High-protein pig feed prepared by microbial fermentation technology

Abstract

The invention relates to the technical field of microbial fermentation, and discloses a high-protein pig feed prepared by a microbial fermentation technology, which is prepared by the following steps: S1, mixing soybean meal, corn straw and bran according to a mass ratio of 5: 3: 2, crushing to 60-80 meshes, adding a compound microbial agent and water, and adjusting the water content to 45-50% to prepare a fermentation base material; the method comprises the following steps: carrying out first-stage solid-state fermentation for 48-60 hours under the condition of 35-38 DEG C, introducing sterile air in the fermentation process and maintaining the pressure in a tank to be 0.05-0.1 MPa and the stirring speed to be 30-50 rpm, and by arranging a complex microbial inoculant synergistic fermentation system, when the high-protein feed is prepared from soybean meal, corn straws and other plant raw materials, the high-protein feed can be prepared from the soybean meal, the corn straws and other plant raw materials. The specific compatibility proportion of bacillus licheniformis, lactobacillus plantarum and saccharomyces cerevisiae is screened, the synchronous effect of cellulose degradation, organic acid synthesis and mycoprotein enrichment is achieved, and efficient passivation of anti-nutritional factors of different raw materials is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of microbial fermentation, in particular to a high-protein feed for pigs prepared by utilizing the microbial fermentation technology. Background Art

[0002] Microbial fermentation refers to the process of using microorganisms to convert raw materials into products needed by humans through specific metabolic pathways under suitable conditions. The production level of microbial fermentation mainly depends on the genetic characteristics of the strain itself and the culture conditions.

[0003] High-protein pig feed produced using microbial fermentation technology involves a process that transforms plant-based and waste materials into high-nutrition feed through targeted manipulation of microbial metabolic activity. This is a key approach to increasing feed protein content and digestibility. During the fermentation process, the microbial flora secretes a variety of enzymes that degrade anti-nutritional factors in the raw materials and synthesize active substances such as small peptides and organic acids, thereby enhancing the nutritional value of the feed and the pigs' immunity.

[0004] Currently, due to multiple technical bottlenecks in traditional fermentation processes, the production of high-protein pig feed relies on relatively extensive microbial strain combinations and fermentation condition control strategies, making it impossible to monitor the dynamic changes of key metabolic indicators during the fermentation process in real time. Imbalanced microbial flora and abnormal accumulation of metabolites in the fermentation system can lead to reduced protein conversion efficiency, excessive residual anti-nutritional factors, and an insufficient proportion of acid-soluble protein in the fermentation product, seriously affecting the digestibility and absorption rate of the feed. Furthermore, in the staged fermentation process, the temperature, ventilation volume, and timing of inducer addition are not dynamically adjusted according to the characteristics of the different feedstocks. This can easily lead to incomplete cellulose degradation during the solid-state fermentation stage and insufficient synthesis of functional peptides during the liquid-phase fermentation stage. Excessive residual trypsin inhibitors in soybean meal can reduce protein utilization by the pig intestine. Furthermore, existing technologies lack precise control over the composition of the fermentation end product, making it difficult to achieve targeted enrichment of high-value-added components, resulting in unstable immune-enhancing effects of the feed. Experiments have shown that conventional fermented feeds generally have a low proportion of acid-soluble protein, excessively high neutral detergent fiber content, and fluctuating total viable bacterial counts, failing to meet the standardized requirements for healthy pig farming.

[0005] Therefore, an optimization method for preparing high-protein feed for pigs using microbial fermentation technology is proposed to solve the above problems. Summary of the Invention

[0006] (1) Technical problems solved

[0007] In view of the shortcomings of the existing technology, the present invention provides a high-protein feed for pigs prepared by microbial fermentation technology, which solves the problems raised in the above background technology.

