Polypeptide composition for improving disease resistance of animals and preparation method thereof

Abstract

The invention provides a polypeptide composition for improving disease resistance of animals and a preparation method thereof, and the polypeptide composition comprises the following components in parts by weight: 20-30 parts of soybean meal polypeptide, 15-25 parts of seabuckthorn seed meal polypeptide, 10-15 parts of a houttuynia cordata extract, 5-10 parts of a licorice extract and 5-10 parts of astragalus polysaccharide. The synergistic effect of polypeptide and polysaccharide components in the composition can effectively enhance the immunity of animals, so that the resistance of the animals to external pathogens is improved, and the infection probability is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of animal husbandry, and in particular to a polypeptide composition for improving the disease resistance of animals and a preparation method thereof. Background Art

[0002] With the continuous expansion of animal husbandry, animals are vulnerable to pathogens such as bacteria, viruses and parasites under intensive breeding and high-intensity environmental pressure, resulting in decreased immunity and increased disease incidence. In this case, conventional anti-disease means mainly rely on antibiotics and chemical drugs. However, the long-term use of these drugs has brought significant problems. Drug resistance problem: Due to the abuse of antibiotics, pathogenic strains gradually develop drug resistance, resulting in decreased sensitivity to drugs, forming "super bacteria", which brings greater challenges to disease prevention and control. This drug resistance is not only produced in animals, but may also be transmitted to humans through the food chain, threatening public health safety. Drug residues: Drug residues caused by long-term use of antibiotics in livestock and poultry products pose a potential hazard to human health. Excessive or improper use of antibiotics can lead to excessive drug residues in meat, milk and egg products. Environmental pressure: The metabolites of antibiotics and chemical drugs in animals and unabsorbed residual drugs will be discharged through feces, enter the environment, pollute water and soil, and then affect the ecosystem, especially aquatic organisms and soil microbial communities.

[0003] In view of the above problems, the animal husbandry industry has gradually paid attention to natural and green disease resistance solutions and sought effective solutions to replace antibiotics. In this regard, plant-derived extracts and active peptides are highly valued because of their natural safety and low toxicity. Plant peptides are usually extracted from plant proteins through a specific enzymatic hydrolysis process, which not only retains biological activity, but also has multiple functions such as enhancing immunity, anti-oxidation, and anti-inflammatory. In addition, natural disease-resistant ingredients such as astragalus polysaccharides, ganoderma lucidum polysaccharides, and green tea polyphenols have been proven to effectively enhance animals' disease resistance and reduce the frequency of disease due to their regulatory effects on the immune system.

[0004] Therefore, by combining plant peptides with natural disease-resistant extracts, a composition with both immunomodulatory and disease-resistant effects is developed, which can not only replace the use of some antibiotics, but also improve animal health and increase breeding efficiency, meeting the needs of antibiotic-free breeding and sustainable development. Summary of the invention

[0005] Based on the problems existing in the background technology, the present invention provides a polypeptide composition for improving the disease resistance of animals and a preparation method thereof.

[0006] The present invention is implemented by the following technical solutions: A polypeptide composition for improving the disease resistance of animals comprises the following components by weight: 20-30 parts of soybean meal polypeptide, 15-25 parts of seabuckthorn seed meal polypeptide, 10-15 parts of houttuynia cordata extract, 5-10 parts of liquorice extract and 5-10 parts of astragalus polysaccharide.

[0007] Furthermore, the method for preparing soybean meal polypeptide comprises the following steps: S101. The soybean meal is crushed and mixed with deionized water to obtain a suspension; S102. adjusting the pH value of the suspension to 8.0-9.0, extracting at 45-50° C. for 2-3 hours, collecting the supernatant by centrifugation after extraction, adjusting the pH value of the supernatant to 4.5-5.0 to precipitate the protein, collecting the precipitate and washing it to neutrality to obtain a crude protein; S103. hydrolyzing the crude protein using a protease to obtain an enzymatic hydrolysate; S104. The enzymatic hydrolysate is ultrafiltered, concentrated, and dried to obtain soybean meal polypeptide.

