Abstract: This study aimed to evaluate effect of using exogenous fibrolytic enzymes on productive performance of dairy cows and milk curve response at different lactation stages. One hundred and sixteen multiparous cows were randomly assigned into two groups; fifty eight cows in each. Each group was contained 12 cows in early lactation 40±6 Days In Milk (DIM), 18 cows in mid lactation (122±4 DIM) and 29 cows in late lactation (216±2 DIM). The animals were fed total mixed ration with or without 15 g fibrolytic enzymes head–1 day–1 for five weeks. Adding fibrolytic enzymes to dairy cows ration caused a significant increase in serum total protein and glucose concentration compared to control group, while Albumin, globulin, ALT, AST, alkaline phosphates activity and total bilirubin and urea concentration were not affected. Insignificant differences were observed in feed intake as dry matter, total digestible nutrient, crude protein and net energy lactation between the two groups. Enzymes supplementation to dairy cows rations increased milk yield, 4% FCM and ECM as well as milk fat contents compared to control group, while insignificant increased protein, lactose, total solid and solid not fat contents. Feed conversions as well as nitrogen efficiency utilization were significantly improved for treated group compared to control. Fibrolytic enzyme supplementation to dairy cows ration slightly increased positive slope (b-value) at early lactation compared to control group and no significant difference at mid lactation was observed. While, significant decrease in negative b-value was noticed for cows fed ration supplemented with fibrolytic enzymes compared to control group. It could be concluded that fibrolytic enzymes supplementation to dairy cows ration at early, mid and lactation has the potential to improve its productive performance as well as it is affect milk curve response.