Polymorphisms in SREBP pathway and variations in milk fatty acid composition in Holstein dairy cows.

Abstract

The objectives of this study are to determine variations in single nucleotide polymorphisms (SNPs) in genes from the sterol regulatory element binding protein (SREBP) pathway and to associate identified SNPs with differences in milk fatty acid composition in Holstein dairy cows. Three genes, SREBP1, SREBP cleavage‐activating protein (SCAP), and insulin induced protein 1 (Insig1) from the SREBP pathway that are involved in the transcriptional regulation of stearoyl‐CoA desaturase (SCD) and other lipogenic genes, were sequenced in exonic and intronic regions to detect SNPs. About 500 cows were genotyped for discovered SNPs using Sequenom MassARRAY system. Phenotypic data comprised of milk samples that were collected monthly throughout the lactation for all the cows and analyzed for fatty acid composition using gas chromatography. Multiple numbers of SNPs from SREBP1, SCAP, and Insig1 were significantly associated with differences in unsaturated fatty acid composition in milk. In particular, depending on the SNP, the percentages of monounsaturated fatty acids, polyunsaturated fatty acids, total unsaturated fatty acids, saturated fatty acids, and/or the ratio of unsaturated to saturated fatty acids were affected. The results of this study indicate the potential of using associated SNPs as DNA markers to select breeding stocks that have a healthier milk fatty acid composition.