1 Prevent fatty liver fish from "nutritional fatty liver" seriously affecting the growth, meat quality and disease resistance of fish; Fatty liver in chickens will lead to a decrease in laying rate and an increase in mortality. The physiological cause of fatty liver syndrome is mainly phospholipid deficiency, because phospholipids are very important for fat metabolism. Phospholipid molecules have emulsifying properties, and the unsaturated fatty acids contained in them can esterify cholesterol and regulate the transportation and deposition of fat and cholesterol in the blood. Animals synthesize phospholipids in the liver and can transport these fats to the outside of the liver by forming lipoproteins. Lipoprotein is a complex of phospholipids, cholesterol, triglycerides and apoprotein. Without enough phospholipids, lipoproteins cannot be formed, and the liver will be full of fat. Because the thin tissue of the liver wall is infiltrated by fat, other important chemical processes and synthesis can not be carried out smoothly, so other related functions of the body will also be affected. Therefore, adding a certain amount of phospholipids to the feed can make the synthesis of lipoprotein go smoothly, transport the fat in the liver and prevent the occurrence of fatty liver. Cao et al. (1997) studied grass carp. The results showed that the fatty lipid content of grass carp liver was greatly reduced by adding a certain amount of soybean phospholipids to the feed.
2 improve the composition of animal body fat. Adding appropriate amount of soybean phospholipids to feed can increase slaughter rate, reduce abdominal fat and improve meat quality. Because soybean phospholipids contain a certain amount of unsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the content of these unsaturated fatty acids in the body fat of animals fed with soybean phospholipids will increase accordingly, thus achieving the purpose of improving body fat. Shao Naiping (1996) fed rats with soybean phospholipids with high-fat feed. Results: The contents of cholesterol, triglyceride and very low density lipoprotein in serum of rats decreased significantly, which indicated that soybean phospholipids had the function of reducing blood lipid. The experiment of Cao et al. (1997) showed that the fatty acid composition of liver and pancreas changed after grass carp was fed with 5% phospholipid for 52 days, and the contents of EPA and DHA increased significantly, which indicated that soybean phospholipids could improve the body fat composition of grass carp. The experiment of Wang Ruojun et al. (1997) showed that soybean phospholipids can completely replace soybean oil in broiler diet, which can improve slaughter rate, reduce abdominal fat and improve meat quality.
3 improve growth efficiency and feed conversion rate
3. 1 Studies at home and abroad show that the emulsifying ability of piglets to fat is weak due to insufficient bile secretion within 14d after weaning. Adding phospholipids to piglet feed can improve the digestibility of crude protein and energy, reduce diarrhea caused by indigestion, promote metabolism, increase weight gain and feed conversion rate. Gunther( 1994) research showed that adding 0.2% defatted soybean phospholipids to weaned piglets' diets could increase the daily gain of piglets by 9.5% and reduce the feed-to-weight ratio by 7.5%. Adding 0.6% can increase the daily gain 17. 1% and decrease the feed-to-weight ratio 12%. Gan Yiling (2000) conducted experiments on weaned piglets with soybean phospholipids. The results showed that the daily gain of piglets added with soybean phospholipids increased by 6.8%, and the feed was saved by about 5.4%. Adding soybean phospholipids to the diet of growing pigs also has the same effect. The experiment of Li Li (1999) showed that adding 5% soybean phospholipids to the diet of growing pigs could increase their daily gain by 7%.
3.2 Cattle studies have confirmed that adding phospholipids can significantly improve the digestibility of non-dairy fat in artificial milk. Adding 40 ~ 50g/d soybean phospholipids to calf feed, the average daily gain of the experimental group in five months was 870~880g, which was 53% ~ 64% higher than that of the control group. At the same time, adding phospholipids and fat to the feed can solve the problems of metabolic disorder and growth retardation when calves are fed a synthetic diet of casein, lactose, minerals and vitamins.
3.3 Poultry research reports that adding phospholipids to broiler feed can improve the growth status of broilers, increase the storage of vitamin A in liver and promote bone growth. Geng Qinghui's experiment (1996) showed that adding 2% modified phospholipids to broiler diet could increase weight gain by 7% ~ 10% and feed reward by 5% ~ 8%. Feeding layers with feed containing 1.5% soybean phospholipids increased the laying rate by 9.9% and the feed reward by 9.2%. Chang Kaicheng (1998) completely replaced 3% of the oil in the diet of laying hens with concentrated soybean phospholipid, and the laying hens in the phosphatide group produced 7. L% eggs, protein consumption decreased by 7. 1%%.
3.4 In the rapid growth after hatching, aquatic animals and fish need rich phospholipids to form cell components. When the biosynthesis of phospholipids can not fully meet the needs of larvae, it is necessary to add phospholipids to the feed. In addition, phospholipids in feed can also promote the utilization of cholesterol by crustaceans and improve the growth and survival rate of crustaceans. Shrimp needs different amounts of phospholipids at different growth stages. Young shrimp need a lot of phospholipids because they can't synthesize enough phospholipids for growth and metabolism. Abramo et al. (198 1) proved that lobsters need lecithin to survive in the process of shelling. Japanese scientists pointed out that 0.5% ~ L% phospholipids in feed are necessary for the growth and survival of young shrimp. The experiment of Xue Yongrui et al. (1989) showed that adding 2% modified soybean phospholipids to carp feed could increase the yield by 30.7%, reduce the feed coefficient by 0.2 1 and reduce the feed cost by 9.63%. Boston (1990) added 4% or 8% soybean phospholipids to the feed, which obviously reduced the feed coefficient of Atlantic salmon. Kanagana et al. (1985) reported that adding 1% soybean phospholipids to shrimp feed can improve the growth rate and survival rate of shrimp.
Quality standard and suitable addition amount of soybean phospholipids
The quality standards of phospholipids as feed additives are generally: water content < 22%, acetone insoluble matter > 45%, ether insoluble matter < 4%, acid value < 5.5. In practical application, soybean phospholipids should be determined according to the amount of phospholipids originally contained in feed, the size of animals, the content of fat and saturated fatty acids in feed, the cost of feed and the type and concentration of phospholipids. Generally speaking, the appropriate addition amount of compound feed for freshwater fish, pig, shrimp and broiler is 5%, 2% and 5.5% respectively.