This study was conducted in to compare soybean Meal (SBM, CP: 451±2.8 g/kg DM) with a chemically protected soybean meal (Yasmino Max®, CP: 459±1.7g/kg DM) and fishmeal (FM, CP: 510±0.9g/kg DM) using Dutch Protein Evaluation System. Ruminal incubations for test feeds and laboratory techniques were performed according to Protocol for in situ Rumen Incubations published by CentraalVeevoeder Bureau Standards. Truly absorbed protein in the small intestine (DVE) contributed by (1) feed protein escaping rumen degradation, (2)microbial protein synthesized in the rumen and (3) a correction for endogenous protein losses in the digestive tract, the difference between the potential microbial protein synthesis based on rumen degraded feed CP and that based on energy available for microbial fermentation in the rumen (OEB) and fermentable organic matter (FOM) were calculated according to DVE/OEB model. According to the results in spite of the fact that FM is considered to be a valuable source of protein due to its high protein content andruminal stability, Yasmino Max®provides animal with more DVE (260.95±6.9 g/kg DM) compared withSBM(196.47±4.3) and FM (239.79±0.7). Although FM had a relatively low CP degradability in rumen, it has a higher OEB value (123.13±0.6 g/kg DM) compared with SBM(117.85±3.7) and Yasmino Max®(90.32±6.0) which reflects the effect of FOM (334.09±10.5, 306.41±16.6 and 206.97±1.4 g/kg DM for SBM, Yasmino Max and FM respectively)on OEB value. In conclusion among the tested feedstuffs,Yasmino Max® is the most favorable since it delivers more DVE to animal and has a better balance between the rumen available N and fermentable energy.

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