A feed composition for promoting gut health in micropterus salmoides and a method of preparing the same

Abstract

This invention relates to a feed composition for promoting the intestinal health of California bass and its preparation method, belonging to the technical field of aquaculture feed. The feed composition for promoting the intestinal health of California bass includes rice protein peptides, mineral premix, microencapsulated compound vitamin-yeast extract, yeast cell wall, and attractant. Based on the total mass of the microencapsulated compound vitamin-yeast extract, it contains 35-50% yeast extract, 30-45% compound vitamins, and 15-25% cell wall material. The feed composition of this invention is scientifically designed based on the physiological characteristics, nutritional requirements, and intestinal flora characteristics of California bass. Through microencapsulation technology, vitamins and yeast extract are organically combined to achieve precise regulation of the intestinal flora of California bass, increasing the abundance of beneficial bacteria and decreasing the abundance of harmful bacteria, thereby significantly improving its intestinal health, growth performance, and disease resistance.

Description

Technical Field

[0001] This invention belongs to the technical field of aquaculture feed, and more specifically, relates to a feed composition that promotes the intestinal health of California bass and its preparation method. Background Technology

[0002] Largemouth bass, also known as California bass, is one of my country's important freshwater economic fish species, prized for its rapid growth, delicious meat, and high nutritional value. In recent years, with the promotion of intensive, high-density aquaculture, the largemouth bass farming industry has faced numerous challenges. Among these, intestinal health problems are particularly prominent due to factors such as antibiotic overuse in feed, water quality deterioration, and stress responses. These problems manifest as intestinal flora imbalance, impaired intestinal barrier function, and decreased immune function, ultimately affecting growth performance and survival rates.

[0003] To improve the gut health of California bass, existing technologies mainly employ the following strategies: The first type of strategy attempts to regulate the gut microbiota structure by adding yeast extracts, oligosaccharides, lactic acid bacteria, or other ingredients to the feed. However, existing technologies mostly use single ingredients or simple combinations, making it difficult to achieve precise, multi-target regulation of the gut microbiota of largemouth bass, and failing to simultaneously promote the proliferation of multiple beneficial bacteria and inhibit the growth of multiple harmful bacteria.

[0004] The second strategy mainly involves adding vitamin premixes to the feed to meet the vitamin requirements of fish. However, active ingredients such as vitamins are easily deactivated during feed processing (pelletizing temperature is usually 70-90℃) and storage (light, oxygen, humidity), resulting in a significant reduction in the actual intake of effective ingredients and making it difficult to achieve the expected results.

[0005] The third strategy attempts to combine multiple functional ingredients, such as yeast extract with vitamins, or probiotics with prebiotics. However, existing compound additives lack effective synergistic mechanisms between the components, failing to fully leverage the synergistic effects of yeast extract and vitamins in regulating gut microbiota.

[0006] In addition, existing aquatic feed technologies lack optimized design for the specific physiological needs, gut microbiota characteristics, and aquaculture environment of largemouth bass. While they are generally applicable, they are not specific enough to meet the special needs of largemouth bass at different growth stages. The release and absorption of functional components in the digestive tract are not synchronized, and some components are degraded or excreted before reaching the site of action, resulting in low bioavailability and unsatisfactory economic benefits.

[0007] Therefore, there is an urgent need to develop a new type of feed that can precisely regulate the gut microbiota of California bass and significantly improve its growth performance. Summary of the Invention

[0008] The purpose of this invention is to provide a feed composition that promotes the intestinal health of California bass and its preparation method, which has the characteristics of improving its growth performance and disease resistance.

[0009] The objective of this invention can be achieved through the following technical solutions: A feed composition for promoting gut health in largemouth bass, comprising, by weight, the following components: Rice protein peptides, 25-55 parts; 15-20 parts of mineral premix; 15-25 parts of microencapsulated complex vitamin-yeast extract, based on the total mass of the microencapsulated complex vitamin-yeast extract, contain 35-50% yeast extract, 30-45% complex vitamins, and 15-25% wall material; 10-20 parts of yeast cell wall; 5-10 portions of appetite stimulant.