[0008] Further, in step S103, the crude protein is hydrolyzed by protease, specifically: the crude protein is dispersed in a buffer solution, alkaline protease is added, the amount of enzyme added is 1%-2% of the weight of the crude protein, the pH value is adjusted to 8.5-9.0, the temperature is maintained at 45-50°C, the hydrolysis time is 1-2h, and after the hydrolysis is completed, it is heated to 85-90°C, maintained for 10min, and cooled to room temperature to obtain a preliminary enzymatic solution; the pH value of the preliminary enzymatic solution is adjusted to neutral, trypsin is added, the amount of trypsin added is 0.5%-1% of the weight of the crude protein, the temperature is maintained at 45-50°C, the hydrolysis time is 1-2h, after the hydrolysis is completed, it is heated to 85-90°C, maintained for 10min, and cooled to room temperature to obtain an enzymatic solution.

[0009] Soybean meal peptides have immunomodulatory and antioxidant effects, can increase the activity of immune cells and enhance the immune function of animals. The rich amino acids in soybean meal peptides help promote protein synthesis and improve the overall health of animals.

[0010] In order to obtain a polypeptide with a better immune enhancement effect, alkaline protease and trypsin are used in combination in the present invention. Alkaline protease is first used for preliminary hydrolysis under alkaline conditions, and then trypsin is used for fine hydrolysis under neutral conditions to generate a variety of short-chain polypeptides and disease-resistant active ingredients. After the combined action of alkaline protease and trypsin, soybean meal protein is gradually decomposed into short-chain polypeptides, and the polypeptides finally obtained are mainly low-molecular-weight small peptides, and the molecular weight is generally between 500-2000 Daltons. This small molecule polypeptide is more easily absorbed by the animal intestine due to its high solubility and bioavailability, which helps to improve the disease-resistant effect.

[0011] Furthermore, the preparation method of seabuckthorn seed meal polypeptide comprises the following steps: S201. The seabuckthorn seed meal was crushed and mixed with deionized water to obtain a suspension, the pH of the suspension was adjusted to 12, and the extraction was performed at 37° C. for 50 min, and the extraction was repeated 2-3 times, and the supernatant was collected by centrifugation; S202. The pH value of the supernatant was adjusted to 5.0-5.5, phytase and tannase were added at 0.1-0.5% of the mass of seabuckthorn seed meal, and the mixture was hydrolyzed at 35-50°C for 2-5h. After the hydrolysis was completed, the mixture was heated to 85-90°C and maintained for 10min to obtain a pretreated hydrolyzate; S203. Hydrolyzing the pretreated hydrolyzate with a protease to obtain a hydrolyzate; S204. Ultrafilter, concentrate and dry the enzymatic hydrolyzate to obtain seabuckthorn seed meal polypeptide.

[0012] Furthermore, in step S203, the specific operation of enzymolyzing the pretreated hydrolysate with protease is as follows: adding trypsin to the pretreated hydrolysate, the amount of trypsin added is 1-2% of the mass of the sea buckthorn seed meal, adjusting the pH value to 8.0-8.5, maintaining the temperature at 45-50°C, the hydrolysis time is 1-2h, heating to 85-90°C after the hydrolysis is completed, maintaining for 10min, cooling to room temperature, and obtaining a preliminary hydrolysate; adjusting the pH value of the preliminary hydrolysate to neutral, adding a composite protease, the amount of the composite protease added is 1-2% of the mass of the sea buckthorn seed meal, maintaining the temperature at 45-50°C, the hydrolysis time is 1-2h, heating to 85-90°C after the hydrolysis is completed, maintaining for 10min, cooling to room temperature, and obtaining a hydrolysate.

[0013] Furthermore, the composite protease is flavor protease and neutral protease, and the weight ratio thereof is (1-2):1.

