Method for improving survival rate of transporting pelteobagrus vishnui

Abstract

The invention discloses a method for improving the survival rate of yellow catfish transportation, comprising the steps of: (1) selecting healthy yellow catfish fry to be put into aquaculture water tank, water filling in the water tank, then adding composite polysaccharide nanoparticles and composite probiotics, and the yellow catfish fry is temporarily kept in the tank for 1 3 days without food; (2) the yellow catfish fry temporarily kept without food by water and step (1) are packed in aquatic product special oxygen bag, immediately oxygenating and sealing and ensuring that oxygen content is 6 7mg / L, and the bag is put into the carton of inner foam for transportation; the composite polysaccharide nanoparticles include chitosan, astragalus polysaccharide, oligoxylose, roxburghii polysaccharide and wolfberry polysaccharide and are made. The composite polysaccharide nanoparticles of the present invention are conducive to the absorption of polysaccharide and act on tissue, increase water solubility, dispersibility, and the absorption of fish body thereto, effectively avoid the side effect of polysaccharide accumulation and pollute water body, reduce the time and economic cost added to the feed, thus realize the relief of the fish stress under transportation stress.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fish transportation, and particularly relates to a method for improving the survival rate of pelteobagrus fulvidraco transportation. BACKGROUND

[0002] Aquaculture is a rapidly developing industry in the world, providing one of the most sustainable forms of edible protein and nutrient production. According to a report by the Food and Agriculture Organization in 2020, fish provide more than 1.33 billion people worldwide with 20% of their per capita animal protein intake. In 2018, the world's aquaculture fish production reached 82.1 million tons. With the development of economy, the demand for live aquatic products, especially high-value varieties, increases, and fish transportation becomes the key to live fish consumption. Transportation involves capture, loading, transportation, unloading and stocking, and many studies have shown that aquatic animals are severely stressed during transportation, causing negative effects and economic losses to the aquaculture industry. These stresses lead to some physiological responses, such as the release of catecholamines and corticosteroids, and increased glucose levels in the blood, or reduced immune system function, leading to disease and death. In addition, continuous stress during fish transportation will lead to quality deterioration.

[0003] Pelteobagrus fulvidraco is also known as yellow cheek fish, yellow bone fish, yellow spine fish and river dragon shield. It is distributed in the Yangtze River, Yellow River, Pearl River and Heilongjiang River basins in China. It has a sweet and flat taste, can benefit the spleen and stomach, and has diuretic and edema-reducing effects. The meat is tender, nutritious and of high economic value. Because the pectoral fin and dorsal fin of pelteobagrus fulvidraco have hard spines, they are easy to cause skin abrasions on the fish body during live fish transportation, leading to secondary bacterial and fungal infections, which has a certain impact on the survival rate and quality of pelteobagrus fulvidraco. SUMMARY

[0004] The purpose of the present application is to overcome the above technical deficiencies and provide a method for improving the survival rate of pelteobagrus fulvidraco transportation, which solves the technical problems in the prior art that live fish transportation is easy to cause skin abrasions on the fish body, leading to secondary bacterial and fungal infections, which has a certain impact on the survival rate and quality of pelteobagrus fulvidraco.

[0005] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0006] A method for improving the survival rate of pelteobagrus fulvidraco transportation, the specific steps are:

[0007] (1) Select healthy pelteobagrus fulvidraco fry and put them into a breeding tank, fill the tank with water, then add complex polysaccharide nanoparticles and complex probiotics, and temporarily feed the pelteobagrus fulvidraco fry in the tank for 1-3 days;

[0008] (2) Fill the water and step (1) temporarily fed pelteobagrus fulvidraco fry into a special oxygen bag for aquatic products, immediately fill the oxygen and seal the bag to ensure the oxygen content is 6-7 mg / L, and then put the bag into a carton with foam for transportation;

[0009] The complex polysaccharide nanoparticles are made of chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide.