[0010] Among them, rice protein peptides are powdered rice protein after enzymatic treatment. They serve as diluents and carriers, facilitating the uniform dispersion of trace components.

[0011] The mineral premix provides essential minerals such as calcium, phosphorus, magnesium, zinc, manganese, iron, copper, iodine, and selenium to meet the physiological needs of California bass for bone development and enzyme activity regulation. In particular, zinc and selenium have antioxidant properties and can protect the integrity of intestinal cell membranes.

[0012] Microencapsulated multivitamin-yeast extract combines enzymatically hydrolyzed yeast extract with vitamins using microencapsulation technology. The enzymatically hydrolyzed yeast extract is rich in functional components such as β-glucan, mannooligosaccharides, and nucleotides. β-glucan can activate macrophages and enhance immune function; mannooligosaccharides can specifically bind to pathogenic intestinal bacteria (such as E. coli and Salmonella), preventing them from adhering to the intestinal epithelium; nucleotides promote intestinal cell proliferation and repair; and yeast polypeptides provide nutrient substrates for beneficial bacteria. The multivitamin provides essential vitamins (vitamins A, D3, E, K, B vitamins, etc.) to meet the basic nutritional needs of California bass. Vitamin A participates in intestinal epithelial cell differentiation, vitamin E protects cell membranes, and vitamin C enhances immune function. A serving size of 15-25 servings provides significant effects while offering a good cost-effectiveness ratio.

[0013] Yeast cell walls are rich in β-1,3-glucan and mannan oligosaccharides, which have dual functions of immune enhancement and mycotoxin adsorption.

[0014] Palatability enhances feed palatability, promotes feeding, and ensures that California bass ingest sufficient functional components.

[0015] Furthermore, the preparation method of the rice protein peptide includes the following steps: Rice protein powder and deionized water are mixed at a solid-liquid ratio of 1:6-9, and the pH is adjusted to 8-8.5. Then, 0.5-1.5% (by weight of rice protein) of alkaline protease is added, and the mixture is enzymatically hydrolyzed at 50-55℃ and 100-150 rpm for 2-4 hours. The temperature is then raised to 90-95℃ and held for 10-15 minutes to inactivate the enzyme. Finally, the mixture is cooled to room temperature, the pH is adjusted to 6.5-7.0, and then centrifuged and spray-dried to obtain the product.

[0016] Furthermore, the alkaline protease is derived from Bacillus subtilis or Bacillus licheniformis.

[0017] Furthermore, the rice protein peptide has a crude protein content of ≥70% and a degree of hydrolysis of 15-25%.

[0018] Furthermore, the yeast extract is an enzymatically hydrolyzed yeast extract.

[0019] Furthermore, the wall material is selected from a mixture of maltodextrin and gum arabic in a mass ratio of (2-4):1.

[0020] Furthermore, based on the total mass of the multivitamin, it contains 12-18% vitamin A, 1-2% vitamin D3, 8-15% vitamin E, 0.1-0.3% vitamin K3, 6-12% vitamin C, 0.1-0.3% vitamin B1, 0.2-0.5% vitamin B2, 1.5-2.5% vitamin B3, 0.6-1.2% vitamin B5, 0.2-0.4% vitamin B6, 0.006-0.012% vitamin B7, 0.06-0.12% vitamin B9, and 0.0006-0.0012% vitamin B12, with the remainder being vitamin carriers.

[0021] The vitamin carrier is preferably at least one of defatted rice bran, wheat flour, corn flour, wheat flour, and rice husk powder.

[0022] Furthermore, based on the total mass of the mineral premix, it contains 30-40% calcium dihydrogen phosphate, 5-10% potassium chloride, 3-5% magnesium sulfate, 2-3% zinc sulfate, 1.5-2.5% manganese sulfate, 2-3% ferrous sulfate, 0.5-1.0% copper sulfate, 0.05-0.1% calcium iodate, and 0.005-0.02% sodium selenite, with the remainder being a mineral carrier.

