Pseudosciaena crocea feed additive with immunological enhancement effect as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of fish feed, and particularly relates to a larimichthys crocea feed additive with an immunological enhancement effect and a preparation method and application thereof.The feed additive comprises catechu selenium polysaccharide, lily polysaccharide and white mulberry root-bark polysaccharide, and the three components can improve the immunological enhancement effect and the oxidation resistance through multiple ways; in addition, the raw materials can play respective effects and promote each other, so that the anti-stress ability, appetite and even amplification of intestinal flora of the large yellow croaker are greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fish feed, and in particular relates to a large yellow croaker feed additive with immune enhancement effect and a preparation method and application thereof. Background Art

[0002] Large yellow croaker (Larimichthyscrocea), class of bony fishes, order of Perciformes, family of Sciaenidae, genus of yellow croaker, is one of China's traditional "four major marine products" and is mainly distributed in coastal waters of Zhejiang, Fujian, Guangdong and other places. It has high nutritional value and delicious meat, and is deeply favored by consumers. It is one of the main economic fish species in my country's coastal waters.

[0003] At present, large yellow croaker is mainly cultured in seawater cages. Sorting, net changing, fishing and other operations during the breeding process are very likely to cause large yellow croaker to be in a state of stress. In addition, the stress response of farmed large yellow croaker is further aggravated by the increase in water temperature and typhoon invasions in summer, resulting in a series of adverse effects in the breeding process, such as low feed utilization rate, frequent diseases, slow growth, and increased mortality, which seriously affect the development of the large yellow croaker breeding industry.

[0004] At present, it is reported that catechin selenium polysaccharides, lily polysaccharides and mulberry bark polysaccharides can enhance the immune function of fish, but due to their high prices and the large amount of addition required for a single component to have the expected effect, the cost-effectiveness of adding this functional component to feed is not high. In view of the problems existing in the relevant background technology, it is necessary to develop a feed additive that can enhance the immune function of large yellow croaker to alleviate or even eliminate the stress hazards during the breeding process and ensure the survival rate and quality of farmed large yellow croaker. Summary of the invention

[0005] In view of the series of adverse reactions mentioned in the above background technology, such as low feed utilization rate, frequent diseases, slow growth, high mortality rate, etc., caused by high water temperature and typhoon in summer in farmed large yellow croaker, and the high cost caused by the large addition amount of a single component, the present invention provides a large yellow croaker feed additive with immune enhancement effect, and a preparation method and application thereof. The three components of catechu selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide are compounded in a specific proportion to produce a synergistic effect, thereby improving the immune ability and anti-stress ability of the large yellow croaker, improving feed utilization rate, promoting the healthy growth of the large yellow croaker, and ensuring stable production.

[0006] In view of the above purpose, the present invention provides a technical solution: A large yellow croaker feed additive with immune enhancement effect comprises catechu selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide, wherein the addition amount of catechu selenium polysaccharide is 20-30wt%, the addition amount of lily polysaccharide is 40-50wt%, and further, the addition amount of mulberry bark polysaccharide is 30-40wt%.

[0007] The present invention provides a large yellow croaker feed additive with an immune-enhancing effect. The additive is compounded with catechu selenium polysaccharide, lily polysaccharide, and mulberry bark polysaccharide. The three components can produce excellent synergistic effects after being compounded in a specific ratio, thereby improving the immune ability and anti-stress ability of the large yellow croaker, improving feed utilization, promoting the healthy growth of the large yellow croaker, and ensuring stable production. Among them, catechu selenium polysaccharide is a new type of bioactive substance that combines catechins and selenizers and is formed through a polysaccharide carrier. It can simultaneously exert the antioxidant effect of catechu polysaccharides and the immune-enhancing effect of organic selenium; lily polysaccharide is extracted from lily, is rich in lily bulbs, and is one of the main active ingredients of lily. It is mainly composed of D-glucose, D-mannose and galactose bonded by β-pyranosidic bonds, and releases the active hydrogen on its hydroxyl group to capture free radicals, thereby blocking the chain reaction of free radicals, so it can play a good antioxidant role and hormone regulation. It can not only regulate the secretion of proteins, but also enhance the vitality of immune cells, play an immunomodulatory and anti-inflammatory role. Morus alba polysaccharide is an active substance extracted from the roots of mulberry trees. It has the function of clearing lipid peroxides in the body, improving the abnormal peroxidation state in fish, and alleviating its peroxidation damage to the body. It can also significantly promote lymphocyte proliferation, improve the cellular immune function of fish, and reduce myocardial damage in fish in chronic hypoxic environments. At the same time, it effectively inhibits inflammatory factors such as interleukin-1B, tumor necrosis factor-α, and interleukin-6, thereby playing an anti-inflammatory role.