[0010] Preferably, the preparation method of the complex polysaccharide nanoparticles comprises the following steps: respectively weighing chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide, adding deionized water and stirring at 20-30 DEG C for 40-70 min to make them fully dissolved, and preparing five polysaccharide solutions; then, under the condition of ultrasonic dispersion, the above-mentioned five polysaccharide solutions are added into ethanol solution at a constant speed, and after stirring at 25-30 DEG C for 80-120 min, the solution is concentrated by rotary evaporation at 40-60 DEG C, when the solvent is evaporated to 2 / 3 of the original volume, deionized water is added to make up to the original volume, and the operation of rotary evaporation concentration and deionized water supplement is repeated for 5 times, and then the mixed polysaccharide solution is freeze-dried for 24-32 h to obtain the complex polysaccharide nanoparticles.

[0011] Preferably, in step (1), the body weight of the juvenile yellow catfish is 7.77±1.70 g, the height of the culture water tank is 78 cm, the diameter is 100 cm, the temperature of the culture water is 20-25 DEG C, the dissolved oxygen is 6-7 mg / L, and the ph is 7.8-8.4.

[0012] Preferably, in step (1), the adding concentration of the complex polysaccharide nanoparticles is 0.02-0.3 g / L, the complex probiotics are lactic acid bacteria and bacillus subtilis, and the adding concentration of the complex probiotics is 0.1-0.3 g / L.

[0013] Preferably, the mass ratio of chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide is 1-12:3-23:1.5-6:1-8:8-30, and the concentration of the chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide in the polysaccharide solution is respectively 10-120 mg / L, 30-230 mg / L, 15-60 mg / L, 10-80 mg / L and 80-300 mg / L.

[0014] Preferably, the ultrasonic time of the ultrasonic dispersion is 10-30 min, and the power is 40-60 W.

[0015] Preferably, the transportation temperature is 20-25 DEG C.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] The present application adds the composite polysaccharide nanoparticles to the temporary water body, the nano drug delivery system can be uniformly dispersed after dissolving in water due to small particle size, large specific surface area and high solubility, which is beneficial to the absorption of polysaccharide and the action on the tissue, increases the solubility and dispersibility of the water body, and the absorption of the fish, effectively avoids the side effects caused by the polysaccharide accumulation and pollution of the water body, reduces the time and economic cost caused by adding to the feed, so as to realize the relief of fish stress under transportation stress, and significantly improve the survival rate of yellow catfish in the transportation process.

[0018] Traditional Chinese medicine polysaccharide has great development potential as a green, safe and residue-free fish feed additive due to its various biological activities and no toxic side effects. Polysaccharide can promote the production of more than 50 kinds of cytokines such as interferon, tumor necrosis factor and interleukin. Plant polysaccharide can also enhance immunity by increasing the level of immunoglobulin in the body. Different levels of polysaccharide from wolfberry can significantly promote the proliferation of T and B lymphocytes, polysaccharide from Astragalus can also promote the proliferation of T lymphocytes, enhance the cellular immunity of animal body, and polysaccharide from Rosa roxburghii Tratt can improve the immunity of fish. Appropriate amount of composite polysaccharide may be a safe and effective immunostimulant, which can significantly enhance the humoral immune response of fish. Xylo-oligosaccharide has prebiotic characteristics in aquaculture, and prebiotics have high stability in the acidic environment of animal intestines. They can improve the body's immunity and promote the sugar metabolism level in fish. Prebiotics have been widely used in aquaculture. The combination of prebiotics and Chinese herbal polysaccharide can improve the active ingredients and biological titer of Chinese herbal polysaccharide, and fully exert the synergistic effect between the two. The combination of traditional Chinese medicine polysaccharide and prebiotics can improve the antioxidant capacity and immune capacity of fish more than the use of prebiotics alone.