[0023] The mineral carrier is preferably at least one of stone powder, zeolite powder, defatted bone meal, shell powder, and calcium phosphate.

[0024] Furthermore, the attractant is selected from at least one of squid viscera powder, fish soluble paste, betaine, and dimethyl-β-propionic acid thiatin.

[0025] Furthermore, the preparation method of the microencapsulated complex vitamin-yeast extract includes the following steps: A1. Preparation of yeast extract: Take active dry yeast, add deionized water at a mass ratio of 1:(4-6), adjust the pH to 5.5-6.0, add 0.5-1.0% compound enzyme preparation, hydrolyze at 50-55℃ for 4-6 hours, inactivate enzyme at 90-100℃ for 5-15 minutes, centrifuge to collect the supernatant, concentrate to a solid content of 30-40%, and obtain concentrated yeast extract; A2. Preparation of the mixed solution: Mix the concentrated yeast extract with the compound vitamins, add the wall material, stir evenly, and adjust the solid content to 30-40%; A3. Microencapsulation: Microencapsulation was performed using spray drying or freeze drying to obtain microencapsulated complex vitamin-yeast extract.

[0026] Further, in step A1, the active dry yeast is selected from at least one of Saccharomyces cerevisiae and Candida utilis; the compound enzyme preparation is selected from protease and glucanase in a mass ratio of (1.5-2.5):1.

[0027] Further, in step A2, the mass ratio of the concentrated yeast extract to the compound vitamins is 70:30 to 85:15; the amount of wall material added is 8-15% of the total mass of the concentrated yeast extract and the compound vitamins.

[0028] More preferably, the mass ratio of the concentrated yeast extract to the complex vitamins is 75:25 to 80:20.

[0029] Furthermore, in step A3, the process parameters of the spray drying method are: inlet air temperature 160-180℃, outlet air temperature 80-90℃, and feed rate 15-20mL / min.

[0030] Further, in step A3, the process parameters of the freeze-drying method are: pre-freezing temperature -40 to -30℃, pre-freezing time 3-5 hours, freeze-drying temperature -50 to -40℃, vacuum degree 5-15Pa, and drying time 24-48 hours.

[0031] The preparation method of the microencapsulated complex vitamin-yeast extract of the present invention uses a complex enzyme preparation for enzymatic hydrolysis, which can simultaneously release multiple active ingredients such as proteins, polysaccharides, and nucleotides; the pH is adjusted to 5.5-6.0, which is the optimal activity range of the complex enzyme preparation; hydrolysis is carried out at 50-55℃ for 4-6 hours, which can fully release intracellular contents while avoiding the destruction of heat-sensitive components; and the enzyme is inactivated at 90-100℃ for 5-15 minutes to completely inactivate the enzyme preparation and prevent subsequent reactions; during the microencapsulation process, the yeast extract is used as the internal phase, the vitamin is used as the active ingredient, and the wall material is used as the protective layer to form a "sandwich" structure. By controlling the process parameters, the efficient encapsulation and sustained release of active ingredients can be achieved.

[0032] A method for preparing the feed composition as described above includes the following steps: S1. Raw material pretreatment: Pass each raw material through a 60-120 mesh sieve; S2. Mixing: Mix rice protein peptides, mineral premix, microencapsulated compound vitamin-yeast extract, yeast cell wall, and palatability enhancer at 20-30 rpm for 15-30 minutes to obtain the composition.

[0033] In the application of the above-mentioned feed composition in California bass farming, the feed composition is added to the complete feed at an amount of 0.5-2%, preferably 1-1.5%.

