Antioxidant and antimicrobial activities of phytonutrients as antibiotic substitutes in poultry feed

Globally, there is increasing demand for safe poultry food products free from antibiotic residues. There is thus a need to develop alternatives to antibiotics with safe nutritional feed derivatives that maximize performance, promote the intestinal immune status, enrich beneficial microbiota, promote health, and reduce the adverse effects of pathogenic infectious microorganisms. With the move away from including antibiotics in poultry diets, botanicals are among the most important alternatives to antibiotics. Some botanicals such as fennel, garlic, oregano, mint, and rosemary have been reported to increase the poultry's growth rate and/or feed to gain ratio. Botanicals' role is assumed to be mediated by improved immune responses and/or shifts in the microbial population in the intestine, with the elimination of pathogenic species. In addition, modulation of the gut microbiota resulted in various physiological and immunological responses and promoted beneficial bacterial strains that led to a healthy gut. There is thus a need to understand the relationship between poultry diets supplemented with botanicals and good health of the entire gastrointestinal tract if we intend to use these natural products to promote general health status and production. This current review provides an overview of current knowledge about certain botanicals that improve poultry productivity by modulating intestinal health and reducing the negative impacts of numerous pathogenic bacteria. This review also describes the efficacy, negative effects, and modes of action of some common herbal plants applied in poultry as alternatives to reduce the use of antibiotics.