An experiment was carried out to evaluate protein degradability on animal performance, ruminal and blood metabolites and ruminal ecosystem. Eight multiparous Holstein cows were used in a change over design in four period. Supplemental protein which provided via Soybean Mal (SBM), Meat Meal (MM), urea were added to basal diet based on the providing same CP protein. Treatments were provided via Soybean Mal (SBM), Meat Meal (MM), urea and with flowing rumen degradability (T1: 74.5, T2: 70.4, T3: 68.7 and T4: 63.7%). Each experimental period was conducted for 21 days (14 days for adaptation and 7 days for sampling). There were no significant difference between treatments for DMI. However, trend indicates that by reduction of RDP in diet milk production decreases. No difference were observed for milk composition, body weight, pH and blood metabolites. Ruminal ammonia nitrogen was numerically higher for does fed T1 (9.25 vs 7.81, 6.94 and 7.98) and this trend was observed for blood urea nitrogen as well. Protozoa number was higher in does fed SBM with Urea.

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