Award details

Sustainable Control of Parasites in Ewes (SCOPE)

Reference	BB/X000923/1
Principal Investigator / Supervisor	Dr Hannah Vineer
Co-Investigators / Co-Supervisors
Institution	University of Liverpool
Department	Infection Biology & Microbiomes
Funding type	Research
Value (£)	520,556
Status	Current
Type	Research Grant
Start date	01/11/2022
End date	31/12/2025
Duration	38 months

Abstract

We will conduct the first randomised, controlled study investigating the impact that treating periparturient ewes with moxidectin has on subsequent productivity and infection of lambs, and on the development of AR. Selection for AR will be measured as the number of treatments required by lambs. AR will be measured phenotypically using faecal egg count reduction tests. Change in population genetic structure in response to selection pressure will be measured as genetic distance between treatment groups and following anthelmintic treatments, based on three established mtDNA markers. Changes in nematode community diversity over time will be quantified using ITS-2 rDNA nemabiome metabarcoding. These data will be used to develop and validate a differential equation-based mathematical model of nematode transmission and the development of moxidectin-resistant Teladorsagia circumcincta in ewes and lambs. We will make use of several existing modules (model components) simulating nematode population dynamics and the development of AR. These modules, however, used a fixed faecal egg count profile for periparturient ewes and did not simulate infection in ewes. Thus, our ability to predict the impact of anthelmintic treatment strategies on nematode transmission and AR was limited to lambs only. Therefore, we will develop and validate a novel module simulating the periparturient rise in faecal egg counts in ewes. This extended model will be used to run an array of simulations predicting the change in moxidectin-resistance haplotype frequency over a period of 10 years, under a range of management and regional climate scenarios. We have identified a range of scenarios for simulation to address known gaps in our knowledge/evidence base. Additional needs-led scenarios for simulation will be codeveloped with stakeholders.

Summary

This project will slow the development of anthelmintic resistance (AR) in UK sheep flocks by developing and promoting evidence-based strategies for sustainable treatment of ewes at lambing time. Guidelines for the sustainable control of parasites in ewes (SCOPE) will be developed by quantifying the production and epidemiological impacts of periparturient ewe treatments and simulating selection for anthelmintic resistance under a range of flock management strategies and climatic conditions, using gastrointestinal nematode (GIN) epidemiological models that I have already developed. The project addresses a STAR-IDAZ International Research Consortium in Animal Health's priority research topic and several key challenges. By providing farmers with information and guidance to help them minimise inputs whilst at the same time upholding high standards of welfare and productivity, the project also aligns with Defra's Animal Health and Welfare Pathway. Helminth infections are a major economic and welfare burden to UK ruminant production enterprises, costing the UK sheep industry an estimated £41m per year. Parasitic gastroenteritis and anthelmintic resistance (AR) are now considered by UK industry professionals to be the second most important sheep disease and syndrome in the UK. GIN infections in periparturient ewes are of particular concern due to the direct effects of infection on lamb exposure to infection. Most UK farmers treat periparturient ewes with moxidectin, yet treating ewes at lambing time has the potential to select heavily for AR. Despite this risk, the epidemiological and evolutionary impacts of anthelmintic treatment of periparturient ewes on GIN populations have not yet been robustly quantified. To date, no controlled, randomised study investigating the impact of ewe treatments on AR has been conducted in the UK, nor in Europe, and no studies of this nature have investigated the use of moxidectin. The overarching aim of this project is to provide an evidence base for industry guidelines for the sustainable use of anthelmintics to control GIN in ewes, which promote high levels of welfare and productivity, yet slow the development of AR. We will achieve this with three specific objectives which combine empirical parasitology, population genetic analyses and mathematical modelling. 1. Quantify the consequences of ewe treatments for GIN epidemiology, AR, GIN population diversity, and lamb productivity 2. Develop and validate a mathematical model to simulate the development of AR following anthelmintic treatment of ewes 3. Simulate the outcome of treatment strategies for controlling the PPR-FEC in ewes throughout the UK, and determine the most sustainable regional approaches We will work closely with industry stakeholders throughout, including project partners, to develop guidelines/recommendations for the sustainable anthelmintic control of parasites in ewes. These will be disseminated through partners and at industry events, and the impact of our research will be evaluated through farmer surveys of behaviour change. The outcomes of this research will feed directly in to updated nationwide industry guidelines for the sustainable control of parasites in ewes.

Committee	Research Committee A (Animal disease, health and welfare)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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