The food poultry origin such as eggs and meat supply high quality and readily digested protein and energy and are also a compact source of readily-available micrnutrients. Thus, the economc and nutritional demands of our modern society for food from poultry necessitate the raising of poultry under intensive production system in densely-populated colonies or flocks, which resulted in stress. Under such circumstances, anti-microbail feed additives such as anitbiotics are often used ot suppress or elminate harmful mcroorganisms in the intestine and to improve growht ad feed efficiency. However, one major aspect of food production and safety today is the reduction in teh use of anitbiotics and other medicinal products in the poultry production largely ude to fears over bacterial resistance and possible transmission of these antibiotic residues into the human food chain. On the other hand there are increasing demands to improve feed hygiene, to maintain poultry health and welfare, and to reduce the environmental impct of poultry production. During the lst two deecades considerable resech has been done on exploring the beneficial effects from the growth promoters and findings suitable alternative to antibiotics. Research is also going on teh find out more such natural products t o enhance the performance of poultry. With these aspects in veiw, this book has been cimpiled in 13 different chapters and the firrst five being on Mcroflora of digestive tract of poultry, Probiotics, Predbiotics, Synbiotics and Organic acids. Probiotics, prebiotics and organic acids modulate the gut microflora and may help in alleviating entreric disorder and thereby improve the performacne o the birds. Recently considerable attention has been paid to the use of herbal extracts (phytobiotics) and bacteriocins, which are dealt in the Cahpter 5 and 7, respectively. Antioxidants, maintain the quality of feed and minimize stess in chickens, while enzyme and emulsifiers enhance digestion and utilization of intact nutrients and therefore, fewer nutrients remain meat quality, which are dealt with in Chapter 8. A recent addition to dietary substance that improves growth and feed efficiency in poultry is cytokines and egg antiobodes, which are given in Chapter 9 and 10, respectively. In addition to enhancing the digestion and utilization of nutrients, enzymes reduce the environmental pollution by minimize the use of growth prmoters for endhancing the performance and health of poultry is biosecurity. Without wich the concept of poultry farming without anitmicrobial growth promoters is difficult to exist. The importance of bio-security in modern concept of poultry farming is given in chapter 13. One major aspect is that most of the information contained in this volume are based on the experimental findings of the authros themselves.