Effects of several oligosaccharides on ruminal fermentation in sheep: An in vitro experiment

This study was conducted to investigate the effects of the dietary inclusion of various not digestible oligosaccharides (NDOs) such as isomalto-oligosaccharides (IMO), mannanoligosaccharides (MOS) and fructo-oligosaccharides (FOS) at doses varying from 0% to 1.0% on the rumen fermentation parameters (volatile fatty acid (VFA), bacterial protein and ammonia nitrogen (NH3-N) concentrations in ruminal fluids and the NDF contents in the culture residues) in sheep, using in vitro batch cultures from rumen inoculates. Whatever the NDO type, the VFA production was significantly increased and the NH3-N concentrations gradually decreased according to the added doses, more intensively with IMO and FOS than with MOS compared to the rumen inoculates from the not supplemented controls. The bacterial protein concentrations were also significantly increased when FOS and MOS were dietary added while this parameter tended to decrease with IMO. The IMO and FOS supplementations have also induced significant and progressive decreases in the NDF contents. These results show that these NDOs have differentially improved rumen fermentations in sheep probably by specifically promoting the proliferation of some bacterial species. Furthermore, FOS (which has modified all the investigated parameters) would be a potential useful food additive in sheep.