Abstract Background Postweaning body weights, are important economic traits, especially for meat type farm animals. This study was conducted to perform a genome-wide association study (GWAS) to detect quantitative trait loci associated with postweaning weight traits in Lori-Bakhtiari sheep. Methods Body weight records, incloding 6-month weight (6MW), 9-month weight (9MW) and yearling weight (YW) were collected during 1989 to 2017 in the flock of Lori-Bakhtiari sheep at Shooli Breeding Station in Shahre-Kord, Iran. Estimates of breeding values (EBVs) for the studied traits were estimated by analysis of animal mixed models, using WOMBAT software. A total of 132 animals were selected by two-tailed selection strategy, based on EBVs for body weight. Genomic DNA was extracted from whole blood samples, using 〖DNP〗^TM Kit and then were genotyped using Illumina 50k ovine SNP chip. De-regressed estimates of breeding values (dEBVs) were used as a pseudo-phenotypes. Quality control and GWAS analyses were performed using Plink 1.90 beta software. After quality control, a total of 130 animals and 41323 SNPs were remained for further analyses. Results Based on Bonferroni-adjusted p-values, 3 SNPs, located on chromosomes 10 and 13 were significantly (p < 0.05) associated with the studed traits and accounted for 0.02 and 0.48% of total genetic variations of 6MW and 9MW, respectively. The identified SNPs were located within two genes, ATPase Phospholipid Transporting 8A2 (ATP8A2) and Plexin Domain Containing 2 (PLXDC2), both protein coding genes. Based on molecular and cellular functions, both detected genes could be considered as candidate genes for post weaning body weight traits. Conclusion The detected QTLs and candidate genes in the present study could be subjected to more studied for construction of breeding programs for genetic improvement of growth performance in meat type sheep.
