High-protein pig feed and preparation method thereof

Abstract

The application discloses high-protein pig feed and a preparation method thereof, and particularly relates to the field of high-protein pig feed preparation. Beer yeast cell wall residues and defatted tenebrio molitor sand are subjected to protease enzymolysis, enzyme inactivation, drying and crushing to obtain modified protein cores. Konjac glucomannan is subjected to sodium periodate oxidation, purification and drying to obtain oxidized konjac glucomannan. The modified protein cores are dispersed in a solvent, and a zinc nitrate hexahydrate solution, a 2-methylimidazole solution and a mixed solution of oxidized konjac glucomannan and tannic acid are added dropwise to carry out a reaction to obtain high-protein composite microparticles. The high-protein composite microparticles are uniformly mixed with high-protein basic feed to obtain the high-protein pig feed. The high-protein composite microparticles have a pH-responsive controlled-release shell layer, can provide stomach protection for the modified protein cores, realize targeted release in the intestinal tract, help to improve the protein utilization rate, improve intestinal health, and have good storage stability.

Description

Technical Field

[0001] This invention relates to the field of high-protein pig feed preparation, and particularly to a high-protein pig feed and its preparation method. Background Technology

[0002] With the intensive development of modern pig farming, the precision of pig feed nutrition and the diversification of functions are key to improving breeding efficiency. The weaning stage is an important period for pig growth and development, but their digestive system is not yet fully developed, and their ability to digest and absorb protein in feed is limited. They are prone to problems such as diarrhea and stunted growth due to factors such as antigenic proteins and anti-nutritional factors in feed.

[0003] Traditional pig feed formulations often rely on corn and soybean meal-based diets, which can provide basic energy and protein, but ignore individual differences and the refined needs of different growth stages. Weaned piglets' digestive systems are not yet fully developed, and antigenic proteins in conventional feeds (such as soybean antigens) can easily cause diarrhea, leading to stunted growth or even death.

[0004] Patent document CN103976177B discloses a high-protein pig feed and its preparation method. The technical solution mainly focuses on the compounding of natural plant raw materials and the preparation of nutritional seasoning powder to increase the protein content of the feed, promote intestinal peristalsis, reduce fat absorption, and reduce the incidence of disease in pigs.

[0005] Existing high-protein pig feed technologies suffer from substantial drawbacks such as low protein utilization, limited functionality, poor storage stability, and environmental unfriendliness. Traditional feeds typically involve a simple physical mixture of raw materials like corn and soybean meal, lacking microstructural design. This results in proteins being prematurely degraded in the highly acidic environment of the pig's stomach, failing to reach the intestines efficiently for absorption and utilization.

[0006] Directly used protein feed often suffers from problems such as tightly packed cell walls, making protein release difficult. Anti-nutritional factors or unpleasant flavors also affect palatability and bioavailability. Traditional high-protein feeds only focus on protein content figures, neglecting the stress that high protein intake puts on gut health and lacking regulation of the gut microbiota, easily leading to nutritional diarrhea. Furthermore, exposed protein feed is prone to moisture absorption and oxidation, resulting in short shelf life and poor storage stability. Due to low absorption efficiency, large amounts of undigested protein ferment in the intestines, producing ammonia gas, which not only causes nitrogen emissions and environmental pollution but also leads to high ammonia concentrations in pigsties and induces respiratory diseases. Summary of the Invention

[0007] The main objective of this invention is to provide a high-protein pig feed that can effectively solve the problems mentioned in the background section.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing high-protein pig feed includes the following steps: S1: Mix brewer's yeast cell wall residue with defatted mealworm sand, hydrolyze with protease, inactivate the enzyme, dry under vacuum to constant weight, and pulverize through an 80-100 mesh sieve to obtain modified protein core; S2: Dissolve konjac glucomannan in water, add sodium periodate under light-protected conditions, and adjust the pH to 3.5-4.0 to carry out the oxidation reaction. After the reaction is completed, purify and dry to obtain oxidized konjac glucomannan. S3: Disperse the modified protein core from step S1 in a solvent, add zinc nitrate hexahydrate solution, and simultaneously add 2-methylimidazole solution and a mixed solution containing oxidized konjac glucomannan and tannic acid from step S2, and react to obtain high-protein composite microparticles. S4: Mix the high-protein composite microparticles obtained in step S3 with the high-protein basal diet evenly to obtain high-protein pig feed.

