Premix for promoting healthy growth of mandarin shrimps and preparation method thereof

Abstract

The invention relates to a premix for promoting healthy growth of mandarin shrimps and a preparation method of the premix, and belongs to the technical field of aquatic feed processing. The premix is prepared from the following components in parts by weight of dry substances: 10 to 30 parts of fermented soybean meal extract, 10 to 20 parts of krill meal, 0.2 to 1.0 part of low-temperature-resistant protease and 0.1 to 0.5 part of microencapsulated astaxanthin, the low-temperature-resistant protease still keeps at least 50% of enzymatic activity at the optimum temperature under the condition of 15-30 DEG C; a microcapsule wall material used by the microencapsulated astaxanthin is an edible high polymer material. The premix disclosed by the invention is particularly suitable for nutrient enrichment and intestinal health maintenance of juvenile shrimps in a low-temperature environment, and has the characteristics of effectively improving the nutrient utilization rate of the feed in the low-temperature environment, enhancing the immunity and disease resistance of the diamond shrimps and promoting healthy growth of the diamond shrimps.

Description

Technical Field

[0001] The invention belongs to the technical field of aquatic feed processing, and in particular relates to a premix for promoting the healthy growth of king prawns and a preparation method thereof. Background Art

[0002] The giant tiger prawn, scientifically known as Penaeus monodon, is highly sought after in the international aquaculture market for its large size, rapid growth, delicious meat, and nutritious properties. It is one of the world's three major farmed shrimp species. In my country's southern coastal regions, the cultivation of giant tiger prawns has become a significant aquaculture species, boasting significant economic value and promising market prospects.

[0003] The juvenile stage of a King Kong shrimp's growth cycle is a crucial period for the success of aquaculture. Juvenile shrimp's physiological functions are not yet fully developed, their digestive systems are relatively fragile, and their nutritional needs are comprehensive and precise, making them more sensitive to environmental changes. Therefore, providing high-quality, nutritionally balanced, easily digestible feed is essential for ensuring the healthy growth of juvenile King Kong shrimp, improving survival rates, and shortening the aquaculture cycle.

[0004] However, in the actual breeding process, the traditional King Kong shrimp juvenile feed generally has the following problems: 1. Low digestion efficiency at low temperature: The intestinal tract of juvenile shrimp is not fully developed, conventional proteases are not active enough at low temperatures, and the utilization rate of nutrients is not high, resulting in low feed conversion rate and affecting the digestion and absorption of protein by juvenile shrimp.

[0005] 2. Influence of anti-nutritional factors: Plant proteins such as soybean meal contain anti-nutritional substances such as trypsin inhibitors, which will inhibit the growth of young shrimp if used directly.

[0006] 3. Fishmeal dependence: Fishmeal resources are in short supply and have high costs. Excessive reliance on fishmeal leads to increased breeding costs.

[0007] 4. Loss of nutrients: High-temperature processing (such as traditional granulation) destroys heat-sensitive components (such as enzyme preparations and astaxanthin), reduces the nutritional value of the feed, affects the quality of the feed, and cannot meet the nutritional requirements of the juvenile shrimp for growth and development.

[0008] 5. Weak antioxidant capacity: Astaxanthin in feed easily loses its effectiveness due to oxidative degradation, resulting in decreased immunity of young shrimp and poor prevention and control of blue body disease.

[0009] Therefore, it is of great practical significance to develop a premix that can adapt to low temperature environment, has comprehensive nutrition and can promote the healthy growth of juvenile king prawns. Summary of the Invention

[0010] The purpose of the present invention is to provide a premix for promoting the healthy growth of king prawns and a preparation method thereof, which is particularly suitable for nutritional enhancement and intestinal health maintenance of juvenile shrimps in low-temperature environments. It has the characteristics of effectively improving the nutrient utilization rate of feed in low-temperature environments, enhancing the immunity and disease resistance of king prawns, and promoting their healthy growth.

[0011] The purpose of the present invention can be achieved through the following technical solutions: A premix for promoting the healthy growth of krill, comprising the following components, measured by dry matter weight: 10-30 parts of fermented soybean meal extract, 10-20 parts of krill meal, 0.2-1.0 parts of cold-resistant protease, 0.1-0.5 parts of microencapsulated astaxanthin, 0.5-1 parts of motherwort, 0.2-0.5 parts of eucommia leaf extract, and 0.3-0.8 parts of photosynthetic bacteria; the cold-resistant protease is an enzyme that maintains at least 50% of its optimal temperature activity under conditions of 15-30°C; and the microcapsule wall material used for the microencapsulated astaxanthin is an edible polymer material.

