PSX-10 Genome-wide association studies for clinical mastitis in dairy cattle

Mastitis, the inflammation of the mammary gland caused by both gram-positive and gram-negative bacteria, causes the global dairy industry over $20 billion annually in losses due to changes in milk yield and quality. The goal of this study was to identify genetic variants, genes, and biological pathways that are associated with mastitis. We performed genome-wide association studies (GWAS) on 1,858 cows from two lactations with both medium (n = 87,493) and high density (n = 624,300) single nucleotide polymorphisms (SNP) using a single SNP mixed linear model implemented in GCTA software. A total of 288 SNPs across all evaluated models passed the 5% genome-wise false discovery rate threshold across all autosomes with emphasis on chromosomes 3, 14, 16, 12, 6, and 2. These SNPs were mapped to their corresponding genes using the bovine genome. Gene enrichment analysis was then performed to identify significant biological pathways associated with mastitis. The current study identified potential genes that are involved in the MAPK, C5a, and ion binding pathways, which have been previously associated with immune function and inflammation. Further validation and investigation are required to confirm the identified genes and pathways before implementation in breeding programs.