[0034] The beneficial effects of this invention are: (1) The feed composition of the present invention is scientifically designed based on the physiological characteristics, nutritional requirements and intestinal flora characteristics of California bass. Through microencapsulation technology, vitamins and yeast extract are organically combined to achieve precise regulation of the intestinal flora of California bass, increasing the abundance of beneficial bacteria and decreasing the abundance of harmful bacteria, thereby significantly improving its intestinal health, growth performance and disease resistance. Specifically, the mineral premix and compound vitamins form a basic nutritional support system, providing essential micronutrients for California bass, while also providing necessary trace elements (such as zinc and manganese, which are cofactors for many enzymes) for the growth of beneficial intestinal bacteria. The compound vitamins and yeast extract form a dual "nutrition-immunity" regulatory mechanism. Vitamins protect the active ingredients in the yeast extract from oxidative damage, while the yeast extract improves the bioavailability of vitamins. Microencapsulation technology protects vitamins from inactivation during processing and storage, achieving sustained release of active ingredients, extending the duration of action, improving bioavailability, and reducing the amount added. The yeast cell wall and the microencapsulated compound vitamins-yeast extract form a synergistic "cell wall-intracellular contents" effect, regulating intestinal flora and immune function at different levels.

[0035] (2) This invention achieves precise regulation of the intestinal flora through a dual synergistic mechanism of "inhibition-immunity": mannan oligosaccharides in the yeast cell wall can specifically bind to pathogenic bacteria such as Vibrio, preventing them from adhering to the intestinal epithelium; at the same time, organic acids such as lactic acid and acetic acid produced by beneficial bacteria lower the intestinal pH and inhibit the growth of pathogenic bacteria. β-glucan in the microencapsulated complex vitamin-yeast extract activates macrophages, and vitamins A, E, and C enhance immune function, forming a synergistic regulatory network of "innate immunity-adaptive immunity" to improve the overall defense capability of the intestine. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to specific embodiments, but the scope of protection of this invention is not limited thereto. Experimental methods not specifically described in the embodiments are generally performed under conventional conditions or according to the manufacturer's recommendations. Unless otherwise specified, all reagents and materials used are commercially available.

[0037] Raw material description: Rice protein peptides: crude protein content ≥70%, degree of hydrolysis 15-25%, moisture ≤8%; Yeast cell wall: β-glucan ≥25%, mannan oligosaccharide ≥20%, moisture ≤10%; Active dry yeast: Saccharomyces cerevisiae, with a viable count ≥15 billion CFU / g, β-glucan content ≥15%, mannan oligosaccharide content ≥10%, moisture content ≤8%, and protein content ≥40%.

[0038] Example 1 A feed composition for promoting the gut health of California bass comprises the following components by weight: 39 parts rice protein peptides, 18 parts mineral premix, 20 parts microencapsulated complex vitamin-yeast extract, 15 parts yeast cell wall, and 8 parts palatability enhancer (cuttlefish viscera powder).

[0039] The premixed minerals contain 35% calcium dihydrogen phosphate, 7.5% potassium chloride, 4% magnesium sulfate, 2.5% zinc sulfate, 2% manganese sulfate, 2.5% ferrous sulfate, 0.75% copper sulfate, 0.075% calcium iodate, and 0.015% sodium selenite, with the remainder being mineral carriers (stone powder), accounting for approximately 45.66%.

[0040] The preparation method of the above-mentioned microencapsulated complex vitamin-yeast extract is as follows: A1. Preparation of yeast extract: Take 100 parts of active dry yeast, add distilled water at a mass ratio of active dry yeast to distilled water of 1:5, adjust the pH to 5.8, add 0.9 parts of compound enzyme preparation (protease: glucanase = 2:1), hydrolyze at 52℃ for 5 hours, inactivate the enzyme at 95℃ for 10 minutes, centrifuge to collect the supernatant, concentrate to a solid content of 35±1%, and obtain concentrated yeast extract; A2. Preparation of the mixed solution: Concentrated yeast extract and compound vitamins were mixed at a mass ratio of 80:20 to obtain a mixed solution; a wall material, a mixture of maltodextrin and gum arabic (mass ratio 3:1), was added to the mixed solution at 12% of the total mass of the yeast extract and compound vitamins; the mixture was stirred for 30 minutes to ensure thorough and uniform mixing; the solid content was adjusted to 38±1% with deionized water. A3. Microencapsulation: Microencapsulation was carried out using spray drying, with an inlet air temperature of 170℃, an outlet air temperature of 85℃, a feed rate of 18mL / min, and passing through an 80-mesh sieve to obtain microencapsulated compound vitamin-yeast extract.