[0012] Furthermore, the premix also includes 1-5 parts of vitamin premix fortified nutritional requirements of juvenile king prawns during the low temperature period, 1-5 parts of trace element premix, 0.5-3 parts of phospholipids, 0.1-1 parts of cholesterol, 0.5-2 parts of prebiotics, and a carrier and a diluent to make up to 100 parts.

[0013] Furthermore, the fermented soybean meal extract is a concentrated product obtained by extracting soybean meal through solid or liquid fermentation treatment using probiotic strains.

[0014] Specifically, the fermented soybean meal extract is a concentrated product rich in small molecule peptides, probiotic metabolites and bioactive substances obtained by solid or liquid fermentation of soybean meal using selected probiotic strains, and then using water extraction, alcohol extraction or enzymatic hydrolysis.

[0015] Furthermore, the probiotic strain is at least one of Bacillus subtilis, lactic acid bacteria, Clostridium butyricum, Saccharomyces cerevisiae and yeast.

[0016] When soybean meal is fermented with specific probiotics, anti-nutritional factors such as trypsin inhibitors, phytic acid, and soy antigens are significantly degraded, reducing their negative impact on digestion and absorption by juvenile shrimp. Furthermore, the fermentation process breaks down some large protein molecules into small peptides and free amino acids, making them more easily digestible and absorbable by juvenile shrimp. Fermented soybean meal is nutritious, easily digestible, and contains beneficial microorganisms. The fermentation process produces organic acids, B vitamins, probiotics, and their metabolites (such as bacteriocins), which help improve the intestinal microecological environment, inhibit the growth of harmful bacteria, and enhance feed palatability. It provides juvenile shrimp with a rich supply of protein and trace elements, promoting intestinal health and improving feed palatability and utilization.

[0017] Krill meal is rich in various nutrients such as protein, fat, vitamins, minerals and astaxanthin, which can enhance immunity and shell hardness. Its protein and fat composition is close to the nutritional requirements of juvenile king prawns. It has high nutritional value and palatability, and can provide comprehensive nutritional support for juvenile shrimp.

[0018] Furthermore, the low-temperature resistant protease still maintains at least 50% of its enzyme activity at its optimum temperature under the conditions of 15-30°C.

[0019] When kept at low temperatures (e.g., 15-25°C), shrimp secrete less digestive enzymes and their activity decreases. Cold-resistant proteases, particularly those derived from cryogenic microorganisms, can maintain high catalytic activity at lower temperatures, compensating for the shrimp's endogenous enzyme deficiency.

[0020] Furthermore, the low-temperature resistant protease is an alkaline protease derived from microorganisms, and has a pH range of 7.5-10.0 and a temperature range of 40-60°C.

[0021] The intestinal environment of shrimp is usually neutral to alkaline. Alkaline protease has better activity and stability under this pH condition and can work more effectively.

[0022] Furthermore, the cold-resistant protease efficiently hydrolyzes large proteins in feed (especially plant and some animal proteins, which are difficult to digest at low temperatures) into small peptides and amino acids within the digestive tract of juvenile king prawns. These small molecules are more easily absorbed and utilized by the intestines, significantly improving the apparent digestibility and biological value of the protein. Furthermore, the effective breakdown of protein promotes the formation of bioactive peptides, which have various physiological functions, including immune regulation and growth promotion.

[0023] Specifically, the cold-resistant protease is at least one of Antarctic krill complex enzyme, Bacillus licheniformis protease, Alcalase® alkaline protease, Bacillus subtilis mutant AprEM, cold-adapted protease derived from Pseudomonas, AG175, low-temperature protease produced by deep-sea cold-adapted bacteria, and alkaline protease produced by marine Bacillus.

[0024] Furthermore, the microencapsulated astaxanthin is prepared by microencapsulation treatment using a spray drying method, an emulsification-solvent evaporation method, or a complex coacervation method.

[0025] Astaxanthin is a powerful natural antioxidant that has multiple physiological functions for juvenile king prawns, including enhancing body color, anti-oxidation and anti-stress, improving immunity and promoting growth.

