Role in aquatic feed processing
Soybean phospholipids have excellent physiological activity and surfactant effects, and are a natural and efficient nutritional additive. The addition of soybean phospholipids to the feed can play an emulsifying, wetting, dispersing and surfactant role, providing nutrients such as choleamine, phosphorus, inositol, choline and fatty acids, improving feed energy and nutritional value, improving feed conversion rate, reducing feed coefficient, improving palatability, having a lure effect; helping animals digest and absorb fats and fat-soluble vitamins; protecting unsaturated acids in feed; promoting animal growth and development, improving the survival rate of young animals, improving aquatic animal production performance; preventing fatty liver and enhancing disease resistance Improve the physical quality and yield of granulation; reduce feed loss and energy consumption during extrusion molding; prevent dust flying and feed grading; reduce the dissolution loss of water-soluble nutrients in aquatic feed; improve drift and sedimentation in aquatic feed, reduce feed waste and water pollution; provide unknown growth factors.
1. Binder
Phospholipids are added to compound feeds and premixes to play a role in adhesion, reduce dust flying and automatic grading during feed processing, and maintain the uniformity of feed mixing.
2. Emulsification stabilizer
The phospholipid molecule has two groups, hydrophilic and lipophilic, so it is a good fat emulsifier. Phospholipids can inhibit the loss of fat in the bait, increase the absorption of fat by animals, promote growth, and improve the conversion rate of bait. For juvenile shrimp, it can compensate for the reduced fat digestion capacity caused by lack of bile, prevent the high mortality rate of juvenile shrimp, and improve the survival rate.
3. Suspension
Phospholipids not only emulsify fat in water but also have an effect on water-insoluble components. Phospholipids prevent sedimentation of insoluble components suspended in an emulsion. Usually the pelleted feed will expand in the water, and will often disperse and drift and settle to the bottom, which will cause waste of feed and water quality pollution. The use of a special phospholipid product suitable for fish and crustaceans can improve the wear resistance of pellet feed, enhance the cohesion of feed in the water after expansion, thereby improving this drifting and settling condition, which is conducive to the suspension of feed in water and convenient for fish and shrimp to eat.
4. Lubricity
Phospholipids have good lubricity, which can reduce the loss of feed during extrusion molding, reduce feed wear on equipment, and improve granulation yield and particle quality. At the same time, it also reduces the energy consumption in the granulation process and minimizes the increase in product temperature, so the particles can be cooled down quickly, and the risk of mildew is reduced, which is especially important for bagged products.
5. Liposome embedding agent
Using the properties of phospholipid bilayer film, liposomes can be made to embed various water-soluble and fat-soluble substances. Therefore, processors currently use this property of phospholipids to bury feed into particulate feeds for feeding fry, crustaceans and shellfish larvae during the opening period. The liposome-embedded feed particles can be suspended in water and maintain their stability, and are easily swallowed by seedlings such as fish and shrimp, and the nutrients in the feed are easily digested and absorbed.
Applications in aquatic feeds
1. Promote growth and improve survival rate
A large number of studies have shown that phospholipids can effectively promote the growth of juvenile fish and improve their survival rate. Researchers at the Belgian University conducted 10 experiments on the feeding of phospholipid compounds with carp, sea bass and turbot as experimental fish, and found that phospholipids have a growth-promoting effect on juveniles, and found that carp juveniles fed without phospholipids had decreased growth and high mortality. Phosphatidylcholine and phosphatidyl inositol have a significant effect on improving the growth and survival rate of carp that start feeding, but the addition of choline or inositol to the microfeed did not produce a significant effect, and it was found that choline and inositol could not replace phosphatidylcholine and phosphatidylositol; and phosphatidylcholine may have the effect of preventing choline deficiency. Compared with foreign countries, China's research on the application of phospholipids in aquatic products started late, and the feed formula contains 2% soybean modified phospholipids, which makes the feed particularly good and the growth rate of fish is fast. Different levels of phospholipids are added to the feed, and as the level of phospholipids in the feed increases, the growth performance tends to increase. The addition of soybean phospholipids to the feed of juvenile fish can play a good role in promoting the growth of juvenile fish and improving its survival rate, especially for some precious fish species, which can reduce the economic risk of their breeding. However, depending on the type of fish, attention should be paid to the change in the amount added. Phospholipids in feed can promote the use of cholesterol in crustaceans and improve the growth and survival rate of crustaceans. The addition of phospholipids to feed (such as soy phospholipids) can promote the metabolism of cholesterol in shrimp, especially from the liver and pancreas to the lymphatic gland. The addition of soybean phospholipids to shrimp feed can promote growth, improve feed efficiency and survival rate, and also promote the digestion of protein in the feed and improve utilization. According to the national university of Singapore, the addition of 1% degreased phospholipids to the diet of female crabs can significantly improve the hatching rate of crab eggs and the survival rate of young crabs, and the addition of sufficient amount of lecithin to the early diet of artificially bred hairy crabs plays a key role in smooth dehulling.
2. Improve body fat composition
Adding an appropriate amount of soy phospholipids to the feed can increase slaughter rates, reduce belly fat and improve meat quality. Since soybean phospholipids contain a certain amount of unsaturated fatty acids, such as 20 carbontaenoic acid (epa) and 2carbohexaenoic acid (dha), the content of these unsaturated fatty acids in the body fat of fish will increase accordingly. When soybean phospholipids with a mass score of 5% were added to the feed and fed for 52 days, the epa and dha content of grass carp was significantly increased. Similar effects are also found in the composition of body fats in other fish such as carp, true seabream, and high-headed sturgeon, indicating that soybean phospholipids have a promoting effect on improving the quality of aquatic products. With the increase in the level of feed phospholipids, the total fat and neutral fat content in the loach fish body are increased, and the ratio of 20:5n-3 and full n-3 fatty acid content in neutral fat is reduced, and the polar fat content in the whole fish body is reduced, and the ratio of almost all n-3 fatty acids in polar fat is reduced. Adding soybean phospholipids to the feed can improve body fat, reduce crude fat content, and correspondingly improve the nutritional value of fish and improve the taste of food.