[0008] (2) Technical solution

[0009] To achieve the above objectives, the present invention provides the following technical solution: a high-protein feed for pigs prepared by microbial fermentation technology comprises the following steps:

[0010] S1: soybean meal, corn stalks, and bran are mixed in a mass ratio of 5:3:2 and ground into 60-80 mesh, a composite microbial agent and water are added, and the moisture content is adjusted to 45-50% to prepare a fermentation base;

[0011] S2: The fermentation base is placed in a sealed fermentation tank and the first stage solid-state fermentation is carried out at 35-38°C for 48-60 hours. During the fermentation process, sterile air is introduced and the pressure in the tank is maintained at 0.05-0.1 MPa. The stirring speed is 30-50 rpm.

[0012] S3: adding the inducing peptide solution and enzyme preparation to the first stage fermentation product, adjusting the pH to 6.5-7.0, and performing the second stage liquid fermentation at 45-50°C for 24-36 hours to obtain a fermentation slurry;

[0013] S4: Separating the fermentation slurry by plate and frame filter pressing to obtain solid fermentation material and fermentation filtrate;

[0014] S5: The solid fermentation material is dried by air flow to a moisture content of ≤8%, and crushed to 100 mesh to obtain a basic feed;

[0015] S6: The fermentation filtrate is concentrated to 30% of the original volume through a 50 kDa ultrafiltration membrane and spray-dried to obtain a protein additive;

[0016] S7: Mix the basic feed and the protein additive in a mass ratio of 8:2 to obtain a high-protein feed for pigs.

[0017] Preferably, the composite microbial agent comprises Bacillus licheniformis CICC10019, Lactobacillus plantarum CGMCC1.557 and Saccharomyces cerevisiae CICC1001, the ratio of the viable bacteria count of the three is (3-4): (2-3): 1, and the total addition amount is 1.5-2.5% of the mass of the fermentation base.

[0018] Preferably, the method for preparing the inducing peptide solution comprises:

[0019] Ⅰ. Mix pig bone powder and cellulase in a mass ratio of 10:1, add pH 5.0 acetate buffer, and hydrolyze at 50℃ for 4 hours to obtain an enzymatic solution;

[0020] II. The enzymatic hydrolysate was separated by a 10 kDa ultrafiltration membrane, and the permeate was collected and concentrated using a 500-800 Da nanofiltration membrane;

[0021] III. The concentrated solution is freeze-dried to obtain the inducing peptide powder with a molecular weight of ≤3kDa, which is prepared into an aqueous solution with a mass concentration of 5% when used.

[0022] Preferably, during the first stage fermentation process:

[0023] When the pH is detected to be lower than 4.5, 5% sodium bicarbonate solution is automatically added to maintain the pH at 4.8-5.2.

[0024] Samples were taken every 12 hours to detect the reducing sugar content. When the reducing sugar content was ≤1.5 mg / g, 10% glucose solution was added.

[0025] Preferably, the enzyme preparation is composed of composite cellulase and acid protease at an enzyme activity ratio of 2:1, and the total addition amount is 0.8-1.2% of the mass of the second stage fermentation system, wherein the composite cellulase activity is ≥5000U / g and the acid protease activity is ≥3000U / g.

[0026] Preferably, the amount of the inducing peptide solution added is 3-5% of the volume of the second stage fermentation system, and the time of addition is 4-6 hours after the start of the second stage fermentation.

[0027] Preferably, the liquid fermentation in step S3 adopts three-level gradient temperature control: 0-8h: 45±1°C, stirring speed 100rpm, 9-20h: 48±1°C, stirring speed 150rpm, 21-36h: 50±1°C, stirring speed 200rpm.

[0028] Preferably, the airflow drying in step S5 adopts a three-stage temperature variable process: the first stage: drying at 80°C for 30 minutes, wind speed 8m / s, the second stage: drying at 65°C for 40 minutes, wind speed 5m / s, and the third stage: drying at 45°C for 20 minutes, wind speed 3m / s.

[0029] Preferably, the prepared high-protein feed for pigs meets the following indicators: crude protein content ≥45%, acid-soluble protein ratio ≥80%, neutral detergent fiber ≤15%, total viable bacteria ≥1×10 9 CFU / g, pepsin digestibility ≥92%.

