Preparation method of fertilizer for reservoir culture of bighead and application thereof

Abstract

The present application relates to the technical field of aquaculture, in particular to a preparation method and application of a fertilizer for reservoir culture of Hypophthalmichthys nobilis. The fertilizer comprises corn starch residue, distiller's grains, sugar cane residue, cerium oxide, lanthanum oxide, Chinese herbal medicine extract, brewing yeast, animal bifidobacterium, clostridium butyricum, acid protease, ferrous sulfate, magnesium sulfate, zinc sulfate, copper sulfate, citric acid, sodium alginate, calcium chloride, silicon dioxide and calcium carbonate. The present application realizes efficient utilization of rare earth, fermentation product enrichment and nutrient slow release by pre-complexing rare earth with citric acid, stepwise fermentation combined with pH regulation and calcium alginate microcapsule granulation, and effectively promotes rapid growth of Hypophthalmichthys nobilis.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, and in particular to a method for preparing a growth promoter for bighead carp farming in reservoirs and its application. Background Technology

[0002] Silver carp are typical filter-feeding fish, and their growth is highly dependent on the abundance and population structure of plankton in the water. In large-scale reservoir aquaculture, insufficient or unstable natural food sources have become the core bottleneck restricting their yield.

[0003] To alleviate this contradiction, fertilizers are commonly used in production to cultivate plankton. Currently, commercially available fertilizers are mainly divided into three categories: The first category consists of chemical fertilizers such as urea and superphosphate, which act quickly but have short-lived effects, are prone to settling and unevenly dispersed in large bodies of water, and require frequent application; the second category consists of organic fertilizers made from fermented poultry and livestock manure and crop straw, which are nutritionally complete but decompose slowly and may consume dissolved oxygen, posing a risk of water quality deterioration; the third category consists of microecological preparations containing Bacillus subtilis, photosynthetic bacteria, etc., which have a mild effect, but the activity of the bacterial community is easily affected by environmental factors such as low temperatures, resulting in unstable efficacy.

[0004] Furthermore, while existing technologies attempt to add rare earth elements to promote algal growth, rare earth oxides are poorly soluble in water, resulting in low bioavailability and limited practical effectiveness. Simultaneously, the lack of effective pH control during microbial fermentation leads to a single type of metabolite and limited product functionality. Most products are in powder form, which dissolves and settles rapidly in water, making it difficult to achieve sustained nutrient release in large reservoirs.

[0005] Therefore, how to improve the bioavailability of rare earth elements, optimize fermentation stability, and endow products with slow-release properties to meet the needs of large-scale aquaculture is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the prior art by providing a method for preparing a growth promoter for bighead carp farming in reservoirs and its application. Through citric acid pre-complexation, step-by-step fermentation combined with pH control and calcium alginate microencapsulation granulation, the invention achieves efficient utilization of rare earth elements, enrichment of fermentation products and slow release of nutrients, thereby effectively promoting the rapid growth of bighead carp.

[0007] To achieve the above objectives, this invention provides a growth promoter for bighead carp farming in reservoirs, comprising the following raw materials in parts by weight: 45-50 parts corn starch residue, 2-4 parts distiller's grains, 18-22 parts sugarcane bagasse, 4-6 parts cerium oxide, 7-9 parts lanthanum oxide, 0.1-0.3 parts traditional Chinese medicine extract, 0.01-0.02 parts brewer's yeast, 0.015-0.025 parts Bifidobacterium animalis, 0.025-0.035 parts Clostridium butyricum, 0.4-0.6 parts acidic protease, 0.7-0.9 parts ferrous sulfate, 0.15-0.25 parts magnesium sulfate, 0.08-0.12 parts zinc sulfate, 0.06-0.09 parts copper sulfate, 1-2 parts citric acid, 3-5 parts sodium alginate, 0.5-1 part calcium chloride, 15-20 parts silicon dioxide, and 2-3 parts calcium carbonate.

[0008] In an optional embodiment, the corn starch residue is a byproduct of starch industrial production, and its crude protein content is ≥18wt%.

[0009] In one optional embodiment, the herbal extracts include Phellodendron bark extract, Astragalus membranaceus extract, and Rheum palmatum extract.

