Microbial microcapsule for feed and preparation method thereof

Abstract

The invention relates to the technical field of microbial preparations, in particular to a microbial microcapsule for feed and a preparation method of the microbial microcapsule. The preparation method comprises the following steps: firstly, culturing activated probiotics, and preparing a core material solution; dispersing sodium alginate and whey protein into deionized water, and sterilizing to obtain an enteric wall material solution; the method comprises the following steps: mixing a core material solution with an enteric wall material solution, extruding and adding into a calcium chloride solution to form gel; and finally, adding the gel into the gastric-soluble wall material solution, stirring, washing, and freeze-drying to obtain the microbial microcapsule for the feed. Wherein the gastric-soluble wall material solution is a mixture solution of oxidation modified carboxymethyl chitosan and polydopamine modified bamboo powder. The prepared microbial microcapsule has good embedding performance and storage stability, and can effectively improve the intestinal health of livestock and poultry and improve the production performance.

Description

Technical Field

[0001] This invention relates to the field of microbial preparation technology, specifically to a microbial microcapsule for feed and its preparation method. Background Technology

[0002] With the continuous advancement of agricultural technology, the scale and intensification of animal husbandry are increasing, and efficient, safe, and sustainable farming models have become the core goal of the industry's development. Scientifically formulated feed can significantly improve animal production performance and economic benefits, promoting the sustainable development of animal husbandry. Studies have shown that adding beneficial active microorganisms (probiotics) to feed enhances the body's immune function, regulates the intestinal microecological environment, inhibits the reproduction of harmful bacteria, improves feed conversion rate, maintains animal health, and promotes growth.

[0003] However, the application of microorganisms in feed still faces some challenges at present. The highly acidic environment of an animal's stomach and pepsin can kill a large number of probiotics, resulting in extremely low survival rates of orally administered probiotics at the target site. Furthermore, existing probiotic products with microcapsule structures exhibit weak bonding between the core and wall materials and poor biocompatibility. Chinese patent CN202410745749.2 discloses a method for preparing microcapsules encapsulating probiotics, using probiotics as the core material and sodium alginate and whey protein as the wall material. While this invention effectively encapsulates probiotics, the microcapsule surface is not tightly packed at low concentrations, making it susceptible to loss of probiotic activity if moisture or other impurities from the environment enter the microcapsule. Therefore, this paper proposes a microbial microcapsule for feed and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a microbial microcapsule for feed and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing microbial microcapsules for feed, comprising the following steps: Step 1: The activated probiotics were cultured and prepared into a core material solution; Step 2: Sodium alginate and whey protein were added to deionized water, ultrasonically dispersed at 25-30℃, and sterilized to obtain an enteric wall material solution. Step 3: The core material solution and the enteric wall material solution are mixed evenly and then added to the calcium chloride solution by extrusion. The mixture is then allowed to stand to form a gel. Step 4: The gel was added to the gastric wall material solution and stirred, then washed and freeze-dried to obtain microbial microcapsules for feed.

[0006] Furthermore, in step 1, the probiotics are any one or more of Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium lactis.

[0007] Furthermore, in step 1, the concentration of probiotics in the core material solution is 1.0 × 10⁻⁶. 9 ~1.0×10 10 CFU / mL.

[0008] Furthermore, in step 2, the concentration of sodium alginate in the enteric wall material solution is 2-3 wt%, the concentration of whey protein is 1-1.5 wt%, the ultrasonic power is 400-500 W, and the ultrasonic time is 10-15 min.

[0009] Furthermore, in step 3, the core material solution and the enteric wall material solution are mixed at a volume ratio of 1:(3~4).

[0010] Furthermore, in step 3, the concentration of the calcium chloride solution is 1~1.5wt%.

[0011] Furthermore, in step 4, the content of each component in the gastric wall material solution, by weight percentage, is 1-2% modified chitosan, 1-2% modified bamboo powder, and the remainder is water.

[0012] Further, in step 4, the modified chitosan is prepared by adding sodium periodate to an aqueous solution of carboxymethyl chitosan, adjusting the pH of the reaction to 8.0-8.5 with sodium hydroxide, stirring the reaction at 30-40°C in the dark for 20-24 hours, precipitating with anhydrous ethanol, washing and purifying, and freeze-drying to obtain modified chitosan; the degree of oxidation of the modified chitosan is 30-40%.

