Two experiments were carried out to evaluate cultivation of Spanish Panicum Mombasa (SPM) in five Cutting interval (CI) 30, 45, 60, 75 and 90 day and its effect on in vitro rumen fermentation and dairy goats performance feeding at 0, 25 and 50% SPM as a replacement of clover hay (CH).  30 days  CI recorded the highest values of CP, EE, and ash content being 17.9, 2.1 and 12.7, respectively. The lowest recorded CF content being 24.6%.  Regarding in vitro rumen fermentation, methanogenesis trail of samples collecting from different SPM in CI days showed that the lowest gas production (GP) was at 90 days  CI. In a performance trail,  24 baladi lactating goats were divided into  (T1) control group,  (T2) group fed rations supplemented with 25 and (T3) 50% of SPM as a replacement from CH.   (T3) ranked the highest milk yield followed by   (T2) compared significantly (P<0.05) with the control. T3 recorded (P<0.05) the best value of protein, fat, TS and Ash contents of milk Colostrum composition and the same results were obtained on the first, second and third months of milk composition. Blood analyses for AST, ALT cholesterol, TG, albumin, urea, creatine, and Malondialdehyde (MDA) contents exhibited  significant  differences (P<0.05) between diet (T3) and the control (T1), while diet T3 group exhibited   higher values of Glutathione Peroxidase (GPx) compared with control.  Diets contain 25 or 50% of SPM as a replacement of CH were suitable for feeding ruminant, greater profitability and animal health under Egyptian condition.