Over-reliance and inappropriate use of anthelmintics has resulted in the evolution of anthelmintic resistant nematodes. A study conducted by members of the OviFEC project team found high levels of anthelmintic resistance on Irish sheep farms, with almost half of all anthelmintic treatments being ineffective.

To mitigate the effect of anthelmintic resistance, an alternative sustainable approach is required; one such approach is the use of breeding to select for animals that have a natural resistance to gastrointestinal nematodes.

A small number of countries internationally have commenced breeding for resistance to gastrointestinal nematodes in sheep. Ireland aims to develop such a breeding value as part of the Department of Agriculture, Food and the Marine-funded OviFEC project.

Breeding for reduced susceptibility

Preliminary analysis of faecal egg count (FEC) data on Irish flocks was undertaken by the project team and showed that considerable genetic variation existed within the trait.

A health index on traits such as lameness and dag score now forms part of the national breeding objectives, however FEC was not included in the health index previously as more phenotypes (available routinely) are required before its inclusion in the national breeding objectives.

Although the underlying genetics of FEC in sheep have been studied extensively internationally, with the exception of New Zealand and Australia no other country has included FEC as a breeding goal trait in their sheep indexes.

OviFEC will focus on:

  • Collecting faecal egg counts on a large cohort of informative lambs.
  • Developing national genetic and genomic evaluations for FEC.
  • Ensuring the long-term legacy of OviFEC by developing a simple streamlined process to assist farmers to collect FEC phenotypes routinely for genetic evaluations in the future.
  • Project strategy

    The Central Progeny Testing (CPT) and Teagasc research flocks among others will play a central role in the recording of FEC data for the project. This will also enable the project to harness routinely collected data on a range of production traits such as lambing, lamb performance, ewe traits etc.

    In addition, parentage will also be available on all animals through a combination of farmer recording and genomic DNA information. For the initial study, FEC data will be collected for approximately 1,000 lambs in Teagasc Athenry on two occasions during summer 2022.

    All lambs will be exposed to a natural gastrointestinal nematode challenge at pasture and individual lamb FEC samples will be recorded two times once the FEC of the grazing group reaches approximately 600 eggs per gram.

    This research will enable the team to decide if one or two independent FEC samples are required for future genetic studies and is central to the development of future sampling strategies for FEC in Ireland.

    In 2023, larger groups of lambs, most likely from the CPT flocks, will be individually sampled based on the protocol developed as part of the first research project. The accumulation of data from 2022 and 2023 will enable genetic analysis to be undertaken to determine the heritability of FEC in the Irish sheep population.

    The relationship between FEC and other traits including dag score, lameness and lamb weight will also be estimated. This research is required for the development of a breeding value for FEC which can be incorporated into the existing €uro-Star indexes.

    New service

    As part of OviFEC, a new service will be designed by Sheep Ireland for the recording of FEC in existing performance recording flocks as part of the national breeding programme. This service will enable flocks to obtain all the necessary information and materials required to repeat the FEC recording protocol.

    As part of OviFEC, a web-based interface to place and pay for FEC sampling kits and associated FEC analysis and to select the specific animals for testing will be developed. The farmer will also receive information on the necessary steps required for the successful recording of FEC on individual animals.

    The OviFEC project represents an important milestone in breeding sheep with resistance to gastrointestinal nematodes in Ireland.

    As part of this project, a phenotyping protocol for future FEC sampling as well as the development of a breeding value for FEC will be available for the Irish sheep industry.

    Key points

  • Over-reliance and inappropriate use of anthelmintics has resulted in the evolution of anthelmintic resistant nematodes.
  • To mitigate the effect of anthelmintic resistance, an alternative sustainable approach is required; genetics is one such approach.
  • The OviFEC project aims to develop a breeding value for resistance to gastrointestinal nematodes, enabling farmers to select rams based on their genetic potential for reduced faecal egg counts.
  • Measurements for the development of a breeding value for FEC will commence in summer 2022.
  • *This OviFEC project update was compiled by Noirin McHugh, Orla Keane, Fiona McGovern, Philip Creighton and Donagh Berry, all from Teagasc and Sean Godfrey, Thierry Pabiou and Kevin McDermott from Sheep Ireland.