indicated that rumen fluid pH and temperature values were in the range of 6.5 to 7.0 and 39.3 to 39.7◦C, respectively, and these ranges were considered as an optimal level for microbial digestion of fiber and protein. Excessive N supply, a release of ruminal NH3 that often exceeds its rate of incorporation in to microbial protein, resulted in loss of a great part N as NH3 absorbed from the rumen.