Abstract
The increasing global trend towards antibiotic-free animal products has led to a growing need for feed additives that meets the requirements of the modern poultry industry in terms of providing growth factors, improving performance, preventing diseases, while leaving no residual antibiotics in animal products. The effectiveness and mode of action of several common plant-derived materials used as supplements, that act as growth promoters for poultry are summarized in this article, such as plant extracts, essential oils, isolated compounds, extrudates, oleoresins, and herbal parts. Plant-derived substances are used in animal feed as supplements (not as primary feed) to increase nutrients in diets, and more importantly, to play a functional role in improving the health of internal organs such as the intestines and liver, thus maximizing the utilization of the feed. They also inhibit the growth of pathogenic microorganisms, including bacteria, fungi, and parasites, and enhance the taste and color of the feed ingredients. These feed supplements are known as phytogenic feed addivives (also frequently referred to as phytobiotics or botanicals), they have been widely investigated, and remain of interest to researchers and in the feed and veterinary companies, based on an analysis of information presented in numerous studies published worldwide regarding the use of plant-derived materials as a promising alternative to traditional growth factors that have negative effects on health and the development of resistance to pathogenic bacteria.

Key words: Poultry feed, Plant extracts, Herbal plants, Essential oils, Bioactive compounds