[0030] Preferably, the invention comprises the following components and their mass percentages: 35-40% fermented soybean meal protein, 25-30% fermented corn straw, 15-20% fermented bran, 20-25% concentrated fermentation filtrate protein powder, 0.5-1% multivitamin premix, and 0.3-0.8% mineral element premix.

[0031] (3) Beneficial effects

[0032] Compared with the prior art, the present invention provides a high-protein feed for pigs prepared using microbial fermentation technology, which has the following beneficial effects:

[0033] 1. In the present invention, by setting up a composite bacterial agent collaborative fermentation system, when using plant raw materials such as soybean meal and corn stalks to prepare high-protein feed, a specific compatibility ratio of Bacillus licheniformis, Lactobacillus plantarum and Saccharomyces cerevisiae is screened to achieve the simultaneous effects of cellulose degradation, organic acid synthesis and bacterial protein enrichment, ensuring the efficient passivation of anti-nutritional factors of different raw materials. At the same time, the two-stage process of solid-state fermentation and liquid fermentation is coupled. Under the condition of directional induction peptide activating the secretion of microbial extracellular enzymes, the pH and reducing sugar concentration are controlled in real time. This can solve the problems of unstable protein conversion rate and insufficient proportion of acid-soluble protein in traditional fermentation processes, ensure the crude protein content and the proportion of small molecule proteins in feed, and improve the digestion and absorption efficiency of protein by pigs.

[0034] 2. In the present invention, by constructing a dynamic feeding and gradient temperature control mechanism, during the staged fermentation process, the changes in the system metabolic parameters are monitored in real time and sodium bicarbonate solution is automatically added to maintain pH stability, and glucose solution is dynamically supplemented according to the reducing sugar consumption rate, accurately matching the nutritional requirements of microorganisms during the growth period. Combined with the three-level gradient temperature increase strategy and the step-by-step increase in stirring intensity in the liquid fermentation stage, the synergistic hydrolysis activity of the complex cellulase and the acid protease is fully stimulated, so that the residual rate of trypsin inhibitor in soybean meal is reduced, the degradation rate of corn straw fiber is improved, and the neutral detergent fiber content in the feed is reduced, thereby avoiding intestinal damage to pigs caused by nutrient absorption disorders and ensuring increased daily weight gain of fattening pigs.

[0035] 3. In the present invention, by integrating functional component targeted enrichment technology, a molecular retention membrane is used to separate small peptides in the ultrafiltration and concentration stage of the fermentation filtrate, and a highly active protein additive is obtained after spray drying. Combined with the three-stage variable temperature airflow drying process of the solid-state fermentation material, the lactobacillus, bacteriocin and heat-sensitive active substances of the vitamin B group are retained to the maximum extent, so that the total number of viable bacteria in the final product is stable. Based on the differences in immune needs of sows, piglets and fattening pigs at different physiological stages, the ratio of basic feed to protein additives is adjusted to achieve a precise ratio of immune-enhancing peptides and antioxidants, thereby solving the defect of unstable immune function enhancement effect of conventional fermented feed, reducing the diarrhea rate of suckling piglets and improving the IgA level of sows during lactation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart for the preparation of high-protein feed for pigs using microbial fermentation technology. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] Example 1:

[0039] The high-protein feed for pigs prepared by microbial fermentation technology comprises the following steps:

[0040] S1: soybean meal, corn straw, and bran are mixed in a mass ratio of 5:3:2 and ground into 60 mesh, a composite microbial agent and water are added, and the moisture content is adjusted to 45% to prepare a fermentation base;

[0041] S2: The fermentation base was placed in a sealed fermentation tank and the first stage solid-state fermentation was carried out at 35°C for 48 hours. During the fermentation process, sterile air was introduced and the pressure in the tank was maintained at 0.05 MPa. The stirring speed was 30 rpm.

