Feed additive for improving egg laying capacity of laying fowls

Abstract

The invention relates to a feed additive for improving the egg laying capacity of laying fowls, and belongs to the technical field of animal medicine. The feed additive is specifically a bullacta exarata polypeptide-polysaccharide compound, bullacta exarata polypeptide is extracted by hydrolyzing bullacta exarata meat, and laminarin is a natural polysaccharide component extracted from laminaria japonica. Results of the invention show that the bullacta exarata polypeptide-polysaccharide compound can significantly promote proliferation of ovarian granular cells of laying fowls and enhance the oxidation resistance of the cells, so that the egg laying performance of the laying fowls is improved, specifically, the egg laying number and the average egg weight are improved. Therefore, the feed additive disclosed by the invention has relatively good economic benefits and application prospects, and can be widely applied to breeding of laying fowls, so that the breeding benefits are increased, and the production performance of the laying fowls is improved.

Description

Technical Field

[0001] The invention relates to the technical field of animal medicine, and in particular to a feed additive for improving the egg-laying ability of laying birds. Background Art

[0002] In recent years, with the rapid development of the breeding industry, how to improve the egg-laying capacity of laying poultry has become an important issue in modern breeding. At present, there are many feed additives on the market to improve the egg-laying capacity of laying poultry, including amino acids, vitamins, minerals and certain plant extracts. These feed additives promote egg production by regulating the nutritional status of laying poultry and improving their physiological functions. However, existing feed additives mostly focus on providing basic nutrition or regulating endocrine, and often fail to deeply regulate the physiological mechanisms of laying poultry at the cellular and molecular levels, resulting in limited effects and sometimes causing drug resistance problems.

[0003] In addition, the egg-laying capacity of laying birds is not only related to nutritional components, but also closely related to factors such as ovarian health, follicular development, and hormone regulation. In the egg-laying process of laying birds, the proliferation and functional maintenance of ovarian granulosa cells play a vital role. The function of ovarian granulosa cells not only directly affects the development of follicles and yolk quality, but is also closely related to the overall reproductive health of laying birds. Therefore, improving the growth and functional maintenance of ovarian granulosa cells has become a potential research direction for improving egg-laying capacity. Summary of the invention

[0004] The purpose of the present invention is to provide a feed additive for improving the egg-laying ability of laying hens, thereby improving the egg-laying ability of laying hens by promoting the proliferation of ovarian granulosa cells and resisting oxidative stress damage.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In the first technical solution, the present invention provides a feed additive for improving the egg-laying ability of laying fowl, wherein the feed additive is a mud snail polypeptide-polysaccharide complex, wherein the mud snail polypeptide is obtained by hydrolyzing mud snail meat, and the polysaccharide is kelp polysaccharide.

[0007] Preferably, the method for preparing the mud snail polypeptide-polysaccharide complex comprises the following steps:

[0008] (1) dissolving mud snail polypeptide and laminarin in water in a mass ratio of 1:1 to obtain a polypeptide-polysaccharide mixed solution;

[0009] (2) adding the polypeptide-polysaccharide mixed solution into a reaction vessel and reacting at 100° C. for 1.5 h to obtain a mud snail polypeptide-polysaccharide complex solution;

[0010] (3) concentrating the mud snail polypeptide-polysaccharide complex solution;

[0011] (4) The concentrated mud snail polypeptide-polysaccharide complex solution is transferred to a freeze dryer and freeze-dried to obtain the mud snail polypeptide-polysaccharide complex.

[0012] Preferably, the method for preparing the mud snail polypeptide comprises the following steps:

[0013] (1) Take out the fresh mud snail meat and rinse it with water;

[0014] (2) placing the mud snail meat in liquid nitrogen for rapid freezing and then grinding it into powder;

[0015] (3) Mix the powder with isopropyl alcohol and perform degreasing treatment;

[0016] (4) filtering and collecting the defatted mud snail powder and drying it;

[0017] (5) mixing the dried mud snail powder and distilled water in a mass volume ratio of 1:12 to form a mud snail powder mixed solution;

