Biological applications and future perspectives of bioactive compounds as pig feed additives

Restrictions or prohibitions on the use of antibiotics in pig feed for growth promotion have been introduced in many countries. Bioactive compounds (BCs) as functional additives are emerging as an alternative to overcome these restrictions. These compounds include natural extracts from animals, plants, and microorganisms, as well as their chemically synthesized counterparts. Their growing popularity is due to their abundant sources, safety, and multiple biological functions, including antibacterial, antioxidant, anti-inflammatory, immunomodulatory, and intestinal health-promoting effects. This review summarizes the various types of BCs developed to date, including polyphenols, polysaccharides, aldehydes, terpenes, and polypeptides, and their use in pig production. It also discusses how these BCs can be used in pig farming, particularly to improve sows' reproductive performance, reduce diarrhea in piglets, and enhance the meat quality of finishing pigs. Despite these functions, the broader application of BCs remains limited due to the challenges such as poor water solubility, low stability, intestinal malabsorption, and low bioavailability. These challenges can potentially be addressed through emerging technologies, particularly nanotechnology, genetic engineering, and artificial intelligence. This review also highlights how these technologies may facilitate the translation of BCs into practical applications within commercial pig production. Finally, this review focuses on future perspectives of BCs in pig feed by exploring how advances in cell biology, materials science, and genetic engineering may interact to shape the future trajectory of BCs use in the pig industry.