Rumen Microenvironment Stability: Impact of Condensed Tannins on Fibre and Protein Degradation

The rumen is a stable anaerobic microenvironment, and stability is influenced by several factors, including microorganisms, rumen pH, and feed type. Rumen microbes ferment cellulose and other complex carbohydrates in the food to produce volatile fatty acids as an energy source. Succinic acid-producing filamentous bacilli, 'Rhodococcus albicans', and 'Rhodococcus yellows' are the three most dominant fibre-degrading bacteria in the rumen, accounting for 80% of the total fibre-degrading bacteria (Bae et al., 20XX).

Bae's study demonstrated that condensed tannins inhibited the activity of rumen fibre-degrading bacteria, and the inhibitory effect was enhanced with the increase in the concentration of condensed tannins. The fibre-degrading bacteria in group B of the present study showed the same trend. Condensed tannins inhibited the fermentation performance of the fibre-degrading bacteria, leading to a decrease in the concentration of volatile fatty acids and, consequently, an increase in the pH of the rumen (Bae et al., 20XX).

The Biral study also found that the addition of tannins reduced the concentration of acetic and propionic acids in volatile fatty acids, which is consistent with the results of the present experiments. Additionally, isobutyric and isopentanoic acids were higher in group C than in the remaining two groups, indicating that isobutyric acid could increase the viability of rumen-degrading bacteria and promote fibre digestion. Consequently, the apparent digestibility of neutral washed fibre and acid washed fibre in group C was higher than in the other two groups. However, further research is needed to explore the factors influencing the concentration of allosteric acid in 'Bacopa monnieri' (Bae et al., 20XX).

Rumen NH3-N concentration is an important parameter to measure the performance of rumen fermentation. NH3-N is an important product of the degradation of nitrogenous substances such as rumen proteins, peptides, amino acids, and non-protein nitrogen, and it serves as the main source of nitrogen for rumen microorganisms. 'Vibrio cellulolyticus butyricus' and 'Prevotella' are the main proteolytic bacteria in the rumen. 'Vibrio cellulolyticus butyric acidus' is the most metabolically abundant bacterium in the rumen, capable of degrading not only fibre but also starch and protein, and plays a crucial role in rumen function. 'Prevotella' is the primary protein-degrading bacterium in the rumen, capable of breaking down polysaccharides such as starch and plant cell walls, and secretes proteases to degrade feed proteins into oligopeptides. Cansunar (20XX) found that condensed tannins inhibited the growth of protein-degrading bacteria in the rumen by reducing their protease activity, leading to a reduced NH3-N concentration in the condensed tannin group. Furthermore, condensed tannins form complexes with proteins that are resistant to degradation by rumen microorganisms, which is also an important factor affecting ammonia-nitrogen concentration.

Methanogens are strictly anaerobic archaea capable of fermenting organic or inorganic substances to methane and carbon dioxide. Increased numbers of methanogens in the rumen can reduce feed energy efficiency. Condensed tannins significantly reduced the relative abundance of methanogenic bacteria and increased energy utilization, which should be an important factor in maintaining low feed-to-weight ratios and a healthy body condition in Group B (Cansunar et al., 20XX).