Abstract

Increase in milk production as a result of intense genetic selection in dairy cattle has been accompanied by increase in the incidence of several reproductive and metabolic related disorders, including ketosis. Several investigations have studied candidate genes and biological pathways that characterize metabolic status of dairy cattle and ketosis early in lactation, however, little is known about genome-wide regions and key regulatory genes underlying this trait. In this study, we report a genome-wide association analysis on milk BHB concentrations (as an indicator of ketosis) predicted by mid-infrared (MIR) spectroscopy in dairy cattle using a single SNP regression mixed linear model. Our study detected several significant regions associated with MIR predicted milk BHB concentrations on chromosomes 6 (first lactation) and chromosomes 14 and 20 (later lactations). One highly significant SNP on chromosome 14 was located within DGAT1 gene, which is known to have significant effects on milk fat/protein yield and other production traits. The significant regions on chromosomes 6 and 20 were not reported to be linked to metabolic associated disorders or ketosis in previous investigations. Enrichment analysis of the list of candidate genes within the identified regions for milk BHB concentrations has yielded molecular functions and biological process that may contribute to inflammatory response and lipid metabolism in dairy cattle. The result of this study can be used for further analysis to identify causal variations and key regulatory genes that affect clinical/ subclinical ketosis. Key words: milk BHB concentrations, MIR spectroscopy, clinical/subclinical ketosis, genome-wide association, dairy cattle

Shadi Nayeri, Victoria Kroezen, Mehdi Sargolzaei, Allison Fleming, Flavio Schenkel, Christine Baes, Angela Canovas, James E. Squires, Filippo Miglior

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Biology & Species - Bovine (dairy) 2, , 634, 2018
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