[0008] At the same time, the present invention team found that catechu selenium polysaccharide, lily polysaccharide, and mulberry bark polysaccharide can not only enhance the immune enhancement effect through multiple pathways, but also promote each other while exerting their respective effects. Among them, catechu selenium polysaccharide and lily polysaccharide can not only enhance the body's anti-hypoxia and anti-inflammatory abilities, but also cooperate with each other to significantly promote the appetite function of fish, improve feed utilization, and enhance fish immunity. In addition to enhancing the cellular immune function and anti-inflammatory ability of fish, lily polysaccharide and mulberry bark polysaccharide can also improve the abundance of fish intestinal flora, inhibit the growth of pathogens, increase the biodiversity of intestinal flora, and improve the gastrointestinal immunity of fish. In addition, the three components of catechu selenium polysaccharide, lily polysaccharide, and mulberry bark polysaccharide cooperate with each other to improve the activity of digestive enzymes and antioxidant enzymes in the stomach, hepatopancreas, and intestines of fish, improve the digestive ability of fish, and improve the anti-stress ability. The three components are compounded so that the additive can achieve a good immune enhancement effect with a small amount of addition, reduce costs, and increase production.

[0009] Furthermore, the addition amount of catechu selenium polysaccharide is 25-30wt%, the addition amount of lily polysaccharide is 40-45wt%, and the addition amount of mulberry bark polysaccharide is 30-35wt%.

[0010] Preferably, the added amount of catechu selenium polysaccharide is 25wt%, the added amount of lily polysaccharide is 40wt%, and the added amount of mulberry bark polysaccharide is 35wt%.

[0011] Furthermore, the preparation method is: a) mixing catechu selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide uniformly to obtain a crude product; b) The crude product in step a) is sieved, dissolved and then spray-dried to obtain a large yellow croaker feed additive with an immune enhancement effect.

[0012] Furthermore, in step a), after the crude product is sieved, 25 to 35 wt % of water is added to dissolve it.

[0013] Preferably, an 80-mesh sieve is used for sieving.

[0014] Preferably, 30 wt % of water is added to fully dissolve.

[0015] Furthermore, in step b), the spray drying is centrifugal spray drying.

[0016] Further, the parameters of the centrifugal spray dryer are: The inlet air temperature is 170-190℃; Feed rate is 35-45 mL / min; The compressed air pressure is 0.8~1.2MPa; The speed of the nozzle atomizer is 1500~3000r / min; The air outlet temperature is 70~85℃.

[0017] Preferably, a centrifugal spray dryer is selected with an inlet air temperature of 180°C, a feed rate of 30 mL / min, a compressed air pressure of 1 MPa, a nozzle atomizer speed of 2000 r / min, and an outlet air temperature of 80°C.

[0018] Furthermore, a large yellow croaker feed additive with immune enhancement effect is used in large yellow croaker feed.

[0019] Furthermore, the addition amount of a large yellow croaker feed additive with an immune enhancement effect in large yellow croaker feed is 0.1 to 0.15 wt%.

[0020] The present invention has the following technical effects:

[0021] 1. As a new type of bioactive substance, catechin selenium polysaccharide has both antioxidant effect and immune enhancement effect of organic selenium, which can enhance the physique of yellow croaker and improve feed utilization and survival rate.

[0022] 2. Lily polysaccharides release active hydrogen on their hydroxyl groups and capture free radicals, thereby blocking the chain reaction of free radicals, playing an antioxidant and hormone regulating role. It can also enhance the vitality of immune cells and play an anti-inflammatory role.

[0023] 3. Mulberry bark polysaccharide can improve the abnormal peroxidation state in fish, alleviate the peroxidation damage to the body, and can also significantly promote lymphocyte proliferation, improve the cellular immune function of fish, and reduce myocardial damage in fish in chronic hypoxic environment. At the same time, it can effectively inhibit inflammatory factors such as interleukin-1B, tumor necrosis factor-α, and interleukin-6, and play a good anti-inflammatory role.

[0024] 4. The combination of three ingredients, catechin selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide, can enhance the immune-enhancing effect through multiple pathways. While exerting their respective effects, they can also promote each other, thereby improving the immunity and anti-stress ability of large yellow croaker. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific embodiments.

[0026] In all the embodiments and comparative examples involved in the present invention, in the cage culture experiment, the initial average weight of the large yellow croaker selected was 200±2.0g, and the large yellow croakers in each group were randomly allocated. Three groups of repeated experiments were set for each embodiment or comparative example, and the culture was continuously carried out for 5 months to finally obtain data.

