Genome-Wide Association and Selection Signature Analyses of Hematological and Serum Biochemical Traits in Yunling Cattle

Yunling cattle, a native breed native to subtropical regions, exhibit remarkable traits such as heat tolerance, strong immunity, and tick resistance. To characterize the genetic architecture of blood physiological and biochemical traits associated with these adaptations, we performed a genome-wide association study (GWAS) using whole-genome resequencing data from 97 individuals combined alongside 39 blood traits (30 analysed after quality control). Significant association signals were detected for seven traits: albumin (ALB), homocysteine (CYS), white blood cell count (WBC), bilirubin (BIL), indirect bilirubin (I-BIL), low-density lipoprotein cholesterol (LD-CHO), and red cell distribution width (RDW). Notably, loci related to leukocyte parameters overlapped with strong selection signals and were mapped to classical bovine leukocyte antigen (BOLA) genes, including BOLA, BOLA-DQB and BOLA-DQA5, which are located within the MHC region and are known to be involved in immune regulation. For lipid-related traits, the strongest signals were identified near RPL22L1 and SLC7A14 on chromosome 1, while additional associated genes included XPOT, SLC16A7, SCAI, SYT14 and ATP2B2. Additionally, regarding metabolic and protein parameters, NHSL1 showed a strong association with bilirubin; this gene has previously been reported to be associated with hypertension. Red blood cell parameters revealed candidate genes such as NAV3, LSAMP, ACACA, and others linked to erythrocyte variation. For Homocysteine-related traits, CIITA was significantly associated with Homocysteine levels; CIITA is known to be involved in immune regulation. In conclusion, this study provides a genome-wide characterization of the genetic architecture of blood traits in Yunling cattle, identifying several candidate genes (e.g., MOB1B, CIITA and BOLA genes) associated with blood physiological and biochemical traits. These candidate loci provide a foundation for further functional validation; validation in larger and independent populations is needed before any application.