[0018] (6) adjusting the pH of the mud snail powder mixture to 7.0, heating it in a water bath to 50° C., adding 3% of the mass of the mud snail powder neutral protease, and reacting for 90 minutes;

[0019] (7) raising the water bath temperature to 55° C., adjusting the pH to 9.0, adding 3% alkaline protease by mass of mud snail powder, and continuing hydrolysis for 90 minutes;

[0020] (8) After the reaction is completed, the enzyme is inactivated;

[0021] (9) transferring the inactivated enzymatic hydrolysate to a centrifuge tube, centrifuging, and separating the supernatant;

[0022] (10) filtering the supernatant using a 0.45 μm filter membrane to obtain a mud snail solution;

[0023] (11) First, the mud snail solution was initially filtered using a 10 kDa ultrafiltration membrane to collect the permeate, and then secondary filtered using a 3 kDa ultrafiltration membrane to collect the retentate;

[0024] (12) concentrating the retentate to obtain a mud snail polypeptide solution;

[0025] (13) The mud snail polypeptide solution is transferred to a freeze dryer and freeze-dried to obtain the mud snail polypeptide.

[0026] Preferably, the laying fowl is a Hy-Line brown laying hen, and the amount of the mud snail polypeptide-polysaccharide complex used is 0.05% of the amount used in the basic feed;

[0027] The egg-laying capacity includes the number of eggs laid and the average egg weight of the Hy-Line brown laying hens.

[0028] In the second technical solution, the present invention provides a feed for improving the egg-laying ability of laying fowls, wherein the feed is composed of a basic feed and the aforementioned feed additive, and the amount of the feed additive used is 0.05% of the amount of the basic feed used.

[0029] Preferably, the laying poultry is a Hy-Line brown laying hen, and the egg-laying capacity includes the number of eggs laid and the average egg weight of the Hy-Line brown laying hen.

[0030] In a third technical solution, the present invention provides a use of a mud snail polypeptide-polysaccharide complex in the preparation of a feed preparation for improving the egg-laying capacity of laying poultry by improving the proliferation capacity and anti-oxidative stress damage capacity of ovarian granulosa cells, wherein the mud snail polypeptide-polysaccharide complex is prepared by the preparation method of the mud snail polypeptide-polysaccharide complex described in claim 2;

[0031] The mud snail polypeptide is prepared by the mud snail polypeptide preparation method described in claim 3.

[0032] Preferably, the laying poultry is a Hy-Line brown laying hen, and the egg-laying capacity includes the number of eggs laid and the average egg weight of the Hy-Line brown laying hen.

[0033] Preferably, the ability to resist oxidative stress damage is the ability to resist oxidative stress damage caused by peroxides.

[0034] The beneficial effects of the present invention are:

[0035] The mud snail polypeptide-polysaccharide complex provided by the present invention is used as a feed additive and has the effect of significantly improving the egg-laying ability of laying birds. Through the action of the complex, the proliferation ability and the ability to resist oxidative stress damage of ovarian granulosa cells of Hy-Line Brown laying hens can be significantly enhanced, thereby increasing the number of eggs produced and the weight of eggs.

[0036] Compared with the use of mud snail polypeptide or laminarin alone, the complex of the present invention combines the unique advantages of mud snail polypeptide and laminarin, and greatly enhances its effect of promoting the proliferation of ovarian granulosa cells through the synergistic effect of the two. The experimental results show that at a lower concentration, the mud snail polypeptide-polysaccharide complex can significantly increase the proliferation rate of ovarian granulosa cells, and at a high concentration, the proliferation effect is more significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The protective effect of mud snail polypeptide-polysaccharide complex on oxidative stress damage;

[0038] Figure 2 The effect of mud snail polypeptide-polysaccharide complex on the egg production rate of Hy-Line Brown laying hens;

[0039] Figure 3This is the effect of mud snail polypeptide-polysaccharide complex on the average egg weight of Hy-Line brown laying hens. DETAILED DESCRIPTION

[0040] The embodiments of the present invention are for better explanation of the present invention, but the content of the present invention is not limited to the embodiments. Therefore, those skilled in the art can make non-essential improvements and adjustments to the implementation scheme according to the above invention content, which still fall within the protection scope of the present invention.

