Dietary inclusion of by-products containing phytomelatonin to improve sheep health, production, and reproductive performance: a review

Abstract

Melatonin regulates seasonality and circadian rhythms, released from the pineal gland and extra-pineal tissues responding to darkness, and has a well-known influence on sheep reproductive performance. Advantages of phytomelatonin over synthetic melatonin include co-factors (polyphenols and flavonoids), a higher antioxidant capacity, a lower overdose risk, and addressing the growing demand for organic animal products. However, few studies have evaluated the potential of phytomelatonin as an alternative source of synthetic melatonin and its impact on animal performance. To date, no comprehensive review has been conducted on the potential of fruit and vegetable by-products as a source of phytomelatonin to improve sheep productivity and health. Therefore, this review was conducted using Google Scholar, PubMed, and Scopus, and various plants rich in phytomelatonin were identified, including Zea mays, coffee beans, mung bean sprouts, and tomatoes. Phytomelatonin could improve reproductive performance of animals through antioxidant properties and microbial modulation. Supplementing vegetable and fruit by-products could enhance sheep production and sustainability, reduce waste, and contribute to a more circular economy. However, the concentration of phytomelatonin necessary for improving reproductive performance is still unknown due to the limited studies conducted. Therefore, more studies are needed to evaluate the effects of animal phytomelatonin supplementation on reproductive performance.