[0019] Composite polysaccharide has advantages over single polysaccharide in regulating the metabolism of four types of fish intestinal probiotics, and realizes the functional complementation of multiple polysaccharides. Each polysaccharide has its own advantages in promoting the growth and acid production of various microorganisms. Among them, polysaccharide from wolfberry has strong activity on lactic acid bacteria and bifidobacterium, and can promote the accumulation of propionic acid and isovaleric acid; chitosan has weak proliferation activity on mixed bacteria, but has the best activity on FP bacteria. Polysaccharide from Astragalus and polysaccharide from wolfberry and other polysaccharides can promote the growth of different intestinal probiotics, and have the characteristics of functional complementation. The composite polysaccharide obtained by scientific compounding of several polysaccharides can exert the advantages of several polysaccharides at the same time, has good proliferation activity on all probiotics, especially on Bacteroides, and achieves the purpose of synergistic effect, thereby maintaining the physiological activity of fish.

[0020] Meanwhile, compared with single polysaccharide, the activity and effect of complex polysaccharide are more obvious, which can play an antioxidant protective effect through various ways such as improving the enzyme activity of defense system, reducing the accumulation of free radicals in the body and reducing the damage of free radicals to cells. Single polysaccharide has certain beneficial activity, but the immune activity of single polysaccharide is weak, and only a few bacteria can occupy the growth advantage when single polysaccharide is applied to the fish intestinal tract because only a few bacteria in several intestinal probiotics can hydrolyze and utilize the polysaccharide. The complex polysaccharide prepared by mixing multiple polysaccharides in a specific ratio can play a synergistic effect. The more complex polysaccharide combination is more easily utilized by more microorganisms, thereby playing a better role in maintaining the intestinal tract homeostasis and regulating intestinal flora metabolism. Compared with single polysaccharide, complex polysaccharide has more advantages in promoting the generation of active peptides by microorganisms, can accumulate more dipeptides with ACE inhibitory activity, DPP-IV inhibitory activity and alpha-glucosidase inhibitory activity, and has greater hypoglycemic or antioxidant potential. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0022] It is particularly emphasized that, unless otherwise specified, the raw materials or reagents in the present application are purchased through commercial channels.

[0023] Example 1

[0024] A method for improving the survival rate of yellow catfish transportation, the specific steps are:

[0025] (1) healthy yellow catfish fry is selected and put into a breeding water tank, water is injected into the tank, then complex polysaccharide nanoparticles and complex probiotics are added, and the yellow catfish fry is temporarily fed in the tank for 1 day;

[0026] (2) water and the yellow catfish fry temporarily fed in step (1) are put into a special oxygen bag for aquatic products, immediately oxygenated, sealed and guaranteed to contain 6 mg / L of oxygen, the bag is put into a carton with foam for transportation, the transportation density is 1:4 (m fish:m water), the transportation time is 8 h, and the transportation temperature is 25℃;

[0027] The complex polysaccharide nanoparticles comprise chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide.

[0028] Further, the preparation method of the composite polysaccharide nanoparticles is as follows: respectively take the chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide, add deionized water and stir at 20℃ for 40min, so that they are fully dissolved, and prepare 5 kinds of polysaccharide solutions; then, under the condition of ultrasonic dispersion, the above-mentioned 5 kinds of polysaccharide solutions are added into the ethanol solution at a constant speed, stirred at 25℃ for 80min, and then concentrated at 40℃ by rotary evaporation, when the solvent is evaporated to 2 / 3 of the original volume, add deionized water to make up to the original volume, repeat the operation of rotary evaporation concentration and deionized water supplement for 5 times, and then freeze-dry the mixed polysaccharide solution for 24h, to obtain the composite polysaccharide nanoparticles.

[0029] Further, the body weight of the juvenile yellow catfish in step (1) is 6.07g, the height of the aquaculture water tank is 78cm, the diameter is 100cm, the temperature of the aquaculture water is 20℃, the dissolved oxygen is 6mg / L, and the ph is 7.8.

