Candidate gene search for milk production and composition, milk coagulation properties, and milk protein profile in dairy sheep from a New Zealand flock

The objective of this study was to perform genome-wide association analysis and thus search for candidate genes for milk production and composition, milk coagulation properties (MCP), and milk protein profile in dairy sheep from a New Zealand flock. After quality control, 45,801 single nucleotide polymorphisms (SNPs) were included in the analysis, 147 ewes, and 470 individual records. A total of 87 SNPs and 55 candidate genes were found across <i>Ovis aries</i> autosomes (OAR) 2, 3, 6, 16, 18, 20, 25, and 26. Of particular importance, were the candidate genes PDZRN4 for milk yield, and BMP2K for contents of α_s1- and α_s2-caseins. No SNPs were found in the casein genes, LALBA or PAEP. Only one SNP was significant for MCP, and overall, the genetic architecture of MCP was similar to that of ratio of casein to calcium, pH, lactose, and the ratio of casein to protein. Further studies with larger flocks and with genomic imputation are required to validate the findings of this study before incorporating markers or genes into breeding programmes.