Strategies to promote sustainable parasite control and reduce anthelmintic usage

Challenges

Helminth parasites (worms and fluke) are a major constraint on efficient and sustainable livestock production in Scotland, and beyond. Parasitic gastroenteritis, 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 & 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.

The essential role that dungs beetles play in the breakdown and integration of faecal matter into the soil is well established. However, there has been some interest in the role of the phoretic mites that the dung beetles carry. 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 little information on their potential role in reducing numbers and subsequent pasture contamination with helminth eggs and larvae 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, but very little is known about their impacts on areas like parasite epidemiology, parasite longevity and life history traits or the interactions between host and environment.

Questions

Solutions

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 of phoretic mites may 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 basket 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.