BACKGROUND: This research aimed to investigate bioaccessibility of garlic oil extract (GOE) and riceberry rice bran oil extract (RBRBOE) and to enhance the stability and delivery of plant-derived essential oils. Two EOs were used to formulate through encapsulation techniques of microencapsulated black soldier fly (BSF) protein with a GOE matrix, (mBSF-GOE), and a nanoemulsified RBRBOE, (nRBRBOE). A completely randomized design was used for the treatments, with various ratios of feed additives between the mBSF-GOE and nRBRBOE supplementations at 0:0, 6:0, 4:2, 2:4, and 0:6 mg in diet, with the R: C ratio at 60:40 using in vitro gas study. RESULTS: The combination of mBSF-GOE and nRBRBOE at 4:2 mg for 12 and 24 h after fermentation had a significant impact on several factors (p <
0.01, <
0.05), including gas kinetics, cumulative gas production (96 h), in vitro dry matter degradability (IVDMD), and ruminal fermentation products. Specifically, the levels of propionate (C3) and total VFAs went up, while ruminal methane (CH CONCLUSIONS: Based on this study, it could be concluded that the supplementation of mBSF-GOE combined with nRBRBOE-based bioactive components could potentially be used as a ruminant feed enhancer to enhance fermentation efficiency and as technological feed additive substances to inhibit the methanogen population while mitigating CH