DEGRADATION AND UTILIZATION OF FORAGE HEMICELLULOSE BY RUMEN BACTERIA, SINGLY IN COCULTURE OR ADDED SEQUENTIALLY

Procedures far sequential addition experiments were developed to study the mechanisms involved in the synergistic and inhibitory interaction s observed in forage hemicellulose digestion by rumen bacterial cocult ures. One organism was allowed to ferment a forage substrate, the cult ure tube was sterilized and then inoculated with a second organism. No differences were found in the extent of degradation or utilization be tween fermentations sterilized by oxidation or heat, and based on ease of handling, heat was used in all subsequent experiments. Studies wer e conducted with Fibrobacter succinogenes A3c, Ruminococcus flavefacie ns B34b and Prevotella ruminicola H2b, singly and in all possible comb inations. Results from the sequential addition studies substantiated e arlier suggestions that the increase observed in hemicellulose utiliza tion results from initial solubilization of the hemicellulose from the forage by the non-utilizer and subsequent utilization of this solubil ized polysaccharide by the utilizing, but non-degrading organism.