Identification of single nucleotide polymorphisms of AADACL3 gene and their genetic associations with body weight and size traits in Chinese Holstein cows

The growth and development of dairy heifers are economically important traits, as they directly influence rearing costs, age at first calving, and subsequent milk production. Our previous genome-wide association study (GWAS) identified the AADACL3 gene as one of important candidates for body weight and body size traits of Chinese Holstein heifers. Here, we validate the genetic effects of AADACL3 on growth traits in an independent population. By performing whole-genome resequencing (∼10× coverage) on 30 Holstein sires, a total of 24 SNPs in the coding region and 5′, 3′ flanking sequences of AADACL3 gene were identified. Subsequently, these SNPs were genotyped in 2023 Holstein heifers by targeted capture sequencing (TCS). Using a mixed linear model in SAS 9.4, single-locus association analysis revealed that 15 SNPs were significantly associated with body weight at 2,3,4,7,9,10 and 11 month ages ( P < 0.0476), and 17 SNPs were significantly associated with body size traits (body height, body length, and heart girth) at 3, 6, 9, and 12 months of age ( P < 0.0358). Haplotype-based association analysis observed that block1 was significantly associated with 15 growth traits ( P < 0.0234); block2 was significantly associated with 22 growth traits ( P < 0.0281); block3 was significantly associated with 12 growth traits ( P < 0.0351). Correspondingly, significant additive and allelic substitution effects of the SNPs were observed as well. Our findings provide AADACL3 gene as genetic markers for genomic selection program of Holstein heifers.