Abstract
Poultry growth performance and feed efficiency are closely related to the intestinal microbiota quantity, wall structure and the activity of the immune system. Several antibiotics was used in poultry feeds as growth promoters to enhance growth and improve feed efficiency and to reduce mortality in the poultry industry. All commonly used feed antibiotic-growth promoters have been banned and not used in feeds in certain countries due to increased concerns about the potential for antibiotic resistant strains of bacteria and residues of antibiotics in animal tissues. After this decision many scientists have searched for alternatives to antibiotics. Many approaches or alternative natural replacements include probiotics, prebiotics, organic acids, plant extracts, etheric oils and immune stimulants have been applied to maximize performance, maintain animal productivity, preventing and controlling enteric pathogens and reducing antibiotic use in the animal production in recent years. The use of a single replacement or ideal combinations of various alternatives with good management and livestock practices may play a key role in maximizing performance and preserving animal productivity. The purpose of this review is to provide an overview of the recent knowledge on the use of the natural replacements in poultry feeds as feed additives and their effects on the poultry performance.