Copy number variation association studies for sheep tail-relevant traits in Hulunbuir sheep

Tail type is an important trait that influences meat quality and consumer purchasing attitudes. As a novel genetic marker, the study of genomic copy number variations (CNVs) provides a new research method to study the genetic mechanisms underlying trait formation. In the present paper, we conducted CNV-based association studies for sheep tail type and growth traits in Hulunbuir sheep. A total of 167 CNVs and 288 individuals were analyzed at the marker and individual level, respectively. Association studies of 10 traits were carried out using two mixed linear models. We found that three, one and one CNV loci were significantly associated with tail type, tail length and tail fat weight, respectively, which together contained a total of 52 candidate genes. Out of these genes, five have been documented to be associated with fat metabolism in sheep. Our findings provide a reference for further studies on fat deposition in sheep as well as a theoretical basis for breeding Hulunbuir sheep with the required tail type.