[0014] Seabuckthorn seed meal polypeptides are rich in vitamins and active ingredients, can enhance the immunity and anti-inflammatory ability of animals, and reduce oxidative stress reactions inside and outside cells. In addition, the components of seabuckthorn seeds can promote intestinal health, enhance digestion and absorption functions, and provide more effective nutritional support for the body. In the present invention, trypsin is first used to act on macromolecular proteins, hydrolyze their main peptide bonds, and decompose them into smaller polypeptide fragments, effectively reducing the molecular weight of the protein, making it easier for subsequent composite proteases to act on the residual peptide chains, and further decompose them into small molecular polypeptides. The combination of flavor protease and neutral protease can act on unused peptide bonds, improve enzymolysis efficiency, increase the diversity and specificity of polypeptide types, and thus obtain more comprehensive physiological activity. The polypeptides obtained after multi-step enzymolysis are rich in content and have small molecular weight characteristics. These polypeptides show excellent antioxidant properties in vivo, help to scavenge free radicals, and reduce oxidative damage. This polypeptide composition can effectively regulate the immune system of animals, improve the activity of antibodies and immune cells in the body, enhance disease resistance, and is particularly suitable for promoting animal health as a functional additive in feed.

[0015] Furthermore, the preparation method of Houttuynia cordata extract is specifically as follows: crush the washed and dried Houttuynia cordata, use ethanol as the extraction solvent, put the Houttuynia cordata powder and ethanol in a Soxhlet extractor at a weight ratio of 1: (8-12), heat and reflux, the extraction temperature is 40-50°C, the extraction time is 40-60min, the extraction is performed 2-3 times, the extracts are combined and concentrated, and finally placed in a dryer for drying at a drying temperature of 50-60°C to obtain the Houttuynia cordata extract.

[0016] Houttuynia cordata extract has natural antibacterial, antiviral and anti-inflammatory effects, and can effectively inhibit a variety of pathogenic microorganisms. Its unique ingredients can activate the immune system, promote the proliferation of immune cells, and increase the resistance of animals to infection.

[0017] Furthermore, the preparation method of licorice extract is specifically as follows: crush the washed and dried licorice, use 40-60% ethanol aqueous solution as the extraction solution, put the licorice powder and ethanol aqueous solution into a Soxhlet extractor at a weight ratio of 1: (12-16), heat and reflux, the extraction temperature is 40-60°C, under the condition of ultrasonic power of 75-85W, the extraction time is 40-60min, extract 2-3 times, combine and concentrate the extracts, and finally place them in a dryer for drying at a drying temperature of 50-60°C to obtain the licorice extract.

[0018] Licorice extract contains glycyrrhizic acid and flavonoids, which have immunomodulatory, anti-inflammatory and antiviral effects, can help relieve inflammatory responses and enhance the body's resistance. At the same time, the analgesic and antioxidant properties of licorice extract also help improve the overall health of animals.

[0019] Astragalus polysaccharide is an important immunopotentiator with significant immunomodulatory effects. It can increase the activity of macrophages and lymphocytes, increase the production of antibodies, and strengthen the immune system of animals. Astragalus polysaccharide also has antiviral and antibacterial effects, which can improve the resistance of animals to pathogens in the environment.

[0020] The invention also discloses a method for preparing a polypeptide composition for improving animal disease resistance, comprising the following steps: uniformly mixing soybean meal polypeptide, seabuckthorn seed meal polypeptide, houttuynia cordata extract, licorice extract and astragalus polysaccharide to obtain the polypeptide composition for improving animal disease resistance.

[0021] Finally, the invention discloses the application of the polypeptide composition for improving the disease resistance of animals, which is used as a feed additive to improve the disease resistance of animals, and the added amount accounts for 0.1-5% of the total feed amount.

[0022] Beneficial effects of the present invention: The synergistic effect of the polypeptide and polysaccharide components in the composition of the present invention can effectively enhance the immunity of animals, improve their resistance to external pathogens, and reduce the chance of infection. The seabuckthorn seed meal polypeptide, licorice extract and houttuynia extract in the composition all have antioxidant and anti-inflammatory effects, which help to reduce cell damage caused by oxidative stress, reduce inflammatory reactions, and maintain cell health. Soybean meal polypeptide and seabuckthorn seed meal polypeptide can help improve the intestinal microenvironment, enhance the intestinal absorption of nutrients, improve feed utilization, and thus promote the growth and development of animals. Licorice extract, houttuynia extract and astragalus polysaccharide work together to effectively resist common pathogens and viral infections, further enhance the disease resistance of animals, and reduce the risk of disease transmission. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0024] The alkaline protease, trypsin, flavor protease and neutral protease used in the examples and comparative examples of the present application were purchased from Shanghai Yuanye Biotechnology Co., Ltd.; astragalus polysaccharide was purchased from Shaanxi Bolin Biotechnology Co., Ltd.

