Unfortunately, reports on the value of oil extracts in poultry nutrition are scarce. This study showed that the supplementation of 200 ppm oil extract derived from thyme and cinnamon in broiler diets significantly
improved the live weight gain and feed conversion ratio during a growing period of 6 weeks, in addition to
decreasing serum cholesterol level and H/L ratio in blood. Thus, oil extract derived from herbal plants
could be considered as a potential growth promoter for poultry due to its digestive stimulating and antimicrobial effect.