[0041] Example 1

[0042] Preparation of mud snail peptides

[0043] (1) Take out the fresh mud snail meat and rinse it repeatedly with running water to remove dirt and impurities on the surface to ensure it is clean.

[0044] (2) The mud snail meat is quickly frozen in liquid nitrogen and then ground into powder using a liquid nitrogen grinder.

[0045] (3) Mix with isopropanol in a ratio of 1:4 (m / v) and degrease in a 40°C water bath for 120 min, stirring several times during the process.

[0046] (4) Filter and collect the defatted mud snail powder, place it in a preheated electric constant temperature blast drying oven, set the temperature to 60° C., and dry it for 24 hours.

[0047] (5) The dried mud snail powder is weighed and mixed with distilled water in a mass-to-volume ratio of 1:12 to form a mud snail powder mixed solution.

[0048] (6) The pH of the solution was adjusted to 7.0 using 1 M sodium hydroxide or hydrochloric acid, heated to 50° C. in a water bath, and neutral protease (3% by weight of mud snail powder) was added and reacted for 90 minutes.

[0049] (7) The water bath temperature was raised to 55° C., the pH was adjusted to 9.0, and alkaline protease was added at 3% by weight of the mud snail powder, and the hydrolysis was continued for 90 minutes.

[0050] (8) After the reaction is completed, the temperature is raised to 90°C and heated for 10 minutes to inactivate the enzyme.

[0051] (9) The inactivated enzymatic hydrolysate was transferred to a centrifuge tube and centrifuged at 12,000 rpm for 15 minutes using a high-speed centrifuge to separate the supernatant.

[0052] (10) filtering the supernatant using a 0.45 μm filter membrane to obtain a mud snail solution;

[0053] (11) First, the mud snail solution was initially filtered using a 10 kDa ultrafiltration membrane to collect the permeate, and then secondary filtered using a 3 kDa ultrafiltration membrane to collect the retentate;

[0054] (12) The retentate was transferred to a rotary evaporator and concentrated to 1 / 5 of the volume of the retentate to obtain a mud snail polypeptide solution.

[0055] (13) The mud snail polypeptide solution was transferred to a freeze dryer and freeze-dried under low temperature and low pressure conditions of -50°C and 0.2 mBar to obtain the mud snail polypeptide.

[0056] Example 2

[0057] Preparation of Mud Snail Polypeptide-Polysaccharide Complex

[0058] (1) dissolving mud snail polypeptide and laminarin in deionized water in a mass ratio of 1:1 to obtain a polypeptide-polysaccharide mixed solution;

[0059] (2) adding the polypeptide-polysaccharide mixed solution into a reactor and reacting at 100° C. for 1.5 h to obtain a mud snail polypeptide-polysaccharide complex solution;

[0060] (3) transferring the mud snail polypeptide-polysaccharide complex solution to a rotary evaporator and concentrating it to 1 / 5 of the volume of the mud snail polypeptide-polysaccharide complex solution;

[0061] (4) The concentrated mud snail polypeptide-polysaccharide complex solution is transferred to a freeze dryer and freeze-dried to obtain the mud snail polypeptide-polysaccharide complex.

[0062] Example 3

[0063] Detection of the effect of mud snail polypeptide-polysaccharide complex on the proliferation of ovarian granulosa cells of Hy-Line Brown laying hens

[0064] Experimental procedure A: Primary culture of ovarian granulosa cells from Hy-Line Brown laying hens

[0065] 1. Ovarian extraction and preliminary cleaning:

[0066] Hy-Line brown laying hens at the peak of egg-laying period were killed, and their ovaries were removed and immediately placed in pre-cooled sterile PBS (phosphate buffered saline) to prevent tissue degeneration.

[0067] 2. Separation of small yellow follicles:

[0068] Small yolk follicles were isolated from the ovaries and washed with PBS to remove blood, debris, and external contaminants;

[0069] Use a sterile scalpel to cut the small yolk follicle, gently release the yolk, and rinse again with PBS to remove the yolk residue.

[0070] 3. Separation of granular cell layer:

[0071] Carefully separate the granulosa cell layer in the follicle, transfer the separated granulosa cell layer to a 50 mL sterile centrifuge tube, and let it stand for 5 minutes to help the cells settle.