[0042] S3: adding the inducing peptide solution and enzyme preparation to the first stage fermentation product, adjusting the pH to 6.5, and performing the second stage liquid fermentation at 45-50°C for 24 hours to obtain a fermentation slurry;

[0043] S4: Separating the fermentation slurry by plate and frame filter pressing to obtain solid fermentation material and fermentation filtrate;

[0044] S5: The solid fermentation material is dried by air flow to a moisture content of ≤8%, and crushed to 100 mesh to obtain a basic feed;

[0045] S6: The fermentation filtrate is concentrated to 30% of the original volume through a 50 kDa ultrafiltration membrane and spray-dried to obtain a protein additive;

[0046] S7: Mix the basic feed and the protein additive in a mass ratio of 8:2 to obtain a high-protein feed for pigs.

[0047] The composite microbial agent comprises Bacillus licheniformis CICC10019, Lactobacillus plantarum CGMCC1.557 and Saccharomyces cerevisiae CICC1001, the live bacterial count ratio of the three being (3-4):(2-3):1, and the total addition amount being 1.5% of the mass of the fermentation base.

[0048] The preparation method of the inducing peptide solution comprises:

[0049] Ⅰ. Mix pig bone powder and cellulase in a mass ratio of 10:1, add pH 5.0 acetate buffer, and hydrolyze at 50℃ for 4 hours to obtain an enzymatic solution;

[0050] II. The enzymatic hydrolysate was separated by a 10 kDa ultrafiltration membrane, and the permeate was collected and concentrated by a 500 Da nanofiltration membrane;

[0051] III. The concentrated solution is freeze-dried to obtain the inducing peptide powder with a molecular weight of ≤3kDa, which is prepared into an aqueous solution with a mass concentration of 5% when used.

[0052] During the first stage of fermentation:

[0053] When the pH is detected to be lower than 4.5, 5% sodium bicarbonate solution is automatically added to maintain the pH at 4.8-5.2.

[0054] Samples were taken every 12 hours to detect the reducing sugar content. When the reducing sugar content was ≤1.5 mg / g, 10% glucose solution was added.

[0055] The enzyme preparation is composed of composite cellulase and acidic protease at an enzyme activity ratio of 2:1, and the total addition amount is 0.8% of the mass of the second stage fermentation system, wherein the enzyme activity of the composite cellulase is ≥5000U / g, and the enzyme activity of the acidic protease is ≥3000U / g.

[0056] The amount of the inducing peptide solution added was 3% of the volume of the second stage fermentation system, and the time of addition was 4 hours after the start of the second stage fermentation.

[0057] In step S3, the liquid fermentation adopts three-level gradient temperature control: 5h: 45°C, stirring speed 100rpm, 9h: 48°C, stirring speed 150rpm, 21h: 50°C, stirring speed 200rpm.

[0058] Step S5 airflow drying adopts a three-stage temperature change process: the first stage: drying at 80°C for 30 minutes, wind speed 8m / s, the second stage: drying at 65°C for 40 minutes, wind speed 5m / s, and the third stage: drying at 45°C for 20 minutes, wind speed 3m / s.

[0059] The prepared high-protein feed for pigs meets the following indicators: crude protein content ≥45%, acid-soluble protein ≥80%, neutral detergent fiber ≤15%, total viable bacteria ≥1×10 9 CFU / g, pepsin digestibility ≥92%.

[0060] The invention comprises the following components and their mass percentages: 35% fermented soybean meal protein, 25% fermented corn straw, 15% fermented bran, 20% concentrated fermentation filtrate protein powder, 0.5% multivitamin premix, and 0.5% mineral element premix.

[0061] Example 2:

[0062] The high-protein feed for pigs prepared by microbial fermentation technology comprises the following steps:

[0063] S1: soybean meal, corn straw, and bran are mixed in a mass ratio of 5:3:2 and ground into 60 mesh, a composite microbial agent and water are added, and the moisture content is adjusted to 45% to prepare a fermentation base;

[0064] S2: The fermentation base was placed in a sealed fermentation tank and the first stage solid-state fermentation was carried out at 35°C for 48 hours. During the fermentation process, sterile air was introduced and the pressure in the tank was maintained at 0.05 MPa. The stirring speed was 30 rpm.