[0010] In an optional embodiment, the preparation method of the herbal extract includes the following steps: mixing Phellodendron bark, Astragalus root, and Rhubarb in a weight ratio of (0.8-1.2):(0.8-1.2):(0.8-1.2) to obtain a mixture; adding water equivalent to 9-11 times the weight of the mixture, decocting and extracting for 1.5-2.5 hours, filtering, and collecting the filtrate; adding water equivalent to 7-9 times the weight of the mixture to the filter residue, decocting and extracting again for 1-2 hours, filtering, and collecting the filtrate; combining the two filtrates, concentrating under reduced pressure, and spray drying to obtain the herbal extract.

[0011] In one alternative implementation, the brewer's yeast, Bifidobacterium animalis, and Clostridium butyricum are all commercially available.

[0012] In one optional embodiment, the growth promoter has a particle size of 0.5-2 mm.

[0013] This invention also provides a method for preparing the aforementioned growth promoter for bighead carp farming in reservoirs, comprising the following steps: S1. Cerium oxide, lanthanum oxide, citric acid and water are mixed and reacted to obtain a complex solution; S2. Mix corn starch residue, distiller's grains, sugarcane bagasse, complex solution, traditional Chinese medicine extract, ferrous sulfate, magnesium sulfate, zinc sulfate, copper sulfate, acidic protease, silicon dioxide, calcium carbonate and water to obtain fermentation substrate; S3. Inoculate the fermentation substrate with brewer's yeast for the first fermentation, then inoculate with Bifidobacterium animalis for the second fermentation, and finally inoculate with Clostridium butyricum for the third fermentation to obtain the fermentation product; the pH of the first, second, and third fermentations is controlled between 4.8 and 6.0. S4. Mix the fermentation product, sodium alginate solution and calcium chloride solution, and granulate to obtain the growth promoter for bighead carp farming in reservoirs.

[0014] In an optional embodiment, in S1, the weight ratio of cerium oxide to water is (4-6):(73-77).

[0015] In an optional implementation, in S1, the reaction temperature is 60-70°C and the time is 2-3 hours.

[0016] In an optional embodiment, in S2, the corn starch residue, distiller's grains, and sugarcane bagasse are pre-crushed and passed through a 30-50 mesh sieve before mixing.

[0017] In an optional embodiment, in S2, the moisture content of the fermentation substrate is 40-45 wt%.

[0018] In an optional implementation, in step S3, the first fermentation temperature is 28-30℃, the time is 47-49 hours, and the aeration rate during this stage is 0.7-0.9 vvm. During this stage, the material is turned over every 11-13 hours for aerobic fermentation. The second fermentation temperature is 30-32℃, the time is 71-73 hours, during which aeration is stopped, the material is compacted, and facultative anaerobic fermentation is carried out. The third fermentation temperature is 35-37℃, the time is 71-73 hours, during which nitrogen is introduced to replace the air, the mixture is sealed, and strictly anaerobic fermentation is carried out. Here, 0.7-0.9 vvm refers to an aeration rate of 0.7-0.9 times the volume of the fermentation substrate per minute. For example, when the volume of the fermentation substrate is 100L, the aeration rate is 70-90L / min.

[0019] In an optional implementation, in step S3, during the first, second, and third fermentations, the pH is maintained between 4.8 and 6.0 through the buffering effect of calcium carbonate. When the pH of the fermentation system is detected to be below 4.5, calcium carbonate is added to adjust it to 5.0.

[0020] In an optional embodiment, in S4, the fermentation product is vacuum dried at 45-50°C until the moisture content is ≤8wt%, and then pulverized through a 70-90 mesh sieve.

[0021] In an optional embodiment, in S4, the sodium alginate solution has a mass fraction of 1.5-2.5%, and the calcium chloride solution has a mass fraction of 0.3-0.7%.

[0022] In an optional embodiment, in S4, the granulation method is spray granulation, wherein the inlet air temperature of the spray granulation is 60-70°C and the outlet air temperature is 40-45°C.

[0023] This invention also provides the application of the growth promoter for bighead carp farming in reservoirs, or the growth promoter for bighead carp farming prepared according to the preparation method, in the large-scale reservoir farming of silver carp.

