Crude protein and metabolizable energy levels are the most important nutritional measures to evaluate poultry diets. The experiment was performed with 144 Sinai laying hens (25 wk.) divided into 6 groups (two energy levels; 2700 and 2850 kcal/kg diet) and three protein levels: 14, 16 and 18 %.  The essential amino acid methionine was added to both diets containing 14 and 16% CP to reach the level of sulfur amino acids equal to that in the 18% protein diet in a factorial experimental design (2X3). The results could be summarized as follows: increasing both energy or protein levels displayed highly significant improvements (P≤ 0.01) in final body weight (FBW), change body weight (CBW), feed conversion ratio (FCR), egg number (EN), egg weight (EW), daily egg mass (EM) and hen-day egg production rate (HDEP), while low-energy diets caused significant increase (P≤ 0.01) in daily intake of feed (DFI), protein (DPI), energy (DEI); protein efficiency ratio (PER) and metabolizable energy efficiency ratio (MEE). The increase in protein levels led to a significant increase (P≤0.01) in DPI and PER. Birds fed diets with 16% or 18% protein at high-energy level attained the highest FBW, CBW, EN, EW, EM and HDEP values and no significant variations were observed among them. Egg quality criteria, fertility and hatchability were not significantly affected by studied factors. Increasing energy to 2850 kcal/kg resulted in a highly significant increase (P≤ 0.01) in cholesterol, and increasing protein level to 18% exhibited an increase in AST and ALT levels in the blood compared to other treatments. It could be concluded that fortification with methionine was not able to effectively compensate for the low-CP diet.
From an economic perspective, it can be suggested that 16% CP diet fortified with methionine and 2850 kcal/kg is optimal for Sinai laying hens in order to maximize profitability during the study period from 25– 40 week.