Biological properties of essential oil emphasized on the feasibility as antibiotic substitute in feedstuff

The discovery and application of antibiotics in animal feeds have boomed the development of intensive animal husbandry in the last century, until the emergence of antibiotics-resistant bacteria. To alleviate the risks aroused by antibiotics-resistant bacteria, effective antibiotic substitutes are urgently needed to replace antibiotics. Essential oils (EOs) derived from plants are illustrated as the promising antibiotic substitutes used in animal feeds, as same as their current views for poultry and livestock industries in the future. It has been widely demonstrated that the phytochemicals in EOs show multiple biofunctionability and are less likely to induce resistance in bacteria. The beneficial effects of EOs feed supplementation on the intestinal inflammation, intestinal flora, immunity, digestion, and growth performances have been already extensively examined. However, the cost-effectiveness, odor, volatility, instability and bioavailability are the challenges in effectively utilizing EOs in animal intestines. Based on previous researches, and these challenges can partially be resolved by microencapsulation and nanotechnology are promising techniques to deal with these challenges. This article presents the feasibility and foundation of EOs application as antibiotic substitutes in animal feeds, and illustrates the mechanisms, functional performances and superiority of EOs compared with antibiotics.