The role of corn gluten meal in feed
It is understood that the protein content of corn gluten meal is as high as 40% to 60%, and its protein content is 21% and 3.7% higher than that of bean cake and fish meal respectively. It is rich and can be used to replace protein feed such as bean cake and fish meal in the feed market where bean cake and fish meal are in short supply; for this reason, the following editor will introduce the role of corn gluten meal in feed in detail.
1. Classification and structural composition of zein
According to solubility, zein can be divided into: albumin which is soluble in water; globulin which is insoluble in water but soluble in salt; prolamin which is insoluble in water but soluble in ethanol; insoluble in water and alcohol but soluble in Dilute acid or dilute alkaline gluten. These four proteins are unevenly distributed in various parts of corn kernels, gliadin (40%) and glutenin (37%) are mainly distributed in the embryo body; while albumin and globulin are mainly distributed in the germ, and their content is less . The protein content in corn gluten powder is as high as 40%~70%. Corn gluten powder is mainly composed of zein and glutelin, of which gliadin accounts for about 68% and gluten accounts for about 28%. Due to the large amount of non-polar amino acids in zein, the solubility in aqueous solution is very poor, and the solubility is high in 60%~95% alcohol aqueous solution, the insolubility and acid resistance of zein in water have caused The digestion and utilization of corn gluten meal by the animal body cannot achieve the desired effect. In recent years, with the continuous deepening of the research on zein, the hydrolysis of zein to improve the utilization of corn gluten powder has gradually attracted people's attention. It has been reported in literature at home and abroad that adding a certain amount of exogenous protease preparation can improve the digestion and utilization rate of corn gluten powder by animal organisms.
The nutritional components of corn gluten meal produced by different purposes and different production processes are different, and the degree of change is large, which directly affects the effective utilization rate of its feed raw materials and the economic benefits of feed formulations. It can be seen from Table 1 that the protein content of corn gluten meal is 21% and 3.7% higher than that of bean cake and fish meal respectively, which is obviously different from bean cake. feed. In addition, the fat content of corn gluten meal is higher than that of bean cakes and corn seeds. According to research at home and abroad, adding fat to the diet can increase the weight gain of livestock and poultry by 15% to 20%, and reduce the consumption of feed per kilogram of weight gain by 10% to 15%. It can reduce the oxidation of amino acids and have more amino acid conversion Adult protein can improve the digestibility of amino acids; it can inhibit the conversion of glucose and other precursor substances into fat; under high temperature conditions, it is also beneficial to increase energy intake, reduce body heat consumption of livestock and poultry, and slow down heat stress. In addition, high fat content can also effectively improve the palatability of feed. It can be seen that corn gluten meal is comparable to soybean cake and fish meal as an important protein source of compound feed.
3. The role of corn gluten meal in feed
Today, corn gluten meal is mainly used in the feed industry in China. However, corn gluten powder can be used to extract natural food pigments, zein, glutamic acid and other substances, and can also prepare corn active peptides with various physiological functions, such as glutamine peptides, high F value oligopeptides, reducing Blood pressure peptide and zein peptide, etc., greatly increase its economic value.
3.1 Corn Gluten Meal as Feed Protein Source
Corn gluten powder has high protein content and rich amino acids, but the amino acid composition is unbalanced, rich in branched chain amino acids (leucine, isoleucine, valine), sulfur-containing amino acids, proline and phenylalanine etc., are especially rich in glutamic acid, but lack basic and acidic amino acids, such as tryptophan and lysine, which are very low.
Corn gluten meal is mainly composed of gliadin, which limits the digestion and utilization of animals due to its special structure and strong hydrophobicity, although the microorganisms in the animal digestive tract and digestive enzymes in the intestinal tract can digest and degrade part of it to a certain extent Corn gluten meal, but very limited digestion. It has been reported in the literature that adding exogenous protease can promote the digestion and absorption of corn gluten powder in animals. Corn gluten powder produced by digestive enzymes or biodegradation has significant biologically active peptides and high F value oligopeptide molecules. In addition to being easily digested and absorbed by animals, corn active peptides also have physiological activities such as anti-oxidation, eliminating fatigue, and lowering blood pressure; high F-value oligopeptide molecules can improve the functions of liver, kidney, intestines, and stomach of animals.
