Application of polypeptide in preparation of feed additive for improving disease resistance of prawns

Abstract

The invention relates to application of polypeptide in preparation of a feed additive for improving disease resistance of prawns, and belongs to the technical field of aquaculture. The polypeptide is anglerfish bone polypeptide, and the molecular weight of the anglerfish bone polypeptide is 1000-5000 Da. The anglerfish bone polypeptide prepared by fermentation pretreatment and enzymolysis processes can effectively improve the growth performance, disease resistance and immune function of litopenaeus vannamei. The prawns fed with the feed additive show significant final weight gain and relatively high survival rate, and especially show strong resistance when coping with infection of common pathogenic bacteria such as vibrio parahaemolyticus and the like. Therefore, the survival rate and the production efficiency of the prawns in the culture process are improved, the use of antibiotics can be reduced, the drug residues and the drug resistance of pathogenic bacteria are reduced, and the development of the green and sustainable prawn culture industry is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of aquaculture, and in particular relates to the application of a polypeptide in the preparation of a feed additive for improving the disease resistance of shrimp. Background Art

[0002] In recent years, with the continuous expansion of intensive shrimp farming, the deterioration of the aquaculture environment has become increasingly prominent. Especially under high-density farming conditions, harmful microorganisms in the water increase, the aquaculture water environment is prone to change, and various diseases are easily caused, which seriously threatens the growth and survival rate of shrimp. Frequent diseases not only bring huge economic losses to farmers, but also seriously restrict the sustainable development of the shrimp industry.

[0003] In order to deal with the disease problem, antibiotics and other chemical drugs are widely used in traditional aquaculture models to prevent and control diseases. However, long-term reliance on antibiotics not only leads to drug residues in shrimp, but also aggravates the drug resistance of pathogens, causing the prevention and control effect in the aquaculture process to gradually decline. In addition, the abuse of antibiotics will also damage the ecological environment of the water body and affect the health of other aquatic organisms. Therefore, how to reduce the use of antibiotics and other drugs while ensuring the healthy growth of shrimp has become an urgent problem to be solved.

[0004] Based on this, developing a feed additive that can improve the disease resistance of shrimp can not only enhance the immunity of shrimp and reduce the incidence rate, but also reduce the use of antibiotics and chemical drugs, thereby effectively avoiding drug residues and drug resistance problems, ensuring the safety and quality of shrimp products, and promoting the green and sustainable development of the shrimp industry. Summary of the invention

[0005] The purpose of the present invention is to provide an application of a polypeptide in the preparation of a feed additive for improving the disease resistance of shrimp, thereby effectively ensuring the healthy growth of shrimp.

[0006] To achieve the above object, the present invention provides the following technical solutions: First, the present invention provides an application of a polypeptide in the preparation of a feed additive for improving the growth and disease resistance of shrimp, wherein the polypeptide is a monkfish bone polypeptide, and the monkfish bone polypeptide is prepared by the following preparation method: (1) After cleaning the monkfish bones, cut them into small pieces and put them into water for degreasing; (2) drying the defatted monkfish bones, crushing them into powder, and sieving them to obtain monkfish bone powder; (3) resuscitating the Bacillus subtilis to obtain a Bacillus subtilis bacterial liquid; (4) Mix monkfish bone powder and water in a mass-to-volume ratio of 1:5, and add Bacillus subtilis solution to a final concentration of 1×10 8 bacteria / mL, fermentation pretreatment 24h; (5) After fermentation pretreatment, the fermentation product is collected and filtered to obtain fermented fish bone liquid; (6) After heating and sterilizing the fermented fish bone liquid, add 0.03 times the amount of alkaline protease for enzymatic hydrolysis; (7) After enzymatic hydrolysis is completed, heat to terminate the activity of alkaline protease; (8) Centrifuging and collecting the supernatant to obtain fishbone polypeptide liquid a; (9) Coarsely filtering the fish bone polypeptide liquid using a 0.45 μm microfiltration membrane to obtain fish bone polypeptide liquid b; (10) adding the fish bone polypeptide solution to an ultrafiltration system equipped with a 5000Da ultrafiltration membrane for ultrafiltration to obtain a permeate with a Da value less than 5000 and a retentate with a Da value greater than 5000; (11) adding the permeate to an ultrafiltration system equipped with a 1000Da ultrafiltration membrane for ultrafiltration, collecting the retentate to obtain a 1000-5000Da monkfish bone polypeptide solution; (12) freeze-drying the monkfish bone polypeptide liquid to obtain the monkfish bone polypeptide.

