ABSTRACT
This study conducted to evaluate the influence of Ziziphus spina-christi leaves (ZSCL) as natural growth promoter and monensin as a synthetic growth promoter when both were supplemented into the basal diet that consisted of 40% berseem hay and 60% concentrate feed mixture (CFM) which served as control ration (R1). Tested rations consisted of control ration supplemented with 30 mg monensin (R2) or 15 g ZSCL (R3), per Kg DM intake. Nine Ossimi rams averaged 65±2.7 kg live body weight, 16-18 months old divided into 3 groups (3 animals each) according to live body weight for nutrients digestibility and dietary nitrogen utilization. Three Ossimi rams with rumen fistulae per treatment were used for rumen fermentation activity and total gas production. Twenty-one Rahmani lambs averaged 24±0.48 kg body weight and 4 months old divided into 3 groups (7 animals each) according to live weight for 120 days to investigate the growth performance of growing lambs fed the experimental rations. Results revealed no differences among the rations (P>0.05) in daily feed intake. Also, no effect was observed on digestibility of DM, EE and NFE among the experimental rations, while, digestibility of OM and CP in R2 ration were significantly (P