Bioprospecting essential oils of exotic species as potential mitigations of ruminant enteric methanogenesis

The inclusion of essential oils (EOs) in the diet of ruminants is one of the strategies used to alter ruminal microbial fermentation, improving feed efficiency, while simultaneously reducing enteric methane (CH4) production. This study aimed to evaluate the effects of three new EOs from plants exotic to the Azores, Pittosporum undulatum (PU), Hedychium gardnerianum (HG), and Cryptomeria japonica (CJ), on biogas production kinetics and in vitro CH4 production. Three levels of EOs (40, 80, and 120 μL/g dry matter (DM) were added to the basal diet to evaluate ruminal fermentation using the in vitro gas production technique. Added 800 mL of rumen inoculum with 5 g DM of the basal diet (BD) to all experimental units for 96 h, except for the blanks, to which only the inoculum was added. The total gas and CH4 produced by treatment incubation were recorded every hour after incubation until 96 h. The results showed that the gas production decreased significantly (P