[0007] Preferably, the Bacillus subtilis has a preservation number of CGMCC1.14985, the fermentation pretreatment temperature is 30°C, and during the fermentation pretreatment, the final concentration of the Bacillus subtilis liquid is 10 8 Pieces / mL; The conditions of the enzymatic hydrolysis are 55° C., pH 8.5, and enzymatic hydrolysis for 3 hours.

[0008] Preferably, the disease resistance of the shrimp is the disease resistance of the shrimp to Vibrio parahaemolyticus, and the shrimp is Penaeus vannamei; The feed additive is added in an amount of 2 g of the feed additive per 1 kg of shrimp basic feed.

[0009] Then, the present invention provides a feed additive for improving the growth and disease resistance of shrimps. The feed additive is monkfish bone polypeptide, and the monkfish bone polypeptide is prepared by the above-mentioned preparation method.

[0010] Preferably, the improving the growth and disease resistance of shrimp refers to improving the growth and disease resistance of shrimp by increasing the pepsin and intestinal protease activities of shrimp and the non-specific immunity of shrimp; The prawn is Penaeus vannamei.

[0011] Then, the present invention provides a feed for improving the growth and disease resistance of shrimp, the feed consists of a basic feed and monkfish bone polypeptide, each 1kg of the basic feed corresponds to 2g of monkfish bone polypeptide, and the monkfish bone polypeptide is prepared by the above-mentioned preparation method.

[0012] Preferably, per 1 kg of the basic feed consists of 300 g of fish meal, 60 g of fermented soybean meal, 60 g of puffed soybean meal, 30 g of soybean meal, 100 g of peanut meal, 60 g of rapeseed meal, 20 g of squid viscera powder, 30 g of corn meal, 200 g of high-gluten flour, 80 g of shrimp shell powder, 20 g of soybean oil, 20 g of fish oil, 10 g of vitamin premix, and 10 g of mineral premix; Each 1kg of the vitamin premix contains 320,000 IU of vitamin A, 4g of vitamin B1, 8g of vitamin B2, 4.8g of vitamin B6, 0.016g of vitamin B12, 600,000 IU of vitamin D, 16g of vitamin E, 4g of vitamin K, 28g of niacin, 40g of inositol, 16g of calcium pantothenate, 0.064g of biotin, and 1.28g of folic acid; Each 1kg of the mineral premix contains 12g of magnesium sulfate monohydrate, 9g of calcium iodate, 36g of potassium chloride, 1.5g of copper methionine, 10g of zinc sulfate monohydrate, 1g of iron sulfate monohydrate, 0.25g of cobalt methionine, and 0.00036g of sodium selenite; The prawn is Penaeus vannamei.

[0013] Then, the present invention improves the application of a polypeptide in a feed additive for improving the digestion ability of Penaeus vannamei, wherein the polypeptide is a monkfish bone polypeptide, and the monkfish bone polypeptide is prepared by the above-mentioned preparation method, and the improvement of the digestion ability of Penaeus vannamei is to improve the pepsin activity and intestinal protease activity of Penaeus vannamei.

[0014] Then, the present invention improves the application of a polypeptide in a feed additive for improving the non-specific immunity of Litopenaeus vannamei. The polypeptide is a monkfish bone polypeptide, and the monkfish bone polypeptide is prepared by the above-mentioned preparation method.

[0015] Preferably, the improving the nonspecific immunity of Penaeus vannamei is to improve the activities of lysozyme and superoxide dismutase of Penaeus vannamei.

[0016] Finally, the present invention provides a method for improving the growth and disease resistance of Penaeus vannamei, characterized in that the method is to feed Penaeus vannamei with a feed containing monkfish bone polypeptide, the feed is composed of a shrimp basic feed and monkfish bone polypeptide, each 1kg of the shrimp basic feed corresponds to 2g of monkfish bone polypeptide, and the monkfish bone polypeptide is prepared by the above-mentioned preparation method; The feeding method is 4 times a day, once every 5 hours, and the feeding amount is 5% of the shrimp body weight.