[0027] Example 1

[0028] (1) Preparation of additives 25 parts of catechu selenium polysaccharide, 40 parts of lily polysaccharide and 35 parts of mulberry bark polysaccharide are taken by weight, mixed evenly, fully dissolved in 30wt% water, and then centrifugal spray-dried to obtain a large yellow croaker feed additive with immune enhancement effect.

[0029] Specifically, the specific parameters of centrifugal spray drying are: inlet air temperature of 180°C, feed rate of 30mL / min, compressed air pressure of 1MPa, nozzle atomizer speed of 2000r / min, and outlet air temperature of 80°C.

[0030] (2) Preparation of feed The large yellow croaker feed additive with immune enhancement effect prepared in step (1) is added to the large yellow croaker feed, and the added amount is 0.12wt%.

[0031] (3) Cage culture experiment The large yellow croaker was fed with the feed prepared in step (2) twice a day, in the morning (8:00) and evening (16:00), until the large yellow croaker was in a state of satiation. The feeding was continued for five months, and the survival status, body weight and feed utilization rate of the large yellow croaker were recorded.

[0032] (4) Index detection Five months later, samples of surviving large yellow croaker were collected and their serum lysozyme and serum SOD were tested.

[0033] Comparative Example 1

[0034] The difference between this comparative example and Example 1 is that the large yellow croaker feed additive in this comparative example is starch, and the rest of the process is the same as that of the example, and the specific steps are as follows: (1) Preparation of additives 100 portions of starch are taken by weight, mixed evenly, fully dissolved in 30wt% water, and then centrifugal spray drying is performed to obtain a large yellow croaker feed additive with an immune enhancement effect.

[0035] Specifically, the specific parameters of centrifugal spray drying are: inlet air temperature of 180°C, feed rate of 30mL / min, compressed air pressure of 1MPa, nozzle atomizer speed of 2000r / min, and outlet air temperature of 80°C.

[0036] (2) Preparation of feed The large yellow croaker feed additive with immune enhancement effect prepared in step (1) is added to the large yellow croaker feed, and the added amount is 0.12wt%.

[0037] (3) Cage culture experiment The large yellow croaker was fed with the feed prepared in step (2) twice a day, in the morning (8:00) and evening (16:00), until the large yellow croaker was in a state of satiation. The feeding was continued for five months, and the survival status, body weight and feed utilization rate of the large yellow croaker were recorded.

[0038] (4) Index detection Five months later, samples of surviving large yellow croaker were collected and their serum lysozyme and serum SOD were tested.

[0039] Comparative Example 2

[0040] The difference between this comparative example and Example 1 is that in this comparative example, 25 parts of catechin selenium polysaccharides in the original example are replaced with 25 parts of starch, and the rest of the process is the same as that in the example, and the specific steps are as follows: (1) Preparation of additives 25 parts of starch, 40 parts of lily polysaccharide and 35 parts of mulberry bark polysaccharide are taken by weight, mixed evenly, fully dissolved in 30wt% water, and then centrifugal spray-dried to obtain a large yellow croaker feed additive with immune enhancement effect.

[0041] Specifically, the specific parameters of centrifugal spray drying are: inlet air temperature of 180°C, feed rate of 30mL / min, compressed air pressure of 1MPa, nozzle atomizer speed of 2000r / min, and outlet air temperature of 80°C.

[0042] (2) Preparation of feed The large yellow croaker feed additive with immune enhancement effect prepared in step (1) is added to the large yellow croaker feed, and the added amount is 0.12wt%.

[0043] (3) Cage culture experiment The large yellow croaker was fed with the feed prepared in step (2) twice a day, in the morning (8:00) and evening (16:00), until the large yellow croaker was in a state of satiation. The feeding was continued for five months, and the survival status, body weight and feed utilization rate of the large yellow croaker were recorded.

[0044] (4) Index detection Five months later, samples of surviving large yellow croaker were collected and their serum lysozyme and serum SOD were tested.

[0045] Comparative Example 3

[0046] The difference between this comparative example and Example 1 is that in this comparative example, 40 parts by weight of lily polysaccharide in the original Example 1 are replaced by 40 parts of starch, and the rest of the process is the same as that of the example, and the specific steps are as follows: (1) Preparation of additives 25 parts of catechu selenium polysaccharide, 40 parts of starch and 35 parts of mulberry bark polysaccharide are taken by weight, mixed evenly, fully dissolved in 30wt% water, and then centrifugal spray-dried to obtain a large yellow croaker feed additive with immune enhancement effect.

