Rehmannia glutinosa polysaccharide liposome and feed additive and feed containing the same

Abstract

The present invention belongs to the field of feed technology, and discloses a Rehmannia glutinosa polysaccharide liposome and a feed additive and feed containing the same. The Rehmannia glutinosa polysaccharide liposome comprises Rehmannia glutinosa polysaccharide and liposome, and the liposome comprises dimyristoylphosphatidylcholine, monoglyceride, cholesterol and anionic phospholipid; the anionic phospholipid is selected from dipalmitoylphosphatidylglycerol and / or dipalmitoylphosphatidic acid. The Rehmannia glutinosa polysaccharide liposome provided by the present invention uses dimyristoylphosphatidylcholine, monoglyceride, cholesterol and anionic phospholipid as raw materials of the liposome, and through the selection of anionic phospholipids and the control of the timing of adding monoglyceride, a good encapsulation effect can be obtained when only ethanol is used as a solvent; the preparation process is simple and there is little organic solvent residue. As a component of the feed additive, it can be slowly released in the body of raw fish, enhance immunity, promote its intestinal health and growth, and reduce mortality.

Description

Technical Field

[0001] The invention belongs to the technical field of feed, and in particular relates to a rehmannia polysaccharide liposome and a feed additive and feed containing the same. Background Art

[0002] Rehmannia glutinosa (Rehmannia glutinosa), a plant of the Scrophulariaceae family, is a traditional Chinese herbal medicine. Its medicinal part is its tuberous root, which can be divided into fresh, raw, and cooked versions based on their preparation methods and efficacy. Fresh Rehmannia glutinosa is cold in nature, sweet and bitter in flavor, and can clear heat, promote fluid production, and cool blood and stop bleeding; raw Rehmannia glutinosa is cold in nature, sweet in flavor, and can clear heat, cool blood, nourish yin, and promote fluid production; and cooked Rehmannia glutinosa is slightly warm in nature, sweet in flavor, and can nourish yin, tonify blood, and replenish essence and marrow.

[0003] Rehmannia root also has the effect of enhancing immunity. Using Rehmannia root as an additive raw material for aquatic feed can improve the immunity of aquatic animals and reduce the use of antibiotics. Among them, Rehmannia root polysaccharide is the main active ingredient of Rehmannia root that exerts its immune-enhancing effect. However, Rehmannia root polysaccharide has the common defects of large molecular polysaccharides, namely, rapid metabolism in the body, short duration of action, unconcentrated scope of action, large dosage, etc. In order to improve the bioavailability of Rehmannia root polysaccharide and better exert its immune-enhancing effect, the researchers proposed to select liposomes as carriers to embed Rehmannia root polysaccharide therein, so as to improve the bioavailability of Rehmannia root polysaccharide, maintain the effective concentration in the body, prolong the duration of action, achieve a sustained-release or controlled-release effect, and enhance its immune efficacy. However, the Rehmannia glutinosa polysaccharide liposomes provided in the prior art still have many problems. For example, the preparation process of Rehmannia glutinosa polysaccharide liposomes with a high encapsulation rate is complicated, and chloroform and ether are used as solvents, resulting in large solvent residues. They are not suitable for large-scale industrial production, nor are they suitable for use as drugs or addition to feed. On the other hand, the Rehmannia glutinosa polysaccharide liposomes prepared by a simple preparation process using ethanol as a solvent have an encapsulation rate that is difficult to meet the requirements of actual production.

[0004] Therefore, there is an urgent need to provide a Rehmannia glutinosa polysaccharide liposome with a simple preparation process, safe solvent use, and high encapsulation efficiency. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a Rehmannia glutinosa polysaccharide liposome and a feed additive and feed containing the same. The Rehmannia glutinosa polysaccharide liposome provided by the present invention has a simple preparation process, uses only ethanol as a solvent, and has a high encapsulation efficiency. As a component of the feed additive, the liposome can be slowly released in aquatic animals (especially raw fish), promoting intestinal health, enhancing immunity, and reducing mortality.

[0006] The first aspect of the present invention provides a Rehmannia glutinosa polysaccharide liposome.

[0007] Specifically, a Rehmannia glutinosa polysaccharide liposome comprises Rehmannia glutinosa polysaccharide and liposomes, wherein the liposomes comprise dimyristoylphosphatidylcholine, monoglyceride, cholesterol and anionic phospholipids; the anionic phospholipids are selected from dipalmitoylphosphatidylglycerol and / or dipalmitoylphosphatidic acid.