[0009] Preferably, in step S1, the mass ratio of brewer's yeast cell wall residue to defatted mealworm sand is (3-5):(5-7); the protease is one or more of Bacillus licheniformis protease, Bacillus subtilis protease, and Bacillus amyloliquefaciens protease; the amount of enzyme added is 0.1-2.0% of the substrate mass.

[0010] Preferably, step S1 specifically involves: mixing brewer's yeast cell wall residue with defatted mealworm sand, adjusting the pH to 8.5-9.5, stirring and enzymatically hydrolyzing at 40-50℃ for 2-4 hours, and after enzymatic hydrolysis, heating to 90-95℃ to inactivate the enzyme for 10-15 minutes, separating the solid and liquid, washing the precipitate 2-3 times with deionized water, vacuum drying at 50-60℃ to constant weight, pulverizing and passing through an 80-100 mesh sieve to obtain the modified protein core.

[0011] Preferably, in step S2, the mass ratio of konjac glucomannan to sodium periodate is 1:(0.8-1.2); the oxidation reaction is carried out under the following conditions: in the dark, at a temperature of 25-30℃, for 6-8 hours, and at a pH of 3.5-4.0.

[0012] Preferably, step S2 purification specifically involves: placing the reaction solution into a dialysis bag and dialyzing it in deionized water at 4°C for 36-40 hours, and collecting the liquid in the dialysis bag.

[0013] Preferably, in step S3, the solvent is a mixed solution of methanol and deionized water with a mass ratio of (0.8-3.2):1; the mass ratio of modified protein core, zinc nitrate hexahydrate, and 2-methylimidazole is 1:(0.1-0.5):(0.08-0.75).

[0014] Preferably, in step S3, the mass ratio of oxidized konjac glucomannan to tannic acid is 1:(0.2-0.5).

[0015] Preferably, the reaction conditions in step S3 are as follows: continue stirring the reaction at 25-40℃ for 4-6 hours. After the reaction is completed, the solid and liquid are separated, and the precipitate is washed successively with anhydrous methanol, 30% ethanol aqueous solution, and deionized water, and then vacuum dried at 40-45℃ to constant weight.

[0016] Preferably, the high-protein basal diet in step S4 includes the following components by weight: 40-60 parts corn, 15-25 parts soybean meal, 5-15 parts wheat bran, 1-5 parts premix, and 5-30 parts high-protein compound microparticles.

[0017] A high-protein pig feed prepared by the method according to any one of claims 1-9.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. In the technical solution of this invention, in the cell wall residue of brewer's yeast and defatted mealworm sand, the protein is wrapped in a dense cell wall or polysaccharide matrix. The oxidized konjac glucomannan formed by the selective oxidation of konjac glucomannan with sodium periodate has its vicinal diol structure broken to generate active aldehyde groups. In subsequent reactions, the aldehyde groups on the oxidized konjac glucomannan can form hydrogen bonds or hemiacetal structures with the phenolic hydroxyl groups in the tannic acid molecules to construct a cross-linked hydrophilic polymer network as a shell to wrap the modified protein core.

[0019] 2. This invention constructs a pH-responsive controlled-release shell by combining a modified protein core with a ZIF-8 metal-organic framework material. ZIF-8 is formed from zinc nitrate hexahydrate and 2-methylimidazole at room temperature. Its crystal structure remains stable in the acidic gastric juice environment, effectively blocking pepsin from entering the microparticles and preventing small molecule peptides from being prematurely degraded in the stomach. When the composite microparticles enter the weakly alkaline environment of the intestine, the coordination bonds in ZIF-8 break, the framework structure gradually hydrolyzes, releases zinc ions and disintegrates, the shell pores expand, and the internal small molecule peptides are slowly released through concentration gradient diffusion, achieving targeted controlled release in the intestine. This solves the problem that proteins in traditional feed are easily degraded prematurely in the acidic gastric environment and cannot be efficiently absorbed by the intestine.

[0020] 3. This invention encapsulates the modified protein core with a ZIF-8 shell, reducing direct contact between the protein and oxygen, moisture, and other external elements. This lowers the risk of protein oxidation, denaturation, and clumping due to moisture absorption, thus extending the shelf life of feed. Increased protein utilization reduces the amount of ammonia produced by intestinal fermentation of undigested protein, reducing nitrogen emissions and environmental pollution. It also lowers ammonia concentration in pigsties and improves respiratory health in pigs. Furthermore, this invention fully utilizes byproducts such as brewer's yeast cell wall residue and defatted mealworm excrement, achieving waste recycling. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the preparation process of a high-protein pig feed according to the present invention; Detailed Implementation

[0022] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise range thresholds, and these range thresholds should be understood to include values ​​close to these range thresholds. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0023] The following is in conjunction with the appendix Figure 1 The embodiments provided in this specification will be described in detail.

