Animal Nutrition Group, Department of Animal Sciences, University of Wageningen, 6700 AH Wageningen, The Netherlands.
J Sci Food Agric. 2013 Mar 30;93(5):987-94. doi: 10.1002/jsfa.5834. Epub 2012 Aug 30.
Fibrous ingredients for pig diets can be characterized by in vitro fermentation. In vitro fermentation methods often use a one-time measurement of gas production during the incubation of test substrates with one faecal inoculum. The representativeness of this approach can be questioned as measuring time and number of animals from which inoculum originates may influence fermentation results. An in vitro fermentation trial was conducted incubating three fibrous substrates with three inocula in five replicates (different fermentation runs) to test the influence of run and origin of inocula.
Total gas production and maximal rate of gas production differed (P < 0.05) between fermentation runs, but less than substrates (P < 0.01). The ranking order between substrates remained similar for each run. Fermentation of cellulose led to higher coefficients of variation between inocula compared to the fast fermentable substrates oligofructose and soy pectin. Differences ranged from 2% for total gas production up to 25% for maximal rate of gas production.
One fermentation run can provide representative results for substrate ranking. Using multiple inocula mixed from four faecal samples each leads to high coefficients of variation for slow fermentable substrates like cellulose. Future studies should examine the optimal number of animals for inocula preparation to decrease variation.
猪饲料中的纤维成分可以通过体外发酵来进行特征描述。体外发酵方法通常使用一次性测量法，即在一个粪便接种物孵育测试底物时测量气体产生量。但这种方法的代表性值得怀疑，因为测量时间和接种物来源的动物数量可能会影响发酵结果。本试验采用体外发酵试验，用三个接种物在五个重复（不同发酵运行）中孵育三种纤维基质，以检验运行和接种物来源的影响。
发酵运行之间的总产气量和最大产气率存在差异（P < 0.05），但差异小于基质（P < 0.01）。每个运行之间的基质排序顺序相似。与快速发酵基质低聚果糖和大豆果胶相比，纤维素发酵导致接种物之间的变异系数更高。差异范围从总产气量的 2%到最大产气率的 25%。
一个发酵运行可以为基质排序提供有代表性的结果。使用来自四个粪便样本的混合接种物会导致纤维素等缓慢发酵基质的变异系数很高。未来的研究应该检查接种物制备的最佳动物数量，以减少变异。