[0041] Based on the total mass of the multivitamin, it contains 15% vitamin A, 2% vitamin D3, 12% vitamin E, 0.2% vitamin K3, 0.2% vitamin B1, 0.35% vitamin B2, 2% vitamin B3 (nicotinamide), 0.9% vitamin B5 (calcium pantothenate), 0.3% vitamin B6, 0.009% vitamin B7 (biotin), 0.09% vitamin B9 (folic acid), 0.0009% vitamin B12, and 9% vitamin C. The remainder is a vitamin carrier (defatted rice bran), accounting for approximately 57.95%.

[0042] The preparation method of the above-mentioned feed composition that promotes the intestinal health of California bass is as follows: S1. Raw material pretreatment: Rice protein peptides and microencapsulated compound vitamin-yeast extract are pulverized and passed through a 120-mesh sieve, yeast cell walls and palatability enhancers are passed through an 80-mesh sieve, and mineral premixes are passed through a 100-mesh sieve. S2. Premixing: 10% of the total amount of each raw material is premixed and mixed in a three-dimensional mixer at 25 rpm for 20 minutes to obtain a premixed material; S3. Main mixing: Add the remaining raw materials and premixed materials together to a horizontal ribbon mixer and mix at 20 rpm for 25 minutes to obtain a uniformly mixed feed composition.

[0043] Example 2 A feed composition for promoting the gut health of California bass comprises the following components by weight: 25 parts rice protein peptides, 20 parts mineral premix, 25 parts microencapsulated complex vitamin-yeast extract, 20 parts yeast cell wall, and 10 parts palatability enhancer (cuttlefish viscera powder).

[0044] The preparation method of the above-mentioned feed composition that promotes the intestinal health of California bass is the same as in Example 1.

[0045] Example 3 A feed composition for promoting the gut health of California bass comprises the following components by weight: 55 parts rice protein peptides, 15 parts mineral premix, 15 parts microencapsulated complex vitamin-yeast extract, 10 parts yeast cell wall, and 5 parts palatability enhancer (cuttlefish viscera powder).

[0046] The preparation method of the above-mentioned feed composition that promotes the intestinal health of California bass is the same as in Example 1.

[0047] Example 4 Compared with Example 1, this example differs in that the preparation method of the microencapsulated complex vitamin-yeast extract in this example is as follows: A1. Preparation of yeast extract: Take 100 parts of active dry yeast, add distilled water at a mass ratio of active dry yeast to distilled water of 1:4, adjust the pH to 5.8, add 0.75 parts of compound enzyme preparation (protease: glucanase = 1.5:1), hydrolyze at 52℃ for 5 hours, inactivate the enzyme at 95℃ for 10 minutes, centrifuge to collect the supernatant, concentrate to a solid content of 35±1%, and obtain concentrated yeast extract; A2. Preparation of the mixed solution: Concentrated yeast extract and compound vitamins were mixed at a mass ratio of 80:20 to obtain a mixed solution; a wall material, a mixture of maltodextrin and gum arabic (mass ratio 3:1), was added to the mixed solution at 13% of the total mass of the yeast extract and compound vitamins; the mixture was stirred for 30 minutes to ensure thorough and uniform mixing; the solid content was adjusted to 38±1% with deionized water. A3. Microencapsulation: Microencapsulation was performed using freeze-drying. The pre-freezing temperature was -40℃ and the pre-freezing time was 5 hours. The freeze-drying temperature was -50℃, the vacuum degree was 8Pa, and the drying time was 48 hours. The product was then passed through an 80-mesh sieve to obtain microencapsulated compound vitamin-yeast extract.

