Plant extract intestinal promoting feed and preparation method thereof

Abstract

The invention belongs to the field of animal nutrition and feed science, and discloses a plant extract intestinal tract promoting feed and a preparation method thereof.The preparation method comprises the steps that alginic acid modified astragalus polysaccharide and specific probiotics are subjected to interaction screening, active ingredients are packaged in a pH and enzyme dual-response micro-capsule carrier, and a wheat sterol-glucan conjugate is contained in a compound for compatibility; and triple synergistic effects of bacterium promotion colonization, intestinal segment targeted release and immunological enhancement are realized. The preparation method comprises the following steps: S1, extracting and modifying the astragalus polysaccharide; s2, synthesizing a sterol-glucan conjugate; s3, preparing a double-layer micro-capsule carrier and loading active ingredients; and S4, homogenizing, mixing and granulating the micro-capsules and other feed components. Breeding experiments prove that the feed can increase the number of probiotics in animal intestinal tracts, increase the body weight, increase the speed, improve the immune index of animals and remarkably improve the feed conversion efficiency and the health level.

Description

Technical Field

[0001] This invention belongs to the field of animal nutrition and feed science, specifically relating to a plant extract-based intestinal-promoting feed and its preparation method. Background Technology

[0002] In modern livestock and poultry production, plant polysaccharides and probiotic additives are often used to improve feed utilization efficiency and enhance animal health and growth performance. However, unmodified natural polysaccharides are easily degraded by the acidic environment in the stomach, failing to reach the intestines to exert their probiotic proliferation effect. Existing microencapsulation carrier technologies mainly rely on single pH or single enzyme-sensitive materials, making it difficult to achieve precise controlled release in different segments of the stomach and intestines. Furthermore, the compatibility of the carrier with the active ingredient, drug loading, and release efficiency are often limited. Meanwhile, to enhance the body's immune level, traditional formulations typically require the addition of sterols or polysaccharide immunomodulators. This not only complicates feed formulations and diversifies production processes, but also often results in uneven compatibility and poor stability due to the simple superposition of different functional factors, making it difficult to maintain consistent efficacy and controllable costs in production practice. Therefore, there is an urgent need for a novel intestinal-promoting feed and its preparation method that can achieve substantial innovation in the chemical modification of active ingredients, the construction of intelligent dual-response controlled-release carriers, and the synergistic compatibility of immune-nutritional factors, thereby meeting the comprehensive needs of large-scale production for functional integration, high efficiency and stability, and cost-effectiveness. Summary of the Invention

[0003] To address the shortcomings mentioned in the background art, the present invention aims to provide a plant extract intestinal-promoting feed and its preparation method. This involves obtaining a complex polysaccharide specifically promoting Bifidobacterium colonization by grafting ferulic acid onto Astragalus polysaccharide and physically cross-linking it with alginate. This polysaccharide is then encapsulated together with a wheat sterol-glucan conjugate in a pH- and enzyme-responsive microcapsule carrier. Finally, it is compounded and granulated with a high-protein and vitamin-mineral premix, significantly achieving a triple synergistic effect of targeted intestinal release, probiotic colonization promotion, and immune enhancement.

[0004] The objective of this invention can be achieved through the following technical solutions: A plant extract-based intestinal-promoting feed comprises the following ingredients in parts by weight: 5-15 parts of alginate-modified astragalus polysaccharide, 20-40 parts of dual-responsive microcapsule carrier, 2-5 parts of wheat sterol-glucan conjugate, 30-50 parts of protein powder, 10-15 parts of vitamin and mineral premix, and supplemented to 100 parts of feed carrier.

[0005] More preferably, the preparation method of alginate-modified astragalus polysaccharide specifically includes the following steps: S101. Add Astragalus powder to deionized water, sonicate in a water bath, heat and stir under reflux, filter, concentrate to 1 / 4 of the original volume, add ethanol, let stand and centrifuge to obtain crude Astragalus polysaccharide precipitate, wash twice with ethanol and vacuum dry for later use. S102. Dissolve dried Astragalus polysaccharide in sodium bicarbonate solution, stir well, and then add an active esterifying agent to activate it; slowly add ferulic acid methanol solution, and react at room temperature to generate Astragalus-ferulic acid conjugate; S103. After the reaction, adjust the pH to neutral, dialyze in deionized water using a dialysis bag, and then freeze-dry to obtain astragalus-ferulic acid conjugated polysaccharide. Then dissolve it in deionized water, add sodium alginate solution, slowly add CaCl2 and stir.

