Genetic factors controlling wool shedding in a composite E asycare sheep flock

Summary Historically, sheep have been selectively bred for desirable traits including wool characteristics. However, recent moves towards extensive farming and reduced farm labour have seen a renewed interest in E asycare breeds. The aim of this study was to quantify the underlying genetic architecture of wool shedding in an E asycare flock. Wool shedding scores were collected from 565 pedigreed commercial E asycare sheep from 2002 to 2010. The wool scoring system was based on a 10‐point (0–9) scale, with score 0 for animals retaining full fleece and 9 for those completely shedding. DNA was sampled from 200 animals of which 48 with extreme phenotypes were genotyped using a 50‐k SNP chip. Three genetic analyses were performed: heritability analysis, complex segregation analysis to test for a major gene hypothesis and a genome‐wide association study to map regions in the genome affecting the trait. Phenotypes were treated as a continuous or binary variable and categories. High estimates of heritability (0.80 when treated as a continuous, 0.65–0.75 as binary and 0.75 as categories) for shedding were obtained from linear mixed model analyses. Complex segregation analysis gave similar estimates (0.80 ± 0.06) to those above with additional evidence for a major gene with dominance effects. Mixed model association analyses identified four significant ( P  <   0.05) SNP s. Further analyses of these four SNP s in all 200 animals revealed that one of the SNP s displayed dominance effects similar to those obtained from the complex segregation analyses. In summary, we found strong genetic control for wool shedding, demonstrated the possibility of a single putative dominant gene controlling this trait and identified four SNP s that may be in partial linkage disequilibrium with gene(s) controlling shedding.