[0017] The beneficial effects of the present invention are: The present invention finds that after the monkfish bone polypeptide (1000-5000 Da) is prepared by pretreatment with Bacillus subtilis (CGMCC1.14985) and fed to shrimp, the immunity of shrimp is significantly enhanced, especially when fighting against the infection of Vibrio parahaemolyticus, thereby effectively reducing the incidence of diseases and reducing the risk of diseases in the breeding process.

[0018] Secondly, the experimental results showed that the final body weight of shrimp fed with monkfish bone polypeptide was significantly higher than that of the control group, indicating that the polypeptide can effectively promote the growth and development of shrimp. The polypeptide promotes the digestion and absorption of nutrients such as protein by enhancing the activity of pepsin and intestinal protease in shrimp, thereby improving the utilization rate of feed and the growth rate of shrimp.

[0019] Secondly, the present invention significantly improves the activity of lysozyme and superoxide dismutase (SOD) in shrimps through the action of monkfish bone polypeptide, and enhances the nonspecific immune response of shrimps. The increase in lysozyme activity improves the ability of shrimps to resist bacterial infection, while the increase in SOD activity improves the antioxidant capacity of shrimps and reduces the impact of environmental stress on the health of shrimps.

[0020] In general, the monkfish bone polypeptide prepared by the present invention can not only effectively improve the growth performance and disease resistance of shrimp, but also reduce the dependence on antibiotics and chemical drugs in the breeding process, promote the green and sustainable development of the shrimp breeding industry, and has important promotion value and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The comparison results of the final weight of shrimp in different experimental groups are shown; Figure 2 The comparative results of shrimp survival rates in different experimental groups are shown; Figure 3 The comparative results of pepsin and intestinal protease activities of shrimps in different experimental groups are shown; Figure 4 The comparative results of shrimp lysozyme activity and superoxide dismutase activity in different experimental groups are shown; Figure 5 demonstrated the differences in survival rates of different groups of shrimp after infection with Vibrio parahaemolyticus; exist Figures 1 to 5In the table, the statistical symbols are used to indicate that the differences between different experimental groups and the control group are statistically significant. Specifically, * indicates that the difference is significant (P < 0.05), indicating that the difference between the experimental group and the control group reaches the 95% confidence level, indicating that the result is statistically significant. ** indicates that the difference is highly significant (P < 0.01), indicating that the difference between the experimental group and the control group reaches the 99% confidence level, further indicating that the experimental results are highly reliable. *** indicates that the difference is extremely significant (P < 0.001), indicating that the difference between the experimental group and the control group is significant at the 99.9% confidence level, proving that the result is highly statistically significant. DETAILED DESCRIPTION

[0022] The following is intended to elaborate on multiple implementation examples of the present invention, but please note that these descriptions are not meant to define the present invention, but to more deeply show certain aspects, features and implementation methods of the present invention.

[0023] In the description of the present invention, the terms used are only used to describe specific embodiments and do not constitute any limitation of the present invention. In addition, when the present invention refers to a numerical range, it should be understood that all intermediate values ​​within the range are disclosed simultaneously, including upper and lower limits.

[0024] Example 1 (1) Select fresh monkfish bones, remove the remaining muscles, and use clean water to remove blood stains and impurities on the surface; (2) Cut the washed monkfish bones into small pieces of 1-2 cm, heat them in 50°C water for 1 hour to remove the grease in the bones, wash them with clean water, and dry them at 50°C for 6 hours; (3) using a grinder to grind the dried monkfish bones into powder, and passing through a 60-mesh sieve to obtain monkfish bone powder; (4) After reviving Bacillus subtilis (Accession No.: CGMCC1.14985), inoculate into LB medium and culture at 30°C for 12 hours to obtain Bacillus subtilis culture liquid; (5) Mix monkfish bone powder and water in a mass-volume ratio of 1:5, add Bacillus subtilis culture solution, and ferment at 30°C for 24 h. The final concentration of the culture solution is 1×10 8 Bacteria / mL; (6) After fermentation pretreatment, the fermentation product is collected, and after filtering, the fermented fish bone liquid is collected; (7) Heat the fermented fish bone liquid to 85°C and maintain it for 15 minutes to terminate the activity of the bacteria during the fermentation process; (8) Add 0.03 times the amount of alkaline protease, adjust the pH value to 8.5, adjust the water bath heating temperature to 55°C, and perform enzymolysis for 3 hours; (9) After the enzymatic hydrolysis is completed, heat to 90°C and maintain for 15 min to terminate the activity of alkaline protease; (10) Centrifuging at 3000 rpm for 20 min to separate the fish bone peptide liquid after enzymatic hydrolysis from the solid residue, and collecting the supernatant to obtain fish bone polypeptide liquid a; (11) coarsely filtering the fish bone polypeptide liquid using a 0.45 μm microfiltration membrane to obtain fish bone polypeptide liquid b; (12) adding the fish bone polypeptide solution to an ultrafiltration system equipped with a 5000Da ultrafiltration membrane, and performing ultrafiltration at a pressure of 2 bar at room temperature to obtain a permeate of less than 5000Da and a retentate of greater than 5000Da; (13) adding the permeate into an ultrafiltration system equipped with a 1000Da ultrafiltration membrane, performing ultrafiltration at a pressure of 2 bar and room temperature, collecting the retentate, and obtaining a 1000-5000Da fishbone polypeptide solution c; (14) adding the retentate into an ultrafiltration system with a 10,000 Da ultrafiltration membrane, performing ultrafiltration at a pressure of 2 bar and room temperature, collecting the permeate, and obtaining a 5,000-10,000 Da fishbone polypeptide solution d; (15) After the fishbone polypeptide liquid c and the fishbone polypeptide liquid d were concentrated to 1 / 5 of the original volume, they were freeze-dried to obtain monkfish bone polypeptide A (1000-5000Da) and monkfish bone polypeptide B (5000-10000Da).