[0013] Further, in step 4, the modified bamboo powder is prepared as follows: bamboo powder is dispersed in water, Tris particles are added to adjust the pH value to 8~8.5, dopamine hydrochloride is added in an ice-water bath, ultrasonication is performed for 5~10 minutes, and then the temperature is raised to 60~70℃ and stirred for 24 hours. The product is centrifuged, washed, dried and pulverized to obtain modified bamboo powder; wherein, the weight ratio of bamboo powder to dopamine hydrochloride is (2~3):1.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are: This invention provides a microbial microcapsule for feed, which employs an enteric-coated wall material and a gastric-coated wall material to sequentially encapsulate probiotics, resulting in a double-layer wall material structure. In this invention, the enteric-coated wall material is formed by cross-linking a mixture of sodium alginate and whey protein under the action of a hardening agent, calcium chloride; because sodium alginate carries a negative charge, and Ca... 2+Ionic cross-linking occurs between them, thus achieving initial encapsulation of probiotics. A secondary encapsulation is then performed using a gastrointestinal wall material; this material comprises modified chitosan and modified bamboo powder; the modified chitosan is obtained by oxidation of carboxymethyl chitosan, and its molecular chain segments contain aldehyde groups; while the modified bamboo powder is obtained by modifying polydopamine; the polydopamine on the surface of the modified bamboo fiber carries a negative charge and can interact with the Ca on the enteric wall material. 2+ Further ionic cross-linking occurs, increasing the structural density of the enteric wall material and improving the embedding rate. In addition, modified chitosan containing aldehyde groups forms covalent bonds with the amino and hydroxyl groups of polydopamine through chemical reactions, thus obtaining the gastric wall material.

[0015] The microbial microcapsules prepared by this invention have a double-layer wall structure, resulting in higher mechanical strength and better tolerance to simulated gastric and intestinal fluids and at 4°C. They also exhibit higher survival rates and stability of probiotics. Animal experiments have shown that adding the microbial microcapsules of this invention to feed can effectively improve diarrhea in piglets. This is due to two factors: firstly, the probiotics in the microcapsules exert a beneficial effect; and secondly, the chitosan in the gastrointestinal wall material of the microcapsules possesses adhesive and antibacterial properties, forming a physical barrier to protect the gastric mucosa and inhibit bacterial infection. Furthermore, bamboo fiber promotes gastrointestinal development in piglets, creating a synergistic effect with probiotics in the digestive tract and improving piglet production performance. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0017] Materials and sources used in this invention: The probiotic is Lactobacillus casei LC2W, from Bright Dairy emulsion; the carboxymethyl chitosan has a deacetylation degree of 90% and a carboxylation degree of 80%, from Zhejiang Aoxing Biotechnology Co., Ltd.; the bamboo powder is obtained from 5-6 year old Chishui bamboo culms, which are processed by removing the bamboo green, drying (moisture content 10%), and pulverizing through a 200-mesh sieve.

[0018] Example 1: A method for preparing microbial microcapsules for feed, comprising the following steps: Step 1: The activated probiotics were cultured and prepared into a core material solution; the concentration of probiotics in the core material solution was 1.0 × 10⁻⁶. 9 CFU / mL; Step 2: Sodium alginate and whey protein were added to deionized water and ultrasonically dispersed evenly at 25°C. After sterilization, an enteric wall material solution was obtained. In the enteric wall material solution, the concentration of sodium alginate was 2 wt% and the concentration of whey protein was 1 wt%. The ultrasonic power was 400 W and the ultrasonic time was 10 min. Step 3: The core material solution and the enteric wall material solution are mixed evenly and then added to the calcium chloride solution by extrusion. The mixture is allowed to stand to form a gel. The core material solution and the enteric wall material solution are mixed in a volume ratio of 1:3. The concentration of the calcium chloride solution is 1 wt%. Step 4: The gel was added to a gastric wall material solution and stirred, then washed and freeze-dried to obtain microbial microcapsules for feed. The gastric wall material solution contained, by weight percentage, 1% modified chitosan, 1% modified bamboo powder, and the remainder being water. The method for preparing the modified chitosan is as follows: Sodium periodate was added to an aqueous solution of carboxymethyl chitosan, the pH of the reaction was adjusted to 8.0 with sodium hydroxide, and the reaction was carried out at 30°C in the dark with stirring for 20 h. After precipitation with anhydrous ethanol, the mixture was washed, purified, and freeze-dried to obtain modified chitosan; the degree of oxidation of the modified chitosan was 30%. The modified bamboo powder is prepared by: Bamboo powder was dispersed in water, Tris particles were added to adjust the pH to 8, dopamine hydrochloride was added in an ice-water bath, and the mixture was sonicated for 5 minutes and then heated to 60°C and stirred for 24 hours. The product was centrifuged, washed, dried and pulverized to obtain modified bamboo powder; the weight ratio of bamboo powder to dopamine hydrochloride was 2:1.

