There are three main types: (1) Fish meal is divided into two types according to its source: generally domestic fish meal is called domestic fish meal, and imported fish meal is collectively called imported fish meal. Obviously, this method is rough and can't reflect the quality of fish meal. (2) According to the nature and color of raw materials, fish meal can be divided into six types: ordinary fish meal (orange white or brown); White fish meal (gray or grayish yellow, mainly cod); Brown fish meal (orange brown or brown); Mixed fish meal (light black brown or thick black); Whale powder (light black) and fish meal (fish processing residue). (3) Fish meal is divided into six kinds according to the position and composition of raw materials, namely: whole fish meal (fish meal made of whole fish); Fortified fish meal (whole fish meal+fish paste); Coarse fish meal (fish meal, using fish processing residues as raw materials); Fish meal blending (whole fish meal+coarse fish meal); Mixed fish meal (mixed fish meal+meat and bone meal or feather meal); Fish essence powder (fish paste+adsorbent). The above classification methods are different in different countries, and there is no standard in China's feed industry at present, and all three methods are adopted. Fish meal is not only a high-quality source from protein, but also an animal protein feed that cannot be completely replaced by other protein feeds. However, due to the different quality of raw materials, their nutritional components are very different. 1. The main nutritional feature of crude protein fish meal is high protein content, and the crude protein content of general defatted whole fish meal is as high as 60% or more. Among all protein supplements, its protein nutritional value is the highest. Imported fish meal is 60% ~ 72%, and domestic fish meal is slightly lower, generally 45% ~ 60%. It is rich in many essential amino acids, such as lysine (5.5%), tryptophan (0.8%), methionine (2. 1%), cystine (0.65%) and so on. The content of arginine is relatively low (3.65%). Therefore, protein is of good quality and high biological value. 2. Effective energy Fish meal contains no indigestible substances such as cellulose and high crude fat content, so fish meal has high effective energy, and it is easy to make high-energy feed with fish meal as raw material in production. 3. Vitamin fish meal is rich in B vitamins, especially vitamins B 12 and B2, and also contains fat-soluble vitamins such as vitamin A, vitamin D and vitamin E, but it is easy to be destroyed under poor processing and storage conditions. 4. Mineral fish meal is a good mineral source, with high calcium and phosphorus content and appropriate proportion, and all phosphorus is available. The selenium content of fish meal is very high, which can reach more than 2mg/kg. In addition, the contents of iodine, zinc, iron and selenium in fish meal are also high, and there is a proper amount of arsenic. 5. Unknown growth factors Fish meal contains unknown factors that promote growth. This substance has not been purified into a compound and cannot be named, but it can definitely stimulate the growth and development of animals. In the past, it was thought that this substance only existed in animal protein, and it was called animal protein factor (APF). At first, I thought it was mainly vitamin B 12. Later, it was found that this substance does not necessarily exist only in animal protein, but also in distiller's grains leaching solution and dry matter of alfalfa. Therefore, it is called Unknown Growth Factor (UGF). Generally, the protein utilization rate of fish meal prepared by vacuum drying or steam drying is about 10% higher than that prepared by baking. Fish meal generally contains 6% ~ 12% of lipids, among which the unsaturated fatty acid content is high, and it is easy to oxidize and produce odor. Imported fish meal varies according to the process and raw materials of the producing country. The quality of Peruvian fish meal and white fish meal is good, and the crude protein content can reach more than 60%. Sulfur-containing amino acids are about 1 times higher than domestic fish meal, and lysine is also significantly higher than domestic fish meal. Due to the nonstandard variety of raw materials and processing technology, the quality of domestic fish meal is uneven. Livestock feed is used for pigs, chickens, cows and other animals. These feeds need to contain high-quality protein, especially piglets and chickens. Because young animals are in the vigorous growth period, the demand for protein and the demand for protein, the proportion of amino acids is large. Fish meal, as an animal protein, its amino acid ratio is closest to what animals need. Aquatic animal feed takes protein as the main raw material for aquatic animal feed such as fish, crab and shrimp. The ratio of fish meal to amino acids needed by aquatic animals is the closest, and adding fish meal can ensure the rapid growth of aquatic animals. Fur animal feed is used for some fur animals, such as foxes and raccoons. Most fur animals are carnivores, and their growth has a great demand for protein. High-quality fish meal is the first choice for these animals as raw materials in protein. You might as well have a taste ~! The common adulteration of fish meal (1) is the addition of soybean meal, rapeseed meal, cotton meal, peanut meal, etc. In order to increase the weight of fish meal; (2) Adding non-protein nitrogen such as urea, ammonium chloride, biuret and urea phosphate. In order to increase the total nitrogen; (3) protein, a low-quality animal, such as feather powder, hair powder, blood powder, hide powder, meat powder, etc., is mixed into the fish meal. (4) It is more serious to mix inferior or deteriorated fish meal with good fish meal, especially imported fish meal.