Digestion of wood-based hemicellulose extracts as screened by in vitro gas production method and verified in vivo using sheep

The objective of the present study was to evaluate the potential of pressurized hot water extracted hemicellulose fractions from various wood species as feeds for ruminants. In Experiment 1, the fermentability of several hemicellulose extracts was screened using an in vitro gas production method. The samples were extracted from spruce (Picea abies) including mainly galactoglucomannan (GGM), from birch (Betula pendula) consisting mainly of xylan and from larch (Larix sibirica) consisting mainly of arabinogalactan. The GGM and xylan samples were readily fermented by rumen microbes while arabinogalactan was not. Based on the in vitro study, GGM was chosen for an in vivo digestibility trial using sheep, where it was fed at increasing proportions of diet dry matter (0, 47, 94 and 141 g kg-1) in a Latin Square design. The in vivo organic matter digestibility of GGM was relatively low, 0.58, but PHWE extracted hemicellulose has some potential as a feed for ruminants.