[0072] 4. Enzyme digestion treatment:

[0073] Add 5 mL of 0.2% collagenase II solution preheated to 37°C to the granulosa cells and digest in a 37°C water bath for 10 minutes to digest the extracellular matrix and help separate the granulosa cells from the follicular matrix;

[0074] After digestion was completed, 5 mL of 4°C pre-cooled M199 medium was added to the digestion solution to terminate the digestion reaction.

[0075] 5. Cell filtration and centrifugation:

[0076] Filter the cell suspension using a 70 μm cell strainer to remove residual tissue chunks and incompletely digested structures to ensure a pure cell suspension.

[0077] The filtered cell suspension was transferred to a centrifuge tube and centrifuged at 1000 rpm for 8 minutes.

[0078] 6. Resuspension and centrifugation:

[0079] After discarding the supernatant, add M199 medium to the precipitate, mix the precipitate by pipetting to ensure that the cells are evenly distributed, and then centrifuge again at 1000 r / min for 8 minutes.

[0080] 7. Inoculation of cells:

[0081] Add the precipitated cells to new M199 medium, mix gently, and then inoculate the cell suspension into the culture dish;

[0082] After cell seeding, immediately place the culture dish in an incubator set to 5% CO 2 , culture environment of 37℃.

[0083] 8. Cell culture and medium replacement:

[0084] After cell inoculation, the first medium change was performed after 24 hours of culture to remove metabolic waste and dead cells generated during the cell culture process.

[0085] After that, the medium is changed every 2-3 days to remove waste and solve the problem of nutrient deficiency, ensuring that the cells continue to proliferate in the optimal growth state.

[0086] Experimental procedure B: CCK-8 assay to detect the effect of mud snail polypeptide-polysaccharide complex on the proliferation of ovarian granulosa cells of Hy-Line Brown laying hens

[0087] (1) Hy-Line Brown Laying Hen Ovarian Granulosa Cells were inoculated into a 96-well culture plate and placed in a cell culture incubator for further culture;

[0088] (2) The prepared mud snail polypeptide-polysaccharide complex was prepared into mud snail polypeptide-polysaccharide complex solutions of different concentrations using M199 culture medium:

[0089] Low concentration: 1μg / mL, medium concentration: 10μg / mL, second highest concentration: 50μg / mL, high concentration;

[0090] (3) After the cells in the 96-well plate were cultured for 24 hours, the culture plate was removed, the culture medium was removed, and the cells were treated according to the following experimental groups (each group was set up with 5 replicate wells):

[0091] Control group: added M199 culture medium,

[0092] The low concentration group was added with low concentration mud snail polypeptide-polysaccharide complex solution.

[0093] The medium concentration group was added with medium concentration mud snail polypeptide-polysaccharide complex solution.

[0094] The second highest concentration group was added with the second highest concentration mud snail polypeptide-polysaccharide complex solution.

[0095] The high-concentration group was added with high-concentration mud snail polypeptide-polysaccharide complex solution.

[0096] (4) The 96-well plate was placed in the cell culture incubator for 48 h, and the absorbance of each treatment well at 450 nm was detected using CCK-8 reagent.

[0097] Table 1 Effects of mud snail polypeptide-polysaccharide complex on proliferation of ovarian granulosa cells of Hy-Line Brown laying hens

[0098]

[0099] According to the data results in Table 1, the mud snail polypeptide-polysaccharide complex prepared by the present invention shows a significant effect in promoting the proliferation of ovarian granulosa cells. Under the treatment of the mud snail polypeptide-polysaccharide complex at the lowest concentration of 1 μg / mL, the proliferation ability of ovarian granulosa cells increased by 20.91%. This result shows that the mud snail polypeptide-polysaccharide complex can significantly promote the proliferation of ovarian granulosa cells at extremely low concentrations.

