Genome‐Wide Analysis of Resistance to Gastrointestinal Parasites in Portuguese Merino and Merino‐Related Sheep

ABSTRACT Gastrointestinal nematodes (GIN) are one of the main constraints affecting sheep production worldwide. For decades, control methods based on anthelmintics have been extensively used, which ended up in multiple drug‐resistant helminth strains. Selective breeding for disease resistance is a long‐term and sustainable strategy to improve animal health, welfare and productivity. Therefore, we performed a genome‐wide association study using a customized SNP panel to identify genomic regions and molecular mechanisms associated with GIN resistance/susceptibility among Portuguese Merino and Merino‐related sheep. Two SNPs located within centromere protein K (chr 16; 14 439 999 bp) and NADH: ubiquinone oxidoreductase complex assembly factor 2 (chr 16; 19 366 442 bp) genic regions reached genome‐wide Bonferroni significance ( p = 2.08 × 10 −6 ). Additionally, five genome‐wide suggestive SNPs were detected within genic regions of adenomatous polyposis coli regulator of WNT signaling pathway (chr 7; 1 050 994 bp), regulator of G protein signaling 8 (chr 12; 68 278 650 bp) and hypoxia inducible factor 3 subunit alpha (chr 14; 57 059 428 bp), as well as in intergenic regions near calcium binding and coiled‐coil domain 1 and ATP synthase membrane subunit C locus 2 (chr 3 142 391 546 bp) and semaphorin‐6D (chr 7; 65 321 727 bp). Candidate genes located in these regions are involved in intestinal homeostasis, epithelial barrier reinforcement, and regulatory mechanisms of immune response. These results provide new and useful information about the genetic architecture underlying GIN infection in Portuguese Merino sheep. Further analyses are needed to validate these SNPs and assess their contribution to selection strategies focused on breeding animals with enhanced GIN resistance.