Thesis (M.S., Animal and Veterinary Science) -- University of Idaho, 2015 | Dairy cows with greater subcutaneous fat stores release greater concentrations of nonesterified fatty acids (NEFA) into the blood during the periparturient period. Large quantities of circulating NEFA alter circulating phospholipids (PL) fatty acid (FA) profile. Modified cellular FA profile effects immune cell function. The objective of this study was to determine the effect of elevated lipid mobilization during the periparturient period on serum, peripheral blood mononuclear cells (PBMC), and polymorphonucleocytes (PMN) NEFA and PL fraction and milk fatty acid (FA) profile, PBMC and PMN gene expression of selected markers of inflammation and production measures. Thirty-four cows were blocked by parity; treatment group received a high-energy prepartum ration. Control group received a normal-energy ration and monensin. In summary, increased subcutaneous fat stores altered the FA profile of serum, PBMC and PMN NEFA and PL fractions and milk as well as gene expression of PBMC in periparturient dairy cows.