[0024] In one optional implementation, the dosage of the growth promoter is 150-250 grams per meter of water depth, with an application interval of 15-20 days.

[0025] The beneficial effects of this invention are as follows: (1) This invention uses citric acid pre-complexation treatment to convert water-insoluble cerium oxide and lanthanum oxide into water-soluble citric acid rare earth complexes, which greatly improves the bioavailability of rare earth elements. After entering the water body, the soluble rare earth elements can be directly absorbed and utilized by algae, effectively promoting cell division and chlorophyll synthesis of beneficial algae such as diatoms and green algae, and providing more abundant high-quality natural food for silver carp.

[0026] (2) This invention employs a stepwise fermentation process of "Saccharomyces cerevisiae → Bifidobacterium animalis → Clostridium butyricum" and introduces calcium carbonate as a pH buffer. Calcium carbonate gradually neutralizes the organic acids produced by microorganisms during fermentation, maintaining the pH of the three fermentation stages within a suitable range of 4.8-6.0, thus avoiding the problem of excessive acidity inhibiting bacterial activity in traditional fermentation. The stable fermentation environment ensures the activity of probiotics such as Clostridium butyricum and the accumulation of their metabolites, resulting in a product rich in active substances such as butyric acid, small peptides, and vitamins. These substances, after entering the water body with the growth promoter, can be absorbed by zooplankton and can also indirectly improve the intestinal health of silver carp through the food chain, thereby increasing feed utilization.

[0027] (3) This invention uses microencapsulation granulation technology that cross-links sodium alginate with calcium ions to form a dense calcium alginate gel layer on the surface of the particles, giving the product slow-release properties. After the particles are put into water, the surface gel layer dissolves slowly, and the internal nutrients are continuously released, avoiding the nutrient loss caused by the rapid dissolution and sedimentation of ordinary powders, thereby greatly extending the fertilizer effect period, reducing the application frequency, and reducing labor intensity.

[0028] (4) This invention improves the bioavailability of rare earth elements through citric acid pre-complexation, ensures fermentation stability through step-by-step fermentation combined with pH control, and imparts slow-release properties to the product through calcium alginate microencapsulation. The synergistic effect of multiple technologies achieves comprehensive promotion of silver carp growth. Application results show that the growth promoter of this invention can significantly increase the density of plankton in the water, cultivate beneficial algae such as diatoms in a targeted manner, and promote the reproduction of zooplankton (especially rotifers) through the food chain, providing a continuous and stable supply of direct natural food for silver carp, ultimately achieving rapid and healthy growth of silver carp, and effectively meeting the aquaculture needs of a reservoir with an area of ​​approximately 5,000 mu.

[0029] (5) This invention uses industrial and agricultural waste such as corn starch residue, distiller's grains, and sugarcane bagasse as the main raw materials, turning waste into treasure. It not only reduces product costs but also solves the waste disposal problem, and has good social and economic benefits. Attached Figure Description

[0030] Figure 1 This is a comparison chart of the average weight gain of silver carp in different groups in this invention. Detailed Implementation

[0031] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0032] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0033] In the following embodiments and comparative examples of the present invention, the crude protein content of corn starch residue was 20 wt%; the preservation number of Saccharomyces cerevisiae was CGMCC No. 16134; the preservation number of Bifidobacterium animalis was CGMCC No. 1.2268; the preservation number of Clostridium butyricum was CGMCC No. 9652; and the enzyme activity of acidic protease was 50,000 U / g.

[0034] In the following embodiments and comparative examples of the present invention, the preparation method of the herbal extract includes the following steps: mixing Phellodendron bark, Astragalus root, and Rhubarb in a weight ratio of 1:1:1 to obtain a mixture; adding water equivalent to 10 times the weight of the mixture, decocting and extracting for 2 hours, filtering, and collecting the filtrate; adding water equivalent to 8 times the weight of the mixture to the filter residue, decocting and extracting again for 1.5 hours, filtering, and collecting the filtrate; combining the two filtrates, concentrating under reduced pressure, and spray drying to obtain the herbal extract.

