title: Can we use genetic and genomic approaches to identify candidate animals for targeted selective treatment.
abstract: Estimated breeding values (EBV) for faecal egg count (FEC) and genetic markers for host resistance to nematodes may be used to identify resistant animals for selective breeding programmes. Similarly, targeted selective treatment (TST) requires the ability to identify the animals that will benefit most from anthelmintic treatment. A mathematical model was used to combine the concepts and evaluate the potential of using genetic-based methods to identify animals for a TST regime. EBVs obtained by genomic prediction were predicted to be the best determinant criterion for TST in terms of the impact on average empty body weight and average FEC, whereas pedigree-based EBVs for FEC were predicted to be marginally worse than using phenotypic FEC as a determinant criterion. Whilst each method has financial implications, if the identification of host resistance is incorporated into a wider genomic selection indices or selective breeding programmes, then genetic or genomic information may be plausibly included in TST regimes.
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian EH25 9RG, UK. yan.laurenson@gmail.com
authors.forename: Yan C S M
authors.initials: YC
authors.lastname: Laurenson
authors.forename: Ilias
authors.initials: I
authors.lastname: Kyriazakis
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Bishop
mesh_terms: D000818:Animals; D000977:Antiparasitic Agents / Q000627:therapeutic use*; D003198:Computer Simulation; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D023281:Genomics / Q000379:methods*; D008954:Models, Biological; D009348:Nematoda / Q000187:drug effects*; D009349:Nematode Infections / Q000235:genetics / Q000662:veterinary*; D012756:Sheep; D012757:Sheep Diseases / Q000469:parasitology*
chemical_list: D000977:Antiparasitic Agents; D005819:Genetic Markers
keywords: Anthelmintic resistance; Genomic prediction; Modelling; Sheep-Nematodes; Teladorsagia circumcincta