Tarbiat Modares University Journal of Agricultural Science and Technology 1680-7073 20 2 2018 03 01 Impact of Post Peak Daily Metabolizable Energy Intake on Performance of Broiler Breeder Hens 235 247 16140 EN M. Zaghari Department of Animal Science, College of Agriculture, University of Tehran, Karaj, Islamic Republic of Iran. S. Maghami Tekieh Islamic Azad University, Maragheh Branch, Maragheh. Islamic Republic of Iran. A. Safamehr Islamic Azad University, Maragheh Branch, Maragheh. Islamic Republic of Iran. Journal Article One hundred ninety two broiler breeder hens, from 40 to 49 weeks of age, were utilized in a precision feeding study for determining the hens’ energy requirement. Treatments were daily feed allotments containing metabolizable Energy Requirement (ER) estimated by empirical model, <em>ER</em> minus 10 (ER‒10), plus 10 (ER+10), and plus 20 kcal hen^-1 d^-1 (ER+20). Four levels of Metabolizable Energy Intake (MEI) were made by adding 0, 1.2, 2.4 and 3.6 grams corn oil, over the top of daily feed allotment. All birds consumed the same amount of diet, and were provided the same intake of nutrients, except energy. Hens with weight gain of 3.5 g per day had the maximum reproductive performance. Ovary weights were lower in <em>ER</em>-10 hens. This difference was also reflected in Small Yellow Follicle (SYF), and Large Yellow Follicle (LYF) numbers, in which the <em>ER</em>-10 hens had fewer SYF (7.6) and LYF (1.1). Hens that received 462.7 kcal d^-1 (ER), produced 4.04 eggs more than those that received 452.7 kcal d^-1 (ER‒10). However, addition of extra 10 and 20 kcal (ER+10, ER+20) on daily <em>MEI</em> had no beneficial effect on egg production. Using the linear broken line model, the <em>ME</em> requirements for egg production and hatchability were estimated at 458.5, and 456.2 kcal hen^-1 d^-1, respectively. Comparing the current estimated requirement value with earlier reports revealed that broiler breeder hens need more energy in a commercial house than those kept in an experimental house in the cage or pen. In conclusion, during post peak period with average 458.5 kcal <em>MEI</em>, 5 kcal hen^-1 d^-1 more than Ross 308 recommendation can improve broiler breeder hens’ performance. https://jast.modares.ac.ir/article_16140_e165a2677bb8cfa3ed9b1d0a4a8938e4.pdf