In this experiment, the comparison of controlled-feeding and full-feeding on the utilization of dietary NPN-substitute and the changes of blood ammonium and serum urea levels after feeding experimental feed were tested by using eight hogs of crossbred and nine hogs of Large White. For the NPN-substitute feeds, 20% of crude protein in the control feed, formulated similar to that in the previous report, were substituted by 1.1% of urea or 2.4% of di-ammonium phosphate (DAP) supplemented with 0.3% of L-lysine. During the ureasubstitute feeding period, full-feeding group showed good daily gain of 628g, contrast with the controlled-feeding group's 485g, and also showed a better feed conversion. In the cass of DAP feeding, full-feeding group again showed a slightly faster weight gain, but controlledfeeding group showed a better feed conversion. Ammonium level in blood has been at 1-4 μg/ml which lies well within the normal limits. However, urea level in serum showed a rapid rise from the start of urea-substitute feeding.