| The imbalance between degradative and biosynthetic activities of the rumen microorganisms cause a 搘aste?of protein , and it is a hot subject in the field of ruminant nutrition. In the rumen, the degradability of protein feedstuffs by the rumen microorganisms is so fast that most of the ammonia is absorbed by wall of rumen then carry to liver by blood, at which transfer to urea, then release into the environment, which cause the waste of nitrogen.The main purpose of this research is to investigate the mechanism of protein degradation in the rumen, so that present a theory to improve the utilization of nitrogen by ruminant. The conclusions are: degradability difference between different feedstuffs do exist. Of the three protein feedstuffs that under research, soybean meal is the most degradable, and DDG is the least, in which the 48 hours dry matter degradability of soybean meal is 97.9%, for crude protein it is 97.65%; while for DOG, it is 40.98% and 30.73% separately; Some of the amino acids of the undegradated peptide in rumen fluid and the undegradated protein of feedstuffs are much more than others. When feed with soybean meal, rape meal, and DOG, glutamate, aspartate and histidine are the most abundant three amino acids in the peptide of the rumen fluid. In their undegradated protein remaining in polyester bags after 48 hours of incubation in the rumen, the result is different. In the residues of soybean meal, aspartate(6.40%) and glutamate(5.99%) are the most popular amino acid; while for rape meal and DOG, glutamate is the most abundant amino acid,IIII/s4.03% and 5.33% separately ; The degradability of feedstuffs is correlation to the growth rate of microorganisms in rumeri, when the microorganisms in rumen grow fast, the degradation of feedstuffs get faster; different medium makes no difference to the active of microbic protease. The three medium generates 0.023473, 0.026097 and 0.026807 ug tyrosine per ml rumen fluid per minute in soybean meal, rape meal and DDG accordingly. |
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