[0035] Example 1 This embodiment provides a growth promoter for bighead carp farming in reservoirs, comprising the following raw materials by weight: 48 kg corn starch residue, 3 kg distiller's grains, 20 kg sugarcane bagasse, 5 kg cerium oxide, 8 kg lanthanum oxide, 0.2 kg Chinese herbal medicine extract, 0.015 kg brewer's yeast, 0.02 kg Bifidobacterium animalis, 0.03 kg Clostridium butyricum, 0.5 kg acidic protease, 0.8 kg ferrous sulfate, 0.2 kg magnesium sulfate, 0.1 kg zinc sulfate, 0.08 kg copper sulfate, 2 kg citric acid, 4 kg sodium alginate, 0.8 kg calcium chloride, 18 kg silicon dioxide, and 2.5 kg calcium carbonate.

[0036] This embodiment also provides a method for preparing the above-mentioned growth promoter for bighead carp farming in reservoirs, including the following steps: Cerium oxide, lanthanum oxide and citric acid were mixed, 75 kg of water was added, and the mixture was stirred at 70 °C for 2 h to obtain a complex solution.

[0037] Corn starch residue, distiller's grains, and sugarcane bagasse were crushed and passed through a 40-mesh sieve. After mixing, a complex solution, herbal extracts, ferrous sulfate, magnesium sulfate, zinc sulfate, copper sulfate, acidic protease, silicon dioxide, and calcium carbonate (2 kg) were added. Water was added to adjust the moisture content to 42 wt%, and the mixture was stirred evenly to obtain the fermentation base.

[0038] Saccharomyces cerevisiae was added to the fermentation substrate, and the temperature was controlled at 29℃ with an aeration rate of 0.8 vvm for 48 hours of aerobic fermentation, during which the substrate was turned over every 12 hours. Then, Bifidobacterium animalis was added, the material was compacted, aeration was stopped, and the temperature was controlled at 31℃ for 72 hours of facultative anaerobic fermentation. Finally, Clostridium butyricum was added, nitrogen was introduced to replace the air, the mixture was sealed, and the temperature was controlled at 36℃ for 72 hours of strictly anaerobic fermentation. Throughout the fermentation process, the pH was monitored in real time using a built-in pH electrode. When the pH fell below 4.5, 0.5 kg of reserved calcium carbonate was added to adjust the pH to 5.0.

[0039] The fermentation product was vacuum dried at 47℃ to a moisture content of 7wt%, then pulverized through an 80-mesh sieve to obtain the core powder. A 2% sodium alginate solution and a 0.5% calcium chloride solution were prepared. Using a fluidized bed granulator, the core powder was placed in the fluidized bed while simultaneously spraying the sodium alginate and calcium chloride solutions. The inlet air temperature was set to 65℃ and the outlet air temperature to 42℃, producing granules with a particle size of 0.5-2mm, which are then used as a growth promoter for bighead carp farming in reservoirs.

[0040] Example 2 This embodiment provides a growth promoter for bighead carp farming in reservoirs, comprising the following raw materials by weight: 45kg corn starch residue, 2kg distiller's grains, 22kg sugarcane bagasse, 4kg cerium oxide, 7kg lanthanum oxide, 0.1kg traditional Chinese medicine extract, 0.01kg brewer's yeast, 0.015kg Bifidobacterium animalis, 0.025kg Clostridium butyricum, 0.4kg acidic protease, 0.7kg ferrous sulfate, 0.15kg magnesium sulfate, 0.08kg zinc sulfate, 0.06kg copper sulfate, 1.5kg citric acid, 3kg sodium alginate, 0.6kg calcium chloride, 16kg silicon dioxide, and 2kg calcium carbonate.

[0041] This embodiment also provides a method for preparing the above-mentioned growth promoter for bighead carp farming in reservoirs, including the following steps: Cerium oxide, lanthanum oxide and citric acid were mixed, 73 kg of water was added, and the mixture was stirred at 65 °C for 2.5 h to obtain a complex solution.

[0042] Corn starch residue, distiller's grains, and sugarcane bagasse were crushed and passed through a 40-mesh sieve. After mixing, a complex solution, herbal extracts, ferrous sulfate, magnesium sulfate, zinc sulfate, copper sulfate, acidic protease, silicon dioxide, and calcium carbonate (2 kg) were added. Water was added to adjust the moisture content to 42 wt%, and the mixture was stirred evenly to obtain the fermentation base.