[0025] Example 1 A polypeptide composition for improving the disease resistance of animals comprises the following components by weight: 25 parts of soybean meal polypeptide, 20 parts of seabuckthorn seed meal polypeptide, 13 parts of houttuynia cordata extract, 8 parts of liquorice extract and 8 parts of astragalus polysaccharide.

[0026] The preparation method of the composition comprises the following steps: uniformly mixing soybean meal polypeptide, seabuckthorn seed meal polypeptide, houttuynia cordata extract, liquorice extract and astragalus polysaccharide to obtain a polypeptide composition for improving the disease resistance of animals.

[0027] The method for preparing soybean meal polypeptide comprises the following steps: S101. The soybean meal was crushed and mixed with deionized water to obtain a 15% concentration suspension; S102. adjusting the pH value of the suspension to 9.0, extracting at 45° C. for 3 h, collecting the supernatant by centrifugation after extraction, adjusting the pH value of the supernatant to 4.5 to precipitate the protein, collecting the precipitate and washing it to neutrality to obtain a crude protein; S103. Enzymatically hydrolyze the crude protein using a protease: disperse the crude protein in a buffer, add alkaline protease in an amount of 1.5% of the crude protein mass, adjust the pH value to 8.5, maintain the temperature at 45°C, hydrolyze for 2 hours, heat to 90°C after the hydrolysis is completed, maintain for 10 minutes, and cool to room temperature to obtain a preliminary enzymatic hydrolyzate; adjust the pH value of the preliminary enzymatic hydrolyzate to neutral, add trypsin in an amount of 1% of the crude protein mass, maintain the temperature at 45°C, hydrolyze for 2 hours, heat to 90°C after the hydrolysis is completed, maintain for 10 minutes, and cool to room temperature to obtain an enzymatic hydrolyzate; S104. The enzymatic hydrolysate is ultrafiltered, concentrated, and dried to obtain soybean meal polypeptide.

[0028] The preparation method of seabuckthorn seed meal polypeptide comprises the following steps: S201. The seabuckthorn seed meal was crushed and mixed with deionized water to obtain a 15% concentration suspension, the pH of the suspension was adjusted to 12, and the extraction was performed at 37°C for 50 min, repeated 3 times, and the supernatant was collected by centrifugation; S202. The pH value of the supernatant was adjusted to 5.5, phytase and tannase were added at 0.3% of the mass of seabuckthorn seed meal, and the mixture was hydrolyzed at 40°C for 4 hours. After the hydrolysis was completed, the mixture was heated to 90°C and maintained for 10 minutes to obtain a pretreated hydrolyzate. S203. The pre-treated hydrolyzate is hydrolyzed by using a protease: trypsin is added to the pre-treated hydrolyzate, the amount of trypsin added is 2% of the mass of the sea buckthorn seed meal, the pH value is adjusted to 8.5, the temperature is maintained at 50°C, the hydrolysis time is 2h, after the hydrolysis is completed, it is heated to 90°C, maintained for 10min, and cooled to room temperature to obtain a preliminary hydrolyzate; the pH value of the preliminary hydrolyzate is adjusted to neutral, and a composite protease is added, the composite protease is a flavor protease and a neutral protease, and the weight ratio thereof is 2:1; the amount of the composite protease added is 1.5% of the mass of the sea buckthorn seed meal, the temperature is maintained at 45°C, the hydrolysis time is 2h, after the hydrolysis is completed, it is heated to 85-90°C, maintained for 10min, and cooled to room temperature to obtain a hydrolyzate; S204. Ultrafilter, concentrate and dry the enzymatic hydrolyzate to obtain seabuckthorn seed meal polypeptide.