[0006] S104. The mixed reaction solution of Astragalus-ferulic acid polysaccharide obtained by physical cross-linking in step S103 and sodium alginate is processed by spray drying machine, and the composite microspheres formed after drying are collected, which are alginate-modified Astragalus polysaccharide.

[0007] More preferably, the dual-response microcapsule carrier is composed of an outer chitin-chitosan composite membrane and an inner gelatin-sodium alginate composite membrane, with a microcapsule particle size of 50–200 μm.

[0008] More preferably, the wheat sterol-glucan conjugate is a conjugate product obtained by dissolving wheat sterol and β-1,3-glucan in methanol at a molar ratio of 1:1, removing the solvent by vacuum evaporation, and then vacuum drying.

[0009] More preferably, the vitamin and mineral premix includes vitamin A, vitamin D, vitamin E, calcium, phosphorus, and zinc.

[0010] A method for preparing a plant extract-based intestinal-promoting feed includes the following steps: S1. Astragalus polysaccharide was extracted and dried from Astragalus powder, and then obtained by esterification grafting of ferulic acid and physical cross-linking with sodium alginate to produce alginate-modified Astragalus polysaccharide that specifically promotes the colonization of probiotics. S2. Wheat sterol and β-1,3-glucan were coupled in the liquid phase to obtain wheat sterol-glucan conjugate; S3. The outer and inner layers of the microcapsule are constructed sequentially using two composite materials: chitosan-chitin and gelatin-sodium alginate. The active ingredients obtained in steps S1 and S2 are loaded into the microcapsule to form a pH and enzyme dual-responsive microcapsule carrier. S4. The double-layered microcapsules containing active ingredients are mixed with protein powder, vitamin-mineral premix and feed matrix, and then processed using conventional granulation, drying and sieving processes to obtain the finished plant extract intestinal promoting feed.

[0011] More preferably, in step S3, the component ratio of the microcapsule carrier is outer layer:inner layer = 1:1 to ensure dual-response performance.

[0012] More preferably, the protein powder in step S4 is one or more of soy protein isolate, fish meal, and whey protein.

[0013] More preferably, step S4 involves high-shear homogenization premixing of the mixture to improve the uniformity of microcapsule dispersion.

[0014] The beneficial effects of this invention are: This invention combines chemical modification and intelligent controlled-release principles to graft ferulic acid onto Astragalus polysaccharides and cross-link them with alginate to form a complex polysaccharide. This significantly enhances the polysaccharide's acid and enzyme resistance and promotes the adhesion and colonization of Bifidobacteria through its specific molecular structure. The microcapsule construction utilizes chitosan-chitin and gelatin-sodium alginate composite outer and inner layers to achieve dual pH and enzyme-responsive release, ensuring precise release of active components to areas with concentrated intestinal pathogens and effectively improving bioavailability. Wheat sterol-glucan conjugates activate mucosal immune pathways at the molecular level, synergistically enhancing the body's disease resistance. The combination of microcapsules with high-protein, vitamin, and mineral premixes not only promotes balanced nutrient absorption but also effectively reduces feed conversion ratio and increases animal growth rate through multiple functional synergies. Attached Figure Description

[0015] The invention will now be further described with reference to the accompanying drawings.

[0016] Figure 1 Bar charts showing the relative abundance of Bifidobacteria and Lactobacillus in the feces of feed-fed animals prepared in Examples 1-3 and Comparative Examples 1-2; Figure 2 Daily weight gain graphs of feed-fed animals were prepared for Examples 1-3 and Comparative Examples 1-2; Figure 3 28-day weight gain curves of feed-fed animals were prepared for Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1 9. Preparation of Alginic Acid-Modified Astragalus Polysaccharide Weigh 100 g of Astragalus powder and place it in 1 L of deionized water. Sonicate in a 60 ℃ water bath (300 W power) for 20 min, raise the temperature to 80 ℃, reflux and stir for 1 h, filter to remove residue, concentrate the filtrate to 1 / 4 of the original volume at 50 ℃, slowly add 4 L of anhydrous ethanol, let stand at room temperature for 4 h, centrifuge at 4000 r / min for 10 min, discard the supernatant, take the precipitate, wash it twice with anhydrous ethanol, and vacuum dry at 40 ℃ for 4 h to obtain dried Astragalus polysaccharide.

