This study was conducted in order to compare protein value of Soybean Meal (SBM, 451.70±2.8 g/kg DM), a commercial protected soybean meal product (Yasmino Max®, 459.30±1.7 CP g/kg DM) and fishmeal (FM, 510.90±0.9 CP g/kg DM) expressed according to Dutch protein evaluation system. Ruminal incubations for test feeds and laboratory analyses were performed according to Protocol for in situ Rumen Incubations published by Centraal Veevoeder 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) comparing to SBM(196.47±4.3) and FM (239.79±0.7). Although FM has a relatively low CP degradability in rumen, it has a higher OEB value (123.13±0.6 g/kg DM) comparing to 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 feedstuff 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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