Abstract: α-linolenic acid （ALA） is an n-3 polyunsaturated fatty acid （n-3 PUFAs） extracted from a variety of plants. As an essential fatty acid, ALA cannot be synthesized via endogenous metabolism in organisms and must be obtained from external diet or feed sources. It has been demonstrated to possess many important biological activities such as antioxidant and anti-inflammatory properties. In recent years, with the increasing emphasis on the concept of green and healthy livestock farming, ALA, as a natural and safe plant-derived feed additive, has attracted widespread attention from academia and industry in the field of livestock and poultry feed nutrition. This paper systematically reviews the chemical structural characteristics and basic physical and chemical properties of ALA, describes the main metabolic pathways and biotransformation mechanisms of ALA in animals in detail, discusses the key physiological functions and potential mechanisms of ALA in depth, comprehensively analyzes the specific regulatory effects and practical effects of ALA on various quality indicators of livestock and poultry products （including meat, eggs and milk）, and summarizes the research and application progress of ALA in different livestock and poultry production practices such as pigs, poultry and ruminants, aiming to provide a reference for the in-depth research and promotion and application of ALA in livestock and poultry production.

Key words: α-linolenic acid, metabolic pathway, physiological function, quality regulation, livestock and poultry production