<![CDATA[This study aimed to determine the effect of tannins from gambir leaf extract (Uncaria gambir) and mangrove fruit extract (Sonneratia alba) on crude fiber digestibility (CFD), crude fat digestibility, nitrogen-free extract digestibility (NFED), cellulose and hemicellulose digestibility, and methane gas production in vitro. This study employed an experimental design using a 3 × 3 factorial randomized block designed with three replications, with the source of rumen fluid used for each incubation as the blocking factor. Factor A, the addition of gambir leaf extract (GLE) tannin, consisted of A1 (0%), A2 (0.75%), and A3 (1.5%). Factor B, the addition of mangrove fruit extract (MFE) tannins, consisted of B1 (0%), B2 (0.75%), and B3 (1.5%), resulting in nine treatment combinations. The variables observed in this study were CFD, crude fat digestibility, NFED, cellulose and hemicellulose digestibility, and methane gas. Analysis of variance showed that GLE and MFE significantly affected the measured variables (P<0.01). A significant A x B interaction was also observed for the measured parameter (P,0.01), indicating that the effect of GLE supplementation depended on the level MFE supplementation and vice versa. CFD values ranged from 60.04–67.61%, crude fat digestibility values ranged from 59.76–68.56%, NFED values ranged from 60.77–70.17%, and cellulose digestibility values ranged from 62.72–67.69%. Hemicellulose digestibility ranged from 66.50–70.75%, and methane gas production ranged from 14.67–28.00 ml. The combination of 0.75% GLE and 1.5% MFE yielded the best results in improving nutrient digestibility and reducing methane gas production.]]>