[0008] Preferably, the mass ratio of dimyristoyl phosphatidylcholine to monoglyceride, cholesterol and anionic phospholipids is 1:(0.05-0.2):(0.1-0.5):(0.3-1); further preferably, the mass ratio of dimyristoyl phosphatidylcholine to monoglyceride, cholesterol and anionic phospholipids is 1:(0.05-0.1):(0.1-0.3):(0.5-1); more preferably, the mass ratio of dimyristoyl phosphatidylcholine to monoglyceride, cholesterol and anionic phospholipids is 1:(0.05-0.1):(0.2-0.3):(0.5-0.8).

[0009] Preferably, the mass ratio of the Rehmannia glutinosa polysaccharide to the liposome is (0.5-10):100; further preferably, the mass ratio of the Rehmannia glutinosa polysaccharide to the liposome is (1-8):100.

[0010] Preferably, the Rehmannia glutinosa polysaccharide is extracted from raw Rehmannia glutinosa.

[0011] The second aspect of the present invention provides a method for preparing Rehmannia glutinosa polysaccharide liposomes.

[0012] Specifically, a method for preparing Rehmannia glutinosa polysaccharide liposomes comprises the following steps:

[0013] Dissolve dimyristoylphosphatidylcholine, cholesterol and anionic phospholipids in ethanol, add PBS solution of Rehmannia glutinosa polysaccharide after they are fully dissolved, then add monoglyceride, shake and remove ethanol to obtain a suspension; dry the suspension to obtain Rehmannia glutinosa polysaccharide liposomes.

[0014] Dimyristoylphosphatidylcholine, monoglyceride, cholesterol and anionic phospholipids are used as raw materials for liposomes. Dimyristoylphosphatidylcholine, cholesterol and anionic phospholipids are first dissolved in ethanol, and then Rehmannia glutinosa polysaccharide is added, and then monoglyceride is added. The monoglyceride molecule has two hydrophilic hydroxyl groups and one lipophilic hydrocarbon group, which can enhance the emulsification effect of dimyristoylphosphatidylcholine, monoglyceride, cholesterol and Rehmannia glutinosa polysaccharide and improve their encapsulation efficiency.

[0015] Preferably, in the PBS solution of Rehmannia glutinosa polysaccharide, the concentration of Rehmannia glutinosa polysaccharide is 0.5-5 g / L; further preferably, in the PBS solution of Rehmannia glutinosa polysaccharide, the concentration of Rehmannia glutinosa polysaccharide is 1-5 g / L; more preferably, in the PBS solution of Rehmannia glutinosa polysaccharide, the concentration of Rehmannia glutinosa polysaccharide is 2.5-4 g / L.

[0016] Preferably, when the PBS solution of Rehmannia glutinosa polysaccharide is added, the temperature is controlled at 40-60°C.

[0017] Preferably, the shaking process is to control the temperature at 40-60° C. and shake for 20-120 min; further preferably, the shaking process is to control the temperature at 45-60° C. and shake for 30-100 min.

[0018] Preferably, the suspension obtained after removing the ethanol is further subjected to ultrasonic treatment. This process can make the Rehmannia glutinosa polysaccharide more fully and evenly integrated into the liposomes, making the particle size of the prepared Rehmannia glutinosa polysaccharide liposomes more uniform.

[0019] Preferably, the power of the ultrasonic wave is 200-500W, and the ultrasonic treatment time is 2-20 minutes; further preferably, the power of the ultrasonic wave is 200-500W, and the ultrasonic treatment time is 5-10 minutes.

[0020] Preferably, the drying is freeze-drying or spray-drying.

[0021] More specifically, a method for preparing Rehmannia glutinosa polysaccharide liposomes comprises the following steps:

[0022] Dissolve dimyristoylphosphatidylcholine, cholesterol and anionic phospholipids in ethanol, use ultrasonic dispersion to dissolve, add PBS solution of Rehmannia glutinosa polysaccharide at 40-60°C after sufficient dissolution, then add monoglyceride, shake for 20-120 minutes, remove ethanol and perform ultrasonic treatment to obtain a suspension; dry the suspension to obtain Rehmannia glutinosa polysaccharide liposomes.