[0100] Under higher concentration treatment, the proliferation effect of each group was further improved. The proliferation rate of the medium concentration group increased by 55.68% compared with the control group; the second highest concentration group performed particularly well, with a proliferation rate increased by 79.47%; the high concentration group also showed a good proliferation promotion effect, with a proliferation capacity increased by 68.88%. These data show that different concentrations of mud snail polypeptide-polysaccharide complexes can significantly promote the proliferation of ovarian granulosa cells.

[0101] Among them, the effect of the high-concentration group was slightly lower than that of the second-highest concentration group. This may be because the high concentration of mud snail polypeptide-polysaccharide complex triggered cellular stress response or other negative effects, resulting in the inhibition of cell proliferation.

[0102] Example 4 Detection of the effect of using mud snail polypeptide or laminarin alone on the proliferation of ovarian granulosa cells

[0103] (1) Hy-Line Brown Laying Hen Ovarian Granulosa Cells were inoculated into a 96-well culture plate and placed in a cell culture incubator for further culture;

[0104] (2) Laminarin and the mud snail polypeptide prepared in Example 1 of the present invention were prepared in M199 medium to concentrations of 1 μg / mL and 50 μg / mL;

[0105] (3) After the cells in the 96-well plate were cultured for 24 hours, the culture plate was removed, the culture medium was removed, and the cells were treated according to the following experimental groups (each group was set up with 5 replicate wells):

[0106] Control group: added M199 culture medium,

[0107] Mud snail polypeptide low concentration group: 1 μg / mL mud snail polypeptide was added.

[0108] Mud snail polypeptide high concentration group: 50 μg / mL mud snail polypeptide was added.

[0109] Low-concentration laminarin group: 1 μg / mL laminarin was added.

[0110] High-concentration laminarin group: 50 μg / mL laminarin was added;

[0111] (4) The 96-well plate was placed in the cell culture incubator for 48 h, and the absorbance of each treatment well at 450 nm was detected using CCK-8 reagent.

[0112] Table 2 Detection of the effects of mud snail polypeptide or laminarin on the proliferation of ovarian granulosa cells

[0113]

[0114] According to the data results in Table 2, compared with the control group, the absorbance values ​​of the low-concentration mud snail polypeptide group and the low-concentration laminarin group did not show significant changes, indicating that 1 μg / mL mud snail polypeptide and 1 μg / mL laminarin, when used alone, failed to significantly promote the proliferation of chicken ovarian granulosa cells. This result suggests that at low concentrations, the use of mud snail polypeptide or laminarin alone has limited effect on promoting cell proliferation.

[0115] Further analysis showed that although the absorbance of the high-concentration laminarin group was slightly higher than that of the control group, the difference did not reach a statistically significant level, which means that the promoting effect of laminarin on the proliferation of ovarian granulosa cells at a concentration of 50 μg / mL is still not obvious. The absorbance of the high-concentration mud snail polypeptide group was slightly higher than that of the control group. Although it has improved, the effect is still relatively limited and far less than the proliferation-promoting effect of the mud snail polypeptide-polysaccharide complex. This difference shows that the effect of using mud snail polypeptide or laminarin alone in promoting cell proliferation is relatively weak.

[0116] In summary, the complex of mud snail polypeptide and laminarin can significantly enhance cell proliferation ability compared to when used alone. This result shows that the combination of mud snail polypeptide and laminarin may enhance their respective biological activities through synergistic effects, and exert an effect that cannot be achieved when used alone. Therefore, the mud snail polypeptide-polysaccharide complex prepared by the present invention significantly improves the promotion effect on the proliferation of chicken ovarian granulosa cells by integrating the advantages of both.

[0117] Example 5

[0118] Detection of the protective effect of mud snail polypeptide-polysaccharide complex on ovarian granulosa cells oxidative stress injury

[0119] Oxidative stress damage can lead to apoptosis of ovarian granulosa cells, which in turn can cause follicular atresia in laying hens, ultimately leading to a decrease in egg production in laying hens. Therefore, reducing the damage of oxidative stress to ovarian granulosa cells is the key to improving the egg production rate of laying hens.

