Keeping on Top of Parasite Control

With producers looking forward to Spring turn-out, it’s timely to review parasite control plans. A team from SRUC, Moredun, the University of Liverpool and the James Hutton Institute draws on new research to highlight the risks of bought-in stock carrying unwelcome parasites and discuss strategies for their control. 

Grazing cattle are susceptible to a wide range of parasites. These parasites have uniquely well-adapted lifecycles and are continuously adapting in response to changes around them, for example, changing weather patterns. At the same time, grassland management practices are evolving, as reflected by the uptake of herbal leys, rotational grazing and integrated arable/livestock production systems. To keep pace with these changes, our understanding of the interactions between parasites, their host(s) and the environment is developing all the time, prompting ongoing updates to advice about parasite management. Not least, to reflect growing levels of concern about treatment failure to the chemicals that underpin parasite control in cattle, also known as anthelmintic resistance.

Internal parasites (endoparasites)

• Roundworms
  • Gastro-intestinal nematodes incl. Cooperia in the small intestine;
    and Ostertagia and Haemonchus in the stomach (abomasum)
  • Lungworm
• Liver fluke
• Tapeworm
• Protozoa e.g. cryptosporidium

External parasites (ectoparasites)*

• Lice, mites and ticks

* Despite its name, ringworm is a fungal infection and is excluded.

When it comes to parasite management of bought-in cattle, uncertainties about their grazing and treatment history need to be considered, including the risk of introducing anthelmintic resistance through incoming animal movements.  

In the current study, analysis of dung samples collected from almost 400 pens of cattle sold for breeding or fattening through livestock markets across Great Britain between 2019-2022, gives insight into roundworm infections in cattle being traded. Overall, two-thirds were found to be infected with roundworms. Results also showed some evidence of resistance to white wormers in these roundworms. 

For farmers, this highlights the potential risk of introducing roundworms with resistance to one of the main treatment options through bought-in cattle. Effective biosecurity, testing bought-in cattle for roundworms, treating them if needed and keeping them separate from other cattle on the farm for a period of quarantine, is the best form of control. However, responses to a survey of almost 100 cattle farmers across Great Britain suggest that only half of the respondents routinely quarantine incoming animals.  

Through discussions with farmers in North-East Scotland and in the Scottish and Welsh Borders, the project team heard how the management of incoming stock is influenced by available on-farm resources, including space, labour and handling facilities, and buying patterns. For example, direct off-farm or via a livestock mart or dealer, and whether they were bought in a large batch from a single source or in smaller batches from multiple sources. Finally, awareness of parasite risk is often limited: parasite control is rarely the main consideration, and other health concerns, such as Johne’s or BVD, tend to be prioritised. 

Informed by dung sampling results from livestock moving through markets, along with feedback from the farmer survey and discussion groups, an expert working group of veterinarians, advisors, and industry representatives is developing practical recommendations for managing parasites in bought-in cattle.  

In the meantime, the team’s top tips are to: 

• Assume ALL bought-in animals are carrying resistant roundworm infections. 
• Treat bought-in animals with an effective anthelmintic (a lungworm vaccine is also available - speak to your vet about its use).
• Quarantine and, if possible, yard bought-in cattle for 48 hours post-treatment, then keep them separate from the rest of the herd, ideally for three weeks.
• Check that treatments worked by doing a faecal egg count: 10-14 days after treatment if using a white (1-BZ) or clear (3-ML) product or five to seven days after treatment if you used a yellow (2-LV) product. 
• Keep parasite management plans under review.

The project, Biosecurity and Roundworm Advice for Cattle Enterprises (BRACE) was funded by BBSRC and DEFRA. The support of all participating farmers, advisors and livestock markets is gratefully appreciated.  

Sam Beechener, Research Fellow, Sam.Beechener@sruc.ac.uk 

Posted by SAC Consulting on 16/03/2026