The Potential of Seaweed (Gracilaria sp.) and Gambir Leaf (Uncaria gambir) Extract to Improve Rumen Metabolism and Reduce Methane Production

This study evaluated the effect of adding seaweed meal (Gracilaria sp.) and gambir leaf extract (Uncaria gambir) as feed additives on nutrient digestibility, rumen fermentation products, and microbial population in vitro.Treatments comprised three levels of seaweed addition (0, 5, 10%) and three levels of gambir leaf extract (0, 0.7, 1.4%).The results showed that adding seaweed could significantly increase the digestibility of dry matter from 59.05 to 66.95% and the digestibility of organic matter from 58.92 to 68.72% (P<0.05).VFA concentration also increased, while methane production decreased from 20.19mL/g to 14.79mL/g.The addition of gambier leaf extract contributed to stabilizing the rumen pH and suppressing the protozoa population to 7.50x10 4 cells/mL.The best combination was obtained by treating 10% seaweed and 1.4% gambier leaf extract, which showed a synergistic effect in improving rumen fermentation and reducing methane emissions.This study indicates that the combination of seaweed meal and gambir leaf extract has the potential to be an effective natural ingredient-based feed additive to improve livestock production efficiency while supporting the mitigation of greenhouse gas emissions.