CHARACTERIZATION OF LIGNINS IN STRAW, RUMEN LIQUOR AND FECES OF SHEEPFED UNTREATED AND SO2-TREATED WHEAT-STRAW

Sheep were fed two rations based on untreated (WS) and SO2-treated (SO 2-WS) wheat straw and the lignins isolated from straws, rumen liquor a nd faeces underwent high performance size exclusion chromatography (HP SEC). Dioxane lignins (DL) isolated from ball-milled and cellulase pre treated neutral detergent fibre of straws and from their respective fa ecal materials showed similar molecular weight distribution patterns a nd similar weight average molecular weight (($$$) over bar MW) values. Water-soluble lignins (WSL) were isolated from the water extract of t he straws and from the liquid phase of their respective rumen liquor a nd faecal materials. On both rations, rumen WSL were more dispersive a nd had a higher ($$$) over bar MW than the WSL isolated from the respe ctive straws. On each of the rations, the DL isolated from the straw a nd the respective rumen WSL had similar ($$$) over bar MW values. The major fraction of rumen WSL resided in the molecular weight range 1500 -10 000, whereas that of the straw DL resided in the range 10 000-24 0 00. However, there was a certain degree of overlapping with respect to the HPSEC features, between each of the straw DL and its respective r umen WSL. Molecular weight distribution and ($$$) over bar MW of rumen and faecal WSL were very similar in the SO2-WS ration, indicating lit tle absorption of phenolic material from the intestine of sheep fed th is ration.