Abstract: The effect of different Effective Rumen Degradable Protein (ERDP) to Fermentable Metabolizable Energy (FME) on early lactating cow respomes was investigated. Total tract dgestibility of organic matter of various feedstuffs includ~ng barely grain, corn grain, wheat bran, cottomeed meal, soybean meal, sugar beet pulp, alfalfa hay, cotton seeds, corn silage and fish meal was determined using in situ technique. These data were used to predict FME of the feedstuffs. Two diets were provided with different ERDPEME ratio (9.7 and 10.7 g MJ-I). The diets fed to fourteen early lactating Holstein cows averaging 21+16 Days In Milk (DIM) and 3 M Kg d-\\\\\\\' milk yield for seven weeks, using a completely randomized design. Dly matter intake, milk yield and milk composition were measured weekly. Bloodmetabolites includmg glucose and urea nitrogen were measured in weeks 4 and 7. Rumen fluid NH-N was recorded in the Yd week of the experiment. Dly matter intake was significantly (p< 0.05) lower for cows fed det with ERDPEME = 9.7 g MJ-\\\\\\\' than those fed ERDPEME = 10.7 g M-\\\\\\\' (21 vs. 21.6, respectively). Milk yield was significantly (p< 0.05) hgher in cows fedERDPEME = 9.7 g MJ-\\\\\\\' compared with those fed ERDPEME = 10.7 g MJ-\\\\\\\' (35.2 vs. 32.3, respectively). Milk composition, blood metabolites and m e n fluid NH-N were not significantly affected by the treatments (p>0.05). Key words: Effective m e n degradable protein, fermentable metabolizable energy, milk, cow

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