Genome-wide association analysis identifies the genetic basis of body size traits in Tan sheep (Ovis aries)

BACKGROUND: Tan sheep is a Chinese indigenous breed prized for dual-purpose production of premium pelts and flavorful mutton, featuring a distinctive fat-tailed phenotype. The genetic basis of its body conformation remains largely unexplored. RESULTS: We conducted the first whole-genome sequencing-based genome-wide association study in 249 seven-month-old Tan sheep. Comprehensive population genetics analyses confirmed five distinct genetic clusters corresponding to the five sampling sources, supporting the cohort's suitability for the study. Using a mixed linear model, we identified 690 significant SNPs associated with eight traits: 10 for body weight, 2 for body length, 353 for body height, 105 for chest girth, 203 for tail length, 11 for tail circumference, and 6 for cannon circumference. Functional annotation revealed compelling candidate genes, including FBLN1 (weight/height), FGFBP1 (cannon circumference), and MAP3K20/FMNL3 (tail circumference). CONCLUSIONS: These findings illuminate the genetic architecture of growth and tail development in Tan sheep, providing a valuable genomic resource for molecular breeding strategies aimed at enhancing meat production while preserving superior pelt traits.