[0024] like Figure 1 As shown, the preparation process of a high-protein pig feed and its preparation method is as follows, and the specific implementation steps are as follows.

[0025] Example 1

[0026] A method for preparing high-protein pig feed, the specific implementation steps of which are as follows: S1: Weigh 30g of brewer's yeast cell wall residue (3:7 mass ratio) and 70g of defatted mealworm sand, and mix them evenly; adjust the pH of the system to 9.0 with sodium hydroxide solution, add 1.0% of the total substrate mass of the compound enzyme (0.5g of Bacillus licheniformis protease and 0.5g of Bacillus subtilis protease, mass ratio 1:1), and enzymatically hydrolyze for 3 hours at 55℃ and stirring speed of 200r / min; after enzymatic hydrolysis, rapidly raise the temperature to 93℃ and inactivate the enzyme for 12 minutes; separate the solid and liquid by centrifugation, discard the supernatant, wash the precipitate three times with deionized water, place the washed precipitate in a vacuum drying oven at 55℃ and dry to constant weight, remove it and pulverize it with an ultrafine pulverizer, pass it through a 100-mesh standard sieve to obtain the modified protein core.

[0027] S2: Weigh 10g of konjac glucomannan and 10g of sodium periodate in a 1:1 mass ratio. Dissolve the konjac glucomannan completely in 100mL of deionized water. Add sodium periodate under light-protected conditions and adjust the pH to 3.8 with dilute hydrochloric acid. React at 28℃ and 150r / min under light-protected conditions for 7 hours. After the reaction is completed, add 5mL of ethylene glycol and stir for 30 minutes to terminate the reaction. Put the reaction solution into a dialysis bag with a molecular weight cutoff of 8000-14000 and dialyze it in deionized water at 4℃ for 38 hours, changing the deionized water every 6 hours. Collect the liquid in the dialysis bag and dry it in a dryer to constant weight to obtain oxidized konjac glucomannan.

[0028] S3: Prepare 200 mL of a methanol-deionized water mixture with a volume ratio of 2:1 (133 mL methanol, 67 mL deionized water), and disperse 20 g of the modified protein core in it; weigh out 20 g of the modified protein core, 6 g of zinc nitrate hexahydrate, and 8 g of 2-methylimidazole according to a mass ratio of 1:0.3:0.4. First, add the zinc nitrate hexahydrate solution (6 g of zinc nitrate hexahydrate dissolved in 30 mL deionized water) and stir to disperse. Then, simultaneously and slowly add the 2-methylimidazole solution (8 g of 2-methylimidazole dissolved in 40 mL methanol), and the oxidized konjac glucomannan:tannic acid = 1:0.3. The mixed solution (5g of oxidized konjac glucomannan and 1.5g of tannic acid dissolved in 50mL of deionized water) was added dropwise over a period of 60 minutes. After the addition was complete, the reaction was continued at 30℃ and a stirring speed of 250r / min for 5 hours. After the reaction was completed, the precipitate was separated by centrifugation. The precipitate was washed twice with anhydrous methanol (50mL each time), twice with 30% ethanol aqueous solution (50mL each time), and twice with deionized water (50mL each time). The washed precipitate was dried in a vacuum drying oven at 42℃ to constant weight to obtain high-protein composite microparticles with a particle size of 100-200μm.

[0029] S4: Weigh out 50kg of corn, 20kg of soybean meal, 10kg of wheat bran, 3kg of premix, and 15kg of high-protein compound microparticles by weight. Put the above components into a horizontal mixer and mix for 20 minutes until uniform to obtain high-protein pig feed.

[0030] Example 2

[0031] A method for preparing high-protein pig feed, the specific implementation steps of which are as follows: S1: Weigh 40g of brewer's yeast cell wall residue (4:6 mass ratio) and 60g of defatted mealworm sand, and mix them evenly; adjust the pH of the system to 9.2 with sodium hydroxide solution, add 1.5% of the total substrate mass of the compound enzyme (0.75g of Bacillus subtilis protease and 0.75g of Bacillus amyloliquefaciens protease, mass ratio 1:1), and enzymatically hydrolyze for 3.5 hours at 53℃ and stirring speed of 220r / min; after enzymatic hydrolysis, raise the temperature to 95℃ and incubate for 10 minutes to inactivate the enzyme; separate the solid and liquid by plate and frame filtration, wash the precipitate three times with deionized water (80mL each time); vacuum dry at 58℃ to constant weight, pulverize and pass through a 90-mesh sieve to obtain the modified protein core.