3. Prevent fatty liver
Fish trophic fatty liver disease seriously affects its own growth, reducing meat quality and disease resistance. The physiological cause of fatty liver syndrome is mainly the lack of phospholipids, because phospholipids are very important for fat metabolism, phospholipid molecules have emulsifying properties, and the unsaturated fatty acids contained in them can ester cholesterol, regulate the transport and deposition of fat and cholesterol in the blood. Animals synthesize phospholipids in the liver and can continuously transport these fats outside the liver by forming lipoproteins. Lipoproteins are complexes of phospholipids, cholesterol, and triglycerides, and without adequate phospholipids, lipoproteins cannot be formed and the liver is filled with fat. If the thin tissue of the liver wall is infiltrated by fat, other important chemical processes and synthesis cannot proceed smoothly, so that other related functions of the body will be affected. Therefore, a certain amount of phospholipids is supplemented in the feed, so that the synthesis of lipoproteins can proceed smoothly, and the fat in the liver can be transported out to prevent the occurrence of fatty liver. Feeding soybean phospholipid feed can increase the fat transport capacity of apolipoproteins and reduce fat deposition, thereby preventing fatty liver and protecting the liver. Lecithin can improve the absorption of lipids by juvenile fish through its emulsifying properties, making up for the lack of bile secretion; researchers believe that phospholipids can promote the digestion and absorption of lipids. With the increase of soybean phospholipid levels in the feed, serum triglycerides and serum total cholesterol showed a significant downward trend. Therefore, from the comprehensive consideration of improving the health level of fish, it is of certain practical significance to add certain phospholipids to the feed in the juvenile fish and the rapid growth stage.
4. Reduce the incidence of fish deformities
Japan Kanazawa et al. reported that in the fry culture of real seabream, stone seabream, flounder, ayu and other fry feeding special rotifers and other biological feed, the result of deformity and choking death and other phenomena, especially ayu after eating this feed deformity rate (especially body bending) as high as 18% to 80%. The addition of egg yolk phospholipids or soybean phospholipids to rotifer biological bait can reduce the incidence of lateral bending of the body of ayu to 0 to 5%. The Belgian Fisheries Research Institute fed Japanese shrimp larvae phospholipidcholine-added particulate feeds with a feed variability rate of 76% at a mass fraction of 3%, significantly higher than that of juvenile shrimp fed commercially available (41%) and juvenile shrimp in the control group (48%). Soybean phospholipid feed can reduce the incidence of deformity in aquatic animals and is very necessary for the production of seedlings.
5. Anti-stress effect
Feeding soybean phospholipids improves the tolerance of young seabream and striped fish to water temperature, salinity, low dissolved oxygen and exposure to air, and improves the survival rate of seedlings. At the water temperature of 20 °C, striped perch, white bass and hybrid perch were fed natural bait (containing epa and dha) and blended bait (without phospholipids) to compare their cold tolerance; after the water temperature was reduced by 10 °C, the mortality rate of the feeding bait group was 50% to 90%, and the fish fed with natural bait were not found to die, which was due to the fact that the content of unsaturated fatty acids in natural bait was 13% higher than that of the blended bait, indicating that the high content of unsaturated fatty acids in the natural bait could improve the cold tolerance of the fish. The use of phospholipids as an opening bait for turbot found that it did not affect the salt resistance of turbot. When turbot is 20 days after growth, completely replacing brine worms with phospholipid bait can lead to serious anti-stress problems. The Belgian Aquaculture Research Institute found that Japanese shrimp grew well and were resistant to stress by feeding a feed containing 1.5% mass fraction of phospholipid choline; the effect of adding 6.5% mass score to the feed was similar. The addition of soybean phospholipids to feed can enhance the environmental adaptability of aquatic animals and reduce mortality.
6. Improve feed conversion rate and reduce feed coefficient and cost
Tuantou bream fed on 7% rapeseed oil phospholipid feed has the greatest fullness, while visceral fat accounts for the smallest proportion of body weight, and its health is also the best found by the color of the liver. Adding 2% modified soybean phospholipids to the carp bait increased yield by 30.7% compared with the control group, reduced the bait coefficient by 0.21%, and reduced the feed cost by 9.63%. The addition of improved soybean phospholipids with a mass score of 2% to the Nile tilapia bait increased the weight gain rate by 43% compared with the control group, increased the protein efficiency by 31.3%, increased the daily weight gain by 66.1%, and reduced the feed coefficient by 31.4%, and the breeding effect was very obvious. Adding soybean phospholipids to the feed can effectively improve the feed conversion rate, reduce the feed coefficient and cost, increase economic benefits, and comprehensively play a multiplier breeding effect.
7. Other functions
The addition of soy phospholipids to the feed can partially replace fat, but whether it can be completely replaced remains to be studied. Some phospholipids may be involved in the osmotic pressure regulation of migratory fish, eels in the process of water environment conversion, with the decline of salinity, the pe of the gills can be maintained to the greatest extent, and can quickly recover after the environmental salinity is stable. This suggests that eels may rely on pe to complete osmotic mediation activities. Different levels of soybean phospholipids were added to the feed, so that the superoxide dismutase activity in the loach fish increased with the increase of phospholipid levels in the feed; on the contrary, the tendency of catalase decreased.