[0120] (1) Hy-Line Brown Laying Hen Ovarian Granulosa Cells were inoculated into a 96-well culture plate and placed in a cell culture incubator for further culture;

[0121] (2) When the cell density reached about 85%, the culture medium was removed and 50 μg / mL of a serum-free mud snail polypeptide-polysaccharide complex solution, 50 μg / mL of a mud snail polypeptide solution, and 50 μg / mL of a laminarin solution were added, respectively, for pretreatment for 24 h;

[0122] (3) The cells are grouped and processed according to the following groups:

[0123] Control group: cells without pretreatment were treated with M199 medium for 6 h;

[0124] Oxidative stress injury group: cells without pretreatment were treated with M199 medium containing 50 μmol / L H2O2 for 6 h;

[0125] Mud snail polypeptide-polysaccharide complex group: cells pretreated with mud snail polypeptide-polysaccharide complex were treated with M199 medium containing 50 μmol / L H2O2 for 6 h;

[0126] Mud snail polypeptide group: cells pretreated with mud snail polypeptide were treated with M199 medium containing 50 μmol / L H2O2 for 6 h;

[0127] Laminarin group: cells pretreated with laminarin were treated with M199 medium containing 50 μmol / L H2O2 for 6 h;

[0128] (4) After the treatment, the absorbance of each treated well at 450 nm was detected using CCK-8 reagent and the survival rate was calculated.

[0129] from Figure 1 The results showed that the cell survival rate in the oxidative stress injury group was 61.36±3.67%, which was significantly lower than that in the control group, indicating that the establishment of the oxidative stress model was successful and could effectively simulate the damage response of ovarian granulosa cells to oxidative stress.

[0130] In the intervention group, the cell survival rate of the mud snail polypeptide-polysaccharide complex group was 88.52±2.87%, which was significantly higher than that of the oxidative stress injury group and the group using mud snail polypeptide or laminarin alone. The cell survival rates of the mud snail polypeptide group and laminarin group were 67.96±2.99% and 65.66±3.65%, respectively. These data indicate that although pretreatment with mud snail polypeptide or laminarin alone can protect cells to a certain extent, the effect is still limited.

[0131] However, the combined use of mud snail polypeptide and kelp polysaccharide showed a significant synergistic effect, and the cell survival rate was significantly improved after pretreatment, reaching 88.52±2.87%. This result shows that the mud snail polypeptide-polysaccharide complex has a significant protective effect in reducing oxidative stress damage, and can effectively improve the survival rate of ovarian granulosa cells and slow down cell damage caused by oxidative stress.

[0132] Example 6

[0133] Detection of the effect of mud snail polypeptide-polysaccharide complex on egg production rate of Hy-Line brown laying hens

[0134] (1) A total of 240 Hy-Line brown laying hens aged 350 days with good health, consistent body weight and egg production were selected and randomly divided into two experimental treatments, with five replicates in each treatment and 24 hens in each replicate.

[0135] (2) The experiment was divided into a control group and an experimental group. The control group was fed with a basic diet, and the experimental group was fed with a basic diet supplemented with 0.05% mud snail polypeptide-polysaccharide complex, wherein the composition of the basic diet was as follows:

[0136] 61% corn, 25% soybean meal, 5% premix, 1% rapeseed oil, 8% rock flour.

[0137] (3) The experiment was conducted in cages, with the test feed fed twice a day to ensure balanced feeding; all drugs were discontinued during the egg-laying period. The health and mental state of the chickens were observed daily, and the disinfection and cleaning of the test house were carried out according to routine procedures. All groups had free access to food and water.

[0138] (4) After 15 days, the experiment ended and the egg production rate and egg weight were calculated.

[0139] Table 3 Effects of mud snail polypeptide-polysaccharide complex on egg production rate and egg weight

[0140] Experimental Grouping Egg production rate Average egg weight Control group 87.11％ 60.16g Experimental Group <![CDATA[92.87% *** ]]> <![CDATA[63.08g *** ]]>

[0141] From Table 3 and Figure 2 and Figure 3 The results show that compared with the control group, the experimental group that added 0.05% mud snail polypeptide-polysaccharide complex to the feed had an egg production rate of 6.61% and an average egg weight of 4.86%. It can be seen that a small amount of mud snail polypeptide-polysaccharide complex in the basic feed of laying hens can significantly increase the egg production rate and average egg weight of Hy-Line Brown laying hens.

