الفهرس 
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Abstract
The present study was undertaken, therefore, to evaluate the effects of dietary protein and energy levels and their interaction and their interaction on growth performance, nutrient digestibility, carcass traits and some blood parameters of Mamourah cockerels. *The most important results: Feeding the 20% CP diets throughout the experiment positively affected feed intake and weight gain of cockerels and negatively affected protein efficiency ratio and economic efficiency compared with the 18% CP diets but feed conversion ratio and efficiency of energy utilization were not affected. Conversely, birds fed the 18% protein diets exhibited significantly higher digestibility of dry matter, organic matter, crude protein and ether extract than those fed the 20% protein diets but digestibility of other nutrients were not altered. Dietary protein level had no effect on almost all carcass traits and blood parameters examined. However, decreasing dietary ME level did not affect feed intake or nutrient digestibility but positively affected growth performance. Carcass traits were not affected by decreasing dietary ME level but when it reached 2900 kcal kg–1 percent abdominal fat was significantly reduced and the percentages of carcass yield, total edible parts and liver were negatively affected. Dietary energy level had no effect on plasma constituents of birds but cholesterol concentration decreased when ME level reduced to 3000 or 2900 kcal kg–1. The interactions between dietary protein and energy levels were not significant for most variables examined. * Conclusion: Taking the economic aspect into account, optimal dietary CP and ME levels for growing Mamourah cockerels are suggested to be 20% CP and 3000 kcal kg–1.