The mechanism of action of anti nutritional factors and their effects

　　Antinutritional factors mainly reduce the body's utilization of nutrients such as protein and energy by consuming more endogenous proteins, reducing apparent metabolic energy, chelating mineral and trace elements, inactivating or interfering with the body's utilization of vitamins, and other manifestations.

　　1 trypsin inhibitor

　　As the name suggests, trypsin inhibitors have an inhibitory effect on trypsin, reducing enzyme activity and causing indigestion in the body. Undigested proteins are excreted together with trypsin through feces, leading to severe loss of trypsin in the body, stimulating the secretion of a large amount of trypsin in the pancreas, resulting in enlargement of the pancreas, endogenous loss of proteins, and imbalance of sulfur-containing amino acids such as cysteine. They also reduce fat absorption and feed intake, affecting animal growth and development.

　　2 Plant lectins

　　Plant lectins, as an antigen, can quickly recognize and selectively bind to the small intestinal mucosa, damaging its mucosal structure, causing abnormal secretion of enzymes, altering enzyme activity and intestinal environment, and damaging the immune system. Meanwhile, plant lectins affect the secretion of cholecystokinin and other substances, thereby delaying gastric emptying rate and reducing feed intake, leading to poor animal development. When the blood circulation system receives a large amount of plant lectins, it can lead to poisoning of the body.

　　3 Phytic acid

　　Phytic acid, as a strong chelating agent, reduces the solubility of certain nutrients by binding them, thereby reducing nutrient absorption and utilization. Phytic acid interacts with metal ions such as calcium, magnesium, and zinc to form phytate complexes, resulting in a decrease in the solubility of minerals and trace elements in the body, making them difficult to be absorbed and utilized by the body. Phytic acid chelates protein molecules, reduces protein solubility, and binds to proteases to inactivate enzymes, reducing protein and energy utilization efficiency. In addition, phytic acid can stimulate the secretion of endogenous sodium in the body, interfering with the absorption of amino acids and glucose.

　　4 Tannins

　　Tannin is a highly polymerized substance that can bind to proteins, various enzymes, vitamins, and more. Tannins can reduce the digestibility of nutrients, mainly manifested by: ① inhibiting enzyme activity through interactions with trypsin, amylase, etc.; ② Interacting with proteins and carbohydrates to generate insoluble substances; ③ Chelate various ions such as vitamin B12, calcium, zinc, etc. At the same time, tannins can also reduce the feed intake of livestock and poultry, by reacting with salivary mucin and other substances, weakening the lubrication function of saliva and causing dryness in the mouth, resulting in poor palatability of the body.

　　5 Non starch polysaccharides

　　Water soluble non starch polysaccharides (SNSP) have a highly viscous network structure and can bind to digestive enzymes, inhibiting their activity and hindering their digestion of nutrients. SNSP can bind bile acids or lipids, causing the body to excrete a large amount of bile acids and reduce the absorption of fats. SNSP can also increase intestinal viscosity, reduce the concentration of oxygen in the digestive tract, and retain nutrients in the intestine for a long time, providing an environment and nutrient guarantee for the growth and reproduction of microorganisms, leading to intestinal dysfunction.