The composition and characteristics of flavoring agent are the additives used to improve the palatability of feed and increase the appetite of animals. The flavoring agents were composed of flavoring ingredients, stimulating taste components and adjuvant agents. Aroma components (volatile and non-volatile) include vanillin, lemon oil, butyl lactate, vanillin, shallot oil and other aromatic lipids, alcohols, etc. Different livestock and poultry not only have different taste preferences, but also have a very different physiological threshold for a certain odor and taste. In the preparation and selection of applications, the three basic principles of validity, physical and chemical stability and safety standards should be followed. The high temperature process can promote the hydrolysis and oxidation of the flavoring substances, and the feed flavoring agent should be able to withstand the high temperature damage of the process, so as to avoid the smell of the feed. The physical and chemical compatibility of flavoring agent and feed ingredient have great influence on the efficacy. High concentration of copper, phosphorus, potassium urea, oxycholine, fish powder, particle binder, preservatives and drugs and other feed components will have adverse effects on the efficacy and quality of the flavoring agent; And fat, salt, glucose, organic acid, some amino acids and other feed components are beneficial to the feed aroma. The application of feed flavoring agent for feed nutrition, food intake and digestion and absorption is the three key factors to ensure healthy growth and efficient production of livestock and poultry. Any formula is designed based on a certain amount of food intake, which is not suitable for the feed, and the decrease in intake will inevitably affect the total amount of nutrient intake, which will undoubtedly affect the effect of feed. Many feed raw material itself have palatability problems, such as the smell matter in soybeans, beans of exogenous lectins, glucosinolates in rapeseed meal glucoside and its degradation products cause goiter element; Many grains and other plant feedstuffs of tannin, fat oxidation degradation products and so on, will have a bad effect on the food palatability. The feed has good palatability and sufficient intake to ensure the total nutrient demand of livestock and poultry. If the livestock and poultry are in a state of stress, such as noise, shock, crowding, clustering, rotation, transportation, weaning, castration, heat, cold, etc., the animal's appetite will decrease and the intake will decrease. In these cases, it is necessary to add flavoring agents or attractants to the feed.