不同纤维素与淀粉比率等氮纯化底物瘤胃发酵微生物蛋白质合成量

采用持续动态瘤胃模拟装置 (RSI)研究了 6种不同纤维素和淀粉比率 (C S) :0 .14、0 .44、0 .94、1.92、4.75、15 .76,等氮 ( 14.2 2 % ,风干物质基础 )纯化底物养分瘤胃发酵微生物组分及微生物蛋白质合成量。结果显示 :微生物有机物中氮的含量MN MOM在 5 5 0 %～ 6 64 %之间 ;微生物有机物中RNA含量 (RNA MOM ,% )不受日粮C S影响(P >0 0 5 ) ,仅发现微生物氮含量受到日粮碳水化合物比率影响 (P <0 0 5 )。 72小时发酵后 ,瘤胃微生物蛋白质合成效率与底物纤维素和淀粉比率成乘幂负相关关系 :MN RDN =0 .764 9(C S) - 0 .1 0 6 3,n =6,R =- 0 .93 1;MN FOM(g kg) =2 3 .88(C S) - 0 .0 988,n =6,R =- 0 .881。结果表明 ,在瘤胃可利用氮相同条件下 ,微生物蛋白合成效率取决于适宜的底物结构性碳水化合物和非结构性碳水化合物比率

Effect of Cellulose to Starch Ratio in Subctrate on in vitro Microbial Protein Yield with Equal-nitrogen Purifide Substrate

An in vitro 72 hours fermentation incubated with mixed rumen microorganism was conducted to determine response of microbial protein yield to six purified substrates with various ratio of cellulose to starch(0.14～15 76) and same crude protein content of 14.22%(air dry matter basis).It is indicated that microbial nitrogen in microbial organic matter(MN/MOM)is fluctuating among 5.5%～6.6%;RNA per unit MOM in isolated freeze dried bacteria sample is not influenced by the ration of substrate cellulose to starch (C/S) instead of microbial nitrogen content(MN);microbial protein synthesis efficiency expressed as estimated microbial nitrogen converted from rumen degraded substrate nitrogen (MN/RDN) and estimated microbial nitrogen converted from rumen fermedtable organic matter (MN/FOM)is negative exponentially related to C/S;MN/RDN=0.7649(C/S) -0.1063,n=6,R=-0.931;MN/FOM (g/kg)=23.88 (C/S) -0.0988,n=6,R=-0.881.It is concluded that,in case of in vitro fermentation of pure substrate with same available nitrogen,the yield of microbial protein is closely related to the ratio of dietary structural carbohydrate to non-structural carbohydrate.