[0019] Example 2: A method for preparing microbial microcapsules for feed, comprising the following steps: Step 1: The activated probiotics were cultured and prepared into a core material solution; the concentration of probiotics in the core material solution was 5.0 × 10⁻⁶. 9 CFU / mL; Step 2: Sodium alginate and whey protein were added to deionized water and ultrasonically dispersed evenly at 28°C. After sterilization, an enteric wall material solution was obtained. In the enteric wall material solution, the concentration of sodium alginate was 2.5 wt% and the concentration of whey protein was 1.3 wt%. The ultrasonic power was 450 W and the ultrasonic time was 13 min. Step 3: The core material solution and the enteric wall material solution are mixed evenly and then added to the calcium chloride solution by extrusion. The mixture is allowed to stand to form a gel. The core material solution and the enteric wall material solution are mixed at a volume ratio of 1:3.5. The concentration of the calcium chloride solution is 1.2 wt%. Step 4: The gel was added to a gastric wall material solution and stirred, then washed and freeze-dried to obtain microbial microcapsules for feed. The gastric wall material solution contained, by weight percentage, 1.5% modified chitosan, 1.5% modified bamboo powder, and the remainder being water. The method for preparing the modified chitosan is as follows: Sodium periodate was added to an aqueous solution of carboxymethyl chitosan, the pH of the reaction was adjusted to 8.0 with sodium hydroxide, and the reaction was carried out at 35°C with stirring in the dark for 22 hours. After precipitation with anhydrous ethanol, the mixture was washed, purified, and freeze-dried to obtain modified chitosan; the degree of oxidation of the modified chitosan was 35%. The modified bamboo powder is prepared by: Bamboo powder was dispersed in water, Tris particles were added to adjust the pH to 8.3, dopamine hydrochloride was added in an ice-water bath, and the mixture was sonicated for 8 minutes and then heated to 65°C and stirred for 24 hours. The product was centrifuged, washed, dried and pulverized to obtain modified bamboo powder; the weight ratio of bamboo powder to dopamine hydrochloride was 2.5:1.

[0020] Example 3: A method for preparing microbial microcapsules for feed, comprising the following steps: Step 1: The activated probiotics were cultured and prepared into a core material solution; the concentration of probiotics in the core material solution was 1.0 × 10⁻⁶. 10 CFU / mL; Step 2: Sodium alginate and whey protein were added to deionized water and ultrasonically dispersed evenly at 30°C. After sterilization, an enteric wall material solution was obtained. The concentration of sodium alginate in the enteric wall material solution was 3 wt%, and the concentration of whey protein was 1.5 wt%. The ultrasonic power was 500 W, and the ultrasonic time was 15 min. Step 3: The core material solution and the enteric wall material solution are mixed evenly and then added to the calcium chloride solution by extrusion. The mixture is allowed to stand to form a gel. The core material solution and the enteric wall material solution are mixed in a volume ratio of 1:4. The concentration of the calcium chloride solution is 1.5 wt%. Step 4: The gel was added to a gastric wall material solution and stirred, then washed and freeze-dried to obtain microbial microcapsules for feed. The gastric wall material solution contained, by weight percentage, 2% modified chitosan, 2% modified bamboo powder, and the remainder being water. The method for preparing the modified chitosan is as follows: Sodium periodate was added to an aqueous solution of carboxymethyl chitosan, the pH of the reaction was adjusted to 8.5 with sodium hydroxide, and the reaction was carried out at 40°C with stirring in the dark for 24 hours. After precipitation with anhydrous ethanol, the mixture was washed, purified, and freeze-dried to obtain modified chitosan; the degree of oxidation of the modified chitosan was 40%. The modified bamboo powder is prepared by: Bamboo powder was dispersed in water, Tris particles were added to adjust the pH to 8.5, dopamine hydrochloride was added in an ice-water bath, and the mixture was sonicated for 10 min and then heated to 70℃ and stirred for 24 h. The product was centrifuged, washed, dried and pulverized to obtain modified bamboo powder; the weight ratio of bamboo powder to dopamine hydrochloride was 3:1.