[0023] Preferably, the suspension is further filtered through a microporous membrane, which can further enhance the stability of the Rehmannia glutinosa polysaccharide liposomes. However, this step can be omitted based on the cost of feed additives.

[0024] Preferably, the pore size of the microporous filter membrane is 0.45 μm.

[0025] A second aspect of the present invention provides a feed additive.

[0026] Specifically, a feed additive comprises the above-mentioned Rehmannia glutinosa polysaccharide liposome.

[0027] Preferably, the feed additive further comprises chitosan oligosaccharide.

[0028] Preferably, the mass ratio of the chitosan oligosaccharide to the Rehmannia glutinosa polysaccharide liposome is (0.1-1):1.

[0029] A third aspect of the present invention provides a raw fish feed.

[0030] Specifically, a raw fish feed comprises the above feed additive, wherein the addition amount of the feed additive is 2% to 8%.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The Rehmannia glutinosa polysaccharide liposomes provided by the present invention use dimyristoylphosphatidylcholine, monoglyceride, cholesterol, and anionic phospholipids as liposome raw materials. By carefully selecting the anionic phospholipids and controlling the timing of adding the monoglyceride, good encapsulation effects can be achieved using only ethanol as a solvent. The preparation process is simple and the organic solvent residue is low. When used as a feed additive, the polysaccharide can be slowly released into raw fish, enhancing immunity, promoting intestinal health and growth, and reducing mortality. DETAILED DESCRIPTION

[0033] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0034] Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0035] Example 1

[0036] A method for preparing Rehmannia glutinosa polysaccharide liposomes comprises the following steps:

[0037] 10 g of dimyristoylphosphatidylcholine, 2 g of cholesterol and 7.5 g of dipalmitoylphosphatidylglycerol were weighed, and the dimyristoylphosphatidylcholine, cholesterol and dipalmitoylphosphatidylglycerol were dissolved in 40 mL of ethanol and dispersed and dissolved by ultrasonication (300 W) for 20 min. After sufficient dissolution, 0.8 L of a PBS solution of Rehmannia glutinosa polysaccharide with a pH value of 7 and a concentration of 2.5 g / L was added at 50° C., followed by the addition of 0.5 g of monoglyceride. The mixture was shaken for 60 min, and the ethanol was evaporated under reduced pressure at 66° C., followed by ultrasonication (300 W) for 8 min to obtain a suspension. The suspension was freeze-dried at −40° C. to obtain Rehmannia glutinosa polysaccharide liposomes.

[0038] A feed additive comprises, by weight, 1 part of chitosan oligosaccharide and 10 parts of Rehmannia glutinosa polysaccharide liposomes prepared by the above method.

[0039] Example 2

[0040] A method for preparing Rehmannia glutinosa polysaccharide liposomes comprises the following steps:

[0041] 10 g of dimyristoylphosphatidylcholine, 2 g of cholesterol and 7.5 g of dipalmitoylphosphatidic acid were weighed, and the dimyristoylphosphatidylcholine, cholesterol and dipalmitoylphosphatidic acid were dissolved in 40 mL of ethanol and dispersed and dissolved by ultrasonication (300 W) for 20 min. After sufficient dissolution, 0.8 L of a PBS solution of Rehmannia glutinosa polysaccharide with a pH value of 7 and a concentration of 2.5 g / L was added at 50° C., followed by the addition of 0.5 g of monoglyceride. The mixture was shaken for 60 min, and the ethanol was evaporated under reduced pressure at 66° C., followed by ultrasonication (300 W) for 8 min to obtain a suspension. The suspension was freeze-dried at -40° C. to obtain Rehmannia glutinosa polysaccharide liposomes.

[0042] A feed additive comprises, by weight, 1 part of chitosan oligosaccharide and 10 parts of Rehmannia glutinosa polysaccharide liposomes prepared by the above method.

[0043] Example 3

[0044] A method for preparing Rehmannia glutinosa polysaccharide liposomes comprises the following steps:

[0045] 10 g of dimyristoylphosphatidylcholine, 1.5 g of cholesterol and 5.25 g of dipalmitoylphosphatidylglycerol were weighed, and the dimyristoylphosphatidylcholine, cholesterol and dipalmitoylphosphatidylglycerol were dissolved in 35 mL of ethanol and dispersed and dissolved by ultrasonication (300 W) for 15 minutes. After sufficient dissolution, 0.5 L of a PBS solution of Rehmannia glutinosa polysaccharide with a pH value of 7 and a concentration of 3.0 g / L was added at 50° C., followed by the addition of 0.25 g of monoglyceride. The mixture was shaken for 60 minutes, and the ethanol was evaporated under reduced pressure at 66° C., followed by ultrasonication (300 W) for 10 minutes to obtain a suspension. The suspension was freeze-dried at -40° C. to obtain Rehmannia glutinosa polysaccharide liposomes.

