Both stomach and lungworm parasites can have a massive impact on both the thrive and the average daily liveweight gain (ADG) performance in cattle.

Usually, it tends to be an issue that can be seen more so within younger animals, as symptoms are easier to identify – especially in calves during their first grazing season.

Taking a more targeted approach, in dealing with both stomach and lungworm, is a crucial strategy that needs to be undertaken in order to avoid a threat of anthelmintic resistance.

From trials studied in Teagasc Grange, calf-to-beef farms are found to be developing higher anthelmintic resistance levels among stomach worms.

According to Teagasc, lungworm populations have not yet developed forms of anthelmintic resistance. Therefore, farmers should aim to maintain this status and avoid developing any level of resistance.

There are three classes of anthelmintic licensed for the treatment of stomach and lungworm in Ireland. These classes are listed in the table below alongside the parasite stages affected by dose.

It is important that farmers decide which development stage of either the stomach or lungworm that they need to target – as this will allow them to use the most appropriate product to kill off the infecting parasite.

Best practice

Some farmers may question exactly when should they dose their young stock to prevent an infestation of stomach or lungworm.

According to Teagasc, farmers should take stock of performance, clinical signs and fecal egg counts (FEC) into account prior to making a decision on the necessity of dosing.

There are different tests which can be carried out to identify cases of stomach worms, lungworms or liver fluke. These individual tests need to be requested. For example, an FEC test for stomach worms will not provide an indication of a lungworm infestation or vice versa.

From the FEC results, the number of eggs provides an indication of the number of adult worms present in the gut. Farmers should monitor and treat for stomach worms if the count goes above 200 eggs per gram.

When it comes to dosing the animal, read the instructions carefully and aim to avoid underdosing the animal. This can be achieved by following the dose-to-weight calculations provided with instructions of dosing products.

To identify if resistance is an issue on the farm, a drench test should be completed and its effectiveness should be monitored – this should be conducted in accordance with advice from a local vet or advisor.

Finally, when dosing stock during the grazing season, farmers need to avoid turning cattle back out to clean pastures straight away.

To reduce the threat of anthelmintic resistance, it is best to return animals out to a dirty pasture after dosing.

For further information and advice on dosing and dealing with anthelmintic resistance on your farm click here