[0019] Dissolve 10 g of dried Astragalus polysaccharide in 200 mL of 0.1 M sodium bicarbonate solution and stir for 30 min. Then, add 0.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.3 g of N-hydroxysuccinimide in sequence. Activate the carboxyl group for 30 min. Slowly add ferulic acid methanol solution and react at room temperature for 4 h. After the reaction is complete, adjust the pH of the mixture to 7.0.

[0020] The above product was placed in a 3500 Da dialysis bag and dialyzed in flowing deionized water for 48 h, with the dialysate being replaced every 12 h. After dialysis, the product was freeze-dried to obtain astragalus-ferulic acid conjugated polysaccharide. The conjugated polysaccharide was dissolved in 100 mL of deionized water, and 100 mL of 3% (w / v) sodium alginate solution was added to adjust the pH to 6.5. 0.1% (w / v) CaCl2 solution was slowly added dropwise and stirred for 2 h to achieve physical cross-linking of polysaccharide-sodium alginate. The cross-linked mixture was placed in a spray dryer and dried under conditions of 150 °C inlet air temperature and 0.2 MPa spray pressure. Composite microspheres with a particle size in the range of 50–200 μm were collected, and the resulting product was alginate-modified astragalus polysaccharide.

[0021] 10. Preparation of plant extract-based intestinal-promoting feed The plant extract intestinal-promoting feed contains the following ingredients by weight: 5 parts alginate-modified astragalus polysaccharide, 20 parts dual-response microcapsule carrier, 2 parts wheat sterol-glucan conjugate, 30 parts protein powder, 10 parts vitamin and mineral premix, and feed carrier to make up to 100 parts.

[0022] The preparation method is as follows: 50 g of alginate-modified astragalus polysaccharide, 200 g of dual-responsive microcapsule carrier, and 20 g of wheat sterol-glucan conjugate are placed in a 1 L high-shear homogenizer and premixed at 500 rpm for 1 min to wet coarse particles. The homogenizer is then switched to 1500 rpm for 3 min to ensure thorough and uniform dispersion of the powder and microcapsules. The homogenizer is stopped and allowed to stand for 2 min. The premix is ​​transferred to a 5 L propeller mixer, and 300 g of protein powder, 100 g of vitamin-mineral premix, and 330 g of feed carrier are added sequentially. The mixture is stirred at 60 rpm for 5 min to ensure complete homogenization of the powders and absence of significant agglomeration. The machine is stopped and checked; if any particles stick to the walls, they are scraped off with a scraper and mixing continues for 1 min. The homogenized mixture is then fed into a rotary drum dry granulator. The drum speed is set to 30 rpm and the extrusion pressure to 1.0 MPa. Particles with a diameter of 2.0–3.0 mm are collected at the granulation outlet. The granulated particles are spread on a drying tray and placed in a fluidized bed dryer. The drying conditions are: air temperature 55 ℃, air volume 200 m³ / h, drying for 30 min until the particle moisture content is <10%. After drying, the particles are passed through 40 mesh and 80 mesh sieves in sequence, and the intermediate particles are collected, which is the plant extract intestinal promoting feed.

[0023] Example 2 The preparation of alginate-modified Astragalus polysaccharide is the same as in Example 1.

[0024] The preparation process of plant extract-based intestinal-promoting feed is as follows: The plant extract intestinal-promoting feed contains the following ingredients by weight: 15 parts alginate-modified astragalus polysaccharide, 40 parts dual-response microcapsule carrier, 5 parts wheat sterol-glucan conjugate, 50 parts protein powder, 15 parts vitamin and mineral premix, and feed carrier to make up to 100 parts.

[0025] The preparation method of the plant extract intestinal-promoting feed is the same as in Example 1.

[0026] Example 3 The preparation of alginate-modified Astragalus polysaccharide is the same as in Example 1.

