Protein and Carbohydrate Utilization by Rumen Microorganisms Maintained in Continuous in Vitro Culture

Abstract Substrate utilization and end product formation were quantified in a continuously cultured rumen ecosystem. A representative population with a typical fermentation pattern was maintained for 21 days. Linear regression equations described the changes with time in the daily effluent of deoxyribonucleic acid, volatile fatty acids, ammonia, free amino acids, protein, starch, methane, and dry matter. Microbial activity decreased and then increased sharply until the sixth day, then the system was stabilized. Comparison of the experimental data with that predicted from a theoretical fermentation balance demonstrated an excellent fit. Available protein and productive energy losses from microbial fermentation were estimated to be 30 and 50% respectively. The results suggest that this system can be used to quantitatively determine the effects of rumen microbial metabolism on dietary nutrient availability to the host animal.