[0043] Saccharomyces cerevisiae was added to the fermentation substrate, and the temperature was controlled at 28℃ with an aeration rate of 0.7 vvm for 49 hours of aerobic fermentation, during which the substrate was stirred every 12 hours. Then, Bifidobacterium animalis was added, the material was compacted, aeration was stopped, and the temperature was controlled at 30℃ for 73 hours of facultative anaerobic fermentation. Finally, Clostridium butyricum was added, nitrogen was introduced to replace the air, the mixture was sealed, and the temperature was controlled at 35℃ for 73 hours of strictly anaerobic fermentation. Throughout the fermentation process, the pH was monitored in real time using an internal pH electrode, and the pH remained between 4.8 and 6.0, eliminating the need for calcium carbonate supplementation.

[0044] The fermentation product was vacuum dried at 48℃ to a moisture content of 6.5wt%, then pulverized through an 80-mesh sieve to obtain the core powder. A 1.8% sodium alginate solution and a 0.3% calcium chloride solution were prepared. Using a fluidized bed granulator, the core powder was placed in the fluidized bed while the sodium alginate and calcium chloride solutions were sprayed simultaneously. The inlet air temperature was set to 70℃ and the outlet air temperature to 43℃, producing granules with a particle size of 0.5-2mm, which are then used as a growth promoter for bighead carp farming in reservoirs.

[0045] Example 3 This embodiment provides a growth promoter for bighead carp farming in reservoirs, comprising the following raw materials by weight: 50kg corn starch residue, 4kg distiller's grains, 18kg sugarcane bagasse, 6kg cerium oxide, 9kg lanthanum oxide, 0.3kg traditional Chinese medicine extract, 0.02kg brewer's yeast, 0.025kg Bifidobacterium animalis, 0.035kg Clostridium butyricum, 0.6kg acidic protease, 0.9kg ferrous sulfate, 0.25kg magnesium sulfate, 0.12kg zinc sulfate, 0.09kg copper sulfate, 1kg citric acid, 5kg sodium alginate, 1kg calcium chloride, 20kg silicon dioxide, and 3kg calcium carbonate.

[0046] This embodiment also provides a method for preparing the above-mentioned growth promoter for bighead carp farming in reservoirs, including the following steps: Cerium oxide, lanthanum oxide and citric acid were mixed, 77 kg of water was added, and the mixture was stirred at 60 °C for 3 h to obtain a complex solution.

[0047] Corn starch residue, distiller's grains, and sugarcane bagasse were pulverized and passed through a 40-mesh sieve. After mixing, a complex solution, herbal extracts, ferrous sulfate, magnesium sulfate, zinc sulfate, copper sulfate, acidic protease, silicon dioxide, and calcium carbonate (2.4 kg) were added. Water was added to adjust the moisture content to 45 wt%, and the mixture was stirred evenly to obtain the fermentation base.

[0048] Saccharomyces cerevisiae was added to the fermentation substrate, and the temperature was controlled at 30℃ with an aeration rate of 0.9 vvm for 47 hours of aerobic fermentation, during which the substrate was stirred every 12 hours. Then, Bifidobacterium animalis was added, the material was compacted, aeration was stopped, and the temperature was controlled at 32℃ for 71 hours of facultative anaerobic fermentation. Finally, Clostridium butyricum was added, nitrogen was introduced to replace the air, the substrate was sealed, and the temperature was controlled at 37℃ for 71 hours of strictly anaerobic fermentation. Throughout the fermentation process, the pH was monitored in real time using a built-in pH electrode. When the pH fell below 4.5, reserved calcium carbonate was added to adjust it to 5.0 (0.6 kg added).

[0049] The fermentation product was vacuum dried at 50℃ to a moisture content of 8wt%, then pulverized through a 70-mesh sieve to obtain the core powder. A 2.5% sodium alginate solution and a 0.7% calcium chloride solution were prepared. Using a fluidized bed granulator, the core powder was placed in the fluidized bed while simultaneously spraying the sodium alginate and calcium chloride solutions. The inlet air temperature was set to 60℃ and the outlet air temperature to 40℃, producing granules with a particle size of 0.5-2mm, which are then used as a growth promoter for bighead carp farming in reservoirs.

