After the feed is expanded, it forms a "popcorn" state, which not only changes greatly in appearance, but also changes in the molecular structure of the internal organic matter. Puffing makes the starch in feed easier to digest and protein easier to use. Compared with ordinary complete pellet feed, expanded feed has many advantages. On the one hand, gelatinization degrades the starch in feed, which can also denature protein in feed, reduce anti-nutritional factors and increase palatability. But at the same time, it also destroys the vitamins contained in the feed, produces indigestible substances, and increases the cost and other unfavorable factors.
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? First, the advantages of expanded feed
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? 1, improving palatability
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? After puffing, the feed raw materials are rich in unique fragrance and fluffy taste, with high gelatinization and good palatability, which greatly increases the appetite of animals and has obvious food attraction effect.
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? 2. Improve the digestibility
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? After the feed is expanded, the long-chain structure of some organic substances such as protein and fat changes into short-chain structure, which increases the animal's absorption rate of feed.
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? 3. Improve feed quality
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? ① protein is fully combined with starch matrix in the process of feed expansion, which has high absorption rate and is not easy to lose. Only when the digestive enzymes in animals decompose starch can protein be released and the titer of protein be improved.
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? (2) protein degeneration, inactivation of many anti-nutritional factors, changes in the tertiary structure of protein, and shortened hydrolysis time of protein in intestine.
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? (3) Extrusion will produce rumen bypass protein, a non-degradable protein for ruminants, thus avoiding ammonia poisoning and improving the utilization rate of protein.
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? (4) Puffing can release the wrapped oil in raw material molecules, improve the thermal energy value of the oil, form a composite product lipoprotein or lipopolysaccharide with fat and starch or protein, reduce the content of free fatty acid, inactivate lipase, inhibit the degradation of oil, and reduce the rancidity and rancidity of oil components during the storage and transportation of products.
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? 4. Reduce the content of bacteria, molds and fungi in raw materials.
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? Improve the hygienic quality of feed, provide aseptic and cooked feed for animals, reduce the risk of diseases of animals, reduce the addition of various pharmaceutical ingredients, and pave the way for the popularization of antibiotic-free culture; Improve the gelatinization degree of starch and produce modified starch, which has strong water absorption and adhesion. Because the puffed feed is porous and has strong water absorption, more liquid components (such as oil and molasses, etc.) can be added. At the same time, the expanded feed has a much stronger adhesive function than ordinary starch, which greatly reduces the amount of starch added in the expanded production process. This provides more space for the addition of other raw materials, and cheaper raw materials can be selected to replace those expensive raw materials in the formula, which greatly improves the titer of low-quality raw materials and reduces the comprehensive cost of feed, thus not affecting the final feed product quality.
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? 5, improve fiber solubility
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? Extrusion technology can greatly reduce the crude fiber content in feed. The high temperature and high pressure in the extrusion process make the lignin in the cell stroma and cell wall melt until the pressure relief port expands instantly, which breaks some hydrogen bonds and decomposes high molecular substances into low molecular substances. The original compact structure becomes fluffy, and some digestible substances are released, which greatly improves the utilization rate of feed.
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? 6. It is beneficial to feed storage and prolongs the shelf life of feed.
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? Under the action of high temperature, high pressure and puffing, the feed can kill molds, bacteria and fungi in raw materials, improve the hygiene grade of the feed, and effectively reduce the occurrence of animal diarrhea, gastroenteritis, dysentery and other diseases.
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? Taiwan Province.
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? Second, the shortcomings of puffed feed
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? 1, vitamin loss
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? Temperature, pressure, friction and moisture can all lead to vitamin loss. The experiment showed that VA, VD and folic acid lost 1 1% respectively in the process of feed expansion. The losses of ammonium sulfate and ammonium sulfate hydrochloride are 1 1% respectively. The loss rates of ammonium mononitrate and ammonium sulfate hydrochloride are 1 1% and 17% respectively. VK and VC each lost 50%. Compared with processing hard pellet feed, the loss is halved.
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? Under the condition of no natural food at all, a few people feed carp with puffed food, which is estimated to be related to the destruction of heat-sensitive vitamins during feed processing.
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? Puffed feed: How to quantify common aquatic feed? Reduce feed waste and effectively reduce feed cost.
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? 2. Loss of enzyme preparation
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? The optimum temperature of the enzyme is 35-40℃, and the highest temperature cannot exceed 50℃. In the process of puffing and granulating, the temperature can reach 120- 150℃, accompanied by high pressure (changing the spatial multi-dimensional structure and denaturation of enzyme protein) and high humidity (causing high water activity in feed), so most enzyme activities will be lost.
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? It is reported that the survival rate of glucanase in feed after granulation at 70℃ without treatment is only 10%. After treatment at 75℃ for 30 seconds, the survival rate of the treated glucanase was 64%, while the survival rate after granulation at 90℃ was only 65,438 09%, and the phytase activity decreased by more than 50% after granulation at 70-90℃.
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? 3. Loss of microbial agents
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? Bacillus, lactobacillus, streptococcus, yeast, etc. Widely used in feed, very sensitive to temperature. When the puffing granulation temperature exceeds 85℃, their activity will be completely lost.
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? 4. protein and the loss of amino acids.
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? The high temperature in the puffing process caused Maillard reaction between some reducing sugars and free amino acids, which reduced the utilization rate of some protein.
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? In addition, under alkaline conditions, protein can form lysine alanine at high temperature. Under the conditions of overheating and high PH value, some amino acids racemize to form D-type amino acids, which greatly reduces the digestibility of protein.
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? Lysine, arginine and histidine are the most easily heated. In vitro, the enzymatic hydrolysis kinetics of grass carp and Lolita in the intestine of allogynogenetic crucian carp before and after puffing was determined. It is proved that puffing affects the enzymatic hydrolysis speed of feed raw materials, and the enzymatic hydrolysis speed of rapeseed meal, corn and secondary powder is improved after puffing. After puffing, the enzymatic hydrolysis speed of soybean meal, meat and bone meal and fish meal decreased, especially corn. The enzymatic hydrolysis rate of cotton meal before and after puffing has no obvious change.
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? Extrusion can play a positive role in feed raw materials with low protein content and high starch content, but it has a negative effect on feed raw materials with high protein content.
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? Third, the application of puffed feed
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? 1, raising pigs
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? The suckling pig has a small stomach and weak intestinal digestion and absorption ability, so it is easy to have nutritional diarrhea in the process of changing from breast milk to feed. The gelatinization and sterilization of feed is not ideal, which is easy to cause stress reaction in digestive tract of piglets and cause diarrhea and dysentery.
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? Feeding weaned piglets with puffed feed can greatly reduce diarrhea, thus reducing feeding cost, shortening fattening cycle and improving economic benefits.
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? Step 2 keep birds
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? The puffed feed is granular, which is beneficial for chickens and ducks to eat, improves the wear speed of feed in crops, accelerates the digestion and absorption of feed, and improves the absorption and utilization rate of feed. Because puffed feed kills a large number of pathogenic bacteria, it greatly reduces diseases such as diarrhea of poultry.
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? 3. Ruminants
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? Due to the degradation of fiber and the increase of soluble fiber after feed puffing, the digestion and utilization rate of feed for ruminants is greatly improved. It also improves the utilization rate of non-protein nitrogen by ruminants and increases the amount of rumen protein, thus reducing the feeding cost.
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? Expanded feed has a good effect on fattening beef cattle and can also improve the milk fat rate of dairy cows.