[0065] S3: adding the inducing peptide solution and enzyme preparation to the first stage fermentation product, adjusting the pH to 6.5, and performing the second stage liquid fermentation at 45-50°C for 24 hours to obtain a fermentation slurry;

[0066] S4: Separating the fermentation slurry by plate and frame filter pressing to obtain solid fermentation material and fermentation filtrate;

[0067] S5: The solid fermentation material is dried by air flow to a moisture content of ≤8%, and crushed to 100 mesh to obtain a basic feed;

[0068] S6: The fermentation filtrate is concentrated to 30% of the original volume through a 50 kDa ultrafiltration membrane and spray-dried to obtain a protein additive;

[0069] S7: Mix the basic feed and the protein additive in a mass ratio of 8:2 to obtain a high-protein feed for pigs.

[0070] The composite microbial agent comprises Bacillus licheniformis CICC10019, Lactobacillus plantarum CGMCC1.557 and Saccharomyces cerevisiae CICC1001, the live bacterial count ratio of the three being (3-4):(2-3):1, and the total addition amount being 1.5% of the mass of the fermentation base.

[0071] The preparation method of the inducing peptide solution comprises:

[0072] Ⅰ. Mix pig bone powder and cellulase in a mass ratio of 10:1, add pH 5.0 acetate buffer, and hydrolyze at 50℃ for 4 hours to obtain an enzymatic solution;

[0073] II. The enzymatic hydrolysate was separated by a 10 kDa ultrafiltration membrane, and the permeate was collected and concentrated by a 500 Da nanofiltration membrane;

[0074] III. The concentrated solution is freeze-dried to obtain the inducing peptide powder with a molecular weight of ≤3kDa, which is prepared into an aqueous solution with a mass concentration of 5% when used.

[0075] During the first stage of fermentation:

[0076] When the pH is detected to be lower than 4.5, 5% sodium bicarbonate solution is automatically added to maintain the pH at 4.8-5.2.

[0077] Samples were taken every 12 hours to detect the reducing sugar content. When the reducing sugar content was ≤1.5 mg / g, 10% glucose solution was added.

[0078] The enzyme preparation is composed of composite cellulase and acidic protease at an enzyme activity ratio of 2:1, and the total addition amount is 0.8% of the mass of the second stage fermentation system, wherein the enzyme activity of the composite cellulase is ≥5000U / g, and the enzyme activity of the acidic protease is ≥3000U / g.

[0079] The amount of the inducing peptide solution added was 3% of the volume of the second stage fermentation system, and the time of addition was 4 hours after the start of the second stage fermentation.

[0080] In step S3, the liquid fermentation adopts three-level gradient temperature control: 5h: 45°C, stirring speed 100rpm, 9h: 48°C, stirring speed 150rpm, 21h: 50°C, stirring speed 200rpm.

[0081] Step S5 airflow drying adopts a three-stage temperature change process: the first stage: drying at 80°C for 30 minutes, wind speed 8m / s, the second stage: drying at 65°C for 40 minutes, wind speed 5m / s, and the third stage: drying at 45°C for 20 minutes, wind speed 3m / s.

[0082] The prepared high-protein feed for pigs meets the following indicators: crude protein content ≥45%, acid-soluble protein ≥80%, neutral detergent fiber ≤15%, total viable bacteria ≥1×10 9 CFU / g, pepsin digestibility ≥92%.

[0083] The invention comprises the following components and their mass percentages: 35% fermented soybean meal protein, 25% fermented corn straw, 15% fermented bran, 20% concentrated fermentation filtrate protein powder, 0.5% multivitamin premix, and 0.5% mineral element premix.