[0021] Comparative Example 1: Compared with Example 1, the feed microbial microcapsules prepared in this comparative example do not contain gastric wall material.

[0022] Step 1: The activated probiotics were cultured and prepared into a core material solution; the concentration of probiotics in the core material solution was 1.0 × 10⁻⁶. 9 CFU / mL; Step 2: Sodium alginate and whey protein were added to deionized water and ultrasonically dispersed evenly at 25°C. After sterilization, an enteric wall material solution was obtained. In the enteric wall material solution, the concentration of sodium alginate was 2 wt% and the concentration of whey protein was 1 wt%. The ultrasonic power was 400 W and the ultrasonic time was 10 min. Step 3: The core material solution and the enteric wall material solution are mixed evenly and added to the calcium chloride solution by extrusion. The mixture is allowed to stand to form a gel. The core material solution and the enteric wall material solution are mixed in a volume ratio of 1:3. The concentration of the calcium chloride solution is 1 wt%. The gel is washed and freeze-dried to obtain microbial microcapsules for feed.

[0023] Comparative Example 2: Compared with Example 2, the stomach wall material of the feed microbial microcapsules prepared in this comparative example does not contain modified bamboo powder.

[0024] Step 1: The activated probiotics were cultured and prepared into a core material solution; the concentration of probiotics in the core material solution was 5.0 × 10⁻⁶. 9 CFU / mL; Step 2: Sodium alginate and whey protein were added to deionized water and ultrasonically dispersed evenly at 28°C. After sterilization, an enteric wall material solution was obtained. In the enteric wall material solution, the concentration of sodium alginate was 2.5 wt% and the concentration of whey protein was 1.3 wt%. The ultrasonic power was 450 W and the ultrasonic time was 13 min. Step 3: The core material solution and the enteric wall material solution are mixed evenly and then added to the calcium chloride solution by extrusion. The mixture is allowed to stand to form a gel. The core material solution and the enteric wall material solution are mixed at a volume ratio of 1:3.5. The concentration of the calcium chloride solution is 1.2 wt%. Step 4: The gel was added to a gastric wall material solution and stirred, then washed and freeze-dried to obtain microbial microcapsules for feed. The gastric wall material solution contained, by weight percentage, 1.5% modified chitosan and the remainder water. The method for preparing the modified chitosan is as follows: Sodium periodate was added to an aqueous solution of carboxymethyl chitosan, the pH of the reaction was adjusted to 8.0 with sodium hydroxide, and the reaction was stirred at 35°C in the dark for 22 hours. After precipitation with anhydrous ethanol, the mixture was washed, purified, and freeze-dried to obtain modified chitosan. The degree of oxidation of the modified chitosan was 35%.

[0025] Comparative Example 3: Compared with Example 3, the bamboo powder in the stomach wall material of the feed microbial microcapsules prepared in this comparative example was not modified.

[0026] Step 1: The activated probiotics were cultured and prepared into a core material solution; the concentration of probiotics in the core material solution was 1.0 × 10⁻⁶. 10 CFU / mL; Step 2: Sodium alginate and whey protein were added to deionized water and ultrasonically dispersed evenly at 30°C. After sterilization, an enteric wall material solution was obtained. The concentration of sodium alginate in the enteric wall material solution was 3 wt%, and the concentration of whey protein was 1.5 wt%. The ultrasonic power was 500 W, and the ultrasonic time was 15 min. Step 3: The core material solution and the enteric wall material solution are mixed evenly and then added to the calcium chloride solution by extrusion. The mixture is allowed to stand to form a gel. The core material solution and the enteric wall material solution are mixed in a volume ratio of 1:4. The concentration of the calcium chloride solution is 1.5 wt%. Step 4: The gel was added to a gastric wall material solution and stirred, then washed and freeze-dried to obtain microbial microcapsules for feed. The gastric wall material solution contained, by weight percentage, 2% modified chitosan, 2% bamboo powder, and the remainder water. The method for preparing the modified chitosan is as follows: Sodium periodate was added to an aqueous solution of carboxymethyl chitosan, the pH of the reaction was adjusted to 8.5 with sodium hydroxide, and the reaction was stirred at 40°C in the dark for 24 hours. After precipitation with anhydrous ethanol, the mixture was washed, purified, and freeze-dried to obtain modified chitosan. The degree of oxidation of the modified chitosan was 40%.

