New research in Wales has shown that faecal egg count (FEC) sampling can significantly reduce the need to worm dairy and beef youngstock for roundworms without impacting on their health and performance.

A three-year European Innovation Partnership (EIP) Wales study on dairy farms in Ceredigion resulted in all three farms managing their R2 yearling heifers at grass without the need to treat them for gut roundworms; one farm found that it didn’t need to treat its R1 animals for gut worms once they had been vaccinated for lungworm.

The other two, whose farms have a higher worm burden, wormed their R1s less often. They also switched to using white (1BZ) drenches and yellow (2LV) drenches after efficacy testing showed a reduced efficacy of the clear (3ML) wormers.

The data collected during the EIP study showed that there were similar growth patterns to previous years when clear wormers were used and heifers were dosed routinely therefore the changes in worming treatments had no obvious negative effects on performance.

One of the experts involved in the study, Professor Diana Williams, from the University of Liverpool’s Veterinary Parasitology Research Group, said the study demonstrates that the advice around worming needs to change.

“Traditionally the advice to farmers was to dose first season grazing calves in the early part of the season to prevent disease mid-season but because of lots of factors such as climate change and wormer resistance that advice needs to change.

“This project has demonstrated that we can reliably use FEC, alongside growth rate data and calf condition, as a means of monitoring infection during the grazing season and only treat when the animals actually need it rather than dosing by calendar date.’’

Cooperia oncophora was the dominant worm species in the FECs and Ostertagia ostertagi was also present in every sample.

Infections with C. oncophora alone are not normally associated with clinical disease in UK, although they may exacerbate disease caused by the more pathogenic Ostertagia ostertagi.

Climate change, with warmer temperatures earlier and later in the season and changes to rainfall patterns, is making the epidemiology and lifecycle of parasites much less predictable.

“Temperatures of 20°C in mid-November as we have seen this year are not normal,’’ said Professor Williams, who sits on the steering group of Control of Worms Sustainably (COWS) (cattleparasites.org.uk).

Whilst white and yellow wormers can be used during the grazing season, there is a place for using clear wormers, particularly at housing during the autumn and winter.

Gut worms, picked up in the autumn, particularly after a cold spell, go into an arrested stage of development and sit in the wall of an animal’s gut through the winter, causing severe disease in the spring when they wake up and start developing again.

Yellow wormers are not effective at destroying parasites in that arrested stage, Professor Williams advised. “If a clear wormer is to be used, this is the time to use it and, by using it only when it is needed, the risk of increasing resistance levels is much lower.’’

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The EIP study showed big differences in EPG levels on each of the farms in the trial, despite all three having spring calving, and similar grazing systems.

The researchers said that this highlighted why a standard blueprint to roundworm control cannot be implemented.

One of the issues thrown up by the study is the threat of lungworm when wormer used to control gutworms is reduced.

Dealing with the risk of lungworm, and sometimes Type II ostertagiosis, was a factor that confused treatment decisions on the trial farms.

“If you are starting to think about FEC to control gastrointestinal worms you can’t forget about lungworm,’’ warned Professor Williams. “Seek veterinary advice if there is any reduction in growth rates or animals are coughing.’’

Quarantine treating all incoming stock will reduce the risk of bringing lungworm onto the farm and R1 heifers can be vaccinated before turnout to protect against lungworm.