Avian coccidiosis and anticoccidial potential of garlic (Allium sativum L.) in broiler production: a review

Avian coccidiosis is an intestinal infection caused by a parasitic intracellular protozoan of Eimeria species. The effect of coccidian intestinal infection in birds renders significant economic losses in production, and therefore, it is crucial for industry players and researchers to find solutions to its occurrence. The use of synthetic additives and anticoccidial supplements has been established to be effective in preventing and controlling coccidiosis. However, concerns about anticoccidial drug resistance in Eimeria species due to frequent use have been reported. Alternatively, the use of attenuated live vaccines has been successful but it comes with challenges because of poor farm management. Garlic and its bioactive compounds have been found to exhibit anti-inflammatory and antioxidant properties. The anticoccidial potential of garlic is linked to its immunostimulatory activity. Garlic and its derivatives inhibit the sporulation of oocysts in vitro. Supplementation of garlic in coccidiosis-infected broilers improves weight gain and feed efficiency, and reduces fecal oocysts output, lesion score, and clinical signs postinfection. Thus, this review aims to highlight the clinical signs of coccidiosis, the techniques involved in oocysts determination, and the anticoccidial potential of garlic in improving the health of broiler chickens. Future studies can bridge the knowledge gap on the mode of action of the bioactive compounds of garlic against coccidiosis and the Eimeria species-specific gene and immune-protective antigens that they inhibit and improve in infected birds.