[0025] Example 2 (1) Select fresh monkfish bones, remove the remaining muscles, and use clean water to remove blood stains and impurities on the surface; (2) Cut the washed monkfish bones into small pieces of 1-2 cm, heat them in 50°C water for 1 hour to remove the grease in the bones, wash them with clean water, and dry them at 50°C for 6 hours; (3) using a grinder to grind the dried monkfish bones into powder, and passing through a 60-mesh sieve to obtain monkfish bone powder; (4) Mix monkfish bone powder and water in a mass-to-volume ratio of 1:5, add 0.03 times the amount of alkaline protease, adjust the pH value to 8.5, adjust the water bath heating temperature to 55°C, and perform enzymolysis for 3 hours; (5) After the enzymatic hydrolysis is completed, heat to 90°C and maintain for 15 min to terminate the activity of alkaline protease; (6) Centrifuging at 3000 rpm for 20 min to separate the fishbone peptide liquid from the solid residue after enzymatic hydrolysis, and collecting the supernatant to obtain fishbone polypeptide liquid a; (7) coarsely filtering the fishbone polypeptide liquid using a 0.45 μm microfiltration membrane to obtain fishbone polypeptide liquid b; (8) adding the fish bone polypeptide solution to an ultrafiltration system equipped with a 5000Da ultrafiltration membrane, and performing ultrafiltration at a pressure of 2 bar at room temperature to obtain a permeate of less than 5000Da and a retentate of greater than 5000Da; (9) adding the permeate into an ultrafiltration system equipped with a 1000Da ultrafiltration membrane, performing ultrafiltration at a pressure of 2 bar and room temperature, collecting the retentate, and obtaining a 1000-5000Da fishbone polypeptide solution c; (10) adding the retentate into an ultrafiltration system with a 10,000 Da ultrafiltration membrane, performing ultrafiltration at a pressure of 2 bar and room temperature, collecting the permeate, and obtaining a 5,000-10,000 Da fishbone polypeptide solution d; (11) After the fishbone polypeptide liquid c and the fishbone polypeptide liquid d are concentrated to 1 / 5 of the original volume, they are freeze-dried to obtain monkfish fishbone polypeptide C (1000-5000Da) and monkfish fishbone polypeptide D (5000-10000Da).

[0026] Example 3 Testing the effects of different peptides as feed additives on shrimp growth (1) Prepare the basic shrimp feed according to the following formula: Basic feed: 300g fish meal, 60g fermented soybean meal, 60g puffed soybean meal, 30g soybean meal, 100g peanut meal, 60g rapeseed meal, 20g squid viscera powder, 30g corn meal, 200g high-gluten flour, 80g shrimp shell powder, 20g soybean oil, 20g fish oil, 10g vitamin premix, 10g mineral premix.

