MONOSACCHARIDE COMPOSITION OF CELL-WALL CARBOHYDRATES - DIGESTION ANDABSORPTION

Cell-wall monosaccharides (CWM) are a major source of energy to rumina nt animals. Rate and extent of disappearance of CWM greatly varied amo ng forages (grasses, legumes) and among individual CWM, largely due to morphological differences and changes associated with maturity. Xylos e was frequently reported to be one of the least digestible CWM, both in the rumen and the whole-tract. Trials with sheep and cattle have in dicated appreciable microbial CWM fermentation already in the distal p art of the small intestine. There is evidence that interspecies differ ences exist in the capacity of the large intestine to digest CWM, whic h escape ruminal fermentation. Chemical and biological treatments have greatly improved CWM digestibilities, but the extent varied among che micals and CWM. There is lack of knowledge on the quantitative relatio nship between CWM fermentation and production of volatile fatty acids, which is desirable to improve models of ruminal fermentation and ener gy supply to the host.