Genome-Wide Association Study of Body Size Traits in Yanqi Horses

Horse body size serves as a direct production indicator that reflects growth status, with body size traits frequently utilized as principal selection criteria and extensively applied in monitoring animal growth and development as well as evaluating the effi-cacy of genetic selection. The identification of molecular markers associated with body size traits has the potential to expedite animal breeding programs. The Yanqi horse, an important indigenous breed in Xinjiang, is primarily distributed in the Bayingolin Mongol Autonomous Prefecture. However, molecular markers linked to body size in Yanqi horses remain uncharacterized. In the present study, a genome-wide association study was performed on withers height, body length, heart girth, and cannon bone circumference traits in 183 Yanqi horses to identify genomic variants associated with body size characteristics. A total of 185 single-nucleotide polymorphisms were signifi-cantly associated with body size traits, and 359 candidate genes were annotated within 200 kb upstream and downstream of the significant loci. Among these, five genes, GABRB1, FIGN, GABRA4, ENSECAG00000051747, and COX7B2, may be implicated in the growth and development of Yanqi horses. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses indicated that these genes are primarily in-volved in cytoskeletal structures within muscle cells, regulation of the actin cytoskele-ton, and neuroactive ligand-receptor interaction pathways. In summary, this study presents novel markers and candidate gene sets associated with body size traits in Yanqi horses, offering valuable insights for functional gene investigations and pre-senting substantial potential for accelerating the breeding of Yanqi horses.