[0032] S2: Weigh 10g of konjac glucomannan (mass ratio 1:0.9) and 9g of sodium periodate; dissolve the konjac glucomannan in 100mL of deionized water, add sodium periodate in the dark, and adjust the pH to 3.6 with dilute hydrochloric acid; react at 26℃ and in the dark with stirring (150r / min) for 8 hours, add 5mL of ethylene glycol to terminate the reaction, put the reaction solution into a dialysis bag with a molecular weight cutoff of 8000-14000, and dialyze in deionized water at 4℃ for 40 hours (changing the water every 6 hours); dry to obtain oxidized konjac glucomannan.

[0033] S3: Use 180 mL of a methanol-deionized water mixed solvent with a volume ratio of 1.6:1 (110 mL methanol and 70 mL deionized water); weigh 20 g of modified protein core, 8 g of zinc nitrate hexahydrate, and 10 g of 2-methylimidazole according to a mass ratio of 1:0.4:0.5; and add 4 g of oxidized konjac glucomannan and 1.6 g of tannic acid dissolved in 40 mL deionized water at a mass ratio of 1:0.4:0.5. Simultaneously add 2-methylimidazole solution (10 g dissolved in 50 mL methanol) and the above mixed solution, controlling the addition time to 70 minutes. React at 35℃ and a stirring speed of 250 r / min for 4.5 hours. After centrifugation, wash twice each with anhydrous methanol (50 mL each time), 30% ethanol (50 mL each time), and deionized water (50 mL each time); and vacuum dry at 43℃ to obtain high-protein composite microparticles with a particle size of 80-250 μm.

[0034] S4: Weigh out 45kg of corn, 22kg of soybean meal, 8kg of wheat bran, 2kg of premix, and 20kg of high-protein compound microparticles by weight, put them into a twin-shaft mixer and mix for 25 minutes to obtain high-protein pig feed.

[0035] Example 3

[0036] A method for preparing high-protein pig feed, the specific implementation steps of which are as follows: S1: Weigh 50g of brewer's yeast cell wall residue (5:5 mass ratio) and 50g of defatted mealworm sand, mix them evenly; adjust the pH to 8.8 with sodium hydroxide solution, add 0.8g of Bacillus amyloliquefaciens protease (0.8% of the total substrate mass), and enzymatically hydrolyze at 58℃ and stirring speed of 180r / min for 2.5 hours. Then, heat to 90℃ to inactivate the enzyme for 15 minutes, centrifuge to separate the precipitate, wash the precipitate twice with deionized water (80mL each time), vacuum dry at 52℃ to constant weight, pulverize and pass through an 80-mesh sieve to obtain the modified protein core.

[0037] S2: Weigh 10g of konjac glucomannan and 11g of sodium periodate in a mass ratio of 1:1.1. Dissolve the konjac glucomannan in 100mL of deionized water, add sodium periodate under light-protected conditions, adjust the pH to 4.0 with dilute hydrochloric acid, and react at 30℃ and a stirring speed of 150r / min for 6 hours. Add 5mL of ethylene glycol to terminate the reaction. Put the reaction solution into a dialysis bag with a molecular weight cutoff of 8000-14000, and dialyze it in deionized water at 4℃ for 36 hours (changing the water every 6 hours). Dry to obtain oxidized konjac glucomannan.

[0038] S3: Using 200 mL of a methanol-deionized water mixed solvent with a volume ratio of 1:1 (100 mL methanol and 100 mL deionized water), weigh 20 g of modified protein core, 4 g of zinc nitrate hexahydrate, and 6 g of 2-methylimidazole at a mass ratio of 1:0.2:0.3; and dissolve 5 g of konjac glucomannan and 1 g of tannic acid in 50 mL of deionized water at a mass ratio of 1:0.2. Dissolve zinc nitrate hexahydrate in 20 mL of deionized water and add it to the modified protein core dispersion. Then, slowly add 2-methylimidazole solution (6 g dissolved in 30 mL methanol) and the above mixed solution. After the addition is complete, react for 6 hours at 25 °C and a stirring speed of 250 r / min. After centrifugation and washing (washing twice each with anhydrous methanol, 30% ethanol, and deionized water, 50 mL each time), vacuum dry at 40 °C to obtain high-protein composite microparticles with a particle size of 50-300 μm.