[0084] Example 3:

[0085] The high-protein feed for pigs prepared by microbial fermentation technology comprises the following steps:

[0086] S1: soybean meal, corn straw, and bran are mixed in a mass ratio of 5:3:2 and ground into 60 mesh, a composite microbial agent and water are added, and the moisture content is adjusted to 45% to prepare a fermentation base;

[0087] S2: The fermentation base was placed in a sealed fermentation tank and the first stage solid-state fermentation was carried out at 35°C for 48 hours. During the fermentation process, sterile air was introduced and the pressure in the tank was maintained at 0.05 MPa. The stirring speed was 30 rpm.

[0088] S3: adding the inducing peptide solution and enzyme preparation to the first stage fermentation product, adjusting the pH to 6.5, and performing the second stage liquid fermentation at 45-50°C for 24 hours to obtain a fermentation slurry;

[0089] S4: Separating the fermentation slurry by plate and frame filter pressing to obtain solid fermentation material and fermentation filtrate;

[0090] S5: The solid fermentation material is dried by air flow to a moisture content of ≤8%, and crushed to 100 mesh to obtain a basic feed;

[0091] S6: The fermentation filtrate is concentrated to 30% of the original volume through a 50 kDa ultrafiltration membrane and spray-dried to obtain a protein additive;

[0092] S7: Mix the basic feed and the protein additive in a mass ratio of 8:2 to obtain a high-protein feed for pigs.

[0093] The composite microbial agent comprises Bacillus licheniformis CICC10019, Lactobacillus plantarum CGMCC1.557 and Saccharomyces cerevisiae CICC1001, the live bacterial count ratio of the three being (3-4):(2-3):1, and the total addition amount being 1.5% of the mass of the fermentation base.

[0094] The preparation method of the inducing peptide solution comprises:

[0095] Ⅰ. Mix pig bone powder and cellulase in a mass ratio of 10:1, add pH 5.0 acetate buffer, and hydrolyze at 50℃ for 4 hours to obtain an enzymatic solution;

[0096] II. The enzymatic hydrolysate was separated by a 10 kDa ultrafiltration membrane, and the permeate was collected and concentrated by a 500 Da nanofiltration membrane;

[0097] III. The concentrated solution is freeze-dried to obtain the inducing peptide powder with a molecular weight of ≤3kDa, which is prepared into an aqueous solution with a mass concentration of 5% when used.

[0098] During the first stage of fermentation:

[0099] When the pH is detected to be lower than 4.5, 5% sodium bicarbonate solution is automatically added to maintain the pH at 4.8-5.2.

[0100] Samples were taken every 12 hours to detect the reducing sugar content. When the reducing sugar content was ≤1.5 mg / g, 10% glucose solution was added.

[0101] The enzyme preparation is composed of composite cellulase and acidic protease at an enzyme activity ratio of 2:1, and the total addition amount is 0.8% of the mass of the second stage fermentation system, wherein the enzyme activity of the composite cellulase is ≥5000U / g, and the enzyme activity of the acidic protease is ≥3000U / g.

[0102] The amount of the inducing peptide solution added was 3% of the volume of the second stage fermentation system, and the time of addition was 4 hours after the start of the second stage fermentation.

[0103] In step S3, the liquid fermentation adopts three-level gradient temperature control: 5h: 45°C, stirring speed 100rpm, 9h: 48°C, stirring speed 150rpm, 21h: 50°C, stirring speed 200rpm.

[0104] Step S5 airflow drying adopts a three-stage temperature change process: the first stage: drying at 80°C for 30 minutes, wind speed 8m / s, the second stage: drying at 65°C for 40 minutes, wind speed 5m / s, and the third stage: drying at 45°C for 20 minutes, wind speed 3m / s.

[0105] The prepared high-protein feed for pigs meets the following indicators: crude protein content ≥45%, acid-soluble protein ≥80%, neutral detergent fiber ≤15%, total viable bacteria ≥1×10 9 CFU / g, pepsin digestibility ≥92%.

[0106] The invention comprises the following components and their mass percentages: 35% fermented soybean meal protein, 25% fermented corn straw, 15% fermented bran, 20% concentrated fermentation filtrate protein powder, 0.5% multivitamin premix, and 0.5% mineral element premix.

