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Strategies to promote sustainable parasite control and reduce anthelmintic usage

Strategies to promote sustainable parasite control and reduce anthelmintic usage

  • Improving Agricultural Practice
  • 2022-2027
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Helminth parasites (worms and fluke) are a major constraint on efficient and sustainable livestock production in Scotland, and beyond. Parasitic gastroenteritis as well as fluke and anthelmintic resistance featured prominently in a list of priority diseases and syndromes identified through a Ruminant Health and Welfare Group consultation with 600 UK stakeholders.

Most farmers attempt to control helminth infections in their stock by the routine administration of chemical (anthelmintic) treatments. However, this is not sustainable for several reasons, including the development and spread of anthelmintic resistance, rendering treatments ineffective. There is also increasing concern about the fate of such chemicals (wormers and flukicides) in the environment, when released in the dung and or urine of treated animals. Most, if not all, compounds used to treat or control pests and parasites have the potential to negatively impact important invertebrates, such as dung beetles, flies, and aquatic fauna. This can occur when the actives or their metabolites are excreted in the faeces and or urine of treated animals, or leach into the environment because of poor storage, application, or disposal. These factors have highlighted the need to integrate veterinary medicines with alternative control approaches, such as rotational or heather grazing, to reduce dependence on anthelmintic products and minimising environmental impacts.

The essential role that dungs beetles play in the breakdown and integration of faecal matter into the soil is well established. Recently, there has been some interest in the role of the phoretic mites carried by dung beetles; as these have been shown to be extremely effective in reducing the incidence of nuisance horn flies in Australia and the USA, by directly ingesting fly larvae in faecal pats. There is, however, little information on their potential role in reducing the number of helminth eggs and larvae and subsequent pasture contamination under Scottish and UK farming conditions.

Feeding on plants rich in plant secondary metabolites is an active area of research and can be included in sustainable parasite control strategies, to minimise the environmental impact of parasitic disease control. There are potential production and sustainability benefits from using these novel alternative approaches, as a healthy pasture invertebrate community is important for the structure and function of soils and grasslands. For example, soil invertebrates contribute to improving soil microbial composition and health, nutrient recycling, aerating soils and improving soil and plant environments as well as providing food sources for birds and mammals.  Very little is however known about the impacts of these alternative approaches on areas like parasite epidemiology, parasite longevity and life history traits or the interactions between host and environment.


  • How do we minimise the wider environmental impacts and externalities from farming such as impacts on biodiversity, soils, land management, air quality, flood prevention, water quality and climate change?


This project investigates the environmental impacts of grazing and the use of traditional wormers along with an assessment of the impacts of a range of alternative parasite management strategies on livestock productivity and environmental impact.


Impact of grazing management strategies on biodiversity, soil health, livestock health and productivity

We are exploring the tension between the environmental benefits of livestock grazing vs the impacts of treatment with anthelmintics; evaluating livestock performance under different pasture management regimes; and assessing environmental implications of alternative strategies for animal health and welfare, specifically worms and fluke, and requirement for anthelmintic treatment.


Evaluating the impact of anthelmintics on phoretic mites, and the role of mites in reducing roundworm and fluke burdens on pasture

We are investigating the impact phoretic mites might have in controlling helminth infections and possibly reducing the need for anthelmintic treatment. We are looking at the impact of anthelmintic treatments on the mites themselves and developing guidance on the use of sustainable parasite control strategies for farmers.


Heather Profitability and environmental impact assessment

Feeding livestock on plants rich in plant secondary metabolites is one of the strategies that has been researched as part of the range of options available for sustainable parasite control, to minimise the environmental impact. To improve the uptake of such measures and motivate farmers and businesses to change their practices, we propose a cost-benefit analysis to assess the profitability, sustainability, and scalability of some of the alternative measures.


Anthelmintics and the environment study

We are assessing the patterns of anthelmintic usage on UK livestock farms from various relevant sources to gain a better understanding of the environmental impacts of frontline anthelmintics and develop stakeholder-friendly advice and resources to better communicate best practices to industry.

Overall, this project is supporting more sustainable parasite control in its broadest sense, striking the correct balance between promoting animal health, welfare, and productivity with reducing reliance on chemical treatments, improving treatment timings, reducing environmental impacts, and conserving biodiversity.

Project Partners



2022 / 2023
2022 / 2023

To assess the impact of grazing management strategies on biodiversity, soil health and livestock health and productivity, pastures were seeded with drug-susceptible roundworms to generate plots with known levels of parasite resistance and nematode species diversity. Dung beetle and soil chemistry assessments have been undertaken on these paddocks. While to evaluate the impact of anthelmintics on phoretic mites, pitfall traps and sheep faecal sampling have been conducted in order to collect dung beetles with and without phoretic mites for species identification.

To assess the feasibility, acceptability, profitability and environmental impact of heather grazing in consultation with industry stakeholders; interaction with industry partners was organized. From this interaction it would appear that there is interest in identifying and using complimentary parasite control strategies to reduce anthelmintic inputs and that there is acceptence of the logistical limitations and knowledge gaps that require consideration prior to uptake. There is however recognition of the need for alternatives that could be incorporated into a more sustainable roundworm control strategy. Finally an assessment of the pattern of use of frontline anthelmintics in the UK, and in particular Scotland; to determine these patterns historical farmer surveys (undertaken over the last 20 years) and ongoing farmer surveys and anthelmintic sales records have been collated.

Under the auspices of a SEFARI Gateway-funded Special Advisory Group (SAG), project principal investigators (PIs) have been working with industry-led SCOPS and COWS groups, acknowledged and trusted experts in best practice advice, as well as the Veterinary Medicines Directorate (VMD) to raise the issue of anti-parasitics and the environment. The groups met to develop materials and advice, to help farmers and the industry make informed decisions around if/when to treat, what product to use and how best to dispose of unused chemicals. The SAG had a number of successful outcomes, namely it was able to bring the anthelmintics and the environment topic to the attention of the respective sheep and cattle industry groups, SCOPS and COWS, and to develop easy-to-easy understand resources to help farmers, vets and advisors make informed decisions,based on SCOPS and COWS product tables. Additionally, two of the PIs have been involved in the development of the sheep drench test check component of the UK Government's Defra Health and Welfare Pathway and involved in discussions with Scottish Government's Agriculture Reform Implementation and Oversight Board. Materials have been generated to help facilitate the roll-out of the drench check. Discussions between one of the PIs and leading industry stakeholders, including Soil Association Scotland, animal feed industries and livestock co-ops are ongoing to identify research priorities and facilitate the incorporation of nutritional alternatives in animal feed to reduce anthelmintic use.


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Increasing uptake of best practice

The aim of research deliverable is to explore the uptake of practices which improve the efficiency, productivity and sustainability of land, crop and livestock management throughout Scotland. The research builds on previous work within the RESAS Strategic Programme and on collaborations with UK and international partners.

  • Improving Agricultural Practice
  • 2016-2022