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 goals of this research were to 1) identify genetic variants, genes, and biological pathways that are associated with mastitis, and 2) identify genetic variants, genes, and biological pathways that are associated with somatic cell count. In Chapter 3, we describe 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. A total of 289 SNPs across all models reached genome-wide significance at 5% false discovery rate (FDR) and were mapped to 100 different nearby genes which have been identified in previous studies and are quantitative trait loci for somatic cell count. Significant SNPs and genes were mapped to the bovine genome to reveal corresponding genes to allow gene enrichment analysis to identify significant biological pathways associated with mastitis. In Chapter 4, we describe genetic associations affecting lactation average somatic cell count using 624,300 single nucleotide polymorphisms (SNP) on performed on 364 Holstein and Jersey cows in their first lactation. A total of 205 SNPs reached genome-wide significance at 5% FDR and were mapped to 68 unique genes.
| Identifer | oai:union.ndltd.org:CALPOLY/oai:digitalcommons.calpoly.edu:theses-4500 |
| Date | 01 June 2024 |
| Creators | Chen, Zikai Kevin |
| Publisher | DigitalCommons@CalPoly |
| Source Sets | California Polytechnic State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Master's Theses |
Page generated in 0.0015 seconds