Abstract
Following the European Union's restriction on antibiotic growth promoters, research on enhancing gut health has been accelerated. As the poultry industry is facing issues that were previously managed by antimicrobial growth promoters, the hunt for the best remedies continues to find suitable alternatives. Simultaneously, social pressure is mounting to reduce the usage of antibiotics and replace them with other feed additives. Consumers believe a number of accessible options to be safe, with phytogenics playing a crucial role. This review describes how the use of fennel seeds could be beneficial for poultry. An overview of the broad chemical diversity of fennel is presented together with their physicochemical and biological properties. According to investigations, fennel seeds have a variety of biological effects in birds, including improved performance, higher immune cell proliferation, reduced oxidative stress, and boosted antibody titers against infectious diseases. The efficacy of poultry outcomes is determined by the stage and age of the plants, the extraction process, the geographical location, the chicken species, management techniques, and the concentrations administered. The present review focuses on the effects of fennel seeds as a feed additive on poultry growth, carcass quality, blood biochemistry, antioxidant activity, immunity, and microbiological aspects.