The use of antibiotics as growth promotors or for the prevention of some poultry diseases has face global concern and serious criticism. Their addition to poultry feed show hazardous effects including development of antimicrobial resistance and the potential harmful effect on humans’ health. To eliminate these threats, there is increasing interest to search for natural alternatives. Plant derivatives such as garlic (Allium sativum L.) and its derivatives are nowadays extensively used in poultry production system. Dietary supplementation of broilers and layers with garlic induced improvement of production parameters, carcass quality, and intestinal integrity. Modulation of the immune response against important viral diseases and increasing the immune organs body weight ratio resulting from supplementation of poultry with garlic. Moreover, garlic showed modulation of gut health through the antibacterial and antiparasitic activities. Treatment with garlic also can mitigate the oxidative stress and reduce the free radicals production. Reduction of cholesterol level, but improvement of some liver and blood parameters were also reported following dietary inoculation of garlic. This review was designed to search on the impact of garlic as feed additives on performance, immunity, gut health, antioxidant status, and blood parameters of poultry.

Feed additive antibiotics have been used for many decades as growth promotors or antibacterial substances world-wide. However, the adverse impacts of using antibiotics in animal or poultry feeds were informed. Therefore, searching for alternatives such as probiotics, prebiotics, phytobiotics, post-biotics, bacteriophages, enzymes, essential oils, or organic acids (OAs) became urgent. The OAs are produced by beneficial intestinal bacteria through the fermentation process of carbohydrates. The OAs and their salts are still used as feed preservatives. They have been long added to feed in order to minimize contamination and growth of harmful bacteria and fungi, reduce the deterioration, as well as prolong the shelf life of feed commodities. Moreover, they have been mostly added to poultry feed as a blend to obtain a maximum beneficial effects. The supplementation of poultry with OAs could improve the growth performance parameters and carcass traits, promote utilization of nutrients, boost the immune response, and inhibit the growth of pathogenic bacteria. Therefore, this review article provides valuable insights into the potential benefits of using OAs-antibiotics alternative in reducing the microbial load, enhancing the performance parameters in broilers and layers, improving the gut heath, as well as boosting of the immune response.