[0030] Further, the adding concentration of the composite polysaccharide nanoparticles in step (1) is 0.02g / L, the composite probiotics are lactic acid bacteria and bacillus subtilis, and the adding concentration of the composite probiotics is 0.1g / L.

[0031] Further, the concentration of the chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide prepared into polysaccharide solution is respectively 10mg / L, 30mg / L, 15mg / L, 10mg / L and 80mg / L.

[0032] Further, the ultrasonic time of the ultrasonic dispersion is 10min, and the power is 40W.

[0033] Further, the transportation temperature is 20℃.

[0034] Example 2

[0035] A method for improving the survival rate of yellow catfish transportation, the specific steps are:

[0036] (1) select healthy juvenile yellow catfish and put them into an aquaculture water tank, then add water, composite polysaccharide nanoparticles and composite probiotics to the tank, and temporarily feed the juvenile yellow catfish in the tank for 2 days;

[0037] (2) fill the water and the juvenile yellow catfish temporarily fed in step (1) into a special oxygen bag for aquatic products, immediately fill oxygen, seal and ensure the oxygen content to be 6.5mg / L, put the bag into a carton with foam, and transport it, the transportation density is 1:4(m fish:m water), the transportation time is 8h, and the transportation temperature is 25℃;

[0038] The composite polysaccharide nanoparticles comprise chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide.

[0039] Further, the preparation method of the composite polysaccharide nanoparticles is as follows: respectively taking chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide, adding deionized water and stirring at 25℃ for 55min to make them fully dissolved, and preparing 5 kinds of polysaccharide solutions; then, under the condition of ultrasonic dispersion, the above-mentioned 5 kinds of polysaccharide solutions are added into the ethanol solution at a constant speed, and after stirring at 27℃ for 100min, concentrated under the condition of rotary evaporation at 50℃, when the solvent is evaporated to 2 / 3 of the original volume, add deionized water to make up to the original volume, repeat the operation of rotary evaporation concentration and deionized water supplement for 5 times, and then freeze-dry the mixed polysaccharide solution for 28h to obtain the composite polysaccharide nanoparticles.

[0040] Further, the body weight of the juvenile yellow catfish in step (1) is 7.77g, the height of the aquaculture water tank is 78cm, the diameter is 100cm, the temperature of the aquaculture water is 23℃, the dissolved oxygen is 6.5mg / L, and the ph is 8.7.

[0041] Further, the adding concentration of the composite polysaccharide nanoparticles in step (1) is 0.17g / L, and the composite probiotics are lactic acid bacteria and bacillus subtilis, and the adding concentration of the composite probiotics is 0.2g / L.

[0042] The concentration of chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide prepared into polysaccharide solution is respectively: 65mg / L, 130mg / L, 37.5mg / L, 45 / L and 190mg / L.

[0043] Further, the ultrasonic time of ultrasonic dispersion is 20min, and the power is 50W.

[0044] Further, the transportation temperature is 23℃.

[0045] Example 3

[0046] A method for improving the survival rate of yellow catfish transportation, the specific steps are:

[0047] (1) Select healthy juvenile yellow catfish and put them into an aquaculture water tank, then add water, composite polysaccharide nanoparticles and composite probiotics to the tank, and temporarily feed the juvenile yellow catfish in the tank for 3 days;

[0048] (2) Put water and the juvenile yellow catfish temporarily fed in step (1) into a special oxygen bag for aquatic products, immediately fill oxygen, seal and ensure the oxygen content to be 7mg / L, put the bag into a carton with foam attached, and transport it, the transportation density is 1:4(m fish:m water), the transportation time is 8h, and the transportation temperature is 25℃;

[0049] The composite polysaccharide nanoparticles comprise chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide.