[0039] S4: Weigh out 55kg of corn, 18kg of soybean meal, 12kg of wheat bran, 4kg of premix, and 10kg of high-protein compound microparticles by weight; put them into a mixer and mix for 15 minutes until uniform to obtain high-protein pig feed.

[0040] Example 4

[0041] A method for preparing high-protein pig feed, the specific implementation steps of which are as follows: S1: Weigh 35g of brewer's yeast cell wall residue (3.5:6.5 mass ratio) and 65g of defatted mealworm sand, and mix them evenly; adjust the pH of the system to 8.5 with sodium hydroxide solution, add 2g of Bacillus licheniformis protease (2.0% of the total substrate mass), and enzymatically hydrolyze for 4 hours at 40℃ and 190r / min stirring speed; after enzymatic hydrolysis, rapidly raise the temperature to 90℃ and inactivate the enzyme for 15 minutes; separate the solid and liquid by centrifugation, discard the supernatant, and wash the precipitate twice with deionized water (80mL each time). Place the washed precipitate in a vacuum drying oven at 50℃ and dry it to constant weight. After removal, pulverize it with an ultrafine pulverizer and pass it through an 80-mesh standard sieve to obtain the modified protein core.

[0042] S2: Weigh 10g of konjac glucomannan (mass ratio 1:0.8) and 8g of sodium periodate; completely dissolve the konjac glucomannan in 100mL of deionized water, add sodium periodate under dark conditions, and adjust the pH to 3.5 with dilute hydrochloric acid; react at 25℃ and 140r / min under dark conditions for 8 hours; after the reaction is completed, add 5mL of ethylene glycol and stir for 30 minutes to terminate the reaction; put the reaction solution into a dialysis bag with a molecular weight cutoff of 8000-14000, and dialyze in deionized water at 4℃ for 36 hours, changing the deionized water every 6 hours during the process; collect the liquid in the dialysis bag and dry it in a dryer to constant weight to obtain oxidized konjac glucomannan.

[0043] S3: Prepare 180 mL of a methanol-deionized water mixed solvent with a volume ratio of 0.8:1 (80 mL methanol, 100 mL deionized water), and disperse 20 g of modified protein core in it; weigh out 20 g of modified protein core, 10 g of zinc nitrate hexahydrate, and 15 g of 2-methylimidazole according to a mass ratio of 1:0.5:0.75. First, add the zinc nitrate hexahydrate solution (10 g dissolved in 50 mL deionized water) and stir to disperse. Then, simultaneously and slowly add the 2-methylimidazole solution (15 g dissolved in 75 mL methanol) and the oxidized konjac glucomannan:tannic acid mixture with a ratio of 1:0.5. The solution (6g of oxidized konjac glucomannan and 3g of tannic acid dissolved in 60mL of deionized water) was prepared, and the dropping time was controlled at 80 minutes throughout the process. After the dropping was completed, the reaction was continued at 40℃ and a stirring speed of 260r / min for 4 hours. After the reaction was completed, the precipitate was separated by centrifugation. The precipitate was washed three times with anhydrous methanol (60mL each time), three times with 30% ethanol aqueous solution (60mL each time), and three times with deionized water (60mL each time). The washed precipitate was placed in a vacuum drying oven at 45℃ and dried to constant weight to obtain high protein composite microparticles with a particle size of 200-300μm.

[0044] S4: Weigh out 40kg of corn, 25kg of soybean meal, 5kg of wheat bran, 1kg of premix, and 30kg of high-protein compound microparticles by weight. Put the above components into a horizontal mixer and mix for 30 minutes until uniform to obtain high-protein pig feed.

[0045] Example 5

[0046] A method for preparing high-protein pig feed, the specific implementation steps of which are as follows: S1: Weigh 45g of brewer's yeast cell wall residue (4.5:5.5 mass ratio) and 55g of defatted mealworm sand, and mix them evenly; adjust the pH of the system to 9.5 with sodium hydroxide solution, add 0.1g of Bacillus amyloliquefaciens protease (0.1% of the total substrate mass), and enzymatically hydrolyze for 2 hours at 50℃ and stirring speed of 210r / min; after enzymatic hydrolysis, rapidly raise the temperature to 95℃ and inactivate the enzyme for 10 minutes; separate the solid and liquid by plate and frame filtration, discard the filtrate, and wash the precipitate three times with deionized water (80mL each time). Place the washed precipitate in a vacuum drying oven at 60℃ and dry it to constant weight. After removal, pulverize it with an ultrafine pulverizer and pass it through a 90-mesh standard sieve to obtain the modified protein core.

