Research Article | 13 Dec 2025

Comparative effects of Gamal (Gliricidia sepium)-based diets supplemented with Gambier (Uncaria gambir) or direct-fed microbials on rumen fermentation, nutrient digestibility, microbial protein synthesis, and methane mitigation in beef cattle: An in vitro evaluation

Bella Veliana Utami1 , Mardiati Zain2 , Elihasridas Elihasridas2 , Windu Negara3 , Laras Sukma Sucitra1 , and Zaitul Ikhlas1 Show more
VETERINARY WORLD | pg no. 3855-3869 | Vol. 18, Issue 12 | DOI: 10.14202/vetworld.2025.3855-3869
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Abstract

          
Background and Aim: Enteric methane (CH₄) emissions from ruminants reduce dietary energy efficiency and contribute to global greenhouse gas accumulation. Gliricidia sepium (Gamal), a protein-rich tropical legume, is widely used as a basal forage but may require targeted additives to optimize rumen fermentation. Plant bioactive compounds, such as Uncaria gambir (Gambier), and microbial supplements, such as direct-fed microbials (DFM) containing Saccharomyces cerevisiae, are known to influence fermentation pathways and energy use. This study aimed to compare the effects of Gamal-based diets supplemented with Gambier or DFMs on nutrient digestibility, rumen fermentation characteristics, volatile fatty acids (VFAs), microbial protein synthesis (MPS), fatty acid (FA) profiles, and CH₄ mitigation under in vitro conditions. 
Materials and Methods: Six dietary treatments were evaluated in a randomized block design with three replicates: control, Gamal substitution, Gamal with 0.5% DFM, Gamal with 1% DFM, Gamal with 1% Gambier, and Gamal with 2% Gambier. Substrates were incubated in rumen fluid and buffer for 48 h at 39°C. Dry matter (DM) digestibility, organic matter digestibility, ammonia-nitrogen (NH3-N), VFAs, CH₄ production, MPS, and FA composition were analyzed using standard procedures. Statistical analysis was performed using analysis of variance followed by Duncan’s test. 
Results: Supplementation with DFM improved DM and organic matter digestibility, with the highest values observed in the diet containing 0.5% DFM. The greatest methane reduction was observed with 1% Gambier, which lowered CH₄ output by 33.43% compared with the control. DFM increased total VFAs and propionate concentration, reducing the acetate-to-propionate ratio. Gambier increased the acetate concentration and NH3-N and achieved the highest MPS values. FA profiles shifted according to additive type, with notable changes in saturated, monounsaturated, and polyunsaturated FA. 
Conclusion: Gamal-based diets supplemented with Gambier or DFM positively modified rumen fermentation, but through distinct mechanisms. DFM improved digestibility and fermentation stability, whereas Gambier achieved the greatest CH₄ mitigation at 1% inclusion. Gambier represents a promising, locally available option for sustainable methane reduction in tropical ruminant feeding systems, supporting future in vivo validation. 
          
Keywords: Gamal, methane reduction, rumen fermentation, direct-fed microbial, Gambier, digestibility.