Increased microbial resistance to antibiotics associated with the use of antimicrobial growth promotors (AGPs) in animal production led to the ban of AGPs in 2006 in the E.U. and other countries. The removal of AGPs from animal feed raised special attention to 'natural' alternatives like Essential Oils as feed supplements. Essential Oils are reservoirs of many bioactive compounds with several beneficial properties, and are aligned with current consumer preference for natural and sustainable products. Studies have highlighted that Essential Oils as feed supplements have diverse modes of action, including enhanced feed consumption and flavour, stimulation of the digestive enzymes' secretion, increased gastric and intestinal mobility, antimicrobial, antiviral, antiparasitic, immuno-mudulating, antioxidant and anti-inflammatory activities.