Identification of Candidate Genes and Functional Pathways Associated with Body Size Traits in Hulunbuir Sheep Through GWAS Analysis

(1) Background: The Hulunbuir sheep is a Chinese local sheep breed with good meat quality and exceptional cold-stress resilience. However, the growth performance of the Hulunbuir sheep is lower when compared to that of commercial breeds. Growth traits such as body weight and body size are critical, as they directly influence the meat production in sheep farming. Employing genome-wide association studies can identify SNPs and candidate genes related to growth traits in Hulunbuir sheep. (2) Methods: The chest girth (CG), cannon circumference (CC), hip width (HW), body height (BH), and body length (BL) of 799 Hulunbuir sheep were measured. All the animals were divided into three groups according to their age (Group 1: 0-6 months old, Group 2: 12-24 months old, Group 3: 48-70 months old). Subsequently, genotyping was carried out using the Sheep 40K liquid chip. A multi-trait genome-wide association study (MT-GWAS) was performed for each group of animals. (3) Results: A total of three candidate genes (<i>SLC9C1</i>, <i>VSTM2A</i>, <i>FRG1</i>) associated with body size traits were identified through GWAS analysis and KEGG pathway enrichment for Group 2. (4) Conclusions: This study identified three candidate genes related to body size in Hulunbuir sheep, providing genetic targets for marker-assisted selection (MAS) in Hulunbuir sheep.