中文摘要：

本试验旨在研究不同发酵液表面张力（Surface tension，ST）和中性洗涤纤维（NDF）比表面积（Special sur—face areas，SSA）对人工模拟瘤胃体外发酵中纤维发酵特性的影响，并探讨其影响机理。以水稻秸秆中NDF为发酵底物，采用3×4因子试验设计，即3种发酵底物SSA（3．27m2·g～SSAl，3．73m2·g-1 SSA2，4．44m2·g-1 SSA3）和4种发酵液ST（54mN·m-1 STl，46mN·m-1 ST2，43mN·m-1 ST3，36mN·m-1 ST4）。每个处理设6、12、24、36、48和72h6个时间点，每个时间点3个重复，分别测定NDF消失率、发酵液pH和氨态氮（NH3-N）浓度、各时间点总产气量等体外发酵指标。结果表明，底物SSA越小其快速可降解部分产气量越高；提高底物SSA可显著（P〈O．001）提高NDF的消失率和NH3-N浓度。发酵液ST对产气参数及发酵液pH、NH3-N浓度及NDF消失率有极显著影响（P〈O．001），降低发酵液ST可显著（P％0．001）降低快速发酵部分产气量和延滞时间，但提高（P〈O．001）慢速发酵部分的产气量；当发酵液ST降低至36mN·m-1时，极显著（P＜0．001）抑制底物NDF的消失率并提高发酵液pH和NH3-N浓度。结果提示，底物SSA及发酵液ST的变化对纤维物质的体外发酵特性有直接影响，可通过调节底物与发酵液的界面化学特性来调控瘤胃发酵及饲料利用。

英文摘要：

The experiment was conducted to study the effects of different surface tension （ST） of fermentation liquid and specific surface area （SSA） of neutral detergent fiber （NDF） on the processes of in vitro fermentation and to explore the mechanism. Three types of SSA （3. 27, 3.73 and 4.44 m2 · g-l） of NDF distracted from rice straw, and four levels of ST （54, 46, 43 and 36 mN · m-1 ） were assigned to a 3 × 4 factorial design. The samples were collected to deter- mine the NDF disappearance rate, pH and ammonia nitrogen （NH3-N） concentration at the fer- mentation time of 6, 12, 24, 36, 48 and 72 h, and to determine the total gas production at eachfermentation time. T tion increased results as following. The gas production of fast and slow degradable frac tion increaed（P〈0.001） with the decreasing of SSA of NDF particle. The NDF disappearance rate increased （P〈0. 001）, but pH and the NH3-N concentration decreased （P〈0. 001） as the increasing SSA of NDF. ST had significant （P〈0.01） effect on gas production, pH and NH3-N concentration and NDF disappearance rate. Gas production of fast fermentable parts and lag time significantly （P〈0. 001） decreased, but gas production of slow fermentable parts significantly （P 〈0. 001） increased with the decreasing of ST, NDF disappearance rate had been prominently de- creased （P〈0. 001）, but the pH had been increased when ST below to 36 mN ~ m-1. Those re- suits indicate that substrate＇s specific surface area and liquid surface tension directly influenced in vitro fermentation characteristics of fiber, and the rumen fermentation and feedstuff utilization could be regulated by adjust the SSA of substrate and the ST of rumen liquor.