Effects of Saga Tree Leaves (Adenanthera pavonina L.) Supplementation in By-Product Based Complete Feeds on In Vitro Rumen Fermentation, Digestibility, and Microbial Activity

Abstract

This study investigated the potential of saga tree leaves as a protein supplement to improve the nutritional quality of feed for Madura cattle, an important livestock resource in Indonesia. Traditional cattle feeds in this region primarily consist of low-protein agricultural by-products such as rice straw and corn husks, which limit rumen fermentation efficiency and animal productivity. To address this issue, in vitro gas production experiments were conducted to evaluate the effects of saga tree leaves supplementation at four levels (0%, 10%, 20%, and 30%) on rumen fermentation kinetics, nutrient digestibility, and microbial activity. The experimental design followed a randomized block design with six replications, using rumen fluid from slaughter house to simulate natural digestion processes. The data revealed that supplementation significantly enhanced fermentation parameters. The 10% inclusion level yielded the highest gas production (129.26 mL/500 mg DM) and total volatile fatty acids (32.82 mM), indicating improved microbial activity and energy availability. Ammonia (NH3) concentration peaked at 20% supplementation (329.82 mg/L), suggesting optimal conditions for microbial protein synthesis. Dry matter and organic matter digestibility also improved at 10–20% inclusion, with values exceeding 60%. However, the 30% supplementation level showed reduced efficiency, likely due to antinutritional compounds such as tannins. Quadratic regression analysis identified 15.38% as the optimal inclusion level for maximizing rumen fermentation. These results demonstrate that saga tree leaves can effectively enhance the nutritional value of low-quality cattle feeds when supplemented at 10–20%. The study provides practical insights for smallholder farmers seeking sustainable, locally available feed solutions.