日粮降解氮转化为瘤胃微生物氮效率影响因素的研究

The Study on the Efficiency of Degraded Nitrogen of Different NitrogenSource of Diet Incorporating into Microbial Protein

用１０种不同氮源日粮（４种糊化淀粉尿素日粮、常规尿素日粮、豆饼日粮、甲醛及非甲醛新保护剂保护豆饼日粮）在５头装有瘤胃和真胃瘘管的阉牛中分别进行６×５和４×４两个拉丁方试验，用体内法测定日粮的蛋白质和有机物质的降解率、微生物蛋白质产量及瘤胃氨浓度。同时用瘤胃尼龙袋法测定蛋白质和有机物质降解率。结果表明：不同氮源日粮间降解氮转化为微生物氮的效率差异明显（Ｐ＜０．０１）：降解氮转化效率与瘤胃平均氨浓度有限高曲线负相关（ｒ＝－０．９１９２），与降解氮同体内法测定的瘤胃可消化有机物（ＲＤＯＭ）及瘤胃尼龙袋法测定的瘤胃２４小时可发酵有机物（ＦＯＭ）的比率均有同种类型的曲线负相关（ｒ＝－０．８７９６，ｒ＝－０．９０３７）。说明降解氮转化为微生物氮的效率受饲料蛋白质降解量、降解速度及降解氮与微生物可利用能平衡的影响。

Ten diets of different source of nitrogen[4 kinds of Starea、urea、soybeen meal(SBM)、formaldehyde-treated soybean meal(FSBM)and new method treated soybean meal(NMSBM)]were used in five steers with ruminal and abomasal cannulae by6×5 and 4×4 Latin square designs.The invivo and in sacco technique were investigated.The concentration of NH3 in rumem;degradability of diet nitrogen;efficiency of degradble nitrogen incorporating into microbial protein;microbial protein production;the amount of digestable and fermentable organic matter in rumen were measured.Resuits showed:the efficiency of degraded nitrogen of different nitrogen source of diets incorporating intomicrobial protein is obviously different(P<0.01) and which had negatively unlinear correlation to the mean NH3 concentration (r=-9192) in rumen,and to the ratio of degradable nitrogen to digestable organlc matter(in vivor=-0.8796)of fermentable organic matter (in sacco,r=-0.9037).It demonstrated that the efficiency ofdegradable nitrogen incorporating into microbial protein is not constant ,and which may beeffected by the amount of degradable nitrogen of diet、the specd of diet nitrogen degraded and the ratio of degradable nitrogen to the microbial available energy.