[0027] The preparation process of plant extract-based intestinal-promoting feed is as follows: The plant extract intestinal-promoting feed contains the following ingredients by weight: 10 parts alginate-modified astragalus polysaccharide, 30 parts dual-response microcapsule carrier, 3.5 parts wheat sterol-glucan conjugate, 40 parts protein powder, 12.5 parts vitamin and mineral premix, and feed carrier to make up to 100 parts.

[0028] The preparation method of the plant extract intestinal-promoting feed is the same as in Example 1.

[0029] Comparative Example 1 The preparation process of plant extract-based intestinal-promoting feed is as follows: The plant extract intestinal-promoting feed contains the following ingredients by weight: 10 parts unmodified astragalus polysaccharide, 30 parts dual-response microcapsule carrier, 3.5 parts wheat sterol-glucan conjugate, 40 parts protein powder, 12.5 parts vitamin and mineral premix, and feed carrier to make up to 100 parts.

[0030] The preparation method of the plant extract intestinal-promoting feed is the same as in Example 1.

[0031] Comparative Example 2 The preparation of alginate-modified Astragalus polysaccharide is the same as in Example 1.

[0032] The preparation process of plant extract-based intestinal-promoting feed is as follows: The plant extract intestinal-promoting feed contains the following ingredients by weight: 10 parts alginate-modified astragalus polysaccharide, 30 parts dual-response microcapsule carrier, 40 parts protein powder, 12.5 parts vitamin and mineral premix, and feed carrier to make up to 100 parts.

[0033] The preparation method of the plant extract intestinal-promoting feed is the same as in Example 1.

[0034] Performance testing 11. Analysis of gut microbiota colonization and diversity Fecal samples were collected from each group (Examples 1, 2, 3; Comparative Examples 1, 2) after the feeding period ended. 200 mg of each sample was immediately frozen at -80 °C. Genomic DNA extraction kits were used to extract sample DNA and high-quality genomic DNA according to the instructions. The products were then amplified by PCR. The amplified products were purified, quantified, and quality-checked. Sequencing was performed using an Illumina MiSeq PE250. Raw data underwent quality control, splicing, and dechimeric analysis. OTU clustering, species annotation, and α-diversity index calculations were performed. The results are shown in Table 1 below.

[0035] Table 1. Results of diversity analysis

[0036] As shown in Table 1, the Example Group significantly outperformed the Comparative Group in promoting intestinal probiotic colonization and improving microbial community diversity. The relative abundance of Bifidobacteria in Example 1 was 1.30 times, an increase of approximately 18% compared to Comparative Group 1 and approximately 8% compared to Comparative Group 2; the relative abundance of Lactobacillus was 1.20 times, also exceeding the Comparative Group by 5%–14%. With the increase in the content of active ingredients in the formula, Example 2 showed the most significant improvement in Bifidobacteria and Lactobacillus abundance, reaching 1.70 times and 1.60 times respectively, demonstrating a stronger specific probiotic-promoting effect. Regarding microbial diversity indicators, the Shannon index of the Example Group was higher than that of the Comparative Group (3.6 and 3.8), indicating an effective improvement in community evenness and richness; the Observed OTUs were also superior to those of the Comparative Group (210 and 240) in the range of 230–280, indicating a more diverse and stable microbial community structure.

[0037] 2. Nutrient absorption and growth performance test Healthy animals of the same age were randomly divided into five groups and fed with the feed prepared in Examples 1–3 and Comparative Examples 1–2. Each group consisted of 10 animals and was fed continuously for 28 days. The animals had free access to food and water throughout the day. The animals were weighed and the amount of feed fed and the amount of feed remaining were recorded at a fixed time every day (8:00 AM). The total amount of feed consumed and the weight gain of each group were counted weekly. The weight gain was calculated as FCR = feed consumption (kg) / weight gain (kg). The daily weight gain (ADG) was calculated as (final weight - initial weight) / number of days. The results are shown in Table 2 below.

