Research Article | 06 Jan 2026

Black soldier fly protein–based microencapsulation of lemongrass oil improves rumen fermentation efficiency and mitigates methane production in vitro

Maharach Matra1 , Chaichana Suriyapha2 , Gamonmas Dagaew3 , Rittikeard Prachumchai4 , Srisan Phupaboon5 , Sukruthai Sommai6 , Theerachai Haitook7 , Sajee Kunhareang7 , and Metha Wanapat8 Show more
VETERINARY WORLD | pg no. 39-51 | Vol. 19, Issue 1 | DOI: 10.14202/vetworld.2026.39-51
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Abstract

          
Background and Aim: Essential oils (EOs) are promising natural modifiers of rumen fermentation and methane production; however, their volatility and rapid degradation limit their effectiveness. Microencapsulation can shield bioactive compounds and allow controlled release. Insect-derived proteins, especially from black soldier fly (BSF; Hermetia illucens L.), offer a sustainable and functional wall material, yet their use for rumen-targeted delivery remains unexplored. This study aimed to assess the effects of microencapsulated-lemongrass oil (M-LEO) using BSF protein as a biopolymer wall on gas kinetics, nutrient degradability, rumen fermentation parameters, microbial populations, and methane output in vitro. 
Materials and Methods: A completely randomized design was used with five dietary treatments containing M-LEO at 0, 2, 4, 6, and 8% of total dry matter (DM) substrate. In vitro rumen fermentation was performed using rumen fluid from Holstein-crossbred dairy cattle. Fermentation was measured at 12, 24, and 48 h for gas kinetics, in vitro dry matter degradability (IVDMD) and in vitro organic matter degradability (IVOMD), pH, ammonia-nitrogen (NH₃-N), volatile fatty acids (VFAs), methane production, and microbial populations quantified by real-time polymerase chain reaction. 
Results: M-LEO showed high encapsulation efficiency (85.2%) and significant bioactive content. Supplementing with M-LEO notably improved gas production kinetics and nutrient degradability, with optimal effects at 6% of total DM. At this level, IVDMD and IVOMD increased by up to 11.5% and 10.5%, respectively. Total VFA and propionate concentrations rose significantly (p < 0.05), while acetate proportion and the acetate-to-propionate ratio decreased. Rumen pH and NH₃-N levels stayed within optimal ranges and were unaffected by treatment. Methane production was substantially reduced, with decreases of up to 48.8% at 48 h compared to the control. Additionally, M-LEO boosted populations of key cellulolytic bacteria (Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens) and Megasphaera elsdenii, while significantly suppressing methanogenic archaea (Methanobacteriales). 
Conclusion: Microencapsulation of lemongrass oil with BSF protein effectively enhances rumen fermentation efficiency and significantly decreases methane emissions in vitro. This innovative insect-protein delivery system provides a sustainable and climate-friendly feed additive approach, deserving further validation in vivo. 
          
Keywords: black soldier fly protein, climate-smart ruminant nutrition, essential oil microencapsulation, lemongrass oil, methane mitigation, rumen fermentation, sustainable feed additive, in vitro gas production.