中文摘要：

【目的】探讨日粮中非纤维性碳水化合物/中性洗涤纤维（NFC/NDF）比对山羊瘤胃发酵、瘤胃细菌与瘤胃产乳酸菌菌群结构组成,以及瘤胃产乳酸菌、总细菌与大肠杆菌数量的影响。【方法】试验选用4只装有永久性瘤胃瘘管、健康阉割的长江珠三角白山羊,采用自身对照试验设计,共分3期进行,每期15 d,依次饲喂NFC/NDF比值分别为0.42（Ⅰ期）、1.04（Ⅱ期）、2.73（Ⅲ期）的3期日粮,分别于第13、14和15天采集瘤胃内容物。采用PCR/DGGE（denaturing gradient gel electrophoresis）分析瘤胃微生物区系结构,采用real-time PCR定量瘤胃内容物中总菌、乳酸杆菌、牛链球菌与大肠杆菌数量。【结果】随日粮中NFC/NDF比值提高,瘤胃pH显著降低（P〈0.05）;瘤胃液中乳酸、乙酸、丙酸、丁酸、异丁酸、戊酸、异戊酸和总挥发性脂肪酸（total violate fatty acid,TVFA）浓度均显著增加（P〈0.05）,而乙酸与丙酸比显著降低（P〈0.05）;DGGE图谱分析表明,来自NFC/NDF比值不同的瘤胃样品分别聚成一族;real-time PCR测定表明,随NFC/NDF比值提高,乳酸杆菌数量显著增加（P〈0.05）,总细菌数量显著下降（P〈0.05）,牛链球菌及大肠杆菌数量未发生显著变化（P〉0.05）。【结论】瘤胃发酵模式受日粮NFC/NDF比值的影响,随NFC/NDF比值增加,瘤胃发酵从乙酸型发酵转向丙酸型发酵;同时,瘤胃微生物区系组成发生改变,瘤胃细菌总量下降。

英文摘要：

【Objective】This study was conducted to investigate the changes of the ruminal fermentation and the ruminal microbial composition as dietary NFC/NDF ratio increased.【Method】 Four local goats were gelded and designed for a self-controlled trial.The trial consisted of three periods corresponding to three diets with different NFC/NDF ratios（0.42,1.04,2.73）.【Result】The results showed that,as NFC/NDF ratio in the diet increased,the pH value decreased（P0.05）,and the lactate,acetate,propionate,butyrate,isobutyric acid,valerate,isovalerate and TVFA concentration were increased（P0.05）,and the ratio of the acetate to propionate decreased（P0.05）.The analysis of DGGE profiles showed the sample with different NFC/NDF ratios diet fell into different groups.The real-time PCR results showed the copies of the 16S rRNA genes of Lactobacillus and total bacteria were affected by the dietary NFC/NDF ratio（P0.05）,whereas no significant changes were found in the number of E.coli and the Streptococcus bovis（P0.05）.【Conclusion】 The results indicated that the characteristics of the ruminal fermentation were affected by the ratio of NFC/NDF in the diet,and with the increasing of the ratio of NFC/NDF,the ruminal fermentation was shifted from the acetate type to the propionate type,and the SARA（subacute rumen acidosis） occurred with the change of the ruminal microbiota when the ratio of the dietary NFC/NDF is 2.73.