Genome-wide association study for milk production traits in an economically important local dairy sheep breed

In this study, we conducted a genome-wide association study (GWAS) for five milk production traits in the Valle del Belice sheep. Repeated measurements for milk yield (MY), fat percentage and yield (F% and FY) and protein percentage and yield (P% and PY) on 481 ewes, were available for the analysis. The animals were genotyped using the Illumina Ovine 50k BeadChip. Weighted deregressed breeding values (DEBVw) were used as phenotypes for GWAS analysis. A total of 23 genome-wide significant SNPs were identified: 3 associated with MY, 9 with FY, and 11 with P%. Several SNPs mapped within known candidate genes or previously reported QTL for milk production traits in livestock species. Additional interesting markers were identified on OAR3 for FY and P%. These SNPs supported some previous findings and also added new information useful to understand the genetic mechanisms underlying the milk production and quality traits in dairy sheep.Highlights A total of 23 significant SNPs were detected. Several SNPs mapped within known candidate genes or previously reported QTL for milk production traits. These results could provide information to understand the genetic architecture of milk production traits in dairy sheep.