[0027] Each kilogram of vitamin premix contains vitamin A 320,000IU, vitamin B1 4g, vitamin B2 8g, vitamin B6 4.8g, vitamin B12 0.016g, vitamin D 600,000IU, vitamin E 16g, vitamin K 4g, niacin 28g, inositol 40g, calcium pantothenate 16g, biotin 0.064g, folic acid 1.28g; Each kilogram of mineral premix contains 12g of magnesium sulfate monohydrate, 9g of calcium iodate, 36g of potassium chloride, 1.5g of copper methionine, 10g of zinc sulfate monohydrate, 1g of iron sulfate monohydrate, 0.25g of cobalt methionine, and 0.00036g of sodium selenite.

[0028] (2) The shrimps weighing about 5.5 g were randomly divided into 5 groups, namely, a control group fed with a basic feed, a fishbone polypeptide A group fed with 2 g of monkfish fishbone polypeptide A per 1 kg of basic feed, a fishbone polypeptide B group fed with 2 g of monkfish fishbone polypeptide B per kg of basic feed, a fishbone polypeptide C group fed with 2 g of monkfish fishbone polypeptide C per kg of basic feed, and a fishbone polypeptide D group fed with 2 g of monkfish fishbone polypeptide D per kg of basic feed. Three replicates were set for each group, with 100 shrimps in each replicate. Feeding method: 4 times a day, every 5 hours, feeding amount is 5% of shrimp body weight; (3) After continuous feeding for 42 days, the final body weight and survival rate of the shrimp were tested. The results are shown in Table 1 and Figure 2 and Figure 3 shown.

[0029] Table 1 Effects of different fish bone peptides added as feed on shrimp growth and survival rate

[0030] Combined with Table 1, Figure 1 and Figure 2 The results show that in terms of final body weight, compared with the control group, the experimental groups fed with monkfish bone polypeptides all showed a certain degree of improvement. However, the weight increase of fishbone polypeptide group C and fishbone polypeptide group D did not reach statistical significance, and although fishbone polypeptide group B was statistically significant, its overall improvement effect was still relatively limited. Relatively speaking, the final body weight of fishbone polypeptide group A was significantly improved, showing a clear growth advantage.

[0031] In terms of survival rate, although the experimental groups showed improvements compared with the control groups, only the fishbone polypeptide A group showed statistically significant improvement in survival rate, and the survival rate improvements in other groups did not show significant differences.

[0032] These results show that only the monkfish bone polypeptide A with a molecular weight of 1000-5000 Da prepared by the method of Example 1 can significantly promote the growth of shrimp and improve the survival rate. It shows that whether Bacillus subtilis (CGMCC1.14985) is used for pretreatment and the molecular weight of the monkfish bone polypeptide have an important influence on the function of the polypeptide.

[0033] Example 4 Effects of monkfish bone peptide A on the activities of pepsin and intestinal proteases in shrimp (1) After the breeding experiment in Example 3 was completed, feeding was stopped for 24 hours, and 12 shrimps were randomly selected from the control group and the fish bone polypeptide A group in Example 3, and the stomach tissue and intestinal tissue were obtained by dissection; (2) Add normal saline to gastric tissue and intestinal tissue at a ratio of 1:10 and homogenize (3000 rpm, centrifuge for 10 min); (3) The activity of pepsin and enteropeptide was detected using the Nanjing Jiancheng Biotechnology Protease Kit. The results are shown in Table 2 and Figure 3 shown.

[0034] Table 2 Effects of monkfish bone peptide A on the activity of pepsin and intestinal protease in shrimp

[0035] From Table 2 and Figure 3 The results show that in the experimental group fed with monkfish bone polypeptide A, the pepsin and intestinal protease activities of shrimp were significantly higher than those of the control group. This shows that monkfish bone polypeptide A has a positive effect on the digestive system of shrimp and can significantly increase its digestive enzyme activity.

[0036] Example 5 Effects of monkfish bone peptide A on nonspecific immunity of shrimp (1) After the breeding experiment in Example 3 was completed, feeding was stopped for 24 hours, and 12 shrimps were randomly selected from the control group and the fish bone polypeptide A group in Example 3, and hemolymph was collected by inserting into the pericardial cavity behind the cephalothorax of the shrimps; (2) Place the mixture in a centrifuge tube, centrifuge at 4°C, 5000 rpm for 10 min, and collect the supernatant. (3) The activity of lysozyme and superoxide dismutase was detected using the Nanjing Jiancheng Biological Kit. The results are shown in Table 3 and Figure 4 shown.

