Bioactive polysaccharides and oligosaccharides as possible feed additives to manipulate rumen fermentation in Rusitec fermenters.

Bioactive polysaccharides and oligosaccharides (POSs) have been used as safe non-antibiotic alternatives in animal diets; however, only limited data are available on their effects in rumen manipulation. This study was undertaken to systematically evaluate and compare the efficacies of six different bioactive POSs (10g/kg diet) with respect to ruminal fermentation, feed digestibility, biohydrogenation and bacterial population using a rumen simulation technique. The experiment consisted of 4 independent 12-d incubation periods (each including 8 d for acclimation, followed with 4 d for sample collection). The results demonstrated that Lycium barbarum polysaccharide had no effect and Astragalus polysaccharide only increased the total VFA production. Chitooligosaccharide decreased the propionate proportion with a corresponding increase of acetate to propionate ratio. Fructooligosaccharide increased fatty acid biohydrogenation and the abundances of R. albus, B. fibrisolvens and S. ruminantium. Both Lentinan polysaccharide and xylooligosaccharide increased the total VFA production, fatty acid biohydrogenation and the abundance of B. fibrisolvens. In addition, Lentinan polysaccharide increased 48-h dietary protein degradation and the abundance of R. flavefaciens, while xylooligosaccharide increased 24-h dietary fiber degradation and the abundance of R. albus. In conclusion, bioactive POSs, especially Lentinan polysaccharide and xylooligosaccharide, can serve as potential feed additives to manipulate rumen fermentation.