Short-Chain Fatty Acids in Livestock and Aquatic Animals: Metabolic Divergence, Physiological Functions, and Product Development

The gastrointestinal tract of livestock, poultry, and aquatic animals harbors a vast and complex microbial community, which engages in intricate and interdependent interactions with the host. Short-chain fatty acids (SCFAs), a major class of metabolites produced by the gut microbiota, play pivotal roles in intestinal health, immune regulation, and energy metabolism of these animals. In recent years, with growing recognition of the importance of the gut microbiota and its metabolites in animal health, the diverse physiological functions of SCFAs have been increasingly elucidated. This review summarizes the major types of SCFAs and their production, absorption, metabolic fate, physiological functions, and underlying mechanisms, with emphasis on metabolic divergence across species. In addition, the review highlights the practical limitations of free SCFAs, including volatility, instability, and rapid absorption, particularly in aquaculture systems. Recent advances in SCFA product development, including physical, chemical, and combined physico-chemical modification strategies, are also summarized to illustrate approaches for improving stability, targeted intestinal delivery, and biological efficacy. Overall, this review provides an integrated perspective on the physiological functions and technological development of SCFAs and highlights their potential for sustainable application in animal production systems.