Genome-Wide Association Study of Body Measurement Traits at Birth in Cattle.

Hexi cattle are an indigenous beef population developed through multigenerational crossing of Simmental and Mongolian cattle, exhibiting exceptional adaptability to arid and semi-arid environments alongside robust growth performance. To investigate the genetic architecture underlying early growth traits, we conducted a GWAS for body weight (BW), withers height (WH), body length (BL), and heart girth (HG) in a cohort of 264 Hexi cattle (125 males, 139 females). Phenotypic analyses showed that male calves had significantly higher values for all traits relative to female calves (p < 0.05), confirming the presence of sexual dimorphism. The genomic inflation factors (λ = 0.997-1.016) indicated that population structure was effectively controlled. In total, 11 functional candidate genes were identified under the genome-wide significant threshold of p < 1.0 × 10^-6. Specifically, SLC44A1 associated with BW; PTGS2, POP1, and ERC2 with WH; TIAM1, PROK1, SMOC2, and RFFL with BL; and C3orf80, PROKR1, and FBXO32 with HG. These results not only advance our understanding of the genetic regulation of early development in Hexi cattle but also establish a foundation for implementing marker-assisted and genomic selection in this population.