[0047] Specifically, the specific parameters of centrifugal spray drying are: inlet air temperature of 180°C, feed rate of 30mL / min, compressed air pressure of 1MPa, nozzle atomizer speed of 2000r / min, and outlet air temperature of 80°C.

[0048] (2) Preparation of feed The large yellow croaker feed additive with immune enhancement effect prepared in step (1) is added to the large yellow croaker feed, and the added amount is 0.12wt%.

[0049] (3) Cage culture experiment The large yellow croaker was fed with the feed prepared in step (2) twice a day, in the morning (8:00) and evening (16:00), until the large yellow croaker was in a state of satiation. The feeding was continued for five months, and the survival status, body weight and feed utilization rate of the large yellow croaker were recorded.

[0050] (4) Index detection Five months later, samples of surviving large yellow croaker were collected and their serum lysozyme and serum SOD were tested.

[0051] Comparative Example 4

[0052] The difference between this comparative example and Example 1 is that in this comparative example, 35 parts of Morus alba polysaccharide by weight in the original Example 1 are replaced with 35 parts of starch, and the rest of the process is the same as that of the example, and the specific steps are as follows: (1) Preparation of additives 25 parts of catechu selenium polysaccharide, 40 parts of lily polysaccharide and 35 parts of starch are taken by weight, mixed evenly, fully dissolved in 30wt% water, and then centrifugal spray-dried to obtain a large yellow croaker feed additive with immune enhancement effect.

[0053] Specifically, the specific parameters of centrifugal spray drying are: inlet air temperature of 180°C, feed rate of 30mL / min, compressed air pressure of 1MPa, nozzle atomizer speed of 2000r / min, and outlet air temperature of 80°C.

[0054] (2) Preparation of feed The large yellow croaker feed additive with immune enhancement effect prepared in step (1) is added to the large yellow croaker feed, and the added amount is 0.12wt%.

[0055] (3) Cage culture experiment The large yellow croaker was fed with the feed prepared in step (2) twice a day, in the morning (8:00) and evening (16:00), until the large yellow croaker was in a state of satiation. The feeding was continued for five months, and the survival status, body weight and feed utilization rate of the large yellow croaker were recorded.

[0056] (4) Index detection Five months later, samples of surviving large yellow croaker were collected and their serum lysozyme and serum SOD were tested.

[0057] Comparative Example 5

[0058] The difference between this comparative example and Example 1 is that in this comparative example, 25 parts of catechu selenium polysaccharide and 40 parts of lily polysaccharide by weight in the original Example 1 are replaced with 65 parts of starch, and the rest of the process is the same as that of the example, and the specific steps are as follows: (1) Preparation of additives 65 parts of starch and 35 parts of mulberry bark polysaccharide are taken by weight, mixed evenly, fully dissolved in 30wt% water, and then centrifugal spray-dried to obtain a large yellow croaker feed additive with immune enhancement effect.

[0059] Specifically, the specific parameters of centrifugal spray drying are: inlet air temperature of 180°C, feed rate of 30mL / min, compressed air pressure of 1MPa, nozzle atomizer speed of 2000r / min, and outlet air temperature of 80°C.

[0060] (2) Preparation of feed The large yellow croaker feed additive with immune enhancement effect prepared in step (1) is added to the large yellow croaker feed, and the added amount is 0.12wt%.

[0061] (3) Cage culture experiment The large yellow croaker was fed with the feed prepared in step (2) twice a day, in the morning (8:00) and evening (16:00), until the large yellow croaker was in a state of satiation. The feeding was continued for five months, and the survival status, body weight and feed utilization rate of the large yellow croaker were recorded.

[0062] (4) Index detection Five months later, samples of surviving large yellow croaker were collected and their serum lysozyme and serum SOD were tested.

[0063] Comparative Example 6

[0064] The difference between this comparative example and Example 1 is that in this comparative example, 40 parts of lily polysaccharide and 35 parts of mulberry bark polysaccharide by weight in the original Example 1 are replaced with 75 parts of starch, and the rest of the process is the same as that of the example, and the specific steps are as follows: (1) Preparation of additives 25 parts of catechu selenium polysaccharide and 75 parts of starch are taken by weight, mixed evenly, fully dissolved in 30wt% water, and then centrifugal spray-dried to obtain a large yellow croaker feed additive with immune enhancement effect.

[0065] Specifically, the specific parameters of centrifugal spray drying are: inlet air temperature of 180°C, feed rate of 30mL / min, compressed air pressure of 1MPa, nozzle atomizer speed of 2000r / min, and outlet air temperature of 80°C.

