Cows representing the average (AFP) and high (HFP) fat plus protein selection lines maintained at the ISU dairy were selected to participate in a study to identify indicators of energy mobilization. Differences between HFP and AFP cows in the expression of genes in adipose tissue, and the production of metabolic hormones are being defined. These differences will reveal physiological mechanisms important to the mobilization and utilization of energy reserves. This work will lead to the identification of indicators of metabolic stress, and aid in the selection of dairy cattle better able to sustain optimal levels of milk production.