Association analysis of immune response loci related to Haemonchus contortus exposure in sheep and goats using a targeted approach

Abstract Haemonchus contortus infections are an important source of animal production loss to livestock industry. Genetics of helminth resistance involves a complex set of factors related to the host immune response. The increasing use of genetic markers such as single nucleotide polymorphisms (SNPs) in genome wide association studies (GWAS) offers the potential to identify loci or regions associated with nematode resistance in small ruminants. The aims of this study were: (1) to use a targeted sequencing approach to identify SNPs in 100 genes related to immune response during Haemonchus contortus exposure in growing males of St. Croix, Katahdin and Dorper sheep, and in Kiko, Boer and Spanish goats, and (2) to perform an association analysis for fecal egg count (FEC), packed cell volume (PCV), immunoglobulin levels (IgA, IgG and IgM) and average daily gain (ADG) in the populations under study. After quality control (call rate