According to the Bovans White Leghorn Breeder Guide (Centurion Poultry, 2012), diets were separated into 4 phases: (1) 18 to 22, (2) 23 to 32, (3) 33 to 44, and (4) 45 to 74 wk of age. For each phase, 3 diets were formulated to have 2 percentage points protein differ- ences with the amino acid levels decreased or increased in proportion to CP level (Table 1). Three dietary treatment groups were established from 3 protein levels in each phase: 1) high protein diet, 2) medium protein diet, and low protein diet. Diets were assigned to each individual cage and each individual hen was the experi- mental unit to make 48 replications per treatment.