[0046] A feed additive comprises, by weight, 1 part of chitosan oligosaccharide and 10 parts of Rehmannia glutinosa polysaccharide liposomes prepared by the above method.

[0047] Example 4

[0048] A method for preparing Rehmannia glutinosa polysaccharide liposomes comprises the following steps:

[0049] 10 g of dimyristoylphosphatidylcholine, 3 g of cholesterol and 4.5 g of dipalmitoylphosphatidylglycerol were weighed, and the dimyristoylphosphatidylcholine, cholesterol and dipalmitoylphosphatidylglycerol were dissolved in 40 mL of ethanol and dispersed and dissolved by ultrasonication (300 W) for 15 minutes. After sufficient dissolution, 0.8 L of a PBS solution of Rehmannia glutinosa polysaccharide with a pH value of 7 and a concentration of 2.0 g / L was added at 50° C., followed by the addition of 0.5 g of monoglyceride. The mixture was shaken for 60 minutes, and the ethanol was evaporated under reduced pressure at 66° C., followed by ultrasonication (300 W) for 5 minutes to obtain a suspension. The suspension was freeze-dried at −40° C. to obtain Rehmannia glutinosa polysaccharide liposomes.

[0050] A feed additive comprises, by weight, 1 part of chitosan oligosaccharide and 10 parts of Rehmannia glutinosa polysaccharide liposomes prepared by the above method.

[0051] Example 5

[0052] A method for preparing Rehmannia glutinosa polysaccharide liposomes comprises the following steps:

[0053] 10 g of dimyristoylphosphatidylcholine, 2 g of cholesterol and 2.5 g of dipalmitoylphosphatidylglycerol were weighed, and the dimyristoylphosphatidylcholine, cholesterol and dipalmitoylphosphatidylglycerol were dissolved in 40 mL of ethanol and dispersed and dissolved by ultrasonication (300 W) for 20 min. After sufficient dissolution, 0.6 L of a PBS solution of Rehmannia glutinosa polysaccharide with a pH value of 7 and a concentration of 2.5 g / L was added at 50° C., followed by the addition of 0.5 g of monoglyceride. The mixture was shaken for 60 min, and the ethanol was evaporated under reduced pressure at 66° C., followed by ultrasonication (300 W) for 8 min to obtain a suspension. The suspension was freeze-dried at -40° C. to obtain Rehmannia glutinosa polysaccharide liposomes.

[0054] A feed additive comprises, by weight, 1 part of chitosan oligosaccharide and 10 parts of Rehmannia glutinosa polysaccharide liposomes prepared by the above method.

[0055] Comparative Example 1

[0056] A method for preparing Rehmannia glutinosa polysaccharide liposomes comprises the following steps:

[0057] Weigh 10 g of dimyristoylphosphatidylcholine, 2 g of cholesterol, 7.5 g of dipalmitoylphosphatidylglycerol and 0.5 g of monoglyceride, dissolve the dimyristoylphosphatidylcholine, cholesterol, dipalmitoylphosphatidylglycerol and monoglyceride in 40 mL of ethanol, and use ultrasonic dispersion (300 W) to dissolve for 20 minutes. After sufficient dissolution, 0.8 L of a PBS solution of Rehmannia glutinosa polysaccharide with a pH value of 7 and a concentration of 2.5 g / L is added at 50° C., and then shaken for 60 minutes. After ethanol is evaporated under reduced pressure at 66° C., ultrasonic treatment (300 W) is performed for 8 minutes to obtain a suspension; the suspension is freeze-dried at -40° C. to obtain Rehmannia glutinosa polysaccharide liposomes.

[0058] A feed additive comprises, by weight, 1 part of chitosan oligosaccharide and 10 parts of Rehmannia glutinosa polysaccharide liposomes prepared by the above method.

