Genome-wide Association Study Identifies QTLs for Displacement of Abomasum in Chinese Holstein Cattle.

Displacement of abomasum (DA) is one of the most common and important disorders in dairy cattle. The objective of current study was to detect the quantitative trait loci (QTL) for DA in Chinese Holstein using single-step genomic BLUP methodology. A total of 60,556 producer-recorded DA event records from 32,190 cows, together with 2,336 genotyped animals with 40,054 single nucleotide polymorphism (SNP) markers, were used for the analysis. Genomic data was incorporate into a threshold model for variance component estimation, and the estimated heritability of DA was 0.108 (SE=0.086). Results of GWAS were reported as the proportion of genetic variance explained 20-SNP windows. Eight QTLs covering 129 genes on Bos taurus autosomes (BTA) 2, 4, 7, 10, 14, 17, 20 showed associations with DA. Ten genes, namely BMP4, SOCS4, GCH1, DDHD1, ATG14, ACBP/DBI, SMO, AHCYL2, CYP7A1 and CACNA1A, involved in insulin metabolism and lipid metabolism pathways may be considered as candidate genes of DA in dairy. The identified QTLs, biological pathways and associated genes underlying DA identified from the current study will contribute to the understanding of the genetic architecture of this complex disease.