1. The source of soybean meal
Soybean meal is a by-product of soybean oil extraction. According to the different extraction methods, it can be divided into two types: first-dip soybean meal and second-dip soybean meal. The by-product after extracting soybean oil by leaching method is the first-leaching soybean meal, and the by-product obtained by first pressing the oil and then leaching the oil is called the second-leaching soybean meal. In the whole processing process, the control of temperature is extremely important.
Too high temperature will affect the protein content, which is directly related to the quality and use of soybean meal; too low temperature will increase the moisture content of soybean meal, while high water content will cause Affect the quality of soybean meal during storage. The production process of first-dip soybean meal is relatively advanced and the protein content is high. It is the main variety currently circulating in the domestic spot market.

2. Grading standard of soybean meal
According to national standards, soybean meal is divided into three grades, first-grade soybean meal, second-grade soybean meal and third-grade soybean meal. Judging from the current domestic soybean meal spot market, the total domestic soybean meal processing (excluding imported soybean meal) is about 10 million tons, of which the first-grade soybean meal accounts for about 20%, the second-grade soybean meal accounts for about 75%, and the third-grade soybean meal accounts for about 10 million tons. 5%, the change of the three grades of soybean meal circulation is mainly related to the quality of soybean.
Judging from the market demand for different grades of soybean meal, a few powerful large-scale feed mills in China are using first-class soybean meal, and most feed mills currently mainly use second-class soybean meal (43% protein content), and second-class soybean meal is still the domestic soybean meal consumption. The mainstream product in the market, tertiary soybean meal has been rarely used. Soybean meal is widely used in feed processing, and the proportion of feed for pigs, chickens and ducks is 20%-30%.

3. The natural properties of soybean meal
1. Physical properties
Color: Light yellow to light brown, if the color is too dark, it means overheating, and if it is too light, it means underheating. The color of the whole batch of soybean meal should be basically the same.
Flavor: It has the aroma of roasted soybeans.
Texture: Good uniformity and fluidity, in the form of irregular fragments, powder or granules, without excessive impurities.
 
2. Chemical composition
Soybean meal contains about 43% protein, 2.5%-3.0% lysine, 0.6%-0.7% tryptophan, 0.5%-0.7% methionine, 0.5%-0.8% cystine; less carotene, only 0.2-0.2% 0.4mg/Kg, 3-6mg/Kg of lecithin and riboflavin, 15-30mg/Kg of niacin, 2200-2800mg/Kg of choline. Soybean meal is relatively deficient in methionine, crude fiber is mainly from soybean skin, nitrogen-free extract is mainly disaccharide, trisaccharide, tetrasaccharide, low starch content, low mineral content, less calcium and more phosphorus, less vitamin A, B, B2 . Table 2 reflects the composition comparison of soybean meal and various other oil meals.

The following is a detailed description of each indicator:
1. Protein index: This index is the most important index in the feed industry. Industry insiders generally believe that the higher the protein, the better the feed quality. It can be seen from the above table that the soybean meal with skin and skin is ranked 3rd and 1st in this index, and the high protein content of 48.5% soybean meal without skin can greatly reduce the input of other additives in the feed and improve the livestock. meat yield.

2. Fiber index: This index can play a certain role in the nutritional synthesis of ruminants such as cattle, but has almost no value in the nutritional synthesis of other non-ruminant animals. The ether fiber and crude fiber content of peeled and peeled soybean meal ranked 1st, 4th, 4th and 1st from the bottom.

3. Energy index: This index reflects the energy that unit feed can provide to livestock, in other words, how to achieve the same feeding effect with as little feed as possible. As can be seen from the above table, the soybean meal with skin and peeled is ranked 3rd and 1st respectively.

Here, the scores are determined according to the different effects of each indicator on livestock (Table 1, the data in the expanded arc), and the following results are obtained after aggregation: hulled soybean meal: 33, peeled soybean meal: 37 points, Canadian rapeseed meal: 16 points, cottonseed meal: 20 points, flaxseed meal: 18 points, peanut meal: 29 points, rapeseed meal 11 points, safflower meal: 20 points, sesame seed meal: 26 points, sunflower seed meal: 14 points.
Combining the above indicators, the total score of peeled soybean meal and hulled soybean meal ranks first and second among the ten kinds of meal.