[0029] The preparation method of Houttuynia cordata extract is specifically as follows: crush the washed and dried Houttuynia cordata, use ethanol as the extraction solvent, put the Houttuynia cordata powder and ethanol in a Soxhlet extractor at a weight ratio of 1:10, heat and reflux, the extraction temperature is 45°C, the extraction time is 50 minutes, the extraction is repeated 3 times, the extracts are combined and concentrated, and finally placed in a dryer for drying at a drying temperature of 55°C to obtain the Houttuynia cordata extract.

[0030] The preparation method of licorice extract is specifically as follows: crush the washed and dried licorice, use 50% ethanol aqueous solution as the extraction solution, put the licorice powder and ethanol aqueous solution into a Soxhlet extractor at a weight ratio of 1:14, heat to reflux, the extraction temperature is 55°C, under the condition of ultrasonic power of 80W, the extraction time is 80min, extract 3 times, combine and concentrate the extracts, and finally place them in a dryer for drying at a drying temperature of 55°C to obtain the licorice extract.

[0031] Specifically, for the process of extracting while maintaining a fixed temperature, various types of sensors are set to obtain heating data, and the heating process is intelligently controlled based on the heating data: Construct a heating model for the insulated extraction container and obtain current heating data; Based on the past container heating history data, the heat preservation extraction container heating model is trained to obtain the trained heat preservation extraction container heating model; During the current extraction process, based on the current heating data, the trained heat preservation extraction container heating model is used to control the heating unit to keep the container temperature stable.

[0032] Preferably, the heating history data or the current heating data at least includes the temperature of the key points of the container. , Gas flow , Gas valve opening , the volume of liquid in the container and container pressure etc.; based on this, the input data set is generated , where each item represents the above heating data collected at that moment, for example Indicates the temperature of the key point of the container corresponding to time 0 , Gas flow , Gas valve opening , the volume of liquid in the container and container pressure wait; Based on deep learning technology, a recurrent neural network (RNN) is used to construct the heat preservation extraction container heating model, the input data set is used as the input sequence data of the RNN, and the output sequence data of the hidden layer and the output layer are determined based on the activation function; The heat preservation extraction container heating model is trained based on the heating history data; the loss function of the neural network is

[0033] in, for The predicted temperature at the time; for The real temperature of the moment.

[0034] The heating unit is controlled based on the trained insulation extraction container heating model, which better ensures the stability of the container temperature when the liquid gradually decreases during the extraction process, ensures that the properties of the liquid do not change during the extraction process, and improves the stability of the overall preparation process.

[0035] Example 2 A polypeptide composition for improving the disease resistance of animals comprises the following components by weight: 30 parts of soybean meal polypeptide, 20 parts of seabuckthorn seed meal polypeptide, 13 parts of houttuynia cordata extract, 8 parts of liquorice extract and 8 parts of astragalus polysaccharide.

[0036] The preparation method of the composition and the preparation method of each component are the same as those in Example 1.

[0037] Example 3 A polypeptide composition for improving the disease resistance of animals comprises the following components by weight: 20 parts of soybean meal polypeptide, 20 parts of seabuckthorn seed meal polypeptide, 13 parts of houttuynia cordata extract, 8 parts of liquorice extract and 8 parts of astragalus polysaccharide.

[0038] The preparation method of the composition and the preparation method of each component are the same as those in Example 1.

[0039] Example 4 A polypeptide composition for improving the disease resistance of animals comprises the following components by weight: 25 parts of soybean meal polypeptide, 15 parts of seabuckthorn seed meal polypeptide, 13 parts of houttuynia cordata extract, 8 parts of liquorice extract and 8 parts of astragalus polysaccharide.

[0040] The preparation method of the composition and the preparation method of each component are the same as those in Example 1.

[0041] Example 5 A polypeptide composition for improving the disease resistance of animals comprises the following components by weight: 25 parts of soybean meal polypeptide, 25 parts of seabuckthorn seed meal polypeptide, 13 parts of houttuynia cordata extract, 8 parts of liquorice extract and 8 parts of astragalus polysaccharide.

