The Effects of Drug Treatments on DPIf Utilization 13 Non-protein Nitrogen for Young Chicks Non-protein Nitrogen for Laying Hens The Effects of Drug Treatments on NPN Utilization EXPERIMENTAL PROCEDURES Studies with Laying Hens Experiment I Objectives General procedure Diets Management and data collection Results Studies with Young Birds General Pre-experimental Management Experiment II Objectives General procedure Diets Management and data collection Results Experiment III Objectives General procedure Diets Management and-lata collection $3 iii Page Results Experiment IV Objectives General procedure Diets Management and data collection 59 Results