[0050] Further, the preparation method of the composite polysaccharide nanoparticles is as follows: respectively taking chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide, adding deionized water and stirring at 30 DEG C for 70 min, so as to fully dissolve and prepare 5 kinds of polysaccharide solutions; then, under the condition of ultrasonic dispersion, the above-mentioned 5 kinds of polysaccharide solutions are added into ethanol solution at a uniform speed, after stirring at 30 DEG C for 120 min, concentrated under rotary evaporation at 60 DEG C, when the solvent is evaporated to 2 / 3 of the original volume, add deionized water to make up to the original volume, repeat the operation of rotary evaporation concentration and deionized water supplement for 5 times, then freeze-dry the mixed polysaccharide solution for 32 h, and the composite polysaccharide nanoparticles are obtained.

[0051] Further, the body weight of the juvenile yellow catfish in step (1) is 9.47 g, the height of the aquaculture water tank is 78 cm, the diameter is 100 cm, the temperature of the aquaculture water is 25 DEG C, the dissolved oxygen is 7 mg / L, and the ph is 8.4.

[0052] Further, the adding concentration of the composite polysaccharide nanoparticles in step (1) is 0.3 g / L, the composite probiotics are lactic acid bacteria and bacillus subtilis, and the adding concentration of the composite probiotics is 0.3 g / L.

[0053] The concentrations of chitosan, astragalus polysaccharide, xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide prepared into polysaccharide solution are respectively 120 mg / L, 230 mg / L, 60 mg / L, 80 mg / L and 300 mg / L.

[0054] Further, the ultrasonic dispersion time is 30 min, and the power is 60 W.

[0055] Further, the transportation temperature is 25 DEG C.

[0056] Comparative example 1

[0057] A method for improving the survival rate of yellow catfish transportation, the specific steps are:

[0058] (1) select healthy juvenile yellow catfish and put them into an aquaculture water tank, then add water, composite polysaccharide nanoparticles and composite probiotics to the tank, and temporarily feed the juvenile yellow catfish in the tank for 1 day;

[0059] (2) fill the water and the juvenile yellow catfish temporarily fed in step (1) into a special oxygen bag for aquatic products, immediately fill oxygen, seal and ensure the oxygen content to be 6 mg / L, put the bag into a carton with foam, and transport the bag at a density of fish to water ratio 1:4 (m fish:m water), a transportation time of 8 h and a transportation temperature of 25 DEG C;

[0060] The composite polysaccharide nanoparticles comprise chitosan and astragalus polysaccharide.

[0061] Further, the preparation method of the composite polysaccharide nanoparticles is as follows: the chitosan and the astragalus polysaccharide are weighed respectively, deionized water is added and stirred at 20℃ for 40 min to make them fully dissolved, and two polysaccharide solutions are prepared; then, the two polysaccharide solutions are added into the ethanol solution at a constant speed under ultrasonic dispersion, and after stirring at 25℃ for 80 min, concentrated under rotary evaporation at 40℃, when the solvent is evaporated to 2 / 3 of the original volume, deionized water is added to make up to the original volume, and the operation of rotary evaporation concentration and deionized water supplement is repeated for 5 times, and then the mixed polysaccharide solution is freeze-dried for 24 h to obtain the composite polysaccharide nanoparticles.

[0062] Further, the body weight of the juvenile Pseudobrama in step (1) is 6.07 g, the height of the aquaculture water tank is 78 cm, the diameter is 100 cm, the temperature of the aquaculture water is 20℃, the dissolved oxygen is 6 mg / L, and the ph is 7.8.

[0063] Further, the adding concentration of the composite polysaccharide nanoparticles in step (1) is 0.02 g / L, the composite probiotics are lactic acid bacteria and bacillus subtilis, and the adding concentration of the composite probiotics is 0.1 g / L.

[0064] Further, the concentration of the chitosan and the astragalus polysaccharide prepared into the polysaccharide solution is 10 mg / L and 30 mg / L respectively.

[0065] Further, the ultrasonic time of the ultrasonic dispersion is 10 min, and the power is 40 W.