[0050] Comparative Example 1 The only difference between this comparative example and Example 1 is that citric acid is omitted, the complex solution is not prepared, and cerium oxide and lanthanum oxide are directly added to the fermentation substrate system. Specifically, the preparation method of the fermentation substrate is as follows: The corn starch residue, distiller's grains, and sugarcane bagasse were crushed and passed through a 40-mesh sieve. After mixing, cerium oxide, lanthanum oxide, traditional Chinese medicine extract, ferrous sulfate, magnesium sulfate, zinc sulfate, copper sulfate, acidic protease, silicon dioxide, and calcium carbonate (2 kg) were added. Water was added to adjust the moisture content to 42 wt%, and the mixture was stirred evenly to obtain the fermentation base.

[0051] The remaining raw materials and steps are exactly the same as in Example 1.

[0052] Comparative Example 2 The only difference between this comparative example and Example 1 is that the addition and use of calcium carbonate are omitted.

[0053] Comparative Example 3 The only difference between this comparative example and Example 1 is that the addition and use of sodium alginate and calcium chloride are omitted, and the core powder in Example 1 is used as the final product.

[0054] Experimental Example 1 Experimental Location: Seven bays with similar conditions within a large reservoir were selected as the experimental area. Each bay covered an area of ​​50 mu (approximately 3.3 hectares) with an average water depth of 5 meters. Isolation facilities were installed between the bays to prevent water exchange from interfering with the experimental results.

[0055] Experimental groups: Experimental group 1: Applying the growth promoter for bighead carp farming in reservoirs obtained in Example 1; Experimental group 2: Applying the growth promoter for bighead carp farming in reservoirs obtained in Example 2; Experimental group 3: Applying the growth promoter for bighead carp farming in reservoirs obtained in Example 3; Control group 1: Applying the growth promoter for bighead carp farming in reservoirs obtained in Comparative Example 1; Control group 2: Applying the growth promoter for bighead carp farming in reservoirs obtained in Comparative Example 2; Control group 3: Applying the growth promoter for bighead carp farming in reservoirs obtained in Comparative Example 3; Blank group: No product applied.

[0056] Stocking density: Silver carp fry were stocked at the same density in each bay: 100 fish / acre. The fish sizes were basically uniform, with initial weight of approximately 0.5 kg / fish for silver carp. No artificial feed was provided during the experiment; the silver carp relied entirely on natural food in the water for growth.

[0057] Application method: For both experimental groups 1-3 and control groups 1-3, the product was applied at a dosage of 200 grams per mu (approximately 0.067 hectares) per meter of water depth, once every 15 days. Application was to be done on a sunny morning, evenly spreading the product at the upwind side of the reservoir, allowing the wind to disperse the particles throughout the entire reservoir. No product was applied to the control group.

[0058] Trial period: 4 months in total.

[0059] Monitoring indicators: Plankton indicators: Water samples were collected every 5 days to determine the density and species composition of phytoplankton (diatoms percentage) and the density and species composition of zooplankton (rotifers percentage). Growth indicators: At the end of the experiment, fish were harvested from each bay, and 50 silver carp were randomly selected for weighing and the average weight gain was calculated. Duration of fertilizer effect: Record the number of days after each application when the water transparency remains at 30-50cm and take the average value.

[0060] The test results are recorded in Table 1. Additionally, for a more intuitive comparison, a graph showing the average weight gain of silver carp in different groups is drawn, as shown below. Figure 1 As shown.

[0061] Table 1 Test Results

[0062] from Figure 1 As shown in Table 1, the growth promoters prepared in Examples 1-3 of this invention are significantly superior to the control group and the blank group in terms of silver carp weight gain, phytoplankton density, diatom proportion, zooplankton density, rotifer proportion, and duration of fertilizer effect. Specifically, the average weight gain of silver carp in experimental group 1 reached 2.15 kg / fish, and the phytoplankton density reached 3.2 × 10⁻⁶ kg / fish. 7 The density of zooplankton reached 2.6 × 10⁶ cells / L, with diatoms accounting for as high as 62%. 3 With a concentration of [number] individuals / L and a rotifer content as high as 68%, the fertilizer effect lasted for up to 18 days. Zooplankton, as a direct natural food source for silver carp, showed a good consistency between its density and the weight gain of the silver carp, further validating the technical effectiveness of this product in promoting silver carp growth by optimizing the planktonic food chain structure. In contrast, Comparative Examples 1 and 2 showed significantly reduced weight gain and planktonic cultivation capacity, indicating that rare earth pre-complexation and pH control play a crucial role in product performance. The fertilizer effect of Comparative Example 3 lasted only 8 days, further validating the important role of the slow-release structure in prolonging the fertilizer effect and reducing the application rate.