[0037] Table 3 Effects of monkfish bone peptide A on nonspecific immunity of shrimp

[0038] From Table 3 and Figure 4 The results show that in the experimental group fed with monkfish bone polypeptide A, the activities of non-specific immune enzymes of shrimp: lysozyme and superoxide dismutase (SOD) were significantly higher than those of the control group. This shows that monkfish bone polypeptide A has a significant immune-promoting effect and can effectively enhance the non-specific immune function of shrimp.

[0039] Specifically, lysozyme is an important antibacterial enzyme in the innate immune system of shrimp, which inhibits the growth of pathogenic microorganisms by decomposing bacterial cell walls. The significant upregulation of its activity indicates that fish bone polypeptide A can enhance the antibacterial defense ability of shrimp and help resist common aquatic pathogens. On the other hand, superoxide dismutase (SOD) is a key antioxidant enzyme responsible for removing superoxide anions in the body and reducing the damage of oxidative stress to cells.

[0040] Example 6 From the results in Table 3, it can be seen that the promoting effect of monkfish bone polypeptide A on lysozyme is more significant. Therefore, the present invention speculates that its effect on resisting aquatic pathogen infection is more significant, and thus the anti-Vibrio parahaemolyticus ability of shrimp fed with monkfish bone polypeptide A is tested.

[0041] (1) resuscitating the Vibrio parahaemolyticus preserved by the present invention using TSB medium at 28° C. for 18-24 hours; (2) After several generations of culture, calculate the effective viable count and adjust it to 2×10 7 cfu / mL median lethal concentration; (3) 80 shrimps were randomly selected from the control group, fish bone polypeptide group A, fish bone polypeptide group B, fish bone polypeptide group C, and fish bone polypeptide group D after feeding in Example 3 to conduct a Vibrio parahaemolyticus challenge experiment, divided into 5 replicates; (4) Each tail was injected with 25 μL. The experiment lasted for 14 days. The survival rate of each replicate was counted and the survival rate of each group was calculated. The results are as follows: Figure 5 shown.

[0042] from Figure 5 The results show that the survival rate of the experimental group fed with monkfish fish bone polypeptide A (81.25±4.42) was significantly higher than that of the control group (46.25±3.42), indicating that fish bone polypeptide A has a significant effect in improving the disease resistance of shrimp. Although the survival rates of fish bone polypeptide B group (52.50±5.59), fish bone polypeptide C group (48.75±2.80) and fish bone polypeptide D group (47.50±3.42) were slightly higher than those of the control group, the differences did not reach statistical significance, indicating that the effects of fish bone polypeptides in these groups on improving the survival rate of shrimp were relatively limited.

[0043] This significant difference in survival rate indicates that monkfish bone polypeptide A plays a key role in enhancing the disease resistance of shrimp, especially in resisting Vibrio parahaemolyticus infection. Vibrio parahaemolyticus is a common aquatic pathogen that can easily cause large-scale infection and death of shrimp. The experimental results showed that feeding monkfish bone polypeptide A significantly increased the survival rate of shrimp, which may be due to its activation of nonspecific immune response, enhancing the antibacterial and antioxidant capacity of shrimp, thereby improving the disease resistance and environmental adaptability of shrimp.

[0044] These results further prove that monkfish bone polypeptide A can effectively improve the survival rate by enhancing the immunity and disease resistance of shrimp. This also shows that fish bone polypeptide A has important application potential as a feed additive in the actual breeding process, which can help reduce the disease risk of shrimp and improve the success rate of breeding, and has broad promotion value.

