An experiment was conducted to test the hypothesis that sows can utilize more energy in the diets than growing pigs. Three diets were prepared. One diet contained corn as the sole source of energy and two diets contained corn and SBM or corn and soybean hulls as the energy sources. These diets were fed to gestating sows, lactating sows, and growing pigs. Growing pigs and sows in mid-gestation were housed individually in metabolism crates that were equipped with a slatted T-bar floor, a screen floor, and a urine pan, which allowed for collection of feces and urine. Lactating sows were housed in farrowing crates and fecal samples were collected via rectal palpation. The apparent total tract digestibility (ATTD) of gross energy (GE) and the concentration of digestible energy (DE) and metabolizable energy (ME) were determined in growing pigs and gestating and lactating sows with the exception that ME was not determined in lactating sows. Results indicated that DE and ME in corn were not different between growing pigs and gestating sows, but DE was greater in growing pigs and gestating sows than in lactating sows and ME of corn was greater in gestating sows than in growing pigs. Growing pigs and gestating sows also had greater DE of SBM than lactating sows, but although there was no difference in DE between growing pigs and gestating sows, the ME of SBM was greater in growing pigs than in gestating sows. For soybean hulls, lactating sows had greater DE than growing pigs and gestating sows, and growing pigs tended to have greater ME than gestating sows. The DE in corn and soybean meal was greater than in soybean hulls regardless of the physiological stage of the pigs, but there was no difference in DE between corn and SBM.