Effects of an alpha‐linolenic acid enriched diet on mRNA expression of lipid metabolism genes in bovine milk somatic cells

Abstract

α‐linolenic acid (αLA) is an essential fatty acid that functions in the maintenance of cell membrane fluidity and the synthesis of eicosanoids. This study examined the effect of an αLA‐enriched feed (camelina meal) on mRNA expression of lipid metabolism genes in somatic cells harvested from milk. Primiparous dairy cows (n=18) were fed a ration containing 0, 3, 6, and 9% camelina meal substituting for canola meal (18:1 cis9) in a 4x4 Latin square design. Somatic cells (primarily leukocytes and epithelial cells) were separated out of milk and total RNA was extracted for gene expression analysis with real time rt‐PCR. Expression of acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), lipoprotein lipase and stearoyl CoA desaturase was increased in milk cells with the 6% diet whereas milk fat percent and yield were decreased. A negative correlation was observed between the concentrations of serum triglycerides and expression of ACC and FAS whereas a positive correlation was observed between the concentrations of serum non‐esterified fatty acids and expression of the same two genes. More research is needed to elucidate the relationship between mRNA expression of lipid metabolism genes in milk somatic cells and serum lipid content. Use of total milk somatic cells may not be an accurate method of measuring mammary epithelial cell mRNA expression. Supported by the United Dairymen of Idaho and NIH‐NRRI grant P20 RR15587.