[0059] Comparative Example 2

[0060] A method for preparing Rehmannia glutinosa polysaccharide liposomes comprises the following steps:

[0061] 10 g of dimyristoylphosphatidylcholine, 2 g of cholesterol and 7.5 g of dioleoylphosphatidic acid were weighed, and the dimyristoylphosphatidylcholine, cholesterol and dipalmitoylphosphatidylglycerol were dissolved in 40 mL of ethanol and dispersed and dissolved using ultrasound (300 W) for 20 minutes. After sufficient dissolution, 0.8 L of a PBS solution of Rehmannia glutinosa polysaccharide with a pH value of 7 and a concentration of 2.5 g / L was added at 50° C., followed by the addition of 0.5 g of monoglyceride. The mixture was shaken for 60 minutes, and the ethanol was evaporated under reduced pressure at 66° C., followed by ultrasound (300 W) treatment for 8 minutes to obtain a suspension. The suspension was freeze-dried at -40° C. to obtain Rehmannia glutinosa polysaccharide liposomes.

[0062] A feed additive comprises, by weight, 1 part of chitosan oligosaccharide and 10 parts of Rehmannia glutinosa polysaccharide liposomes prepared by the above method.

[0063] Comparative Example 3

[0064] A method for preparing Rehmannia glutinosa polysaccharide liposomes comprises the following steps:

[0065] Weigh 10 g of dimyristoylphosphatidylcholine, 2 g of cholesterol, and 7.5 g of dipalmitoylphosphatidylglycerol, dissolve the dimyristoylphosphatidylcholine, cholesterol, and dipalmitoylphosphatidylglycerol in 40 mL of ethanol and disperse and dissolve them using ultrasound (300 W) for 20 min. After they are fully dissolved, 0.8 L of a PBS solution of Rehmannia glutinosa polysaccharide with a pH of 7 and a concentration of 2.5 g / L is added at 50° C., followed by shaking for 60 min. After ethanol is evaporated under reduced pressure at 66° C., the mixture is treated with ultrasound (300 W) for 8 min to obtain a suspension. The suspension is freeze-dried at -40° C. to obtain Rehmannia glutinosa polysaccharide liposomes.

[0066] A feed additive comprises, by weight, 1 part of chitosan oligosaccharide and 10 parts of Rehmannia glutinosa polysaccharide liposomes prepared by the above method.

[0067] Product effect testing

[0068] (1) Testing the encapsulation efficiency of Rehmannia polysaccharide liposomes

[0069] 100uL of the Rehmannia polysaccharide liposomes prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were each drawn, and 100uL of protamine solution (10mg / mL) was added respectively. After mixing, the mixture was allowed to stand for 3min, and then 3mL of normal saline was added respectively, and the mixture was centrifuged (4000r / min, 30min). 1mL of the supernatant was taken respectively, and the mixture was made up to 2mL with normal saline, and the polysaccharide content was measured therein to obtain the unencapsulated Rehmannia polysaccharide content. For the precipitate, 0.6mL of TritonX-100 was added, and after demulsification, 2.6mL of normal saline was added, and the mixture was fully mixed. 1mL of the sample was also taken, and the mixture was made up to 2mL with normal saline, and the polysaccharide content was measured therein to obtain the encapsulated Rehmannia polysaccharide content. The encapsulation efficiency of the Rehmannia polysaccharide liposomes prepared in Examples 1 to 5 and Comparative Examples 1 to 3 was calculated respectively.

[0070] Encapsulation efficiency (%) = (1-Cr / Cs) x 100%, where Cr is the amount of free polysaccharide; Cs is the sum of encapsulated Rehmannia glutinosa polysaccharide and free Rehmannia glutinosa polysaccharide.

[0071] The test results are shown in Table 1.

[0072] Table 1

[0073] Group Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Encapsulation efficiency 72.5％ 71.3％ 70.9％ 70.4％ 67.8％ 61.0％ 64.2％ 60.7％

[0074] As shown in Table 1, the encapsulation efficiency of the Rehmannia glutinosa polysaccharide liposomes prepared in Example 1 is significantly higher than that of the comparative example. The encapsulation efficiency of the Rehmannia glutinosa polysaccharide liposomes is significantly affected when the order of adding monoglycerides is unchanged, the type of anionic phospholipids is replaced, or monoglycerides are not added.

[0075] (2) Live fish farming experiment

[0076] The feed additives prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were respectively added to conventional raw fish feed (25% soybean cake, 10% chicken meal, 25% fish meal, 15% bran, 15% flour, 6% fish oil, 2% multivitamins, 1% inorganic salt, and 1% feed binder), and the amount of the feed additive added was 5% of the total weight of the raw fish feed to prepare raw fish feed.