[0066] Further, the transportation temperature is 20℃.

[0067] The difference between the present example and example 1 is that the present example does not introduce xylo-oligosaccharide, roxburgh rose polysaccharide and medlar polysaccharide.

[0068] Comparative example 2

[0069] A method for improving the survival rate of Pseudobrama during transportation, the specific steps are as follows:

[0070] (1) healthy juvenile Pseudobrama is selected and put into an aquaculture water tank, water is added into the tank, then composite polysaccharide nanoparticles and composite probiotics are added, and the juvenile Pseudobrama is temporarily fed in the tank for 1 day;

[0071] (2) water and the juvenile Pseudobrama temporarily fed in step (1) are put into a special oxygen bag for aquatic products, the bag is immediately filled with oxygen and sealed to ensure the oxygen content of 6 mg / L, the bag is put into a carton with foam for transportation, the transportation density is 1:4 (m fish:m water), the transportation time is 8 h, and the transportation temperature is 25℃;

[0072] The composite polysaccharide nanoparticles comprise astragalus polysaccharide and xylo-oligosaccharide.

[0073] Further, the preparation method of the composite polysaccharide nanoparticles is as follows: the astragalus polysaccharide and the xylo-oligosaccharide are weighed respectively, and then added into deionized water and stirred at 20℃ for 40 min to make them fully dissolved, to prepare two polysaccharide solutions; then, the two polysaccharide solutions are added into the ethanol solution at a constant speed under ultrasonic dispersion, and stirred at 25℃ for 80 min, and then concentrated by rotary evaporation at 40℃, when the solvent is evaporated to 2 / 3 of the original volume, deionized water is added to make up to the original volume, and the operation of rotary evaporation concentration and deionized water supplement is repeated for 5 times, and then the mixed polysaccharide solution is freeze-dried for 24 h to obtain the composite polysaccharide nanoparticles.

[0074] Further, the body weight of the Pelteobagrus fulvidraco juvenile fish in step (1) is 6.07 g, the height of the breeding water tank is 78 cm, the diameter is 100 cm, the temperature of the breeding water is 20℃, the dissolved oxygen is 6 mg / L, and the ph is 7.8.

[0075] Further, the adding concentration of the composite polysaccharide nanoparticles in step (1) is 0.02 g / L, the composite probiotics are lactic acid bacteria and Bacillus subtilis, and the adding concentration of the composite probiotics is 0.1 g / L.

[0076] Further, the concentration of the astragalus polysaccharide and the xylo-oligosaccharide prepared into the polysaccharide solution is 30 mg / L and 15 mg / L respectively.

[0077] Further, the ultrasonic time of the ultrasonic dispersion is 10 min, and the power is 40 W.

[0078] Further, the transportation temperature is 20℃.

[0079] The difference between the present comparative example and example 1 is that the present comparative example does not introduce chitosan, roxburgh rose polysaccharide and medlar polysaccharide.

[0080]

[0081]

[0082] The Pelteobagrus fulvidraco juvenile fish after transportation in examples 1-3 and comparative examples 1-2 is measured for the following indexes:

[0083] Transportation can cause an increase in oxygen consumption, promote the generation of reactive oxygen species (ROS), and cause damage to the body. Antioxidant defense plays a key role in the removal of ROS. Superoxide dismutase (SOD) plays an important role in the reaction of O2-, and catalase (CAT) alleviates oxidative stress by degrading hydrogen peroxide. The stress experienced by the temporary rearing group of Amur catfish fry with the addition of complex additives was smaller than that of the non-addition group. Similarly, the overall level of CAT also increased after transportation, and the change in the temporary rearing group was the smallest, indicating that temporary rearing with multiple additives alleviates the stress of Amur catfish fry during transportation.