[0048] Example 5 Compared with Example 1, this example differs in that the preparation method of the microencapsulated complex vitamin-yeast extract in this example is as follows: A1. Preparation of yeast extract: Take 100 parts of active dry yeast, add distilled water at a mass ratio of active dry yeast to distilled water of 1:5, adjust the pH to 5.8, add 0.7 parts of compound enzyme preparation (protease: glucanase = 2.5:1), hydrolyze at 52℃ for 5 hours, inactivate the enzyme at 95℃ for 10 minutes, centrifuge to collect the supernatant, concentrate to a solid content of 35±1%, and obtain concentrated yeast extract; A2. Preparation of the mixed solution: Concentrated yeast extract and compound vitamins were mixed at a mass ratio of 80:20 to obtain a mixed solution; a wall material, a mixture of maltodextrin and gum arabic (mass ratio 2:1), was added to the mixed solution at 14% of the total mass of the yeast extract and compound vitamins; the mixture was stirred for 30 minutes to ensure thorough and uniform mixing; the solid content was adjusted to 38±1% with deionized water. A3. Microencapsulation: Microencapsulation was carried out using spray drying, with an inlet air temperature of 160℃, an outlet air temperature of 80℃, a feed rate of 16mL / min, and passing through an 80-mesh sieve to obtain microencapsulated compound vitamin-yeast extract.

[0049] Example 6 Compared with Example 1, this example differs in that the preparation method of the microencapsulated complex vitamin-yeast extract in this example is as follows: A1. Preparation of yeast extract: Take 100 parts of active dry yeast, add distilled water at a mass ratio of active dry yeast to distilled water of 1:5, adjust the pH to 5.8, add 0.6 parts of compound enzyme preparation (protease: glucanase = 2:1), hydrolyze at 52℃ for 5 hours, inactivate the enzyme at 95℃ for 10 minutes, centrifuge to collect the supernatant, concentrate to a solid content of 35±1%, and obtain concentrated yeast extract; A2. Preparation of the mixed solution: Concentrated yeast extract and compound vitamins were mixed at a mass ratio of 80:20 to obtain a mixed solution; a wall material, a mixture of maltodextrin and gum arabic (mass ratio 4:1), was added to the mixed solution at 10% of the total mass of the yeast extract and compound vitamins; the mixture was stirred for 30 minutes to ensure thorough and uniform mixing; the solid content was adjusted to 38±1% with deionized water. A3. Microencapsulation: Microencapsulation was carried out by spray drying, with an inlet air temperature of 180℃, an outlet air temperature of 90℃, a feed rate of 17mL / min, and passing through an 80-mesh sieve to obtain microencapsulated compound vitamin-yeast extract.

[0050] Comparative Example 1 Compared with Example 1, the difference in this comparative example is that 20 parts of microencapsulated complex vitamin-yeast extract were replaced with 14 parts of yeast extract, 4 parts of complex vitamins and 2 parts of wall material, which were added after premixing.

[0051] Comparative Example 2 Compared with Example 1, the difference in this comparative example is that in step A2 of this comparative example, the concentrated yeast extract and the complex vitamins are mixed at a mass ratio of 50:50.

[0052] Comparative Example 3 Compared with Example 1, the difference in this comparative example is that in step A2 of this comparative example, a single maltodextrin is selected as the wall material.

[0053] Comparative Example 4 Compared with Example 1, the difference of this comparative example is that in step A3 of this comparative example, when using spray drying for microencapsulation, the inlet air temperature is 120°C, the outlet air temperature is 60°C, and the feed rate is 18 mL / min.

[0054] Comparative Example 5 Compared with Example 1, this comparative example differs in that it does not contain yeast extract, does not include step A1, and does not involve adding an equal amount of wall material to an equal amount of compound vitamins in step A2 to obtain a mixed solution, which is then subjected to microencapsulation.

[0055] Comparative Example 6 Compared with Example 1, the difference in this comparative example is that there is no compound vitamin in step A2 of this comparative example. That is, only the concentrated yeast extract is mixed with the wall material to prepare microencapsulated yeast extract (concentrated yeast extract: wall material = 80:20), while 4 parts of compound vitamin are added together with 16 parts of microencapsulated yeast extract in step S2.