[0038] Table 2 Growth performance results

[0039] As shown in Table 2, the example groups outperformed the comparative group in both feed utilization efficiency and weight gain. Compared with the comparative group, the feed conversion ratio (FCR) of Examples 1–3 was significantly reduced, indicating a significant reduction in the amount of feed required for the same weight gain; and the daily gain (ADG) was significantly improved, resulting in faster animal growth. In particular, Example 2, with the highest modified polysaccharide to carrier ratio and the optimal immune conjugation combination, further reduced FCR and increased ADG, demonstrating the optimal effect of the formulation synergy. Example 3, as an intermediate formulation, also maintained excellent performance without extreme addition of each component, demonstrating the flexibility and applicability of the technology.

[0040] 3. Digestive physiological indicators testing Small intestinal brush border mucosa was collected from animals fed with different diets, homogenized, centrifuged, and the supernatant was used as an enzyme source. The activities of amylase, protease, and lipase were measured. After fasting, FITC-dextran was administered by gavage and blood was collected to measure serum FITC concentration to assess intestinal permeability. At the same time, serum endotoxin levels were measured using a LAL kit to reflect the integrity of the intestinal mucosal barrier. The results are shown in Table 3 below.

[0041] Table 3 Results of Digestive Physiological Indicators

[0042] As shown in Table 3, the sample groups of this invention are superior to the comparative group in terms of digestive enzyme activity and intestinal barrier function. The amylase, protease, and lipase activities of Examples 1–3 are in the ranges of 5.0–6.5 U / mg, 3.8–5.0 U / mg, and 4.2–5.5 U / mg, respectively, all significantly higher than those of Comparative Example 1 and Comparative Example 2, indicating that the feed formulation of this invention can effectively promote the secretion and functional enhancement of intestinal digestive enzymes. Among them, Example 2 has the best activity, indicating that the higher proportion of alginate-modified astragalus polysaccharide and the intelligent controlled-release carrier have the strongest synergistic effect.

[0043] In the intestinal permeability assessment, the serum FITC concentration in the example group (10.0–15.0 μg / mL) was significantly lower than that in the control group (20.0–25.0 μg / mL), indicating reduced intestinal barrier permeability and effectively reducing the permeation of harmful substances. Furthermore, the serum endotoxin level (0.15–0.25 EU / mL) was also lower than that in the control group (0.30–0.40 EU / mL), reflecting enhanced mucosal integrity. In summary, the feed of this invention, through chemical modification and dual-response controlled release, achieves the dual beneficial effects of enhanced digestive function and intestinal barrier protection.

[0044] 4. Evaluation of immune function Immunoglobulin (IgA, IgG, IgM) quantification: Using a commercial ELISA kit, standards and samples (serum diluted 1:100) were added, incubated at 37 ℃ for 1 h, washed 3 times, added enzyme-labeled secondary antibody and incubated for another 30 min, and after TMB color development for 15 min, the OD value was measured at 450 nm colorimetrically, and the level of each Ig was calculated according to the standard curve.

[0045] Inflammatory factor (TNF-α, IL-6) and antioxidant enzyme (SOD, GSH-Px) activity assays: TNF-α and IL-6 were quantified using ELISA, with the same procedure as for Ig assays. SOD activity was measured using the WST-1 kit, with U / mg protein calculated based on the rate of inhibition of ×O2•– production. GSH-Px activity was measured using an enzymatic method, with U / mg protein determined based on the NADPH consumption rate. The results are shown in Table 4 below.

[0046] Table 4 Results of Immune Function Evaluation

[0047] Table 4 shows that the immune function and antioxidant capacity of the Example groups were significantly better than those of the Comparative groups. Specifically, the serum IgA, IgG, and IgM levels in Examples 1–3 were significantly higher than those in Comparative Groups 1 and 2. In Example 2, the IgA, IgG, and IgM levels reached 2.0, 9.5, and 3.0 mg / mL, respectively, representing increases of 100%, 46%, and 50% compared to Comparative Group 1, indicating enhanced mucosal and humoral immunity. Furthermore, the levels of inflammatory factors TNF-α and IL-6 were generally lower in the Example groups. In Example 2, TNF-α and IL-6 levels were reduced by 50% and 50% respectively compared to Comparative Group 1, indicating that the feed effectively suppressed the inflammatory response. Regarding antioxidant enzyme activity, the SOD and GSH-Px activities in the Example groups were significantly higher than those in the Comparative Groups. In Example 2, SOD (150 U / mg) and GSH-Px (60 U / mg) were increased by 67% and 71% respectively compared to Comparative Group 1 (90 U / mg, 35 U / mg), contributing to resistance against oxidative stress. In summary, the feed of this invention, through chemical modification and synergistic formulation, effectively enhances the body's immune and antioxidant defenses.