[0077] Live fish were used as the aquatic animal species for the aquaculture experiment. They were fed the raw fish feed supplemented with the feed additives prepared in Examples 1-5 and Comparative Examples 1-3, as well as conventional raw fish feed, to conduct a growth and aquaculture experiment. A recirculating aquaculture system was used for the growth and aquaculture experiment. A total of 450 commercially available raw fish fry with essentially identical growth conditions were randomly divided into nine groups of 50 fish each. The growth and aquaculture experiment was conducted for 40 days under the same environmental conditions, including temperature and pH. The feeding method and aquaculture conditions were conventional. After the aquaculture experiment, the weight gain rate, feed conversion rate, disease incidence rate, and survival rate of the raw fish were measured.

[0078] Table 2 Raw fish farming test results

[0079]

[0080] As shown in Table 2, compared with conventional raw fish feed, the raw fish feed prepared by adding the feed additives prepared in Examples 1 to 5 and Comparative Examples 1 to 3 can improve the survival rate and growth performance of raw fish to a certain extent. However, the raw fish fed with the feed prepared with the feed additives in Examples 1 to 5 of the present invention have significantly better weight gain rate, feed conversion rate, and survival rate than those in Comparative Examples 1 to 3. The feed additives provided by the present invention can increase the slow release of raw fish in the body of raw fish, promote intestinal health and growth, enhance their immunity, and reduce mortality.

Claims

1. A Rehmannia glutinosa polysaccharide liposome, characterized in that: The invention is composed of Rehmannia glutinosa polysaccharide and liposomes, wherein the liposomes are composed of dimyristoylphosphatidylcholine, monoglyceride, cholesterol and anionic phospholipids; the anionic phospholipids are selected from dipalmitoylphosphatidylglycerol and / or dipalmitoylphosphatidic acid; The mass ratio of dimyristoylphosphatidylcholine to monoglyceride, cholesterol and anionic phospholipid is 1:(0.05-0.1):(0.1-0.3):(0.5-1); The Rehmannia glutinosa polysaccharide liposomes are prepared by the following preparation method: dimyristoylphosphatidylcholine, cholesterol and anionic phospholipids are dissolved in ethanol, and after being fully dissolved, a PBS solution of Rehmannia glutinosa polysaccharide is added, followed by adding monoglyceride, shaking, and removing ethanol to obtain a suspension; and drying the suspension to obtain Rehmannia glutinosa polysaccharide liposomes.

2. The Rehmannia glutinosa polysaccharide liposome according to claim 1, characterized in that The mass ratio of the Rehmannia glutinosa polysaccharide to the liposome is (0.5-10):

100.

3. The Rehmannia glutinosa polysaccharide liposome according to claim 2, characterized in that The mass ratio of the Rehmannia glutinosa polysaccharide to the liposome is (1-8):

100.

4. The Rehmannia glutinosa polysaccharide liposome according to any one of claims 1 to 3, characterized in that The rehmannia polysaccharide is extracted from raw rehmannia root.

5. The method for preparing Rehmannia glutinosa polysaccharide liposomes according to any one of claims 1 to 4, characterized in that: The following steps are involved: Dissolve dimyristoylphosphatidylcholine, cholesterol and anionic phospholipids in ethanol, add PBS solution of Rehmannia glutinosa polysaccharide after they are fully dissolved, then add monoglyceride, shake and remove ethanol to obtain a suspension; dry the suspension to obtain Rehmannia glutinosa polysaccharide liposomes.

6. The preparation method according to claim 5, characterized in that In the PBS solution of Rehmannia glutinosa polysaccharide, the concentration of the Rehmannia glutinosa polysaccharide is 0.5-5 g / L.

7. The preparation method according to claim 5, characterized in that The shaking process is to control the temperature to be 40-60° C. and shake for 20-120 minutes.

8. The preparation method according to claim 5, characterized in that The suspension obtained after removing the ethanol was further subjected to ultrasonic treatment.

9. A feed additive, characterized in that The invention comprises the Rehmannia glutinosa polysaccharide liposome according to any one of claims 1 to 4.

10. A raw fish feed, characterized in that: The feed additive according to claim 9 is included; the addition amount of the feed additive is 2% to 8%.

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