[0047] S2: Weigh 10g of konjac glucomannan (mass ratio 1:1.2) and 12g of sodium periodate. Dissolve the konjac glucomannan completely in 100mL of deionized water. Add sodium periodate under dark conditions and adjust the pH to 4.0 with dilute hydrochloric acid. React at 30℃ and 160r / min under dark conditions for 6 hours. After the reaction is complete, add 5mL of ethylene glycol and stir for 30 minutes to terminate the reaction. Put the reaction solution into a dialysis bag with a molecular weight cutoff of 8000-14000 and dialyze in deionized water at 4℃ for 40 hours, changing the deionized water every 6 hours. Collect the liquid in the dialysis bag and dry it in a dryer to constant weight to obtain oxidized konjac glucomannan.

[0048] S3: Prepare 210 mL of a methanol-deionized water mixture with a volume ratio of 3.2:1 (160 mL methanol, 50 mL deionized water), and disperse 20 g of the modified protein core in it; weigh out 20 g of the modified protein core, 2 g of zinc nitrate hexahydrate, and 1.6 g of 2-methylimidazole according to a mass ratio of 1:0.1:0.08. First, add the zinc nitrate hexahydrate solution (2 g dissolved in 10 mL deionized water) and stir to disperse. Then, simultaneously and slowly add the 2-methylimidazole solution (1.6 g dissolved in 8 mL methanol) and the mixture of oxidized konjac glucomannan:tannic acid = 1:0.2. The solution (4g of oxidized konjac glucomannan and 0.8g of tannic acid dissolved in 40mL of deionized water) was added dropwise over a period of 50 minutes. After the addition was complete, the reaction was continued at 25℃ and a stirring speed of 240r / min for 6 hours. After the reaction was completed, the precipitate was separated by centrifugation. The precipitate was washed twice with anhydrous methanol (50mL each time), twice with 30% ethanol aqueous solution (50mL each time), and twice with deionized water (50mL each time). The washed precipitate was dried in a vacuum drying oven at 40℃ to constant weight to obtain high-protein composite microparticles with a particle size of 50-150μm.

[0049] S4: Weigh out 60kg of corn, 15kg of soybean meal, 15kg of wheat bran, 5kg of premix, and 5kg of high-protein compound microparticles by weight. Put the above components into a twin-shaft mixer and mix for 15 minutes until uniform. This will give you high-protein pig feed.

[0050] Comparative Example 1 Brewer's yeast cell wall residue and defatted mealworm sand were mixed at a ratio of 3:7, without enzymatic hydrolysis, enzyme inactivation, or modification treatment. The mixture was then pulverized through a 100-mesh sieve and used as a common protein raw material. The remaining steps were the same as in Example 1.

[0051] Comparative Example 2 In step S3, oxidized konjac glucomannan is not added to the reaction system; only tannic acid is added. The remaining steps are the same as in Example 1.

[0052] Comparative Example 3 In step S3, tannic acid is not added to the reaction system; only oxidized konjac glucomannan is added. The remaining steps are the same as in Example 1.

[0053] Comparative Example 4 In the reaction system of step S3, the modified protein core, oxidized konjac glucomannan, and tannic acid are directly and physically mixed without adding zinc nitrate hexahydrate or 2-methylimidazole. The remaining steps are the same as in Example 1.

[0054] Comparative Example 5 In step S4, no high-protein complex microparticles are added to the feed formulation. Instead, corn, soybean meal, wheat bran, and premix are used in proportion to form a conventional basic feed, with the same mixing process.

[0055] The following performance tests were conducted on the high-protein pig feeds prepared in Examples 1-5 and Comparative Examples 1-5: 1. Growth performance indicators Take 50 kg of pig feed prepared in Examples 1-3 and Comparative Examples 1-5 respectively, remove impurities, and place them in sealed bags. One day before the experiment, place each group of feed in a 25°C environment to warm up, ensuring that the feed temperature is consistent with the ambient temperature during feeding. Feed once each at 7:00, 14:00, and 21:00 daily, with each feeding amount based on the piglets finishing the food within 30 minutes. Clean up any uneaten feed promptly and record the amount remaining. Record the daily feeding amount and uneaten feed amount for each group, calculate the total daily feed intake, and check the piglets' feces at 7:30 and 18:00 daily, recording the number of pigs with diarrhea, the number of days of diarrhea, and observing the self-healing status.