[0066] (2) Preparation of feed The large yellow croaker feed additive with immune enhancement effect prepared in step (1) is added to the large yellow croaker feed, and the added amount is 0.12wt%.

[0067] (3) Cage culture experiment The large yellow croaker was fed with the feed prepared in step (2) twice a day, in the morning (8:00) and evening (16:00), until the large yellow croaker was in a state of satiation. The feeding was continued for five months, and the survival status, body weight and feed utilization rate of the large yellow croaker were recorded.

[0068] (4) Index detection Five months later, samples of surviving large yellow croaker were collected and their serum lysozyme and serum SOD were tested.

[0069] Comparative Example 7

[0070] The difference between this comparative example and Example 1 is that in this comparative example, 25 parts of catechu selenium polysaccharide and 35 parts of mulberry bark polysaccharide by weight in the original Example 1 are replaced with 60 parts of starch, and the rest of the process is the same as that of the example, and the specific steps are as follows: (1) Preparation of additives 40 parts of lily polysaccharide and 60 parts of starch are taken by weight, mixed evenly, fully dissolved in 30wt% water, and then centrifugal spray-dried to obtain a large yellow croaker feed additive with immune enhancement effect.

[0071] Specifically, the specific parameters of centrifugal spray drying are: inlet air temperature of 180°C, feed rate of 30mL / min, compressed air pressure of 1MPa, nozzle atomizer speed of 2000r / min, and outlet air temperature of 80°C.

[0072] (2) Preparation of feed The large yellow croaker feed additive with immune enhancement effect prepared in step (1) is added to the large yellow croaker feed, and the added amount is 0.12wt%.

[0073] (3) Cage culture experiment The large yellow croaker was fed with the feed prepared in step (2) twice a day, in the morning (8:00) and evening (16:00), until the large yellow croaker was in a state of satiation. The feeding was continued for five months, and the survival status, body weight and feed utilization rate of the large yellow croaker were recorded.

[0074] (4) Index detection Five months later, samples of surviving large yellow croaker were collected and their serum lysozyme and serum SOD were tested.

[0075] Comparative Example 8

[0076] The purpose of setting up this comparative example is to determine whether the immunoenhancing effect of catechu selenium polysaccharide on large yellow croaker is the same as the immunoenhancing effect of the additive provided in the present application on large yellow croaker when only catechu selenium polysaccharide is used as a feed additive for large yellow croaker. Therefore, the difference between this comparative example and Example 1 is only that in step 1) of this comparative example, 100 portions of catechu selenium polysaccharide are taken, and in step 2), the amount of additive added is set in a gradient, and the rest of the process is the same as Example 1.

[0077] Comparative Example 9

[0078] The purpose of setting up this comparative example is to determine whether the immune enhancing effect of lily polysaccharide as the feed additive for large yellow croaker is the same as the immune enhancing effect of the additive provided in the present application. Therefore, the difference between this comparative example and Example 1 is that in step 1) of this comparative example, 100 portions of catechu selenium polysaccharide are taken, and in step 2), the amount of additive added is set to a gradient of 55, and the rest of the process is the same as Example 1.

[0079] Comparative Example 10

[0080] The purpose of setting up this comparative example is to determine whether the immunoenhancing effect of Morus alba polysaccharide on large yellow croaker is the same as the immunoenhancing effect of the additive provided in the present application on large yellow croaker when only Morus alba polysaccharide is used as a feed additive for large yellow croaker. Therefore, the difference between this comparative example and Example 1 is only that in step 1) of this comparative example, 100 portions of catechu selenium polysaccharide are taken, and in step 2), the amount of additive added is set in a gradient, and the rest of the process is the same as Example 1.

[0081] Table 1 Composition and weight percentage of feed additives in Example 1 and each comparative example 2. Results

[0082] 2.1 Effect of immune-enhancing feed additives on the survival rate of yellow croaker

