玉米秸青贮与黄贮及苜蓿干草的体外动态消化研究

采用产气量法测定了玉米秸青贮、玉米秸黄贮和苜蓿干草的瘤胃微生物体外动态消化参数。将3种饲料样品及其分离出的相应的中性洗涤纤维（NDF）同时进行72h体外发酵，并测定不同时间点的产气量，中性洗涤可溶物（NDS）的产气量可由饲料样品与其相应的DNF的产气量之间的差值计算得到。结果表明，3种饲料的72h累积产气量没有显著性差异，但3种饲料相应的NDF和NDS部分对产气量的贡献不同（P＜0.05）。其产气量曲线变化趋势受饲料中NDS和NDF的含量及消化率的影响。3种饲料经72h发酵后对瘤胃液的pH值没有显著影响，但对发酵终产物挥发性脂肪酸（VFA）的摩尔百分比有影响（P＜0.05）。

In Vitro Kinetic Digestion Study of Corn Stover Silage and Alfalfa Hay

The in vitro kinetic digestic characteristics of two different corn stover silages and alfalfa hay fermented by ruminal microorganisms of sheep were measured by using gas production method. Each feed sample of the three feedstuffs and its isolated NDF were fermented in vitro and gas production was monitored. Gas yield from NDS was determined as the difference between gas from the unfractionated feed and from its respective NDF. Experimental results suggested that although there have no significant differences among the accumulated gas yields in 72 hours of the three feeds, the contributions of NDF and NDS fractions of each feed were significantly different (P<0.05). The varying trends of gas production curves of each feed were influenced by the content and digestion rate of its respective NDS and NDF fraction. There were no apparent changes of the pH values of ruminal fluids after the fermentation among the three feeds, but the molar percentages of volatile fatty acids were different among the three feeds (P<0.05).