Cooperia parasites when the drug was given orally. Different parasites may be killed more effectively by different routes of administration of drug1,3.
Most injectables have longer meat, milk and bobby calf withholding periods, making them more useful in younger stock, although there are some exceptions.
Pour-On
Pour-ons provide a convenient route of administration that can be the safest option in certain handling situations for operators. Some products have no withholding periods which is useful in all classes of stock (e.g. flexibility to treat all animals, as and when they need it). Pour-ons generally have efficacy against both biting and sucking lice, although there are exceptions.
Short acting
All oral drenches, most injectable and many pour-on drenches are short acting. This means they kill the parasites in the animal at the time (and potentially up to a few days after). After drenching, if animals are returned to contaminated pasture, they will rapidly get reinfected with larvae which may then impact health and productivity.
Long acting
These drenches remain in the body at levels high enough to continue to kill susceptible incoming larvae that are ingested with feed, for the times stated for each worm on the label. This varies between actives and product type. Long acting drenches are a risk factor for drench resistance so should be reserved for when animals need more parasite protection (e.g. young calves on very wormy pasture, poor conditioned older animals, sick animals, and/or when pasture cover is low).
Drenching Young stock
When calves do need a drench, after all other Wormwise guidelines have been followed, consideration should be given to which drench to choose. The best drench any animal can receive is an effective drench and each farm will have different worms that are more susceptible or resistant to different drenches and actives within them.
In general, a triple combination is better than a double, which is better than a single - simply because the worms have less chance of surviving more than one active ingredient. When it comes to mode of application (oral, injection or pour-on), this is best determined by several factors:
- Ability of the user
- Handling facilities on farm
- Age
- Weight of animal
- Temperament of the animals
- Species of worms you want to kill
Oral drenches are easy to give in young small, quiet animals, but as they get heavier, this can be more problematic. Orals that contain levamisole are best for killing Cooperia, which is a key parasite in youngstock. For this reason, a minimum double combination drench containing levamisole should be used in calves. An injectable double containing an ML and levamisole (such as Dectomax® V) is also a good option in this age group, especially if injecting is preferred. In reality, unless Ostertagia or Cooperia resistance is extreme, either oral or injectable should work well.
Pour-on drenches are the easiest to apply but usually cost more as more active is required to penetrate the skin and reach suitable concentrations to kill the parasites. Trials have also found more variability with some pour-ons in their efficacy than orals and injections. Due to their cost and higher risk of variable dosing, pour-ons should be reserved for animals that require these products for additional reasons. For example, if it is long acting and they need longer worm protection, if lice treatment is also required, or if facilities are poor and it is too dangerous to give by oral or injection, or a product with zero withholding is needed. Note: not all pour-ons have persistent activity, lice claims, or nil WHPs.
Treatment Interval
Young stock usually require multiple treatments in their first year of life, often 4-6 weeks apart. After that, as immunity develops, the frequency and number of treatments should reduce. How often animals are treated should depend on their exposure to worms.
If they are grazing ‘clean’ pasture with few worms and are not ‘wormy’, then they should not be treated or not be treated frequently. If they are grazing contaminated pasture, then monthly treatments may be necessary, however steps should be taken to reduce contamination (see Effective Management). Ideally parasite monitoring will help guide treatment type and frequency i.e. weigh animals and/or fecal egg count, coupled with visual assessment.
Examples of a routine drenching and fecal egg count monitoring program for young cattle.
Minerals
With the emphasis now on less drenching, there will be a risk on some farms that animals will be missing out on regular mineral top ups, since many drenches are mineralised. Calves and youngstock should be tested (blood or liver biopsy) every few years to assess the levels of the most frequently diagnosed mineral deficiencies (cobalt/selenium/copper) and to know if supplements are required.
Selenium is required for cell health, growth, immunity and reproduction. Copper is required for many functions including red blood cell production, energy and hormone formation. Both of these minerals are toxic at high doses and the margin of error is low.
Young ruminants also require cobalt (to make vitamin B12) that is needed for the energy cycle and animal growth. Consideration should be given to alternative mineral supplements other than those in drenches, such as oral or injectable minerals.
Adult stock
In an ideal world, healthy adult cattle should not need a worm treatment, as they have developed immunity to parasites. However, there will be times where an animal’s immunity may be compromised. They may be under stress, in ill health or poor condition, and in these circumstances parasites can cause disease, so a targeted worm treatment for these animals can be beneficial.
If controlling lice is required, consider using a lice-only pour on for those cows that don’t need a wormer.
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Parasite overview
Parasites are one of the key contributors to reduced productivity in animals, so having a treatment strategy for parasite control is vital.
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Effective management
Every farm is unique, and effective worm management needs to be tailored to take this into account.
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Drenching best practices
If drenching is to be effective, a drench must be given correctly. Check out our tips for best practice drench administration.
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Sheep drenches and drench usage
There are a variety of drench options available for sheep. Understanding how and when we use them is important.
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Pre-lamb management
Pre-lambing is a crucial time in the Ewe’s production cycle, so giving them the be start to lambing is essential.
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Drench products
When it’s time to reach for the drench gun, Zoetis provide a range of solutions. Check to see if these will suit your farm.
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