[0042] The preparation method of the composition and the preparation method of each component are the same as those in Example 1.

[0043] Comparative Example 1 A polypeptide composition comprises the following components by weight: 25 parts of soybean meal polypeptide, 20 parts of seabuckthorn seed meal polypeptide, 13 parts of houttuynia cordata extract and 8 parts of liquorice extract.

[0044] The preparation method of the composition and the preparation method of each component are the same as those in Example 1.

[0045] Comparative Example 2 A polypeptide composition comprises the following components by weight: 45 parts of soybean meal polypeptide, 13 parts of houttuynia cordata extract, 8 parts of liquorice extract and 8 parts of astragalus polysaccharide.

[0046] The preparation method of the composition and the preparation method of each component are the same as those in Example 1.

[0047] Comparative Example 3 A polypeptide composition comprises the following components by weight: 40 parts of seabuckthorn seed meal polypeptide, 13 parts of houttuynia cordata extract, 8 parts of liquorice extract and 8 parts of astragalus polysaccharide.

[0048] The preparation method of the composition and the preparation method of each component are the same as those in Example 1.

[0049] Comparative Example 4 A polypeptide composition comprises the following components by weight: 25 parts of soybean meal polypeptide, 20 parts of seabuckthorn seed meal polypeptide, 13 parts of houttuynia cordata extract, 8 parts of liquorice extract and 8 parts of astragalus polysaccharide.

[0050] In S103 of the method for preparing soybean meal polypeptide, crude protein is dispersed in a buffer solution, alkaline protease is added, the amount of enzyme added is 1.5% of the crude protein mass, the pH value is adjusted to 8.5, the temperature is maintained at 45°C, the hydrolysis time is 2 hours, and after the hydrolysis is completed, it is heated to 90°C, maintained for 10 minutes, and cooled to room temperature to obtain an enzymatic hydrolyzate; the remaining preparation steps are the same as in Example 1; that is, a single alkaline protease is used to hydrolyze the crude protein to prepare soybean meal polypeptide.

[0051] The preparation method of the composition and the preparation methods of the remaining components are the same as those in Example 1.

[0052] Comparative Example 5 A polypeptide composition comprises the following components by weight: 25 parts of soybean meal polypeptide, 20 parts of seabuckthorn seed meal polypeptide, 13 parts of houttuynia cordata extract, 8 parts of liquorice extract and 8 parts of astragalus polysaccharide.

[0053] Among them, in the preparation method S203 of sea buckthorn seed meal polypeptide, the pre-treated enzymatic solution is enzymolyzed by protease: trypsin is added to the pre-treated enzymatic solution, the added amount of trypsin is 2% of the mass of the sea buckthorn seed meal, the pH value is adjusted to 8.5, the temperature is maintained at 50°C, the hydrolysis time is 2h, and after the hydrolysis is completed, it is heated to 90°C, maintained for 10min, and cooled to room temperature to obtain the enzymatic solution; the remaining preparation steps are the same as in Example 1; that is, a single trypsin is used to enzymolyze the pre-treated enzymatic solution to prepare the sea buckthorn seed meal polypeptide.

[0054] The preparation method of the composition and the preparation methods of the remaining components are the same as those in Example 1.

[0055] Test Example 1 The polypeptide compositions in Examples 1-5 and Comparative Examples 1-5 were added as additives to laying hen feed for feeding; the addition amount was 2%.

[0056] 25-day-old healthy laying hens that were not immunized with any vaccine provided by a laying hen farm were randomly divided into 10 treatment groups and 1 control group (fed with laying hen feed without adding the polypeptide composition), with 100 chickens in each group. Each treatment group was fed with the polypeptide compositions of Examples 1-5 and Comparative Examples 1-5 as additives added to the laying hen feed, twice a day, and other conditions were the same.

[0057] Starting from the 80th day of feeding, the number of sick and dead laying hens in each group was recorded every day until the end of the experiment. Sick laying hens include all the symptoms.