[0083] The fish were fed continuously for 5 months, and the survival rates of different groups of large yellow croaker were recorded in time. The results are shown in Table 2. Compared with the blank control group (Comparative Example 1), the survival rate of large yellow croaker in Example 1 was significantly increased, and the survival rates of Comparative Examples 2 to 7 were all improved to varying degrees compared with Comparative Example 1. The reasons are speculated to be: catechin selenium polysaccharide is a new type of biologically active substance, which can simultaneously exert the antioxidant effect of catechin polysaccharide and the immunoenhancing effect of organic selenium. Lily polysaccharide is mainly composed of D-glucose, D-mannose and galactose through β-pyranosidic bonds. It releases the active hydrogen on its hydroxyl group and captures free radicals, thereby blocking the chain reaction of free radicals. Therefore, it can play a good antioxidant and hormone regulation role. Morus alba polysaccharide is an active substance that can remove lipid peroxides in the body, improve the abnormal peroxidation state in fish, alleviate its effect on peroxidation damage to the body, and significantly promote lymphocyte proliferation. The invention discloses a kind of large yellow croaker feed additive with immunomodulatory effect, and it can improve the cellular immune function of fish, and reduce myocardial damage of fish in chronic hypoxic environment. Secondly, catechu selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide promote each other, and catechu selenium polysaccharide and lily polysaccharide cooperate with each other to strengthen the ability of fish immunity. Lily polysaccharide and mulberry bark polysaccharide cooperate with each other to improve the abundance of intestinal flora of fish, inhibit the growth of pathogenic bacteria, increase the biodiversity of intestinal flora, and improve the gastrointestinal immunity of fish. In addition, catechu selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide cooperate with each other to improve the activity of antioxidant enzymes in the stomach, hepatopancreas and intestine of fish, and improve the anti-stress ability. It can be seen from the above that the invention provides a large yellow croaker feed additive with immunomodulatory effect, and a single component can enhance the immunity and stress ability of large yellow croaker. At the same time, the compound of the three components can further strengthen the enhancing effect of the single component, so that the survival ability of large yellow croaker is greatly improved.

[0084] Table 2 Effects of additives on survival rate of large yellow croaker 1 month 3 months 5 months Example 1 95.47％ 92.33％ 90.67％ Comparative Example 1 84.33％ 77.00％ 68.67％ Comparative Example 2 91.38％ 88.33％ 86.24％ Comparative Example 3 92.67％ 89.67％ 88.33％ Comparative Example 4 91.33％ 90.33％ 88.62％ Comparative Example 5 89.33％ 86.67％ 85.67％ Comparative Example 6 88.33％ 86.43％ 83.33％ Comparative Example 7 89.67％ 85.75％ 82.86％

[0085] 2.2 Effect of an immune-enhancing feed additive on the body weight of yellow croaker

[0086] After 5 months of feeding, the large yellow croakers in different test groups were weighed and the average was calculated. The data obtained are shown in Table 3. The final weight of the large yellow croaker in Example 1 was significantly increased compared with the blank control group (Comparative Example 1). At the same time, the weight growth of the large yellow croaker in the univariate control group (Comparative Examples 2 to 7) was better than that in Comparative Example 1. The reasons may be as follows: catechu selenium polysaccharides, lily polysaccharides, and mulberry bark polysaccharides are bioactive substances that can enhance the immunity of large yellow croakers, so that large yellow croakers can enhance their absorption of feed and increase their weight; secondly, catechu selenium polysaccharides, lily polysaccharides, and mulberry bark polysaccharides can They promote each other. Among them, catechin selenium polysaccharides and lily polysaccharides can work together to significantly promote the appetite of fish, increase food intake, improve feed utilization, and significantly increase weight. The cooperation between lily polysaccharides and mulberry bark polysaccharides can also improve the abundance of fish intestinal flora, inhibit the growth of pathogens, increase the biodiversity of intestinal flora, increase digestive capacity, and increase weight. The three ingredients of catechin selenium polysaccharides, lily polysaccharides, and mulberry bark polysaccharides work together to increase the activity of digestive enzymes in the stomach, hepatopancreas, and intestines of fish, improve the digestive capacity of fish, improve stress resistance, and increase the weight growth rate of large yellow croaker.

[0087] Table 3 Effects of additives on weight gain of large yellow croaker Average weight after 5 months / g Weight gain% Example 1 457.04 128.52 Comparative Example 1 353.29 76.65 Comparative Example 2 390.72 95.36 Comparative Example 3 407.33 103.67 Comparative Example 4 401.59 100.80 Comparative Example 5 377.20 88.60 Comparative Example 6 369.91 84.96 Comparative Example 7 380.37 90.19

[0088] 2.3 Effect of an immune-enhancing feed additive on the utilization rate of large yellow croaker feed

[0089] Feed efficiency ratio (FER) (%) = 100 × (W t -W0) / D d ; Among them, W t W0 and W1 are the final and initial body weights of the experimental large yellow croaker, respectively. d is the dry weight of food intake (g).