[0056] Healthy piglets were selected and randomly divided into 8 groups of 10 piglets each, with half males and half females. Groups 1-3 were fed the high-protein pig feed prepared in Examples 1-3, while groups 4-8 were fed the control examples 1-5.

[0057] Feeding was stopped at 21:00 the day before the test, and the piglets were fasted for 12 hours to ensure they were in a fasting state. Each piglet was weighed individually using an electronic scale, and the weight of each piglet was recorded. The average initial weight on day 0 and the average final weight on day 28 were calculated for each group. The calculation formula is as follows: Average daily weight gain (ADG) = (Average final weight per group - Average initial weight per group) ÷ 28 (days) Average daily feed intake (ADFI) = Total feed intake during the trial period for each group ÷ (Number of animals per group × 28) Feed conversion ratio (F / G) = Average daily feed intake (ADFI) ÷ Average daily gain (ADG) Diarrhea rate = (Total number of diarrhea episodes per group) ÷ (Number of pigs per group × 28) × 100% (Diarrhea episode: 1 piglet with diarrhea for 1 day is counted as 1 episode) 2. Nutrient digestibility Every morning, fresh fecal samples (approximately 200g / head) were collected from each piglet, avoiding contamination (avoiding contact with urine and pen impurities). The samples were placed in a fecal collection box, and 20mL of 10% sulfuric acid solution was immediately added. The samples were stirred evenly, and the group and date were labeled. The fecal samples were mixed evenly over 3 days and dried in a 65℃ oven until constant weight. After cooling to room temperature, the samples were pulverized and passed through a 40-mesh sieve. The experimental results are shown in Table 1-2.

[0058] According to the kit instructions, determine the dry matter (DM), crude protein (CP), and acid-insoluble ash (AIA) content of feed samples and fecal samples respectively.

[0059] Calculate apparent digestibility: Apparent digestibility = 1 − (AIA content in feed / AIA content in feces) × (nutrient content in feces / nutrient content in feed) × 100% (Calculate apparent digestibility of dry matter and apparent digestibility of crude protein separately).

[0060] Table 1: Comparison of initial and final body weight, growth performance, and diarrhea rate of piglets in each experimental group

[0061] Table 2: Results of apparent digestibility of dry matter and crude protein in piglets from different experimental groups

[0062] As shown in Table 1, the average daily weight gain of piglets in Examples 1-5 was significantly higher than that in Comparative Examples 1-5, the feed conversion ratio was much lower than that in Comparative Examples 1-5, and the diarrhea rate was also significantly reduced. This indicates that the high-protein pig feed prepared by the present invention can significantly improve the growth performance of piglets and reduce feed consumption and the risk of diarrhea. Comparative Example 1 did not undergo enzymatic modification of the protein raw materials, resulting in low protein release efficiency and poor growth performance. Comparative Examples 2 and 3 lacked the cross-linking synergy of oxidized konjac glucomannan or tannic acid, resulting in insufficient controlled release and intestinal protection effects, and their performance was second best. Comparative Example 4 did not construct a ZIF-8 metal-organic framework, and the protein was easily degraded prematurely by gastric acid, further reducing growth performance. Comparative Example 5 was a conventional basal diet without the support of high-protein complex microparticles, and it had the worst growth performance among all groups. This fully demonstrates the positive promoting effect of the feed prepared by the process of the present invention on the growth of piglets.

[0063] As shown in Table 2, the apparent digestibility of dry matter and crude protein in Examples 1-5 is significantly higher than that in Comparative Examples 1-5, indicating that the high-protein pig feed of the present invention can significantly improve the digestibility and absorption efficiency of nutrients in piglets. Comparative Example 1 has a low digestibility because the protein raw material is not enzymatically hydrolyzed, making it difficult to break down and utilize the protein. Comparative Examples 2 and 3 have limited controlled-release effects due to incomplete shell cross-linking, resulting in digestibility between the examples and other comparative examples. Comparative Example 4 lacks a pH-responsive controlled-release structure, leading to premature protein degradation and a further decrease in digestibility. Comparative Example 5 is a traditional diet without modified protein core and controlled-release shell design, resulting in the lowest protein utilization rate and the worst digestibility among all groups, confirming the advantages of the feed of the present invention in nutrient digestibility and absorption.