[0056] Test method design: (1) Water solubility test Weigh 1.0 g of the microencapsulated product and add it to 100 mL of deionized water at 25 ± 0.5 °C. Stir magnetically (300 ± 10 rpm) and observe the dispersion over 5 minutes. Record the complete dispersion time with a stopwatch. Continue stirring for another 5 minutes. Filter the solution through a 0.45 μm microporous membrane. Take the filtrate and determine the vitamin content using high-performance liquid chromatography (HPLC). The dispersion time is as follows: <3 minutes is excellent, 3-5 minutes is good, and >5 minutes is poor. The solubility is as follows: >90% is excellent, 80-90% is good, and <80% is poor.

[0057] (2) Animal experiments Experimental animals: healthy juvenile California bass (initial weight 5.0±1g).

[0058] Experiment duration: 5 weeks.

[0059] Experimental groups: Examples 1-6, Comparative Examples 1-6, and blank control group. Examples 1-6 and Comparative Examples 1-6 were respectively mixed with the corresponding group feed composition at 1% of the basal feed. The blank control group was only fed the basal feed and no feed composition was added. Each group was set up with 3 replicates, and each replicate had 30 fish.

[0060] Rearing conditions: water temperature 26±1℃, dissolved oxygen >6mg / L, pH 7.2-7.8, photoperiod 12L:12D; Feeding: 3 times a day (8:00, 14:00, 20:00), the amount of food is 4% of the fish's body weight, and the amount of food should be adjusted according to the fish's weight each week.

[0061] Growth performance was assessed based on initial and final body weight, including: Weight gain rate (%) = [(final weight - initial weight) ÷ initial weight] × 100%; Feed conversion ratio = feed intake ÷ (final body weight - initial body weight); Survival rate (%) = (Number of survivors at the end of the experiment ÷ Initial number of survivors) × 100%.

[0062] Intestinal flora calculation: Intestinal contents were collected, and the number of lactic acid bacteria and Escherichia coli was determined by plate counting method.

[0063] The test results are shown in Tables 1 and 2.

[0064] Table 1

[0065] Table 2

[0066] The test results in Tables 1 and 2 show that, compared with Comparative Examples 1-6, Examples 1-6 exhibited excellent water solubility with a water-soluble dispersion time ≤3.5 minutes and a solubility >90%. This indicates that microencapsulation technology, combined with optimized wall material ratios and process parameters, significantly improves the water solubility and dispersibility of the product, facilitating the rapid release of active ingredients in water and their absorption by fish. The California bass in Examples 1-6 demonstrated significantly superior growth performance, indicating that the feed composition of the present invention can significantly promote the growth of California bass, improve feed utilization, and reduce mortality. Furthermore, the feed composition of the present invention can effectively promote the proliferation of beneficial bacteria, inhibit the growth of harmful bacteria, and improve the balance of intestinal flora. The indicators of Comparative Example 1 (non-microencapsulated) and Comparative Example 6 (added separately) were significantly lower than those of Examples 1-6 (P<0.05), proving that microencapsulation technology plays a crucial role in protecting vitamin activity, improving bioavailability, and achieving a sustained-release effect. All indicators of Comparative Example 5 (without yeast extract) were significantly lower than those of Examples 1-6 (P<0.05), demonstrating that the synergistic effect of yeast extract and multivitamins plays an important role in improving the gut health and growth performance of California bass.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A feed composition for promoting the gut health of largemouth bass, characterized in that, By weight, it includes the following components: Rice protein peptides, 25-55 parts; 15-20 parts of mineral premix; 15-25 parts of microencapsulated complex vitamin-yeast extract, based on the total mass of the microencapsulated complex vitamin-yeast extract, contain 35-50% yeast extract, 30-45% complex vitamins, and 15-25% wall material; 10-20 parts of yeast cell wall; 5-10 portions of appetite stimulant.

2. The feed composition for promoting the intestinal health of largemouth bass according to claim 1, characterized in that, The yeast extract is an enzymatically hydrolyzed yeast extract; the wall material is selected from a mixture of maltodextrin and gum arabic in a mass ratio of (2-4):

1.