[0063] In summary, this invention achieves efficient utilization of rare earth elements, enrichment of fermentation products, and slow release of nutrients through citric acid pre-complexation, step-by-step fermentation combined with pH control, and microencapsulation of calcium alginate, thereby effectively promoting the rapid growth of silver carp.

[0064] Finally, it should be noted that the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A growth promoter for use in reservoir aquaculture of bighead carp, characterized in that, The raw materials include the following parts by weight: 45-50 parts corn starch residue, 2-4 parts distiller's grains, 18-22 parts sugarcane bagasse, 4-6 parts cerium oxide, 7-9 parts lanthanum oxide, 0.1-0.3 parts traditional Chinese medicine extract, 0.01-0.02 parts brewer's yeast, 0.015-0.025 parts Bifidobacterium animalis, 0.025-0.035 parts Clostridium butyricum, 0.4-0.6 parts acidic protease, 0.7-0.9 parts ferrous sulfate, 0.15-0.25 parts magnesium sulfate, 0.08-0.12 parts zinc sulfate, 0.06-0.09 parts copper sulfate, 1-2 parts citric acid, 3-5 parts sodium alginate, 0.5-1 part calcium chloride, 15-20 parts silicon dioxide, and 2-3 parts calcium carbonate.

2. The growth promoter for bighead carp farming in reservoirs according to claim 1, characterized in that, The herbal extracts include Phellodendron bark extract, Astragalus membranaceus extract, and Rheum palmatum extract.

3. The growth promoter for bighead carp farming in reservoirs according to claim 1, characterized in that, The growth promoter has a particle size of 0.5-2 mm.

4. The method for preparing the growth promoter for bighead carp culture in reservoirs according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Cerium oxide, lanthanum oxide, citric acid and water are mixed and reacted to obtain a complex solution; S2. Mix corn starch residue, distiller's grains, sugarcane bagasse, complex solution, traditional Chinese medicine extract, ferrous sulfate, magnesium sulfate, zinc sulfate, copper sulfate, acidic protease, silicon dioxide, calcium carbonate and water to obtain fermentation substrate; S3. Inoculate the fermentation substrate with brewer's yeast for the first fermentation, then inoculate with Bifidobacterium animalis for the second fermentation, and finally inoculate with Clostridium butyricum for the third fermentation to obtain the fermentation product; the pH of the first, second, and third fermentations is controlled between 4.8 and 6.

0. S4. Mix the fermentation product, sodium alginate solution and calcium chloride solution, and granulate to obtain the growth promoter for bighead carp farming in reservoirs.

5. The preparation method according to claim 4, characterized in that, In S1, the reaction temperature is 60-70℃ and the time is 2-3h.

6. The preparation method according to claim 4, characterized in that, In S3, the temperature of the first fermentation is 28-30℃ and the time is 47-49h; the temperature of the second fermentation is 30-32℃ and the time is 71-73h; and the temperature of the third fermentation is 35-37℃ and the time is 71-73h.

7. The preparation method according to claim 4, characterized in that, In S4, the sodium alginate solution has a mass fraction of 1.5-2.5%, and the calcium chloride solution has a mass fraction of 0.3-0.7%.

8. The preparation method according to claim 4, characterized in that, In S4, the granulation method is spray granulation, and the inlet air temperature of spray granulation is 60-70℃, and the outlet air temperature is 40-45℃.

9. The application of the growth promoter for bighead carp farming in reservoirs as described in any one of claims 1-3, or the growth promoter for bighead carp farming prepared by the preparation method according to any one of claims 4-8, in the farming of silver carp in large reservoirs.

10. The application according to claim 9, characterized in that, The dosage of the fertilizer growth agent is 150-250 grams per meter of water depth, with an application interval of 15-20 days.

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