Dose-response effects of the Savory (<i>Satureja khuzistanica</i>) essential oil and extract on rumen fermentation characteristics, microbial protein synthesis and methane production <i>in vitro</i>

Abstract The objective of the present study was to investigate dose-response effects essential oil (EO) and dry extract (EX) Satureja khuzistanica (SK) on in vitro gas production kinetics, rumen fermentation, ruminal methanogenesis microbial protein synthesis. So, EO EX were tested at 0 (as control); 150 (low dose); 300, 450 (intermediate doses) 600 mg/L (high dose). produced over 24 h incubation (GP ) decreased linearly with both dosages (P&lt;0.01). In methane reduced by (14–69%, depending included dose) (7–58%). Microbial (MP) as well efficiency synthesis (EMPS) improved (18.8–49.8% 20.4–61.5% for MP EMPS, respectively) a lesser extent (8.3–25.7% 4.6–24.2% respectively). Ammonia concentration dropped linear quadratic manners (P&lt;0.05), exhibited depressive (in (P&lt;0.01), total protozoa count. A mixed effect observed from VFA Total increased 300 EX, but high dose EX. acetate proportion intermediate dosages, it expense propionate low doses total, these findings confirmed previous research great capacity plant-based feed additives positively modulating fermentation that their may vary used. Specifically, results suggest have potentials improve functions doses, which needs be vivo experiments.