3. The feed composition for promoting the intestinal health of largemouth bass according to claim 1, characterized in that, Based on the total mass of the multivitamin, it contains 12-18% vitamin A, 1-2% vitamin D3, 8-15% vitamin E, 0.1-0.3% vitamin K3, 6-12% vitamin C, 0.1-0.3% vitamin B1, 0.2-0.5% vitamin B2, 1.5-2.5% vitamin B3, 0.6-1.2% vitamin B5, 0.2-0.4% vitamin B6, 0.006-0.012% vitamin B7, 0.06-0.12% vitamin B9, and 0.0006-0.0012% vitamin B12, with the remainder being vitamin carriers.

4. The feed composition for promoting the intestinal health of largemouth bass according to claim 1, characterized in that, Based on the total mass of the mineral premix, it contains 30-40% calcium dihydrogen phosphate, 5-10% potassium chloride, 3-5% magnesium sulfate, 2-3% zinc sulfate, 1.5-2.5% manganese sulfate, 2-3% ferrous sulfate, 0.5-1.0% copper sulfate, 0.05-0.1% calcium iodate, and 0.005-0.02% sodium selenite, with the remainder being a mineral carrier.

5. The feed composition for promoting the intestinal health of largemouth bass according to claim 1, characterized in that, The attractant is selected from at least one of squid viscera powder, fish broth, betaine, and thiamethoxam dimethyl-β-propionic acid.

6. The feed composition for promoting the intestinal health of largemouth bass according to claim 1, characterized in that, The preparation method of the microencapsulated complex vitamin-yeast extract includes the following steps: A1. Preparation of yeast extract: Take active dry yeast, add deionized water at a mass ratio of 1:(4-6), adjust the pH to 5.5-6.0, add 0.5-1.0% compound enzyme preparation, hydrolyze at 50-55℃ for 4-6 hours, inactivate enzyme at 90-100℃ for 5-15 minutes, centrifuge to collect the supernatant, concentrate to a solid content of 30-40%, and obtain concentrated yeast extract; A2. Preparation of the mixed solution: Mix the concentrated yeast extract with the compound vitamins, add the wall material, stir evenly, and adjust the solid content to 30-40%; A3. Microencapsulation: Microencapsulation was performed using spray drying or freeze drying to obtain microencapsulated complex vitamin-yeast extract.

7. The feed composition for promoting the intestinal health of largemouth bass according to claim 6, characterized in that, In step A1, the active dry yeast is selected from at least one of Saccharomyces cerevisiae and Candida utilis; the compound enzyme preparation is selected from protease and glucanase in a mass ratio of (1.5-2.5):

1. In step A2, the mass ratio of the concentrated yeast extract to the compound vitamins is 70:30 to 85:15; the amount of wall material added is 8-15% of the total mass of the concentrated yeast extract and the compound vitamins.

8. The feed composition for promoting the intestinal health of largemouth bass according to claim 6, characterized in that, In step A3, the process parameters for the spray drying method are: inlet air temperature 160-180℃, outlet air temperature 80-90℃, and feed rate 15-20mL / min. The process parameters for the freeze-drying method are as follows: pre-freezing temperature -40 to -30℃, pre-freezing time 3-5 hours, freeze-drying temperature -50 to -40℃, vacuum degree 5-15Pa, and drying time 24-48 hours.

9. A method for preparing a feed composition for promoting the intestinal health of California bass as described in any one of claims 1-8, characterized in that, The preparation method includes the following steps: S1. Raw material pretreatment: Pass each raw material through a 60-120 mesh sieve; S2. Mixing: Mix rice protein peptides, mineral premix, microencapsulated compound vitamin-yeast extract, yeast cell wall, and palatability enhancer at 20-30 rpm for 15-30 minutes to obtain the composition.

10. The use of the feed composition according to any one of claims 1-8 in the farming of California bass, characterized in that, The feed composition is added to the complete feed at a rate of 0.5-2%.

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