[0084] Malondialdehyde (MDA) is the product of lipid peroxidation in the body, and the content of MDA can be used as an important indicator of peroxide accumulation and oxidative stress. Studies have found that MDA can cause damage to protein structure, mainly because it can react with some amino acids inside itself; MDA also damages cells, mainly in terms of damaging mitochondrial respiratory function and related dehydrogenases. Therefore, the content of MDA can be used to indirectly reflect the severity of ROS attack on the body and cell damage. Two complex additive temporary rearing also played a role in reducing MDA levels, among which the MDA level of the Astragalus polysaccharide and chitosan group was lower.

[0085] IgM is a type of specific immune factor produced by B lymphocytes and combined with antigens, which has the function of inhibiting pathogenic activity and regulating antigen specificity. Immunoglobulin M (IgM) is a specific immune factor in fish, but it does not directly exert its immune function, but when the fish is stimulated, it produces immunoglobulin to exert the immune function of the fish. The complex polysaccharide nanoparticle temporary rearing group increased the IgM level in Amur catfish, which can stimulate the fish to exert its immune function.

[0086] Lysozyme is one of the most important non-specific immune factors, and is one of the key elements of innate immunity against bacterial invasion. It is also a key humoral component of the innate immune system. Determining the lysozyme activity level in fish can reflect the state of fish non-specific humoral immunity to a certain extent. Complement is an important component of the fish immune system, and C3 and C4 play an important role in the complement system. The level of C3 can not only reflect the immune pathological damage of the body, but also is an important physiological defense system of the body. When activated, it has biological functions such as bactericidal opsonization and immune adsorption. Complement is also a medium that can connect antibodies and phagocytes, and can strengthen humoral and specific immune functions, and can make non-specific immunity of the organism play an indispensable role. The C3 and lysozyme levels of the transported yellow-head catfish fry increase. The C3 and lysozyme levels of the polysaccharide nanoparticle temporary rearing group are higher than those of the control group without addition.

[0087] In fish, apoptosis can be induced by invasive bacteria, accompanied by the activation of many intracellular proteases and endonucleases, and increased apoptosis damages the intestinal structural integrity. According to the involvement of caspases, the apoptosis pathway is divided into caspase-dependent and caspase-independent transduction pathways. Caspases involved in apoptosis include initiator caspases (such as Casp-2, Casp-8 and Casp-9) and effector caspases (such as Casp-3 and Casp-7), which play a major role in regulating apoptosis. The intestinal apoptosis level of the transported yellow-head catfish fry increases, and transportation has an adverse effect on it. However, the intestinal apoptosis level of the yellow-head catfish fry in the polysaccharide nanoparticle temporary rearing group after transportation is lower than that of the control group without addition.

[0088] The present application adds polysaccharide nanoparticles to the temporary rearing water. The nanoparticle drug delivery system has small particle size, large specific surface area and high solubility, and can be uniformly dispersed after dissolution in water, which is beneficial to the absorption of polysaccharides and the action on tissues, increases the solubility and dispersibility of the water, and the absorption of the fish, effectively avoids the side effects of polysaccharide accumulation and water pollution, reduces the time and economic cost of adding to the feed, thereby realizing the relief of fish stress under transportation stress, and significantly improving the survival rate of yellow-head catfish during transportation.

[0089] Transportation survival rate experiment:

[0090] Select 1500 healthy yellow fish fry (body weight 7.77 ± 1.70 g) into the breeding water jar (high 78 cm, diameter 100 cm), temperature 20℃, dissolved oxygen 6-7mg / L, pG 7.8-8.4. In four water tanks, respectively, 500L, according to the mass ratio 1:4 (m fish:m water) respectively into the fish tank fish set for four groups (120g polysaccharide nanoparticles group (example 1), 120g chitosan + astragalus polysaccharide (comparative example 1), 120g xylo-oligosaccharide + astragalus polysaccharide (comparative example 2) and no addition group), add 50g compound probiotics (lactic acid bacteria and bacillus subtilis) in the jar for 3 days, then load into the nylon oxygen bag sealed with pure oxygen, water transportation mode for transportation, put the transport bag into the simulation transport incubator, simulate transport shock every half hour, the transportation temperature is 20℃, after 0h, 4h, 8h, 12h, 16h and 24h of transportation, collect the sample, record the survival rate.