[0027] experiment: (1) The mechanical strength of the microbial microcapsules was tested.

[0028] Ten products were randomly selected from each group for testing. The particle size of the microbial microcapsules was measured using vernier calipers and the average value was calculated. The microcapsules were placed on an analytical balance, and weights were gradually applied to their front side until they ruptured. The maximum frontal pressure that the balance could withstand was taken as the mechanical strength of the microcapsule, and the average value was calculated. The results are shown in Table 1.

[0029] Table 1. As shown in Table 1, the microbial microcapsules prepared by this invention are uniformly spherical with an average particle size of 3-3.1 mm, meeting the standards for microcapsules, and exhibiting superior mechanical strength. It is evident that the chemical cross-linking reaction between modified bamboo powder and modified chitosan endows the microcapsules with excellent mechanical strength.

[0030] (2) The encapsulation rate of microbial microcapsules, the survival rate under different pH conditions, and the storage stability under different temperatures were tested.

[0031] Encapsulation efficiency test: 1g of microbial microcapsules were dissolved in 9mL of decapsulation solution (a mixed solution of 0.2mol / L sodium bicarbonate and 0.06mol / L trisodium citrate at pH 8) for decapsulation. After washing with physiological saline, the number of viable bacteria was determined using the plate count method. Encapsulation rate = (Number of viable bacteria after encapsulation / Number of viable bacteria before encapsulation) × 100%; Survival rate test of strains in simulated gastric fluid environment: The pH of a 9 g / L sodium chloride solution was adjusted to 2.0 using 0.1 mol / L hydrochloric acid. A 0.3% (w / v) pepsin solution (mass ratio 1:3000) was added to prepare simulated gastric fluid. 1 g of microbial microcapsules was added to 9 mL of simulated gastric fluid, mixed thoroughly, and then incubated at 37℃ (200 rpm) for 4 h with shaking. After uncapsulating the microbial microcapsules, the samples were washed with physiological saline, and the viable bacterial count was determined using the plate count method. Survival rate = (Number of viable bacteria after treatment with simulated gastric fluid / Number of viable bacteria before treatment) × 100%; Survival test of strains in simulated intestinal fluid environment: The pH of PBS solution was adjusted to 8.0 using 0.1 mol / L sodium hydroxide solution. 0.1% (w / v) trypsin solution (mass ratio 1:250) and 0.3% (w / v) sodium cholate were added, stirred to dissolve, and then filtered to obtain simulated intestinal fluid. 1 g of microbial microcapsules were added to 9 mL of simulated intestinal fluid, mixed well, and incubated in a water bath at 37℃ for 3 h. After uncapsulating the microbial microcapsules, they were washed with physiological saline, and the number of viable bacteria was determined using the plate count method. Survival rate = (Number of viable bacteria after treatment with simulated intestinal fluid / Number of viable bacteria before treatment) × 100%; Stability test: The microcapsules were stored at 4℃ and 25℃ for 90 days respectively. After uncapsulation, they were washed with physiological saline and the number of viable bacteria was determined by plate count method. Survival rate = (Number of viable bacteria after preservation / Number of viable bacteria before preservation) × 100%; The experimental results are shown in Table 2. Table 2. As shown in Table 2, the microbial microcapsules prepared in Examples 1-3 exhibited better encapsulation rates, survival rates in different pH environments, and storage stability at 4°C compared to Comparative Examples 1-3. In these examples, sodium alginate and whey protein were used to encapsulate the probiotics, followed by the addition of modified chitosan and modified bamboo powder for secondary encapsulation. This improved the density of the microcapsules, enhancing their mechanical strength and further improving the encapsulation effect. Simultaneously, the double-layer wall material effectively protected the probiotic core material. Whether in simulated gastric or intestinal fluids or at 4°C, the probiotics showed better environmental tolerance, resulting in a higher survival rate compared to the comparative examples.

[0032] (3) Animal experiments were conducted on the microbial microcapsules.

