Submitted to: Proceedings of the US Dairy Forage Research Center Information Conference
Publication Type: Proceedings
Publication Acceptance Date: September 16, 1996
Publication Date: N/A
Technical Abstract: The predominant ruminal cellulolytic bacteria (RCB) share several adaptive features that have allowed these species to compete successfully in the rumen environment. Among these are adherence to fiber, rapid cellulose hydrolysis by cell-bound enzymes, and ability to compete with noncellulolytic opportunist microbes for the products of cellulose hydrolysis. Continuous culture studies reveal that individual species of RCB produce distinct sets of fermentation products in ratios that are unique for each species and relatively independent of growth conditions. This suggests that controlling the population of each species may permit controlling ruminal VFA ratios. The RCB do not grow at pH < 6; ruminal pH is routinely below this level in most cows under conditions of high milk production. Thus genetic engineering to introduce cellulolytic capabilities into noncellulolytic but acid tolerant ruminal bacteria may potentially improve fiber digestion at low pH, but only if these engineered strains ca incorporate some of the same adaptive characteristics that have made the native cellulolytic species successful under less acidic conditions.