[0091] Table 2 yellow fish fry transportation survival rate

[0092]

[0093] Table 2 records the survival rate of yellow fish fry before and after simulation transportation. After 20h of transportation, the survival rate of polysaccharide nanoparticle group is the highest (100%), followed by chitosan + astragalus polysaccharide (55%). The survival rate of xylo-oligosaccharide + astragalus polysaccharide and no addition group is 0 after 24h of transportation.

[0094] The above description describes one preferred embodiment in the present application, which should not be regarded as a limitation on the scope of protection of the claims of the present application. Any modification, equivalent replacement and improvement without departing from the principles and spirit of the present application should be regarded as within the scope of protection of the claims of the present application.

Claims

1. A method for improving the survival rate of yellow catfish during transportation, characterized in that: The specific steps are: (1) Select healthy juvenile yellow catfish and place them in a culture tank, fill the tank with water, then add composite polysaccharide nanoparticles and composite probiotics, and keep the juvenile yellow catfish in the tank without feeding for 1-3 days; (2) filling water and the yellow catfish fry that have been fasted in step (1) into a special oxygen bag for aquatic products, immediately filling the bag with oxygen, sealing the bag and ensuring that the oxygen content is 6-7 mg / L, and placing the bag in a foam-lined carton for transportation; The composite polysaccharide nanoparticles are made of chitosan, astragalus polysaccharide, xylooligosaccharide, roxburghii polysaccharide and wolfberry polysaccharide; The preparation method of the composite polysaccharide nanoparticles is as follows: chitosan, astragalus polysaccharide, oligoxylose, roxburghii polysaccharide and wolfberry polysaccharide are weighed respectively, deionized water is added and stirred at 20-30°C for 40-70 minutes to fully dissolve them, and five polysaccharide solutions are prepared; then, under ultrasonic dispersion conditions, the above five polysaccharide solutions are added dropwise to an ethanol solution at a uniform speed, stirred at 25-30°C for 80-120 minutes, and then concentrated by rotary evaporation at 40-60°C. When the solvent evaporates to 2 / 3 of the original volume, deionized water is added to make up to the original volume, and the rotary evaporation concentration and deionized water replenishment operations are repeated 5 times. Then, the mixed polysaccharide solution is freeze-dried for 24-32 hours to obtain the composite polysaccharide nanoparticles.

2. The method according to claim 1, characterized in that The weight of the yellow catfish fry in step (1) is 7.77±1.70 g, the height of the aquaculture tank is 78 cm, the diameter is 100 cm, the temperature of the aquaculture water is 20-25° C., the dissolved oxygen is 6-7 mg / L, and the pH is 7.8-8.

4.

3. The method according to claim 1, characterized in that In step (1), the added concentration of the composite polysaccharide nanoparticles is 0.02-0.3 g / L, the composite probiotics are lactic acid bacteria and Bacillus subtilis, and the added concentration of the composite probiotics is 0.1-0.3 g / L.

4. The method according to claim 1, wherein The mass ratios of chitosan, astragalus polysaccharide, xylooligosaccharide, roxburghii polysaccharide and wolfberry polysaccharide are 1-12:3-23:1.5-6:1-8:8-30; the concentrations of the chitosan, astragalus polysaccharide, xylooligosaccharide, roxburghii polysaccharide and wolfberry polysaccharide prepared into polysaccharide solutions are 10-120 mg / L, 30-230 mg / L, 15-60 mg / L, 10-80 mg / L and 80-300 mg / L, respectively.

5. The method according to claim 1, wherein The ultrasonic dispersion has an ultrasonic time of 10-30 min and a power of 40-60 W.

6. The method according to claim 1, characterized in that The transportation temperature is 20-25°C.

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