Genome-Wide Association Study Reveals Candidate Genes Underlying Reproduction-Associated Conformation Traits in Jersey Cattle

Reproductive traits are essential in dairy cattle breeding, and improving body conformation is considered beneficial for reproductive performance. This study systematically analyzed the genetic relationships between six key conformation traits—stature (ST), body depth (BD), loin strength (LS), rump angle (RA), rump width (RW), bone quality (BQ)—and reproductive performance in 1631 Jersey cattle from China. Heritability estimates for conformation traits ranged from 0.05 to 0.62. We identified significant phenotypic and genetic correlations between conformation and reproductive traits, and regression analyses confirmed the predictive value of conformation traits for reproductive outcomes. Genome-wide association studies detected 24 significant SNPs associated with ST, RW, RA, and BQ. Subsequent bioinformatics analysis revealed seven candidate genes (AZIN1, OR2H1, HS6ST3, ERCC4, KCNH5, KRT19, KRT35) involved in embryonic development and estrous cycle regulation. Notably, incorporating six SNPs, which are linked to these candidate genes, into genomic prediction models significantly improved the accuracy for predicting Age at First Calving (AFC) and Gestation Length (GL). These results elucidate the shared genetic basis of conformation and reproduction, providing theoretical support for using conformation traits in marker-assisted selection to enhance reproductive efficiency in Jersey cattle.