[0026] Natural astaxanthin is extremely sensitive to light, heat, oxygen, and acidic environments, and is easily degraded and inactivated during feed processing, storage, and animal digestion. Microencapsulation technology involves encapsulating astaxanthin into tiny particles within a specific wall material, effectively isolating it from adverse external factors, protecting it from oxidation and destruction, and potentially improving its release characteristics and bioavailability in the digestive tract.

[0027] Furthermore, the wall material used in the microencapsulation of the microencapsulated astaxanthin is selected from at least one of alginate, chitosan, gelatin, gum arabic, maltodextrin, modified starch, β-cyclodextrin and derivatives thereof.

[0028] Specifically, the β-cyclodextrin derivative may be hydroxypropyl-β-cyclodextrin.

[0029] As a preferred technical solution of the present invention, the microencapsulated astaxanthin is produced using a spray drying method, using a wall material comprising a complex of maltodextrin and hydroxypropyl-β-cyclodextrin, or a complex of gum arabic and maltodextrin. This method is relatively low-cost, amenable to industrial production, and produces microcapsules with good protective properties.

[0030] Furthermore, the embedding rate of the microencapsulated astaxanthin is greater than 90%, and the particle size is 20-100 μm.

[0031] Furthermore, the vitamin premix contains at least two vitamins from the vitamin A, B, C, D, and E groups.

[0032] Furthermore, the trace element premix includes at least calcium, phosphorus and magnesium elements; further, the trace element premix also includes at least one of selenium, copper, iron, zinc, manganese, selenium, iodine and cobalt elements.

[0033] Furthermore, the carrier and diluent are at least one of food-grade zeolite powder, rice husk powder, medical stone powder, wheat bran, sodium alginate or inferior powder.

[0034] A method for preparing the above-mentioned premix comprises the following steps: S1, mixing the premix components in proportion to obtain a mixed material; S2, forming the mixed material of step S1 at a temperature of 35-60°C to prepare a granular or flaky semi-finished product; S3. The molding material obtained in step S2 is subjected to a high-temperature short-time sterilization and drying treatment at 90-120° C. for 5-30 min to obtain a premix finished product.

[0035] Furthermore, the molding process in step S2 is performed using a low-temperature granulator or tablet press, and the peak temperature of the material during the molding process is ≤60°C to reduce the loss of heat-sensitive components.

[0036] Furthermore, the low-temperature granulator is a double-roller extrusion granulator or a low-temperature ring die granulator.

[0037] Furthermore, the high-temperature short-time sterilization in step S3 is performed using a hot air circulation oven, a fluidized bed drying sterilizer or a microwave sterilization device. After the high-temperature short-time sterilization, the moisture content of the premix product is less than 10%.

[0038] The application of the above-mentioned premix as an additive to the feed of juvenile king prawns, especially in a culture environment of 15-25°C, is to improve the nutritional value and bioavailability of the feed.

[0039] Furthermore, the premix is added to the feed of juvenile king prawns at a ratio of 2-10 wt% of the total feed content, so as to improve the growth performance, feed utilization rate and health level of the juvenile king prawns in a low temperature environment.

[0040] Specifically, the base feed for juvenile King Kong shrimp consists primarily of conventional feed ingredients such as fish meal, soybean meal, flour, and oil. The specific content of each ingredient can be adjusted based on the nutritional needs of the juvenile King Kong shrimp, for example, 30-40% fish meal, 20-30% soybean meal, 20-30% flour, 5-10% oil, 0.05-0.5% vitamin premix, and 0.1-1% trace element premix. The crude protein content of the base feed is approximately 35-45%, and the crude fat content is approximately 5-9%.

[0041] Furthermore, the premix is added to the feed for juvenile king prawns in a ratio of 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt% and 9wt% in the total feed content.

[0042] Beneficial effects of the present invention: (1) By optimizing the raw material composition, replacing some of the raw materials with fermented soybean meal and krill meal, and combining cold-resistant enzyme technology, astaxanthin microencapsulation protection technology, and advanced processing technology, the present invention aims to address the problems of low digestibility, easy loss of key nutrients, slow growth, and weak physical fitness in existing juvenile king prawn feeds under low-temperature conditions. The premix of the present invention can significantly improve the weight gain and survival rate of juvenile king prawns, reduce the feed conversion factor, enhance the activity of digestive enzymes, and increase the astaxanthin content in muscle, thus having significant breeding benefits and broad application prospects.