[0107] Comparative Example 1 is different from Examples 1-3 in that no inducing peptide solution is added, and only an equal amount of water is added in the second stage of fermentation.

[0108] Comparative Example 2 is different from Examples 1-3 in that the composite microbial agent is replaced by a single strain of Bacillus subtilis, and the total addition amount is the same.

[0109] Comparative Example 3 is different from Examples 1-3 in that: conventional high-temperature process is adopted for preparation, specifically: soybean meal, corn straw and bran are mixed and steamed at 120° C. for 2 h, and then directly crushed and granulated without microbial fermentation.

[0110] Performance test: The nutritional indexes of the high-protein feeds for pigs prepared in Examples 1-3 and Comparative Examples 1-3 were tested. The results are shown in the following table:

[0111]

[0112] By analyzing the data in the comparison table, it can be seen that the data of the high-protein feed for pigs prepared in Examples 1-3 are all better than those in Comparative Examples 1-3;

[0113] By setting up a composite microbial agent collaborative fermentation system, when using plant-based raw materials such as soybean meal and corn straw to prepare high-protein feed, the specific compatibility ratio of Bacillus licheniformis, Lactobacillus plantarum and Saccharomyces cerevisiae is screened to achieve the simultaneous effects of cellulose degradation, organic acid synthesis and bacterial protein enrichment, ensuring the efficient passivation of anti-nutritional factors of different raw materials. At the same time, the two-stage process of solid-state fermentation and liquid fermentation is coupled. Under the condition of targeted induction peptides to activate the secretion of microbial extracellular enzymes, the pH and reducing sugar concentration are controlled in real time. This can solve the problems of unstable protein conversion rate and insufficient proportion of acid-soluble protein in traditional fermentation processes, ensure the crude protein content and the proportion of small molecular proteins in the feed, and improve the digestion and absorption efficiency of protein by pigs;

[0114] By constructing a dynamic feeding and gradient temperature control mechanism, during the staged fermentation process, the system metabolic parameter changes are monitored in real time and sodium bicarbonate solution is automatically added to maintain pH stability. Glucose solution is dynamically supplemented according to the reducing sugar consumption rate to accurately match the nutritional needs of microorganisms during the growth period. Combined with the three-level gradient temperature increase strategy and step-by-step increase in stirring intensity in the liquid fermentation stage, the synergistic hydrolysis activity of complex cellulase and acid protease is fully stimulated, which reduces the residual rate of trypsin inhibitor in soybean meal, improves the degradation rate of corn straw fiber, and reduces the neutral detergent fiber content in the feed, thereby avoiding intestinal damage to pigs due to nutrient absorption disorders and ensuring increased daily weight gain of fattening pigs.

[0115] This shows that the high-protein feed for pigs prepared by microbial fermentation technology provided by the present invention has a broader market prospect and is more suitable for promotion.

[0116] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0117] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high-protein feed for pigs prepared by microbial fermentation technology, characterized in that: The following steps are involved: S1: soybean meal, corn stalks, and bran are mixed in a mass ratio of 5:3:2 and ground into 60-80 mesh, a composite microbial agent and water are added, and the moisture content is adjusted to 45-50% to prepare a fermentation base; S2: The fermentation base is placed in a sealed fermentation tank and the first stage solid-state fermentation is carried out at 35-38°C for 48-60 hours. During the fermentation process, sterile air is introduced and the pressure in the tank is maintained at 0.05-0.1 MPa. The stirring speed is 30-50 rpm. S3: adding the inducing peptide solution and enzyme preparation to the first stage fermentation product, adjusting the pH to 6.5-7.0, and performing the second stage liquid fermentation at 45-50°C for 24-36 hours to obtain a fermentation slurry; S4: Separating the fermentation slurry by plate and frame filter pressing to obtain solid fermentation material and fermentation filtrate; S5: The solid fermentation material is dried by air flow to a moisture content of ≤8%, and crushed to 100 mesh to obtain a basic feed; S6: The fermentation filtrate is concentrated to 30% of the original volume through a 50 kDa ultrafiltration membrane and spray-dried to obtain a protein additive; S7: Mix the basic feed and the protein additive in a mass ratio of 8:2 to obtain a high-protein feed for pigs.