Claims

1. Use of a polypeptide in the preparation of a feed additive for improving the growth and disease resistance of shrimp, characterized in that: The polypeptide is a monkfish bone polypeptide, and the monkfish bone polypeptide is prepared by the following preparation method: (1) After cleaning the monkfish bones, cut them into small pieces and put them into water for degreasing; (2) drying the defatted monkfish bones, crushing them into powder, and sieving them to obtain monkfish bone powder; (3) resuscitating the Bacillus subtilis to obtain a Bacillus subtilis bacterial liquid; (4) Mix monkfish bone powder and water in a mass-to-volume ratio of 1:5, and add Bacillus subtilis solution to a final concentration of 1×10 8 bacteria / mL, fermentation pretreatment 24h; (5) After fermentation pretreatment, the fermentation product is collected and filtered to obtain fermented fish bone liquid; (6) After heating and sterilizing the fermented fish bone liquid, add 0.03 times the amount of alkaline protease for enzymatic hydrolysis; (7) After enzymatic hydrolysis is completed, heat to terminate the activity of alkaline protease; (8) Centrifuging and collecting the supernatant to obtain fishbone polypeptide liquid a; (9) Coarsely filtering the fishbone polypeptide liquid using a 0.45 μm microfiltration membrane to obtain fishbone polypeptide liquid b; (10) adding the fish bone polypeptide solution to an ultrafiltration system equipped with a 5000Da ultrafiltration membrane for ultrafiltration to obtain a permeate with a Da value less than 5000 and a retentate with a Da value greater than 5000; (11) adding the permeate to an ultrafiltration system equipped with a 1000Da ultrafiltration membrane for ultrafiltration, collecting the retentate to obtain a 1000-5000Da monkfish bone polypeptide solution; (12) freeze-drying the monkfish bone polypeptide liquid to obtain the monkfish bone polypeptide.

2. The use according to claim 1, characterized in that: The deposit number of the Bacillus subtilis is CGMCC1.14985, and the temperature of the fermentation pretreatment is 30°C; The enzymatic hydrolysis conditions are 55° C., pH 8.5, and enzymatic hydrolysis for 3 hours.

3. The use according to claim 2, characterized in that: The disease resistance of the shrimp is the disease resistance of the shrimp to Vibrio parahaemolyticus, and the shrimp is Penaeus vannamei; The feed additive is added in an amount of 2 g of the feed additive per 1 kg of shrimp basic feed.

4. A feed additive for improving the growth and disease resistance of shrimp, characterized in that: The feed additive is monkfish bone polypeptide, and the monkfish bone polypeptide is prepared by the preparation method described in claim 1.

5. The use according to claim 4, characterized in that: Improving the growth and disease resistance of shrimp refers to improving the growth and disease resistance of shrimp by increasing the pepsin and intestinal protease activities of shrimp and the non-specific immunity of shrimp; The prawn is Penaeus vannamei.

6. A feed for improving the growth and disease resistance of shrimp, characterized in that: The feed consists of a basic feed and monkfish bone polypeptide, and each 1 kg of the basic feed corresponds to 2 g of monkfish bone polypeptide. The monkfish bone polypeptide is prepared by the preparation method according to claim 1.

7. The feed according to claim 6, characterized in that Each 1kg of the basic feed consists of 300g of fish meal, 60g of fermented soybean meal, 60g of puffed soybean meal, 30g of soybean meal, 100g of peanut meal, 60g of rapeseed meal, 20g of squid viscera meal, 30g of corn meal, 200g of high-gluten flour, 80g of shrimp shell meal, 20g of soybean oil, 20g of fish oil, 10g of vitamin premix, and 10g of mineral premix; Each 1kg of the vitamin premix contains 320,000 IU of vitamin A, 4g of vitamin B1, 8g of vitamin B2, 4.8g of vitamin B6, 0.016g of vitamin B12, 600,000 IU of vitamin D, 16g of vitamin E, 4g of vitamin K, 28g of niacin, 40g of inositol, 16g of calcium pantothenate, 0.064g of biotin, and 1.28g of folic acid; Each 1kg of the mineral premix contains 12g of magnesium sulfate monohydrate, 9g of calcium iodate, 36g of potassium chloride, 1.5g of copper methionine, 10g of zinc sulfate monohydrate, 1g of iron sulfate monohydrate, 0.25g of cobalt methionine, and 0.00036g of sodium selenite; The prawn is Penaeus vannamei.

8. Use of a polypeptide in a feed additive for improving the digestibility of Penaeus vannamei, characterized in that: The polypeptide is a monkfish bone polypeptide, which is prepared by the preparation method according to claim 1. The method of improving the digestion capacity of Penaeus vannamei is to improve the pepsin activity and intestinal protease activity of Penaeus vannamei.

9. Use of a polypeptide in a feed additive for improving the nonspecific immunity of Penaeus vannamei, characterized in that: The polypeptide is a monkfish bone polypeptide, and the monkfish bone polypeptide is prepared by the preparation method according to claim 1.

10. The use according to claim 9, characterized in that: The method of improving the nonspecific immunity of Penaeus vannamei is to improve the activities of lysozyme and superoxide dismutase of Penaeus vannamei.

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