[0043] (2) The addition of cold-resistant protease and the use of easily digestible raw materials such as fermented soybean meal and krill meal in the present invention will significantly improve the digestion and absorption rate of feed nutrients by juvenile king prawns in a low-temperature environment, thereby promoting their growth and development, and increasing their weight gain rate and specific growth rate. DETAILED DESCRIPTION

[0044] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0045] Table 1 Example 1 A premix for promoting the healthy growth of king prawns, comprising the following components, calculated in percentage by dry matter weight: Table 2 The vitamin premix contains the following vitamins: VA, VD3, VE, VK3, VB1, VB2, VB6, VB12, VC, niacin, calcium pantothenate, folic acid, biotin and inositol.

[0046] The trace element premix includes the following elements: calcium, phosphorus, magnesium, iron, copper, iron, zinc, manganese, selenium, iodine and cobalt.

[0047] The microencapsulated astaxanthin preparation method comprises: using a spray drying method, using maltodextrin and hydroxypropyl-β-cyclodextrin as a composite wall material and polysorbate 80 as an emulsifier, to microencapsulate astaxanthin (purity ≥ 95%). The spray drying process has an inlet air temperature of 180°C and an outlet air temperature of 80°C.

[0048] The preparation method of the fermented soybean meal extract comprises the following steps: fermenting soybean meal by solid-state fermentation, inoculating 3% of Bacillus subtilis, fermenting for 3 days under ventilation conditions at a fermentation temperature of 40° C., and drying and crushing the soybean meal extract after the fermentation is completed.

[0049] The krill powder is dried in advance to reduce its moisture content to below 10%, crushed and sieved through a 60-80 mesh sieve for later use.

[0050] The above-mentioned premix is prepared by the following method: S11, weighing the low-temperature resistant alkaline protease, microencapsulated astaxanthin, vitamin premix, trace element premix, soybean lecithin, cholesterol and oligofructose, and about 50% zeolite powder, are placed in a V-shaped premixer, sealed, and mixed at room temperature for 20 minutes to ensure uniform mixing, to prepare core premix A; S12. The fermented soybean meal and krill meal are sieved through an 80-mesh vibrating screen to remove impurities and lumps. The fermented soybean meal and krill meal are then added to a horizontal ribbon mixer along with the remaining zeolite powder and rice husk powder. The mixture is mixed at a low speed for 5 minutes, and then the core premix A prepared in step S11 is added. Mixing at a medium speed is continued for 25 minutes. S2, the material mixed in step S12 is fed into a roller extrusion granulator through a screw conveyor, the granulation chamber temperature is controlled at 50 ± 2 ° C, and the maximum temperature of the material during the molding process is ensured not to exceed 55 ° C; a granular premix semi-finished product with a diameter of 1.2 mm and a length of 2-3 mm is prepared; S3. Spread the resulting granular semi-finished product in a thin, even layer on a high-temperature-resistant stainless steel mesh tray and quickly transfer it to a preheated microwave tunnel-type drying and sterilization machine. Set the microwave power so that the core temperature of the granular semi-finished product reaches 100-110°C within 3-5 minutes and maintains this temperature for 8-12 minutes. This process also reduces the moisture content of the premix to below 8%.

[0051] S4. The premixed particles that have been sterilized and dried at high temperature for a short time are quickly cooled to room temperature via a cooling conveyor belt.

[0052] After the cooled finished product passes the inspection, it is vacuum packed or nitrogen-filled in an aluminum-plastic composite moisture-proof bag, then put into an outer woven bag and stored in a cool, dry and ventilated environment.

[0053] Example 2 The difference between this embodiment and embodiment 1 is that the premix formula of this embodiment is shown in Table 3 below: Table 3 The preparation method is the same as that in Example 1.

[0054] Example 3 The difference between this embodiment and embodiment 1 is that the premix formula of this embodiment is shown in Table 4 below: Table 4 The preparation method is the same as that in Example 1.

[0055] Comparative Example 1 The difference between this comparative example and Example 1 is that in this comparative example, the fermented soybean meal extract is replaced with ordinary soybean meal, that is, the soybean meal in this comparative example is not fermented, and the other components, preparation steps and parameters are the same.