2. The high-protein feed for pigs prepared by microbial fermentation technology according to claim 1, characterized in that: The composite microbial agent comprises Bacillus licheniformis CICC10019, Lactobacillus plantarum CGMCC1.557 and Saccharomyces cerevisiae CICC1001, the living bacteria count ratio of the three is (3-4): (2-3): 1, and the total addition amount is 1.5-2.5% of the mass of the fermentation base.

3. The high-protein feed for pigs prepared by microbial fermentation technology according to claim 1, characterized in that: The preparation method of the inducing peptide solution comprises: Ⅰ. Mix pig bone powder and cellulase in a mass ratio of 10:1, add pH 5.0 acetate buffer, and hydrolyze at 50℃ for 4 hours to obtain an enzymatic solution; II. The enzymatic hydrolysate was separated by a 10 kDa ultrafiltration membrane, and the permeate was collected and concentrated using a 500-800 Da nanofiltration membrane; III. The concentrated solution is freeze-dried to obtain the inducing peptide powder with a molecular weight of ≤3kDa, which is prepared into an aqueous solution with a mass concentration of 5% when used.

4. The high-protein feed for pigs prepared by microbial fermentation technology according to claim 1, characterized in that: During the first stage of fermentation: When the pH is detected to be lower than 4.5, 5% sodium bicarbonate solution is automatically added to maintain the pH at 4.8-5.

2. Samples were taken every 12 hours to detect the reducing sugar content. When the reducing sugar content was ≤1.5 mg / g, 10% glucose solution was added.

5. The high-protein feed for pigs prepared by microbial fermentation technology according to claim 1, characterized in that: The enzyme preparation is composed of composite cellulase and acidic protease at an enzyme activity ratio of 2:1, and the total addition amount is 0.8-1.2% of the mass of the second stage fermentation system, wherein the composite cellulase activity is ≥5000U / g and the acidic protease activity is ≥3000U / g.

6. The high-protein feed for pigs prepared by microbial fermentation technology according to claim 1, characterized in that: The amount of the inducing peptide solution added is 3-5% of the volume of the second stage fermentation system, and the time of addition is 4-6 hours after the start of the second stage fermentation.

7. The high-protein feed for pigs prepared by microbial fermentation technology according to claim 1, characterized in that: The liquid fermentation in step S3 adopts three-level gradient temperature control: 0-8h: 45±1°C, stirring speed 100rpm, 9-20h: 48±1°C, stirring speed 150rpm, 21-36h: 50±1°C, stirring speed 200rpm.

8. The high-protein feed for pigs prepared by microbial fermentation technology according to claim 1, characterized in that: The airflow drying in step S5 adopts a three-stage variable temperature process: the first stage: drying at 80°C for 30 minutes, wind speed 8m / s, the second stage: drying at 65°C for 40 minutes, wind speed 5m / s, and the third stage: drying at 45°C for 20 minutes, wind speed 3m / s.

9. The high-protein feed for pigs prepared by microbial fermentation technology according to claim 1, characterized in that: The prepared high-protein feed for pigs meets the following indicators: crude protein content ≥45%, acid-soluble protein ≥80%, neutral detergent fiber ≤15%, total viable bacteria ≥1×10 9 CFU / g, pepsin digestibility ≥92%.

10. The high-protein feed for pigs prepared by microbial fermentation technology according to claim 1, characterized in that: The invention comprises the following components and their mass percentages: 35-40% fermented soybean meal protein, 25-30% fermented corn straw, 15-20% fermented bran, 20-25% concentrated fermentation filtrate protein powder, 0.5-1% multivitamin premix, and 0.3-0.8% mineral element premix.

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