Corn gluten meal can be used to replace some protein feeds such as bean cake and fish meal in the feed market where bean cake and fish meal are in short supply. In addition, soybean protein is rich in lysine and tryptophan, but lacks sulfur-containing amino acids. Therefore, compounding soybean protein and corn gluten powder in a certain proportion and then performing enzymatic hydrolysis can play a complementary role and further improve the grain protein powder. The nutritional value and quality are conducive to improving the digestion and absorption of livestock and poultry, and meeting the nutritional needs of livestock and poultry. The layer hen compound feed based on corn gluten powder can increase the egg production rate, and at the same time prevent and treat chicken rickets and other diseases, promote growth, and also help to improve the quality of egg protein. In the cattle industry, using corn gluten meal as a concentrated feed can make some protein that cannot be digested by the rumen better digested and absorbed in the small intestine. Corn gluten powder contains linoleic acid, which can promote fat metabolism in chickens and promote the polymerization of essential amino acids.
3.2 Corn gluten powder improves broiler coloration
Although the coloring degree of broiler skin has nothing to do with its nutritional value, due to the influence of traditional culture, consumers and breeders still regard the coloring degree of broiler chicken as one of the indicators to measure the quality of broiler chicken, which directly affects the price and demand of broiler chicken market. Broiler chickens cannot synthesize lutein by themselves and can only obtain it from the feed. The coloring degree of the skin depends on the effective supply of lutein in the feed and the total amount of lutein deposited in the chicken body. Broilers fed diets such as corn and bean cakes can only obtain normal skin color. In order to obtain the ideal skin color, chemical synthetic colorants such as Jialisu Red and Jialisu Yellow are generally added to broiler feed. , detrimental to the health of consumers.
Corn gluten powder has high lutein content and can be absorbed effectively. It can make eggs golden yellow and chicken skin yellow, increasing nutritional value and selling price. The lutein content in corn gluten powder is 90~180 mg·kg- 1 , more than 5 times that of yellow corn, but the price is close to that of bean cake. In view of this, corn gluten powder can be used instead of chemical synthetic colorants to improve the coloring of egg yolk and chicken.
3.3 Corn Gluten Meal Can Replace Part of Antibiotics
Chen Shipei et al reported that the corn gluten feed made from the by-products of extracting corn syrup from corn starch contains 13% to 16% protein and 7% to 8% citric acid, which has sour, fragrant, sweet taste and palatability. Good, high digestibility characteristics. The citric acid contained in the corn gluten feed has special significance. Using citric acid and other acidifiers instead of pharmaceutical growth promoters will not leave harmful substances in livestock and poultry products, and will not have a withdrawal period like many antibiotics. The requirements of the health organization can also improve the feed intake and digestibility of livestock and poultry.
3.4 Reduce the nitrogen excretion rate and reduce the pollution of livestock and poultry excrement to the environment
Through experiments on the effects of different types of corn gluten meal dietary fiber and energy on nitrogen metabolism of growing pigs, the digestion and absorption, utilization and excretion of nitrogen by growing pigs were further explored, so as to study the low-pollution diet technology more effectively. The results showed that the nitrogen deposition, nitrogen digestibility and total nitrogen utilization rate of the corn gluten meal diet were positively correlated with the digestibility of neutral detergent fiber, acid detergent fiber and crude fiber in the diet; The ratio is linearly negatively correlated with the digestibility of neutral detergent fiber, acid detergent fiber, and crude fiber in the diet, and linearly positively correlated with the content of neutral detergent fiber or crude fiber. The content of neutral detergent fiber or crude fiber in the diet increases, the ratio of fecal nitrogen to dietary nitrogen increases, and the nitrogen excretion increases, which reduces the efficiency of total nitrogen use and is beneficial to environmental protection.
In a word, the protein content of corn gluten powder is high, and its degradation products—bioactive peptides are not only easy to digest and absorb for animals, but also have physiological functions such as anti-oxidation and improving immunity. In addition, corn gluten powder is rich in lutein, which has high feed value. However, the content of gliadin in corn gluten powder is high, and the digestive enzymes and microorganisms in the animal body are very limited in its digestion and utilization, and the expected ideal effect cannot be achieved. By adding exogenous protease preparations, the digestion and utilization rate of corn gluten meal by animals can be improved. Corn gluten meal has a wide source and will be widely used in the feed industry, especially its coloring effect, and its application prospects in poultry feed will be very broad.