This study were conducted to evaluate the effects of physical processing (roasting and electron beam irradiation) of whole soybean on ruminal, post ruminal and total tract digestibilities of dry matter (DM) and crude protein (CP) and to compare responses of performance and physiological lactating dairy cows fed ration containing them. In in situ trail, three ruminally fistulated and one T-shaped cannulated non-lactating Holstein cows were used for in situ and mobile nylon bag techniques. Samples were incubated with rumen for 0, 2, 4, 8, 12, 24 and 48h, then DM and CP degradation were estimated data to fitting disappearance by nonlinear equation. Soybean proteins in different incubation proteins were fractionated using SDS-PAGE technique. Effective CP degradability of untreated, roasted and e-beam irradiated soybean at 0.08/h outflow rate were 61.96, 50.72 and 76.82% percent. Roasting decreased constant degradation rate and effective degradability of DM and CP, but e-beam irradiation increased these parameters. Based upon electrophoretic patterns, the major component of escaped protein in untreated and e-beam irradiated whole soybean was basic subunit of glycinin and in roasted samples were ?-subunit of conglycinin and two subunits of glycinin. In in vivo trail, to evaluate effects of those whole soybean physical treatments on performance and physiological of Holstein lactating cows, In experiment with treatments containing whole soybean, nine non-lactating Holstein cows at 140±15 days in milk were used to investigate production yield and total tract digestibility of soybean. This trail was designed at latin square 3×3 with three replicates through 21 days periods cows were fed with rations containing processed whole soybean at 60% concentrate and 40% hay. DM intake untreated, roasted and e-beam irradiated whole soybean of cows fed ration containing of were differ (P 0.05), but of CP were not significant. There were differences (P 0.05) among digestibilities of DM, OM, NDF, ADF and ruminal acidity of cows treatments. Milk production and energy corrected milk of cows fed ration containing roasted whole soybean were highest. Fat, protein and lactose contents of milk were not differ (P 0.05) amonge treatments. Rumen ammonia nitrogen and VFAs concentration were not significantly affected by treatments in this experimental (P 0.05). In conclusion, feeding roasted whole soybean to lactating cows increase and improve production and composition milk and chemical composition feedstuff. Key Word : Degradation, Whole soybean, SDS-PAGE, Mobile Nylon Bag, Electron Beam Irradiation, Roasting.