Corn is the main grain feed and energy feed in China. Corn has good palatability and no use restrictions. Its nutritional characteristics are as follows: 1. The available energy is high. The metabolic energy of corn is 14.06MJ/kg/kg, and the highest can reach15.06 mj/kg, which is the highest among cereals. This is mainly because there is very little crude fiber in corn, only 2%; The nitrogen-free extract is as high as 72%, and the digestibility can reach 90%. On the other hand, the crude fat content of corn is relatively high, ranging from 3.5% to 4.5%. Corn is an annual gramineous plant, also known as corn, cob and Liugu. According to the research, every100g of corn contains 196 calories,10.2g of crude fiber, 3.8g of protein, 2.3g of fat, 40.2g of carbohydrate, and other mineral elements and vitamins. Corn contains more crude fiber, which is 4- 10 times higher than polished rice and refined flour. Corn also contains a lot of magnesium, which can strengthen the peristalsis of intestinal wall and promote the excretion of waste in the body. The above ingredients and functions of corn are very beneficial to lose weight. When the corn is ripe, the tassel on the ear has diuretic effect, which is also beneficial to lose weight. Corn can be boiled in soup instead of tea, or crushed to make corn flour and tortillas. Puffed popcorn has a large volume, which can eliminate the hunger of obese people, but its calorie content is very low after eating, and it is also one of the substitutes for weight loss. 2. The linoleic acid content is high. The linoleic acid content of corn reaches 2%, which is the highest in grain feed. If the proportion of corn in the diet is above 50%, only corn can meet the requirement of linoleic acid for pigs and chickens (1%). 3. The content of protein is low and the quality is poor. The content of protein in maize is about 8.6%, with unbalanced amino acids and insufficient contents of lysine, tryptophan and methionine. 4. Minerals About 80% of minerals exist in embryos, and the calcium content is very small, about 0.02%; The phosphorus content is about 0.25%, but about 63% of phosphorus exists in the form of phytic phosphorus, and the utilization rate of monogastric animals is very low. The content of other mineral elements is also low. 5. Vitamin fat-soluble vitamins contain more vitamin E, about 20mg/kg, yellow corn contains more carotene, and vitamins D and K are almost absent. Water-soluble vitamins contain more thiamine, less riboflavin and nicotinic acid, and nicotinic acid exists in a combined form. 6. The average lutein content in yellow corn is 22 mg/kg, which is one of the characteristics of yellow corn and is of great significance for coloring yolk, shin and claw. Recently, a study by the German Nutrition and Health Care Association shows that corn has the highest nutritional value and health care function among all staple foods. It can prevent heart disease and cancer. In this study, which lasted 1 year, experts compared the nutritional value and health care function of many staple foods such as corn, rice and wheat. The results show that the vitamin content in corn is very high, which is 5- 10 times that of rice and wheat. At the same time, corn contains a lot of nutrients and health-care substances, which also surprised experts. Besides carbohydrates, protein, fat and carotene, corn also contains nutrients such as riboflavin and vitamins. These substances are of great benefit in preventing diseases such as heart disease and cancer. The research also shows that the nutritional value of special corn is higher than that of ordinary corn. For example, the content of protein, vegetable oil and vitamins in sweet corn is 1-2 times higher than that in ordinary corn; The selenium content of "life element" is 8- 10 times higher; Among 17 amino acids, 13 amino acids are higher than common corn. In addition, the moisture, active substances, vitamins and other nutrients of fresh corn are much higher than those of old corn, because the cultivation branch of corn drops rapidly during storage. Professor Rahman, a famous German nutritionist in charge of this research, pointed out that among the more than 50 kinds of nutritional and health-care substances that have been proved to be the most effective today, corn contains 7 kinds-calcium, glutathione, vitamins, magnesium, selenium, vitamin E and fatty acids. It has been determined that every100g of corn can provide nearly 300 mg of calcium, which is almost the same as that contained in dairy products. Rich calcium can lower blood pressure. If you take 1 g calcium every day, your blood pressure will drop by 9% after 6 weeks. In addition, the carotene contained in corn can be converted into vitamin A after being absorbed by the human body, which has the function of preventing cancer; Plant cellulose can accelerate the discharge of carcinogens and other poisons; Natural vitamin E has the functions of promoting cell division, delaying aging, lowering serum cholesterol, preventing skin lesions, relieving arteriosclerosis and brain function decline. The researchers pointed out that lutein and zeaxanthin contained in corn can fight against eye aging. In addition, eating more corn can also inhibit the side effects of anticancer drugs on human body, stimulate brain cells and enhance people's brain power and memory. According to the national standard of corn quality in China, corn is divided into four categories according to its grain color and grain quality: yellow corn: yellow seed coat, including red and yellow corn. American standard stipulates that the content of other colors corn in yellow corn should not exceed 5.0%. White corn: The seed coat is white, including slightly yellow or pink corn. According to American standards, light yellow means light straw color, and it is stipulated that the corn content of other colors in white jade rice should not exceed 2.0%. Waxy corn: corn rich in viscosity. Miscellaneous corn: More than 5.0% of the above three types of corn are mixed with corn outside this category. In China's national standards, it is defined as corn mixed with more than 5.0% of corn outside this category. The color expressed by American standard can neither meet the color requirements of yellow corn nor white corn, and it contains yellow corn with white top.