Antioxidant is a preparation added to feed to prevent or delay the oxidation deterioration of some active ingredients. It is mainly used in feeds containing high fat to prevent the oxidation and rancidity of fat. It is also used in premix containing vitamins to prevent the oxidation and failure of vitamins.

　　The fat or fat-soluble vitamins, carotenoids and other substances in pig feed are easy to be oxidized and destroyed by the oxygen in the air, which makes the nutritive value of the feed decrease, the palatability become worse, and even lead to the rancid of the feed. The peroxide formed by the pig feed has toxic effect on the animal zero. Adding some antioxidants to pig feed can delay or prevent the automatic oxidation of the substances in the feed.

　　一、Types of antioxidants

　　In order to meet the needs of poultry breeding industry, modern feed production pays great attention to the comprehensiveness and balance of feed nutrients. Therefore, grease, fish meal, fat-soluble vitamins, etc., are often added into the feed. However, these ingredients are often the most easily oxidized in the feed.To sum up, there are mainly the following categories:

　　1. Oil: mainly soybean oil, peanut oil, fish oil and so on.

　　Its common characteristic is to contain very high unsaturated fatty acid, some products free fatty acid content of more than 5%, after a period of improper storage of the environment, its content will be multiplied. Oxidative rancidity occurs easily in the process of production, processing and storage of compound feed. Even some animal and vegetable oils, if there are some adverse factors in the process of processing and storage, will cause serious hydrolysis, oxidation rancidity. In feed mills commonly stored in the open or indoor oil, in the hot environment constantly bubbling, self-temperature rise. This indicated that the oils had developed serious rancidity before they were added to the prepared feed. After adding feed, the rancidity was more serious under the catalysis of other substances, and it quickly spread to the rancidity of other lipid substances.

　　2. Cake: mainly soybean meal, peanut meal, rapeseed meal and so on.

　　3. Bran category: the main fat rice bran, caryon and wheat bran.

　　二、Application of antioxidants in pig feed

　　Antioxidants are mainly used in pig feed in the following aspects: feeding grease, fish meal, animal slaughtering by-products and other high fat pig feed raw materials to prevent the oxidation and rancidity of fat. It is used in alfalfa meal, leaf meal, grass meal and other raw materials with high content of carotene and carotenoid to prevent oxidative damage of vitamin A and pigment and increase the colouring effect and utilization rate. Used in a vitamin containing premixture to prevent its activity from decreasing. It can be added to feed mixed with pigs and other raw materials which are easy to be oxidized to prevent oxidative damage of easy oxide and improve its utilization rate and effect, especially in aquatic bait with high oil content and pet pig feed.