Five tips for worm control in cattle

Young cattle at grass are starting to show symptoms of worm burdens, which means herd owners should be thinking about parasite control over the coming weeks.

Animals at most risk are calves, autumn weanlings and yearling stores, as well as first-calved heifers, as these animals can be under physical stress in their first lactation.

Mature cows should have developed resistance to gut and stomach worms. If cows are struggling to gain flesh, fluke may be the problem rather than worms, so consult with your vet.

Look for classic symptoms, such as very loose dung, lack of condition and thrive, dry coat and coughing after herding animals to fresh grass. When it comes to worming cattle, outlined are five tips to keep in mind.

1. Timing the first dose

Timing the first dose is crucial for effective parasite control. Too early and the wormer is less effective in terms of cover period. Too late and there will be a lot of weight gain lost.

Young calves also need some level of exposure to worms before the first dose, as this builds immunity. Give spring-born calves at least three to four weeks at grass before dosing.

Aim to give the first dose when 25% to 50% of animals in grazing groups are showing signs of a worm burden.

2. Don’t use the same wormer over and over

Do not use the same wormer year in, year out and across the grazing season. Repeated use will see worms building resistance to such products.

Use a different product every so often. When it comes to choosing a different wormer, pay attention to the active ingredient in the product.

Wormers are typically classed as white (benzimidazoles), yellow (levamisoles) and clear products (avermectins).

This is the important bit when changing wormer, not the brand name. You can choose a different brand, but it may have the same active ingredient, reducing the efficacy of the wormer.

Also, don’t choose a wormer because it is the cheapest product available. Some cheaper products require a bigger dosing rate.

In contrast, some higher-priced wormers require a smaller dose. On a per-head basis, there may be little cost difference.

3. Pour-on, oral drenches or injected wormers?

When it comes to pour-ons, oral drenches and injected wormers, it is a case of which product is most practical for your handling set-up.

Pour-on wormers are quick for treating large groups, but they need a dry window for application.

Oral drenches are slower to administer and some animals will spit out the dose. Injected wormers can also be slow to administer, but allow more precise dosing rates.

4. Dosing technique

Always secure cattle in a crush or handling race, as this allows greater accuracy when dosing. Do not attempt to apply pour-on products to free-standing cattle in a loose pen.

When using oral drenches, a head scoop eases the task. Using a long-reach hook is also recommended.

With injected wormers, check if the dose is given into the muscle or under the skin and change the needle regularly.

5. Group cattle in even batches for dosing

Weighing cattle allows dosing rates to be tailored to individual animals, but this is not an option on many farms.

Therefore, when loading the handing race, try to fill the chute with cattle of similar size and weight. Set the applicator to the heaviest animal in each pass, then dose.

This cuts down on variation in dosing rates and limits the risk of bigger animals being under-dosed for worms.

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