[0058] From 120 days to 220 days, the number of eggs laid and broken eggs in each group was recorded every day, and the statistical days were 100 days. Egg laying rate (%) = total egg production during the statistical period / (number of laying hens in the pen × number of statistical days) × 100%; broken egg rate (%) = total broken eggs during the statistical period / (total eggs laid during the statistical period × number of statistical days) × 100%.

[0059] The experimental results are shown in Table 1.

[0060] Table 1

[0061] As can be seen from Table 1, the morbidity rate, broken egg rate, egg production rate and broken egg rate of laying hens in Examples 1-5 are better than those in the control group and Comparative Examples 1-5, indicating that the polypeptide composition used in the present invention can be added to laying hen feed as a feed additive to improve the disease resistance of laying hens, enhance nutrient absorption, and enhance the immunity of laying hens, thereby increasing the egg production rate of laying hens and reducing the broken egg rate.

[0062] Test Example 2 The polypeptide compositions in Example 1 and Comparative Examples 1-5 were added as additives to broiler feed for feeding; the addition amount was 2%.

[0063] Healthy 7-day-old broilers that were not immunized with any vaccine provided by a laying hen farm were randomly divided into 6 treatment groups and 1 control group (fed with broiler feed without adding the polypeptide composition), with 50 chickens in each group. Each treatment group was fed with the polypeptide composition of Example 1 and Comparative Examples 1-5 as an additive added to the broiler feed, twice a day, and other conditions were the same. Jugular vein blood was collected on the 14th, 21st and 29th days of the experiment, and serum was separated to detect Newcastle disease antibodies.

[0064] The test results are shown in Table 2.

[0065] Table 2

[0066] It can be seen from the results in Table 2 that the polypeptide composition of Example 1 of the present invention can effectively increase the Newcastle disease antibody titer of broiler chickens through the mutual cooperation of various effective ingredients, thereby improving the immune function and antiviral ability of broiler chickens.

[0067] Finally, it should be noted that the above-mentioned embodiments only express several implementation methods of the present invention and are not intended to limit the invention. For those skilled in the art, any modification, equivalent replacement, improvement, etc. made without departing from the concept of the present invention should be included in the protection scope of the invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A polypeptide composition for improving the disease resistance of animals, characterized in that: The invention comprises the following components by weight: 20-30 parts of soybean meal polypeptide, 15-25 parts of seabuckthorn seed meal polypeptide, 10-15 parts of houttuynia cordata extract, 5-10 parts of licorice extract and 5-10 parts of astragalus polysaccharide.

2. The polypeptide composition for improving animal disease resistance according to claim 1, characterized in that: The method for preparing soybean meal polypeptide comprises the following steps: S101. The soybean meal is crushed and mixed with deionized water to obtain a suspension; S102. adjusting the pH value of the suspension to 8.0-9.0, extracting at 45-50° C. for 2-3 hours, collecting the supernatant by centrifugation after extraction, adjusting the pH value of the supernatant to 4.5-5.0 to precipitate the protein, collecting the precipitate and washing it to neutrality to obtain a crude protein; S103. hydrolyzing the crude protein using a protease to obtain an enzymatic hydrolysate; S104. The enzymatic hydrolysate is ultrafiltered, concentrated, and dried to obtain soybean meal polypeptide.

3. The polypeptide composition for improving animal disease resistance according to claim 2, characterized in that: In step S103, the crude protein is hydrolyzed by protease, specifically: the crude protein is dispersed in a buffer, alkaline protease is added, the amount of enzyme added is 1%-2% of the weight of the crude protein, the pH value is adjusted to 8.5-9.0, the temperature is maintained at 45-50°C, the hydrolysis time is 1-2h, and after the hydrolysis is completed, it is heated to 85-90°C, maintained for 10min, and cooled to room temperature to obtain a preliminary enzymatic solution; the pH value of the preliminary enzymatic solution is adjusted to neutral, trypsin is added, the amount of trypsin added is 0.5%-1% of the weight of the crude protein, the temperature is maintained at 45-50°C, the hydrolysis time is 1-2h, after the hydrolysis is completed, it is heated to 85-90°C, maintained for 10min, and cooled to room temperature to obtain an enzymatic solution.

