Fifteen lactating crossbred Friesian cows in early lactating were randomly assigned into three groups (five animals each). Three experimental diets were formulated to study the effect of protected protein of concentrate feed mixture (CFM) by zinc sulphate on nutrients digestibility, some rumen fermentation characteristics, some plasma metabolite concentrates and their reflection on milk production and its components of cows fed berssem hay (BH) based diet. The ratio of BH to CFM was 40 to 60 on dry matter basis. Diets were supplemented with CFM; Zn- CFM and combination of Zn- CFM and CFM at rate of (1:1).       The obtained results indicated that digestibility coefficients of OM, CP and NFE were significantly (P<0.05) higher for cows fed combination of                Zn-CFM/CFM and Zn-CFM diets than those fed CFM diet. The improvements in digestibility of nutrients reflected better feeding values in terms of TDN and DCP for diets containing treated CFM than the untreated CFM diet.        Ruminal NH₃-N and NPN concentrations were lower (P<0.05) for cows fed treated CFM by zinc sulphate than those fed untreated diet, indicating efficiency of the protection and/or better synchronization between availability of energy and release of NH₃. On the other hand, ruminal true protein nitrogen (TPN) was higher (P<0.05) for cows fed combination of Zn-CFM/CFM and Zn-CFM diets than those fed CFM diet.       The concentration of plasma urea-N was decreased when cows were given protected CFM-protein than those fed unprotected one, whereas, the concentrations of total protein, albumin and globulin were increased.        Yields of milk, 4% fat-corrected milk (4%FCM) and its components were higher (P<0.05) when cows were fed combination of Zn-CFM/CFM or Zn-CFM diet than those fed CFM diet. Milk non-protein nitrogen (NPN) was lower on Zn-CFM/CFM or Zn-CFM diets. On the other hand, yields of true protein nitrogen, casein nitrogen, non- casein nitrogen and whey nitrogen in milk were higher (P<0.05) for cows fed protected protein than those fed unprotected protein.       Feed cost per one kg 4% FCM was lower for cows fed combination of Zn-CFM and CFM diet than those fed Zn-CFM diet or CFM diet. Accordingly, economic efficiency value was the best with Zn-CFM/CFM diet.