[0033] Twenty-one healthy weaned piglets aged 28 days, weighing (7.91±0.47) kg, and with similar body shape were selected for the experiment. Each piglet was numbered by ear tag and randomly divided into 7 groups based on similar weight and sex, with 3 replicates per group and 1 piglet per replicate. The experimental groups were fed a basal diet supplemented with 0.5% microbial microcapsules, while the control group was fed an antibiotic-free basal diet supplemented with 0.5% lyophilized probiotic powder. The pre-trial period was 3 days, and the formal trial period was 10 days. The pig farm's standard feeding management procedures were followed, with feeding four times a day. The standard for the next feeding was that there was no feed left at the bottom of the feed trough one hour after the previous feeding. At 08:00 on the start and end of the experiment, the piglets were weighed after fasting for 12 hours. The weight gain during the experiment was calculated for each group. The number of diarrhea episodes was also recorded, and the average number of diarrhea episodes per day for each group was calculated. The results are shown in Table 3. Table 3. As shown in Table 3, the microbial microcapsules prepared in Examples 1-3 had a significantly higher effect on the weight gain of piglets than the control group, and also higher than Comparative Examples 1-3. Piglets in the Example group did not experience diarrhea during the formal growth period, while piglets in Comparative Examples 1-3 and the control group experienced diarrhea 4, 2, 1, and 8 times respectively during the formal growth period. This indicates that the microbial microcapsules prepared in this invention can effectively reduce diarrhea and promote the healthy growth of piglets.

[0034] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing microbial microcapsules for feed, characterized in that: Includes the following steps: Step 1: The activated probiotics were cultured and prepared into a core material solution; Step 2: Sodium alginate and whey protein were added to deionized water, ultrasonically dispersed at 25-30℃, and sterilized to obtain an enteric wall material solution. Step 3: The core material solution and the enteric wall material solution are mixed evenly and then added to the calcium chloride solution by extrusion. The mixture is then allowed to stand to form a gel. Step 4: The gel was added to the gastric wall material solution and stirred, then washed and freeze-dried to obtain microbial microcapsules for feed.

2. The method for preparing feed microbial microcapsules according to claim 1, characterized in that: In step 1, the probiotics are any one or more of Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium lactis.

3. The method for preparing feed microbial microcapsules according to claim 1, characterized in that: In step 1, the concentration of probiotics in the core material solution is 1.0 × 10⁻⁶. 9 ~1.0×10 10 CFU / mL.

4. The method for preparing feed microbial microcapsules according to claim 1, characterized in that: In step 2, the concentration of sodium alginate in the enteric wall material solution is 2-3 wt%, and the concentration of whey protein is 1-1.5 wt%; the ultrasonic power is 400-500 W, and the ultrasonic time is 10-15 min.

5. The method for preparing feed microbial microcapsules according to claim 1, characterized in that: In step 3, the core material solution and the enteric wall material solution are mixed at a volume ratio of 1:(3~4).

6. The method for preparing feed microbial microcapsules according to claim 1, characterized in that: In step 3, the concentration of the calcium chloride solution is 1~1.5wt%.

7. The method for preparing feed microbial microcapsules according to claim 1, characterized in that: In step 4, the content of each component in the gastric wall material solution, by weight percentage, is 1-2% modified chitosan, 1-2% modified bamboo powder, and the remainder is water.

8. The method for preparing feed microbial microcapsules according to claim 7, characterized in that: The modified chitosan is prepared by adding sodium periodate to an aqueous solution of carboxymethyl chitosan, adjusting the pH of the reaction to 8.0-8.5 with sodium hydroxide, stirring the reaction at 30-40°C in the dark for 20-24 hours, precipitating with anhydrous ethanol, washing and purifying, and freeze-drying to obtain modified chitosan; the degree of oxidation of the modified chitosan is 30-40%.

9. The method for preparing feed microbial microcapsules according to claim 7, characterized in that: The modified bamboo powder is prepared by dispersing bamboo powder in water, adding Tris particles to adjust the pH value to 8-8.5, adding dopamine hydrochloride in an ice-water bath, sonicating for 5-10 minutes, then heating to 60-70℃ and stirring for 24 hours. The product is then centrifuged, washed, dried, and pulverized to obtain modified bamboo powder. The weight ratio of bamboo powder to dopamine hydrochloride is (2-3):

1.

10. Microbial microcapsules for feed prepared by any one of claims 1 to 9.

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