Validation of QTL affecting resistance to nematodes in Sheep identified in a Back-Cross design in a pure breed population

Abstract

International audienceGastro-intestinal nematodes are of major concern to sheep health worldwide. Identifying the causative genes responsible for resistance would augment the efficiency of selection. Previously, back-cross (BC) sheep (Black Belly * Romane breeds) were genotyped with a 50K SNP chip and were measured for faecal egg count after two successive experimental challenges by H. contortus. The most significant QTL were identified on chromosomes 5, 12, 13, 21. A customized assay including 1000 SNP was created to increase the density ofmarker coverage in these regions and others major QTL regions affecting parasitism resistance in natural infection conditions. In the present study, 277 Romane lambs were experimentally challenged with H contortusand genotyped with the dedicated 1000 SNP. Six out of the eight tested QTL regions have an effect in the Romane pure Breed population