Research Progress on the Physiological Functions of Aspartic Acid and Its Applications in Animal Production

Aspartic acid, a non-essential amino acid required for mammalian growth, has long been overlooked as a simple nutrient. It has been revealed that aspartic acid serves as a key node molecule in the tricarboxylic acid cycle and the urea cycle, and possesses biological activities such as antioxidant, anti-inflammatory, immunomodulatory, and lipid metabolism-regulating effects, garnering widespread attention in the medical, food, and animal husbandry industries. Due to its chiral structure, aspartic acid naturally exists in two configurations, L- and D-forms, which exhibit certain differences in function and chemical properties. In animal husbandry, both configurations of aspartic acid have been applied in various animal models, where they have demonstrated roles in promoting growth, alleviating oxidative stress, modulating immune stress, and regulating gut microbial community structure. Therefore, aspartic acid holds promise as a conditionally functional amino acid for application in animal production. This review summarizes the physicochemical properties, metabolic pathways, and transport mechanisms of aspartic acid, outlines its in vitro synthesis methods, elucidates its physiological functions, and comprehensively reviews the current applications of its different configurations in the field of animal husbandry. The aim is to provide a theoretical foundation for the use of aspartic acid as a green, low-cost, and safe conditionally functional amino acid in animal husbandry.