Soybean meal (SBM) has been used as a most important source of dietary proteins in ruminant diets, whereas relatively greater ruminal degradation of SBM limits nutritive merits on digestion, absorption, and utilization of its protein by ruminants. Biologically or chemically modified SBM such as fermented SBM (FSBM) or soy protein concentrate (SPC), respectively, are natural feeds that become protected SBM. The objective of this study was to assess in situ dry matter (DM) and crude protein (CP) degradation kinetics for SBM (control), FSBM (Bacillus fermentation), and SPC (alcohol extraction) prepared for by CJ CheilJedang (Seoul, South Korea). Three Holstein steers surgically fitted with ruminal cannula were used for in situ measurements for ruminal degradation kinetics. The 3 dietary treatments were compared according to a completely randomized design (n = 3). Kinetics of DM and CP degradation in situ was estimated by the nonlinear regression procedure of SAS. The wash fraction of DM was greater with SBM and FSBM than SPC (P < 0.05), but the potentially degradable fraction of DM was greater with SPC compared with SBM and FSBM (P < 0.05). The soluble fraction of CP was greater with FSBC than SBM and SPC (P < 0.05), while the potentially degradable fraction of CP was lower with FSBM than SBM and SPC (P < 0.05). The ruminal degradation rate was the greatest with SBM followed by FSBM and SPC, leading to the reduced effective ruminal degradability with SPC (36.0%) compared with SBM (56.3%) and FSBM (54.1%). Similarly, in situ DM disappearance at 48 h was the greatest with SBM (93.1%) followed by FSBM (79.9%) and SPC (67.1%), resulting in the same pattern of CP disappearance at 48 h (93.4, 78.2, and 60.7% from SBM, FSBM, and SPC, respectively). The overall results indicate that biological or chemical modification of SBM improved ruminal degradation characteristics by reducing DM and CP degradation rate and content with greater improvement achieved by alcohol extraction. With the consideration of sizably elevated CP concentration of SPC (67.2%) and FSBM (60.6%) relative to SBM (55.9%), SPC and FSBM hold potential for greatly valued sources of protein supplement in ruminant diets.