Extraction of Tannin from Acacia (Acacia mangium) Bark and its use as a Feed Additive for Protecting in vitro Ruminal Degradation of Tofu Dregs

This experiment aimed to extract tannin from acacia bark by using a hot water extraction system at different temperature and pressure. Further, the tannin extract was used as an additive for protecting tofu dregs from microbial degradation in an in vitro rumen fermentation system. Acacia bark was extracted for its tannin by using a hot water extraction system, conducted at different temperature (70 and 120o C) and pressure (1 and 2 bar) for 2 h period. Samples were determined for their phenol, tannin, condensed tannin (CT) and hydrolysable tannin (HT). Tannin extract was added to tofu dregs at various levels, i.e., tofu dregs without tannin (T0), tofu dregs + 1% acacia tannin (T1), tofu dregs + 2% acacia tannin (T2), tofu dregs + 3% acacia tannin (T3), and tofu dregs + 4% acacia tannin (T4). These treatments were subjected to in vitro incubation with buffered-rumen fluid for 48 h. Results revealed that phenol, tannin, CT and HT contents in acacia bark were higher (P<0.001) when extracted at 120o C as compared to that at 70o C. The addition of tannin at 3 and 4% reduced the gas production of tofu dregs right from the early incubation period to the end in comparison to that of control treatment (P<0.05). Total VFA and ammonia concentrations were reduced by 19.9 and 58.6% (P<0.05), respectively, in the addition of 1% tannin extract. Higher levels of tannin additions led to further decrease of these parameters. Similarly, IVDMD and IVOMD of tofu dregs were reduced due to acacia tannin extract addition at 1 to 4% (P<0.05). In conclusion, tannin extract from acacia bark is able to protect microbial degradation of tofu dregs in the rumen environment.