Abstract
Poultry meat and eggs are considered as major sources of food for rapidly increasing human population across the globe. During the rearing of poultry, different antibiotics were included in poultry diets in sub-therapeutic doses to attain improvements in growth performance. Recently, the use of antibiotics in poultry production has been considered as one of the major reasons behind the emergence of antibiotic resistance in human and poultry pathogens. The pressing issue of antibiotic resistance led to complete or partial bans on the use of antibiotics as growth promoters in many parts of the world. Moreover, there have been increased concerns among the consumers about the antibiotic residues in poultry products. These administrative bans led to an increased incidence of bacterial disease outbreaks, thus compromising the poultry performance, welfare, and economic outcomes of poultry producers. This ultimately attracted the attention of researchers to find the alternative strategies that could replace the antibiotics and bring production, health, and food safety benefits to the poultry production systems. These non-antibiotic growth promoters mainly include probiotics, prebiotics, synbiotics, phytogenic substances, organic acids, antimicrobial peptides, enzymes, bacteriophages, and egg yolk antibodies. Inclusion of these non-antibiotic solutions in poultry diets demonstrates promising results in terms of production performance and birds’ health. These promising results are demonstrated through improvements in nutrient absorption, proliferation of beneficial bacteria, reduction in pathogenic bacterial species, production of bacterial metabolites that serve as energy sources for intestinal epithelial cells of the host, and positive modulation of immune responses. Apart from reducing the colonization of bacterial species that are pathogenic for poultry, these alternative solutions have also exhibited satisfactory efficacy in reducing the colonization of foodborne pathogens like Salmonella and Campylobacter jejuni which cause illness in the human population. In this paper, we reviewed studies that evaluated the effects of non-antibiotic growth promoters on different types of poultry. A description of mechanism of action, advantages, disadvantages and effects on production performance, gut health and immune parameters are discussed in this paper.