Managing worm burdens at grass

We have now entered the time of year that is critical for parasite control (worm burdens) for animals at grass – especially in the current damp, humid weather.

Young spring-born calves – particularly those of dairy origin – are a high-risk group. But, saying that, other categories of stock can also be affected too; however, these older cattle should have some immunity to parasites from the grazing season last year.

A solid mid-season control strategy will ensure that animals will perform to their optimum and the main parasites to control at this time of year are gut worms and lungworms.

Tell-tale signs of a worm burden include ill-thrift, loose dung for gut worms and a sharp cough for lungworms.

Additionally, faecal egg counts are very useful at this time of year to develop dosing strategies. Dung from 10-15 calves should be sampled to give a representation of the parasites present and also the level of infection.

If a worm burden is discovered, there are a wide range of products for dosing and product selection will be determined by many factors such as the type of stock being dosed and whether the preference is for an oral drench, pour-on or injection.

There has been development of anthelmintic resistant worms to each of the drug classes in Ireland (white, yellow and clear drenches), so a more targeted approach should be practiced on-farm.