[0056] Comparative Example 2 The difference between this comparative example and Example 1 is that krill meal is replaced with fish meal in this comparative example, and the other components, preparation steps and parameters are the same.

[0057] Comparative Example 3 The difference between this comparative example and Example 1 is that the microencapsulated astaxanthin in this comparative example is replaced with ordinary astaxanthin, that is, the astaxanthin in this comparative example is not microencapsulated, and the other components, preparation steps and parameters are the same.

[0058] Comparative Example 4 The difference between this comparative example and Example 1 is that the low-temperature-resistant alkaline protease is replaced with bromelain (common protease) in this comparative example, and the other components, preparation steps and parameters are the same.

[0059] Comparative Example 5 The difference between this comparative example and Example 1 is that motherwort is not added in this comparative example, and the other components, preparation steps and parameters are the same.

[0060] Comparative Example 6 The difference between this comparative example and Example 1 is that photosynthetic bacteria are not added in this comparative example, and the other components, preparation steps and parameters are the same.

[0061] The premixes prepared in Examples 1-3 and Comparative Examples 1-4 were numbered, wherein the premixes of Examples 1-3 were numbered 1-3, and the premixes of Comparative Examples 1-6 were numbered 4-9.

[0062] Effect verification test plan (1) Preparation of experimental feed Basic feed formula: 33 parts of fish meal, 20 parts of soybean meal, 28 parts of wheat flour, 2.5 parts of fish oil, 1.5 parts of soybean lecithin, 0.1 parts of vitamin premix and 0.5 parts of trace element premix.

[0063] 92% of the basic feed was mixed with 8% of the premixes numbered 1-9 respectively. The mixing method was to spray a small amount of edible oil (about 1%) on the surface of the basic feed, then evenly sprinkle the premixes and mix thoroughly to ensure that the premixes were evenly attached to the surface of the feed particles, thereby obtaining the test feeds 1-9.

[0064] (2) Test subjects A total of 900 healthy, active juvenile King Kong shrimp (King Kong shrimp) from the same batch, with an average initial body weight (IBW) of 0.52 ± 0.03 g, were selected and divided into nine groups of 100 shrimp each, with two replicates per group. Each replicate consisted of a 200-liter, round, fiberglass-reinforced plastic (FRP) culture tank with a central bottom drain, independent aeration, and water circulation. Each tank was stocked with 50 healthy, selected juvenile shrimp. The shrimp were temporarily maintained in the culture system for seven days prior to the experiment to allow them to acclimate.

[0065] (3) Breeding conditions (simulating low temperature period) Water temperature: 22±0.5℃; salinity: 20±1‰; pH: 7.8-8.3; dissolved oxygen: maintained above 5.5mg / L; photoperiod: natural light supplemented by weak light.

[0066] (4) Breeding cycle: 56 days (8 weeks) (5) Feeding Management: Feed four times daily (07:00, 12:00, 17:00, and 22:00). The initial daily feed amount is 8-10% of the shrimp's body weight. Adjust the feeding rate every seven days based on the shrimp's actual feeding (basically, they finish eating within 45 minutes), survival status, and water quality. Accurately record the feed amount for each bucket. Observe and remove leftover bait and feces daily.

[0067] (6) After the rearing period, calculate the survival rate (%) according to: ① Survival rate SR = (number of surviving fish at the end of the period / number of fish released at the beginning of the period) × 100%.

[0068] ② Final average weight FBW = total final weight / final digit, calculate the final average weight (g).

[0069] ③ Weight gain rate WGR=[(FBW-IBW) / IBW]×100%, calculate the weight gain rate (%).

[0070] ④ Feed coefficient FCR = total dry feed amount fed (g) / total weight gain (g), calculate the feed coefficient.

[0071] ⑤ Muscle astaxanthin content: Four shrimps were randomly selected from each group, and their abdominal muscles were taken, freeze-dried, and then crushed. The astaxanthin content in the muscles was determined by high performance liquid chromatography (HPLC) (mg / kg dry matter). ⑥ Antioxidant capacity: Five shrimps were randomly sampled from each group, and their hemolymph was carefully extracted for the determination of superoxide dismutase (SOD) activity.