Claims

1. A feed additive for improving the egg-laying ability of laying fowl, characterized in that: The feed additive is a mud snail polypeptide-polysaccharide complex, the mud snail polypeptide is obtained by hydrolyzing mud snail meat, and the polysaccharide is kelp polysaccharide.

2. The feed additive according to claim 1, characterized in that The preparation method of the mud snail polypeptide-polysaccharide complex comprises the following steps: (1) dissolving mud snail polypeptide and laminarin in water in a mass ratio of 1:1 to obtain a polypeptide-polysaccharide mixed solution; (2) adding the polypeptide-polysaccharide mixed solution into a reaction vessel and reacting at 100° C. for 1.5 h to obtain a mud snail polypeptide-polysaccharide complex solution; (3) concentrating the mud snail polypeptide-polysaccharide complex solution; (4) The concentrated mud snail polypeptide-polysaccharide complex solution is transferred to a freeze dryer and freeze-dried to obtain the mud snail polypeptide-polysaccharide complex.

3. The feed additive according to claim 2, characterized in that The preparation method of the mud snail polypeptide comprises the following steps: (1) Take out the fresh mud snail meat and rinse it with water; (2) placing the mud snail meat in liquid nitrogen for rapid freezing and then grinding it into powder; (3) Mix the powder with isopropyl alcohol and perform degreasing treatment; (4) filtering and collecting the defatted mud snail powder and drying it; (5) mixing the dried mud snail powder and distilled water in a mass volume ratio of 1:12 to form a mud snail powder mixed solution; (6) adjusting the pH of the mud snail powder mixture to 7.0, heating it in a water bath to 50° C., adding 3% of the mass of the mud snail powder neutral protease, and reacting for 90 minutes; (7) raising the water bath temperature to 55° C., adjusting the pH to 9.0, adding 3% alkaline protease by mass of mud snail powder, and continuing hydrolysis for 90 minutes; (8) After the reaction is completed, the enzyme is inactivated; (9) transferring the inactivated enzymatic hydrolysate to a centrifuge tube, centrifuging, and separating the supernatant; (10) filtering the supernatant using a 0.45 μm filter membrane to obtain a mud snail solution; (11) First, the mud snail solution was initially filtered using a 10 kDa ultrafiltration membrane to collect the permeate, and then secondary filtered using a 3 kDa ultrafiltration membrane to collect the retentate; (12) concentrating the retentate to obtain a mud snail polypeptide solution; (13) The mud snail polypeptide solution is transferred to a freeze dryer and freeze-dried to obtain the mud snail polypeptide.

4. The feed additive according to claim 3, characterized in that The laying fowl is a Hy-Line brown laying hen, and the amount of the mud snail polypeptide-polysaccharide complex used is 0.05% of the amount of the basic feed used; The egg-laying capacity includes the number of eggs laid and the average egg weight of the Hy-Line brown laying hens.

5. A feed for improving the egg-laying ability of laying fowl, characterized in that: The feed is composed of a basic feed and the feed additive according to claims 1-4, and the amount of the feed additive used is 0.05% of the amount of the basic feed.

6. The feed according to claim 5, characterized in that The laying poultry is a Hy-Line brown laying hen, and the egg-laying capacity includes the number of eggs laid and the average egg weight of the Hy-Line brown laying hen.

7. Use of a mud snail polypeptide-polysaccharide complex in the preparation of a feed preparation for improving the egg-laying capacity of laying poultry by improving the proliferation capacity and anti-oxidative stress damage capacity of ovarian granulosa cells, characterized in that: The mud snail polypeptide-polysaccharide complex is prepared by the preparation method of the mud snail polypeptide-polysaccharide complex described in claim 2; The mud snail polypeptide is prepared by the mud snail polypeptide preparation method described in claim 3.

8. The use according to claim 7, characterized in that: The laying poultry is a Hy-Line brown laying hen, and the egg-laying capacity includes the number of eggs laid and the average egg weight of the Hy-Line brown laying hen.

9. The use according to claim 8, characterized in that: The ability to resist oxidative stress damage is the ability to resist oxidative stress damage caused by peroxides.

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