4. The polypeptide composition for improving animal disease resistance according to claim 1, characterized in that: The preparation method of seabuckthorn seed meal polypeptide comprises the following steps: S201. The seabuckthorn seed meal was crushed and mixed with deionized water to obtain a suspension, the pH of the suspension was adjusted to 12, and the extraction was performed at 37° C. for 50 min, and the extraction was repeated 2-3 times, and the supernatant was collected by centrifugation; S202. The pH value of the supernatant was adjusted to 5.0-5.5, phytase and tannase were added at 0.1-0.5% of the mass of seabuckthorn seed meal, and the mixture was hydrolyzed at 35-50°C for 2-5h. After the hydrolysis was completed, the mixture was heated to 85-90°C and maintained for 10min to obtain a pretreated hydrolyzate; S203. Hydrolyzing the pretreated hydrolyzate with a protease to obtain a hydrolyzate; S204. Ultrafilter, concentrate and dry the enzymatic hydrolyzate to obtain seabuckthorn seed meal polypeptide.

5. The polypeptide composition for improving animal disease resistance according to claim 4, characterized in that: The specific operation of using protease to hydrolyze the pre-treated enzymatic solution in step S203 is as follows: add trypsin to the pre-treated enzymatic solution, the amount of trypsin added is 1-2% of the mass of the sea buckthorn seed meal, adjust the pH value to 8.0-8.5, maintain the temperature at 45-50°C, the hydrolysis time is 1-2h, and after the hydrolysis is completed, heat to 85-90°C, maintain for 10min, and cool to room temperature to obtain a preliminary enzymatic solution; adjust the pH value of the preliminary enzymatic solution to neutral, add composite protease, the amount of composite protease added is 1-2% of the mass of the sea buckthorn seed meal, maintain the temperature at 45-50°C, the hydrolysis time is 1-2h, after the hydrolysis is completed, heat to 85-90°C, maintain for 10min, and cool to room temperature to obtain the enzymatic solution.

6. The polypeptide composition for improving animal disease resistance according to claim 5, characterized in that: The composite protease comprises flavor protease and neutral protease, and the weight ratio thereof is (1-2):

1.

7. The polypeptide composition for improving the disease resistance of animals according to claim 1, characterized in that: The preparation method of Houttuynia cordata extract is specifically as follows: crush the washed and dried Houttuynia cordata, use ethanol as the extraction solvent, put the Houttuynia cordata powder and ethanol in a Soxhlet extractor at a weight ratio of 1: (8-12), heat and reflux, the extraction temperature is 40-50°C, the extraction time is 40-60min, the extraction is performed 2-3 times, the extracts are combined and concentrated, and finally placed in a dryer for drying at a drying temperature of 50-60°C to obtain the Houttuynia cordata extract.

8. The polypeptide composition for improving disease resistance of animals according to claim 1, characterized in that: The preparation method of licorice extract is specifically as follows: crush the washed and dried licorice, use 40-60% ethanol aqueous solution as the extraction solution, put the licorice powder and ethanol aqueous solution into a Soxhlet extractor at a weight ratio of 1: (12-16), heat and reflux, the extraction temperature is 40-60°C, under the condition of ultrasonic power of 75-85W, the extraction time is 40-60min, the extraction is performed 2-3 times, the extracts are combined and concentrated, and finally placed in a dryer for drying at a drying temperature of 50-60°C to obtain the licorice extract.

9. A method for preparing a polypeptide composition for improving animal disease resistance as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: The polypeptide composition for improving the disease resistance of animals is obtained by uniformly mixing soybean meal polypeptide, seabuckthorn seed meal polypeptide, houttuynia cordata extract, liquorice extract and astragalus polysaccharide.

10. An application of the polypeptide composition for improving the disease resistance of animals as claimed in any one of claims 1 to 8, characterized in that: It is used as a feed additive to improve the disease resistance of animals, and the added amount accounts for 0.1-5% of the total feed.

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