Melatonin is a molecule that plays an active role in reducing many stress factors in plants and has important functions in the growth, development and reproduction of plants. It has many physiological functions that directly affect feed consumption, feed efficiency, energy metabolism and immune system in animal organisms. In addition, its anti-inflammatory, antioxidant, anticancer and antiapoptotic effects are also known. While melatonin has an antioxidative effect at low doses, it can exert a prooxidant effect at high doses. It has been suggested that when melatonin is used as a silage additive, it increases the total acid content of the silage and significantly improves the silage fermentation quality by lowering the pH level and butyric acid. Although it has positive effects on mammary gland involution and general health in ruminants, its effects on yield parameters have not been proven. Broilers and layers are expected high productivity and performance, in this regard, they are faced with stress factors such as intensive feeding and housing conditions. Considering its positive effects on stress factors, health and productivity, melatonin is a promising feed additive. Effects of melatonin additive or supplements on animal productivity and health should be revealed in further studies.