The objective of this study was to comparison of in situ ruminal degradability of DM and CP of extruded soybean (ES), soybean meal (SBM) and guar meal (GM). Extrusion was conducted on ground soybeans (EXP 160 KW). Extrusion temperature and residence time averaged 1550C and 25 second respectively. Four ruminaly fistulated steers (400 ± 20 kg, body weight) were used. Bags (12 × 19 cm, pore size of 48 μm) containing 5 g DM of each sample was incubated in the rumen (4 replicates per each animal) for 0.0, 2, 4, 8, 16, 24, 48, and 72 h. ruminal DM and CP disappearance rates were fitted to the exponential equation. In situ quickly degradable (a) fraction of DM was 0.41, 0.37 and 0.22 for ES, SBM and GM respectively. ES had the highest in situ quickly degradable (a) fraction of DM. In situ (a) fraction of CP was 0.07, 0.27 and 0.22 for ES, SBM and GM respectively. In situ (a) fraction of CP was lowest for ES. Slowly degradable (b) fraction of DM was 0.28, 0.62 and 0.39 for ES, SBM and GM. ES had the lowest in situ (b) fraction of DM. In situ (b) fraction of CP was lowest for GM and had no difference observed between ES (0.78) and SBM (0.72). GM had the lowest rate of degradation (c) (0.03) and had no difference between ES (0.12) and SBM (0.09). Rate of degradation (c) of CP was highest for SBM (0.09) and had no difference between ES (0.04) and GM (0.03). It was concluded that extrusion of soybean caused to decreased (a) and increased (b) fraction of CP.

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