[0090] The feed efficiency of large yellow croaker in different test groups was statistically analyzed and the average was calculated. The data obtained are shown in Table 4. The utilization rate of large yellow croaker in Example 1 was significantly increased compared with that of the blank control group (Comparative Example 1). At the same time, the weight gain of large yellow croaker in Comparative Examples 2 to 7 was better than that in Comparative Example 1. The reasons may be as follows: the immunopotentiation effect of organic selenium in catechu selenium polysaccharides, the enhancement of the vitality of immune cells, and the effect of mulberry bark on reducing myocardial damage in fish in chronic hypoxic environments can help large yellow croaker to increase the utilization rate of feed while enhancing the body's immunity; secondly, the present invention finds that catechu selenium polysaccharides, lily polysaccharides, and mulberry bark polysaccharides can promote each other while exerting their respective effects. The cooperation between catechu selenium polysaccharides and lily polysaccharides can significantly promote the appetite function of fish, improve feed utilization, and enhance fish immunity. The three components of catechu selenium polysaccharides, lily polysaccharides, and mulberry bark polysaccharides cooperate with each other to increase the activity of digestive enzymes and antioxidant enzymes in the stomach, hepatopancreas, and intestines of fish, and improve the digestive ability of fish.

[0091] Table 4 Effects of additives on feed efficiency of large yellow croaker Feed efficiency % Example 1 82.33 Comparative Example 1 71.31 Comparative Example 2 80.07 Comparative Example 3 78.95 Comparative Example 4 79.32 Comparative Example 5 73.57 Comparative Example 6 75.90 Comparative Example 7 73.48

[0092] 2.4 Effect of an immune-enhancing diet on the antioxidant properties of yellow croaker serum

[0093] Serum SOD (superoxide dismutase) is an important indicator of antioxidant activity. The large yellow croaker of Example 1 and Comparative Examples 1 to 7 after being raised for 5 months was sampled and serum SOD was detected. The obtained data are shown in Table 5. The concentration of serum SOD detected in Example 1 is higher than that in the blank control group. At the same time, in the univariate control group (Comparative Examples 2 to 7), the concentration of serum SOD is also significantly increased compared with the control group, indicating that catechu selenium polysaccharides, lily polysaccharides, and mulberry bark polysaccharides can not only increase the antioxidant properties of large yellow croaker, but also promote each other while exerting their respective effects. The speculated reason is that catechin selenium polysaccharides can exert the antioxidant effect of catechin polysaccharides; lily polysaccharides are mainly composed of D-glucose, D-mannose and galactose combined by β-pyranosidic bonds, and can capture free radicals by releasing active hydrogen on their hydroxyl groups, thereby blocking the chain reaction of free radicals, and therefore can play a good antioxidant role; mulberry bark polysaccharides can remove lipid peroxides in the body, thereby improving the abnormal peroxidation state in fish and alleviating its effect on peroxidation damage to the body. At the same time, the three ingredients of catechin selenium polysaccharides, lily polysaccharides and mulberry bark polysaccharides cooperate with each other to enhance the antioxidant capacity of large yellow croaker.

[0094] Table 5 Effects of additives on the antioxidant properties of large yellow croaker serum <![CDATA[Serum SOD / U*ml -1 > Example 1 186.01 Comparative Example 1 135.37 Comparative Example 2 171.77 Comparative Example 3 162.93 Comparative Example 4 161.24 Comparative Example 5 154.21 Comparative Example 6 155.93 Comparative Example 7 151.45

[0095] 2.5 Effect of an immune-enhancing feed on the immune function of yellow croaker

[0096] Serum lysozyme is an enzyme with antibacterial activity, which plays an important role in the immune system and can be used as an indicator of the strength of the immunity of large yellow croaker. Large yellow croakers cultured for 5 months were sampled and their serum lysozyme concentrations were detected. The specific data are shown in Table 6. We can see that compared with the blank control group (Comparative Example 1), the serum lysozyme content of Example 1 is higher. Although the serum lysozyme content of other single variable control groups (Comparative Examples 2 to 7) is higher than that of the blank control group, it is much lower than the serum lysozyme content in Example 1. It is speculated that the reason is that catechin selenium polysaccharide can play the immunoenhancing effect of organic selenium; lily polysaccharide is one of the main active ingredients of lily, which can enhance the vitality of immune cells and enhance the immunoregulatory effect; mulberry bark polysaccharide is a kind of polysaccharide extracted from the roots of mulberry trees. The active substance can significantly promote lymphocyte proliferation, improve the cellular immune function of fish, and reduce myocardial damage in fish in chronic hypoxic environment. At the same time, it can effectively inhibit inflammatory factors such as interleukin-1B, tumor necrosis factor-α, and interleukin-6, thereby playing an anti-inflammatory role. The three components of the additive with immune enhancement effect provided by the present invention have an enhancement effect on the immune system of large yellow croaker. Lily polysaccharide and mulberry bark polysaccharide can cooperate with each other to improve the abundance of intestinal flora of fish, inhibit the growth of pathogens, increase the biodiversity of intestinal flora, and improve the gastrointestinal immunity of fish. In addition, the three components of catechu selenium polysaccharide, lily polysaccharide, and mulberry bark polysaccharide cooperate with each other to improve the activity of digestive enzymes in the stomach, hepatopancreas, and intestines of fish, and improve the anti-stress ability.