[0064] In summary, by preparing a modified protein core and constructing a pH-responsive controlled-release shell composed of ZIF-8 and oxidized konjac glucomannan-tannic acid, high-protein composite microparticles were obtained and added to the basal diet. The high-protein pig feeds in Examples 1-5 achieved intestinal-targeted controlled release of protein, improved protein utilization and nutrient digestibility, improved piglet intestinal health, reduced diarrhea rate, and enhanced feed feeding effect and breeding efficiency. Compared with traditional feeds and control feeds lacking processing technology, it showed superior performance advantages.

[0065] In the description of this specification, the reference to terms such as "embodiment," "various embodiments," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or preparation example is included in at least one embodiment of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing high-protein pig feed, characterized in that, Includes the following steps: S1: Mix brewer's yeast cell wall residue with defatted mealworm sand, hydrolyze with protease, inactivate the enzyme, dry under vacuum to constant weight, and pulverize through an 80-100 mesh sieve to obtain modified protein core; S2: Dissolve konjac glucomannan in water, add sodium periodate under light-protected conditions, and adjust the pH to 3.5-4.0 to carry out the oxidation reaction. After the reaction is completed, purify and dry to obtain oxidized konjac glucomannan. S3: Disperse the modified protein core from step S1 in a solvent, add zinc nitrate hexahydrate solution, and simultaneously add 2-methylimidazole solution and a mixed solution containing oxidized konjac glucomannan and tannic acid from step S2, and react to obtain high-protein composite microparticles. S4: Mix the high-protein composite microparticles obtained in step S3 with the high-protein basal diet evenly to obtain high-protein pig feed.

2. The method for preparing a high-protein pig feed according to claim 1, characterized in that, In step S1, the mass ratio of brewer's yeast cell wall residue to defatted mealworm sand is (3-5):(5-7); the protease is one or more of Bacillus licheniformis protease, Bacillus subtilis protease, and Bacillus amyloliquefaciens protease; the amount of enzyme added is 0.1-2.0% of the substrate mass.

3. The method for preparing a high-protein pig feed according to claim 1, characterized in that, Step S1 is as follows: After mixing the cell wall residue of brewer's yeast with defatted mealworm sand, the pH is adjusted to 8.5-9.

5. The mixture is stirred and enzymatically hydrolyzed at 40-50℃ for 2-4 hours. After the enzymatic hydrolysis is completed, the temperature is raised to 90-95℃ to inactivate the enzyme for 10-15 minutes. After solid-liquid separation, the precipitate is washed 2-3 times with deionized water and vacuum dried at 50-60℃ to constant weight. The precipitate is then pulverized and passed through an 80-100 mesh sieve to obtain the modified protein core.

4. The method for preparing a high-protein pig feed according to claim 1, characterized in that, In step S2, the mass ratio of konjac glucomannan to sodium periodate is 1:(0.8-1.2); the oxidation reaction is carried out under the following conditions: in the dark, at a temperature of 25-30℃, for 6-8 hours, and at a pH of 3.5-4.

0.

5. The method for preparing a high-protein pig feed according to claim 1, characterized in that, Step S2 purification specifically involves: placing the reaction solution into a dialysis bag and dialyzing it in deionized water at 4°C for 36-40 hours, then collecting the liquid from the dialysis bag.

6. The method for preparing a high-protein pig feed according to claim 1, characterized in that, In step S3, the solvent is a mixed solution of methanol and deionized water with a mass ratio of (0.8-3.2):1; the mass ratio of modified protein core, zinc nitrate hexahydrate, and 2-methylimidazole is 1:(0.1-0.5):(0.08-0.75).

7. The method for preparing a high-protein pig feed according to claim 1, characterized in that, In step S3, the mass ratio of oxidized konjac glucomannan to tannic acid is 1:(0.2-0.5).

8. The method for preparing a high-protein pig feed according to claim 1, characterized in that, The reaction conditions in step S3 are as follows: continue stirring the reaction at 25-40℃ for 4-6 hours. After the reaction is completed, the solid and liquid are separated, and the precipitate is washed successively with anhydrous methanol, 30% ethanol aqueous solution, and deionized water, and then dried under vacuum at 40-45℃ to constant weight.

9. The method for preparing a high-protein pig feed according to claim 1, characterized in that, The high-protein basal diet in step S4 includes the following components by weight: 40-60 parts corn, 15-25 parts soybean meal, 5-15 parts wheat bran, 1-5 parts premix, and 5-30 parts high-protein compound microparticles.

10. High-protein pig feed prepared by any one of claims 1-9.

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