Dietary energy level appears to be the most important factor affecting feed intake. In recent years, an increasing numbers of broiler chicks are grown to heavy weights to meet consumer demands for deboned poultry meat. But the feed conversion ratio (FCR) in broiler chicks declines with advancing age, making it more important to minimize their feed costs. It is also known that although broilers generally adjust feed intake to achieve a minimum energy intake from diets containing different energy levels, these adjustments are not always precise (NRC, 1994). Going insight into the scientific literature, one could easily find inconsistent responses of broiler chicks to varying contents of metabolizable energy (ME) in their diets. The main reasons for this discrepancy are the nutrient composition and/or digestibility of diet, the physical form of diet, type and level of added fat, dietary ME level, strain, gender and age of bird, ambient temperature, and the interactive effects of dietary ME and amino acid density and certain additives (Dozier III et al., 2007 and Zhou et al., 2009).