Two projects were conducted to evaluate dietary impacts on mitochondrial respiration of gestating heifers and fetal offspring. Our first hypothesis was that maternal vitamin and mineral supplementation during gestation improves the liver, muscle, and jejunum mitochondrial function of F1 and F2 offspring. In project 1, vitamin and mineral supplementation was provided to the F0 generation of dams from breeding to calving to isolate the effects of nutrition during pregnancy on future generations. Our second hypothesis was that altering limit-fed diets' forage: concentrate ratio would influence mitochondrial respiration in maternal and fetal jejunum and liver. In project 2, replacement heifers were fed high-concentrate and high-forage diets to evaluate the dietary impacts on fetal cellular metabolism of key metabolic organs. In both project 1 and 2, modulations of metabolism occurred in key metabolic organs of gestating heifers.