[0097] Table 6 Effects of additives on immune performance of large yellow croaker <![CDATA[Serum lysozyme / U*ml -1 > Example 1 81.58 Comparative Example 1 54.77 Comparative Example 2 71.42 Comparative Example 3 73.27 Comparative Example 4 74.95 Comparative Example 5 62.41 Comparative Example 6 67.84 Comparative Example 7 69.17 2.6 Synergistic effects of catechu selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide

[0098] From the data in Table 6, we can observe that the content of serum lysozyme obtained in Example 1 is much higher than the content of serum lysozyme in the other comparative examples. In this regard, the researchers of the present invention studied the enhancing effect of a single component on the immune performance of large yellow croaker (Comparative Examples 8 to 10). The results are shown in Table 7. We can see that the addition amount of the large yellow croaker feed additive with immune enhancement provided by the present invention only needs to be 0.10wt% to 0.15wt%, which can play a good role in enhancing the immunity of large yellow croaker. In Comparative Examples 8 to 10, the single components of catechu selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide are used as additives, and their addition amounts need to reach 0.41wt%, 0.62wt% and 0.59wt% respectively to play the effect of coordination with the three components. It is speculated that the reason is that catechu selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide can not only enhance the immune enhancement effect through multiple pathways, but also can promote each other while exerting their respective effects. The three components cooperate with each other to enhance the immune system of fish in multiple ways.

[0099] Table 7 The ability of catechu selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide to enhance the immune system

[0100] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0101] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A large yellow croaker feed additive with immune enhancement effect, characterized in that: The invention comprises catechu selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide. The addition amount of catechu selenium polysaccharide is 20-30wt%, the addition amount of lily polysaccharide is 40-50wt% and the addition amount of mulberry bark polysaccharide is 30-40wt%.

2. The large yellow croaker feed additive with immune enhancement effect according to claim 1, characterized in that: The addition amount of the catechu selenium polysaccharide is 25-30wt%, the addition amount of the lily polysaccharide is 40-45wt%, and the addition amount of the mulberry bark polysaccharide is 30-35wt%.

3. The large yellow croaker feed additive with immune enhancement effect according to claim 2, characterized in that: The added amount of the catechu selenium polysaccharide is 25wt%, the added amount of the lily polysaccharide is 40wt%, and the added amount of the mulberry bark polysaccharide is 35wt%.

4. A method for preparing a large yellow croaker feed additive with immune enhancement effect according to any one of claims 1 to 3, characterized in that: The specific steps are: a) mixing catechu selenium polysaccharide, lily polysaccharide and mulberry bark polysaccharide uniformly to obtain a crude product; b) The crude product in step a) is sieved, dissolved and then spray-dried to obtain a large yellow croaker feed additive with an immune enhancement effect.

5. The method for preparing a large yellow croaker feed additive having an immune enhancing effect according to claim 4, characterized in that: In step a), after the crude product is sieved, 25-35 wt % of water is added to dissolve it.

6. The method for preparing a large yellow croaker feed additive with an immune enhancement effect according to claim 4 or 5, characterized in that: In step b), the spray drying is performed by centrifugal spray drying.

7. The method for preparing a large yellow croaker feed additive with an immune enhancement effect according to claim 6, characterized in that: The parameters of the centrifugal spray dryer are: The inlet air temperature is 170-190℃; Feed rate is 35-45 mL / min; The compressed air pressure is 0.8~1.2MPa; The speed of the nozzle atomizer is 1500~3000r / min; The air outlet temperature is 70~85℃.

8. Use of the large yellow croaker feed additive with immune enhancement effect according to any one of claims 1 to 7 in large yellow croaker feed.

9. The use according to claim 8, characterized in that: The large yellow croaker feed additive with an immune enhancement effect is added in an amount of 0.1 to 0.15 wt % in the large yellow croaker feed.

10. The use according to claim 9, characterized in that: The large yellow croaker feed additive with an immune enhancement effect is added in an amount of 0.12-0.15 wt % in the large yellow croaker feed.

Images