Experiments were conducted with the aim of assessing AME and AMEn content of broiler diets and ingredients as well as determining energy utilization in growing broilers. The use of the conventional nitrogen correction factor yielded AMEn values that were 4-5% lower than AME values for complete broiler diets. Based on observations of complete diets, measures of diet AMEn content were less variable than AME content. With high protein ingredients, such as soybean meal (SBM), the use of N correction heavily penalizes (10-12%) its energy value in comparison to lower protein ingredients like corn (2-5%). For corn, AME and AMEn were little affected by birds age. The effect of nitrogen correction was consistent at around 3%. On the other hand, AME and AMEn contents of SBM were more variable and dependant on the bird age. Increasing either AME or AMEn content of diets did not influence growth performance (P>0.05), but increased deposition of abdominal fat (P<0.01). Estimates of daily maintenance energy requirements (MEm) in broilers were 155 kcal per kg BW0.60 and 143 kcal per kg BW0.75 . This difference becomes more obvious for younger and/or smaller birds. Within the experimental period of 0-42 days, broilers deposited body fat and protein that together represented 35 to 40% of their daily ME intake. However, MEm requirements represented 42-49% of metabolizable energy intake (MEI). Linear and non-linear models were used to quantify total energy retained (TER), as fat (TERF) and protein (TERP) during growing. These models fit the data reasonably well within the first 42 days of age and could be used to predict TER, TERF and TERP. The results could be used to redefine the energy requirements of growing broilers and be used as a base for performance predictions and production models.