A Review of the Control of Coccidiosis in Poultry Using Natural Additives, Focusing on Gut Health and Immunity

Coccidiosis is one of the most common diseases in the poultry industry worldwide (especially in broilers aged 3–6 weeks), causing significant economic losses to poultry farmers and governments every year. Conventional methods (anticoccidial chemical compounds) for the coccidiosis debarment and control always present challenges and disadvantages, such as anticoccidial drug resistance. Herbal secondary metabolites and herbal essential oils, also known as phytogenics, are biologically active ingredients that have recently received attention as feed additives in poultry production. Plant compounds are able to stimulate the production of digestive enzymes, leading to more efficient breakdown and absorption of nutrients from the feed. In addition, they reduce the pathogen burden in poultry due to their antimicrobial and antiviral properties. Various researchers have studied the effect of herbal additives on the gastrointestinal performance and health, and their consequences on systemic health and welfare of birds, flock production efficiency, food safety, and environmental effects. A review of published studies on plant additive supplementation shows conflicting results regarding their efficacy in poultry. It can be concluded that further efforts are still needed to determine the appropriate composition and fully explain their action mechanism. The aim of this review is to investigate the control and management of coccidiosis in flocks and the effects of natural compounds on the gastrointestinal function and immunity of birds.