[0048] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A plant extract-based intestinal-promoting feed, characterized in that, It contains the following ingredients by weight: 5-15 parts of alginate-modified astragalus polysaccharide, 20-40 parts of dual-response microcapsule carrier, 2-5 parts of wheat sterol-glucan conjugate, 30-50 parts of protein powder, 10-15 parts of vitamin and mineral premix, and supplemented to 100 parts of feed carrier.

2. The plant extract intestinal-promoting feed according to claim 1, characterized in that, The preparation method of the alginate-modified astragalus polysaccharide specifically includes the following steps: S101. Add Astragalus powder to deionized water, sonicate in a water bath, heat and stir under reflux, filter, concentrate to 1 / 4 of the original volume, add ethanol, let stand and centrifuge to obtain crude Astragalus polysaccharide precipitate, wash twice with ethanol and vacuum dry for later use. S102. Dissolve dried Astragalus polysaccharide in sodium bicarbonate solution, stir well, and then add an active esterifying agent to activate it; slowly add ferulic acid methanol solution, and react at room temperature to generate Astragalus-ferulic acid conjugate; S103. After the reaction, adjust the pH to neutral, dialyze in deionized water using a dialysis bag, and then freeze-dry to obtain astragalus-ferulic acid conjugated polysaccharide. Then dissolve it in deionized water, add sodium alginate solution, slowly add CaCl2 and stir. 3.S104. The mixed reaction solution of Astragalus-ferulic acid polysaccharide obtained by physical cross-linking in step S103 and sodium alginate is processed by spray drying machine, and the composite microspheres formed after drying are collected, which are alginate-modified Astragalus polysaccharide.

4. The plant extract intestinal-promoting feed according to claim 1, characterized in that, The dual-response microcapsule carrier consists of an outer chitin-chitosan composite membrane and an inner gelatin-sodium alginate composite membrane, with a microcapsule particle size of 50–200 μm.

5. The plant extract intestinal-promoting feed according to claim 1, characterized in that, The wheat sterol-glucan conjugate is obtained by dissolving wheat sterol and β-1,3-glucan in methanol at a molar ratio of 1:1, removing the solvent by vacuum evaporation, and then vacuum drying.

6. The plant extract intestinal-promoting feed according to claim 1, characterized in that, The vitamin and mineral premix includes vitamin A, vitamin D, vitamin E, calcium, phosphorus, and zinc.

7. A method for preparing a plant extract-based intestinal-promoting feed, the plant extract-based intestinal-promoting feed as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Astragalus polysaccharide was extracted and dried from Astragalus powder, and then obtained by esterification grafting of ferulic acid and physical cross-linking with sodium alginate to produce alginate-modified Astragalus polysaccharide that specifically promotes the colonization of probiotics. S2. Wheat sterol and β-1,3-glucan were coupled in the liquid phase to obtain wheat sterol-glucan conjugate; S3. The outer and inner layers of the microcapsule are constructed sequentially using two composite materials: chitosan-chitin and gelatin-sodium alginate. The active ingredients obtained in steps S1 and S2 are loaded into the microcapsule to form a pH and enzyme dual-responsive microcapsule carrier. S4. The double-layered microcapsules containing active ingredients are mixed with protein powder, vitamin-mineral premix and feed matrix, and then processed using conventional granulation, drying and sieving processes to obtain the finished plant extract intestinal promoting feed.

8. The method for preparing the plant extract intestinal-promoting feed according to claim 6, characterized in that, In step S3, the component ratio of the microcapsule carrier is outer layer:inner layer = 1:1 to ensure dual-response performance.

9. The method for preparing the plant extract intestinal-promoting feed according to claim 6, characterized in that, The protein powder in step S4 is one or more of soy protein isolate, fish meal, and whey protein.

10. The method for preparing the plant extract intestinal-promoting feed according to claim 6, characterized in that, Step S4 involves high-shear homogenization premixing of the mixture to improve the uniformity of microcapsule dispersion.

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