Abstract
Forty five mixed breed ewes of 3-3.5 years of age and 40-50 Kg live body weight were used in this study. The ewes were housed inside an open yard with shade and concrete floor. They were fed on the control diet for one month before the beginning of the experiment. At the onset of the breeding season, the animals were classified randomly into nine groups five, per each. Nine diets including the control one were formulated with three levels of digestible energy (DE, 2.2, 2.5 and 2.8 Mcal/Kg diet), each at three levels of phosphorus (low, normal and high) in a 3x3 factorial design. The nine diets were designates as NENP, NELP, NEHP, HENP, HELP, HEHP, LENP, LELP and LEHP. First litter in each diet designates the energy level while, the third litter designates the phosphorus level (H, high, N, normal and L, low). The litters E and P stand for energy and phosphorus, respectively. The animals were fed the respective experimental diets and water ad-libitum for one month after the beginning of the breeding season. A metabolism trial was carried out during the last week of the experiment. Blood samples were taken regularly twice weekly for biochemical examination. Throughout the period of the experiment, the animals were examined regularly by using ultrasonography. The results of this study indicated that, levels of energy and phosphorus affect significantly (P<0.05) nutrients digestibility, some blood constituents and ovarian structure.