[0072] ⑦ Digestive Enzyme Activity: Five shrimp were randomly sampled from each group (after 12 hours of starvation) and rapidly dissected on an ice tray. The hepatopancreas and foregut were removed. The samples were weighed and homogenized in pre-chilled saline (pH 7.4, containing 0.05 M Tris-HCl buffer) at a 1:9 (w / v) ratio. The homogenates were centrifuged at 10,000 rpm for 15 minutes at 4°C. The supernatant was used to determine protease activity.

[0073] The test results are shown in Table 5.

[0074] Table 5 As shown in the test results in Table 1, the survival rate of the king prawns prepared in Examples 1-3 (numbers 1-3) was significantly higher than that in the control examples (numbers 4-9), indicating that the feeds in the Examples are more effective in enhancing disease resistance and reducing mortality in juvenile shrimp. Furthermore, the average weight growth rate and feed conversion rate of Examples 1-3 were higher than those in the control examples, indicating that the feed utilization rates of the Examples were higher. The muscle astaxanthin content of Examples 1-3 was higher, indicating that the microencapsulation technology in the premix effectively increased the deposition efficiency of astaxanthin. In summary, the premix of the present invention offers significant advantages for promoting the healthy growth of king prawns. It can effectively improve the nutrient utilization of feed in low-temperature environments, promote the growth and development of juvenile shrimp, enhance their disease resistance and antioxidant function, and improve their survival rate in aquaculture. It has broad application prospects.

[0075] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A premix for promoting the healthy growth of king prawns, characterized in that: The composition comprises the following components, calculated on a dry matter basis: 10-30 parts of fermented soybean meal extract, 10-20 parts of krill meal, 0.2-1.0 parts of cold-resistant protease, 0.1-0.5 parts of microencapsulated astaxanthin, 0.5-1 parts of motherwort, 0.2-0.5 parts of eucommia leaf extract, and 0.3-0.8 parts of photosynthetic bacteria; The low-temperature resistant protease is an enzyme that maintains at least 50% of its activity at its optimum temperature under the conditions of 15-30°C; the microcapsule wall material used for the microencapsulated astaxanthin is an edible polymer material.

2. A premix for promoting the healthy growth of king prawns according to claim 1, characterized in that: The premix also includes 1-5 parts of vitamin premix fortified nutritional requirements of juvenile king prawns during the low-temperature period, 1-5 parts of trace element premix, 0.5-3 parts of phospholipids, 0.1-1 parts of cholesterol, 0.5-2 parts of prebiotics, and a carrier and a diluent to make up to 100 parts.

3. The premix for promoting the healthy growth of king prawns according to claim 1, characterized in that: The low-temperature resistant protease is an alkaline protease derived from microorganisms, has a pH range of 7.5-10.0, and a temperature range of 40-60°C.

4. The premix for promoting the healthy growth of king prawns according to claim 1, characterized in that: The microcapsule wall material used for the microencapsulated astaxanthin is selected from at least one of alginate, chitosan, gelatin, gum arabic, maltodextrin, modified starch, β-cyclodextrin and derivatives thereof.

5. The premix for promoting the healthy growth of king prawns according to claim 1, characterized in that: The microencapsulated astaxanthin is prepared by microencapsulation treatment using a spray drying method, an emulsification-solvent evaporation method, or a complex coacervation method.

6. The premix for promoting the healthy growth of king prawns according to claim 1, characterized in that: The fermented soybean meal extract is a concentrated product obtained by extracting soybean meal through solid or liquid fermentation treatment using probiotic strains.

7. A method for preparing a premix for promoting the healthy growth of king prawns according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: S1, mixing the premix components in proportion to obtain a mixed material; S2, forming the mixed material of step S1 at a temperature of 35-60°C to prepare a granular or flaky semi-finished product; S3. The molding material obtained in step S2 is subjected to a high-temperature short-time sterilization and drying treatment at 90-120° C. for 5-30 min to obtain a premix finished product.

8. The preparation method according to claim 7, characterized in that The molding process in step S2 is performed using a low-temperature granulator or tablet press, and the peak temperature of the material during the molding process is ≤60°C.

9. Use of the premix according to any one of claims 1 to 6 as an additive in feed for juvenile king prawns, particularly in a culture environment at 15-25°C to improve the nutritional value and bioavailability of the feed.

10. The use according to claim 9, characterized in that The premix is added to the feed of juvenile king prawns at a ratio of 2-10 wt% of the total feed content, so as to improve the growth performance, feed utilization rate and health level of the juvenile king prawns in a low temperature environment.

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