Evaluation of Essential Oils as Additives during Fermentation of Feed Products: A Meta-Analysis

Essential oils (EOs) are secondary metabolites of plants with antimicrobial functions that can be used as silage additives, but their effectiveness has been inconsistent. Therefore, this study aimed to evaluate the effects EOs additives on nutritional quality, fermentative products, microbial population, and in vitro rumen fermentation. A total 17 articles consisting 113 studies (comparisons) were selected for meta-analysis. The results showed EO supplementation increased several parameters nutrient contents such dry matter (DM), crude protein (CP), ether extract (EE) (p < 0.05), decreased fiber content mold population 0.05). also affected fermentability, namely reduced gas production, organic digestibility, some fermentation products VFA, iso-butyrate, iso-valerate, acetic, succinic acid 0.05) did not affect methane production. Sub-group analysis based source revealed only cumin oregano during ensiling These improved qualities DM, CP, EE, inhibiting growth stabilizing pH.