Polymorphisms in lipogenic genes and milk fatty acid composition in Holstein dairy cattle

• Milk fatty acid data from the 305-day lactation were used for association analyses.
• Intragenic haplotypes were tested for association with milk fatty acids.
• DGAT1 polymorphism was associated with palmitic, oleic, and linoleic acids.
• AGPAT1 polymorphism was associated with linoleic and polyunsaturated fatty acids.
• AGPAT6 and LPIN1 were not associated with milk fatty acid composition in Holsteins.

Changing bovine milk fatty acid (FA) composition through selection can decrease saturated FA (SFA) consumption, improve human health and provide a means for manipulating processing properties of milk. Our study determined associations between milk FA composition and genes from triacylglycerol (TAG) biosynthesis pathway. The GC dinucleotide allele of diacylglycerol O-acyltransferase 1:g.10433-10434AA > GC was associated with lower palmitic acid (16:0) concentration but higher oleic (18:1 cis-9), linoleic (18:2 cis-9, cis-12) acid concentrations, and elongation index. Accordingly, the GC dinucleotide allele was associated with lower milk fat percentage and SFA concentrations but higher monounsaturated FA and polyunsaturated FA (PUFA) concentrations. The glycerol-3-phosphate acyltransferase, mitochondrial haplotypes were associated with higher myristoleic acid (14:1 cis-9) concentration and C14 desaturation index. The 1-acylglycerol-3-phosphate acyltransferase 1 haplotypes were associated with higher PUFA and linoleic acid concentrations. The results of this study provide information for developing genetic tools to modify milk FA composition in dairy cattle.