Genome-wide association study of body weight and conformation traits in neonatal sheep

Sheep, an important source of meat, dairy products and wool, play an essential part in the global agricultural economy. Body weight and body conformation are key traits in the sheep industry; however, their underlying genetic mechanisms are poorly understood. In this study, a GWAS was implemented to identify promising genes possibly linked to birth weight (BW) and body conformation traits in neonatal sheep, using a high-throughput chip (630 K). After quality control, 277 individuals and 518 203 variants were analyzed using gemma software in a mixed linear model. A total of 48 genome-wide suggestive SNPs were obtained, of which four were associated with BW, four with withers height (WH), 11 with body length (BL) and 29 with chest girth (CG). In total, 39 genes associated with BW and body conformation traits were identified by aligning to the sheep genome (Ovis aries_v4.0), and most of them were involved in the cell cycle and body development. Promising candidate genes found included the following: FOS like 2 or AP-1 transcription factor subunit (FOSL2) for BW; potassium voltage-gated channel subfamily D member 2 (KCND2) for WH; transmembrane protein 117 (TMEM117), transforming growth factor beta induced (TGFBI), and leukocyte cell-derived chemotaxin 2 (LECT2) for BL; and trafficking kinesin protein 1 (TRAK1) and LOC101102529 for CG. These results provide cues for similar studies aiming at uncovering the genetic mechanisms underlying body development, and marker-assisted selection programs focusing on BW and body conformation traits in sheep.