A narrative review on the beneficial impacts of probiotics on poultry: an updated knowledge

Abstract Probiotics are live microorganisms that can improve the host’s health when given in sufficient doses. Due to growing consumer demand for poultry raised without antibiotics supplementation, the usage of probiotics has been rising gradually over time in poultry. This review aimed to summarize the impacts of probiotics on poultry’s nutrient utilization, growth and carcass parameters, gut morphology, laying performance, biochemical parameters, immunity, and gut microbiota. The results revealed that probiotics enhanced the growth performance via improving digestion of protein, lipids, and carbohydrates, improving feed conversion ratio (FCR), increasing carcass and organs weights, improved liver and kidney function parameters, antioxidant effects, decreased serum lipids and cholesterol, improved poultry immunity via improving gut health and synthesis of antimicrobial peptides and prevention of microbial colonization, improved laying performance, fertility, hatchability and eggshell thickness. Therefore, probiotics have various benefits in poultry production compared to banned antibiotics. However, they are not always guaranteed to be growth promoters due to poorly understood modes of action, including their interaction with the host. So, further studies concerning their impacts on meat quality and histopathological changes are still required.