Fish feed compound additive based on L-dopamine as well as preparation method and application of fish feed compound additive

Abstract

The invention provides a fish feed compound additive based on L-dopamine as well as a preparation method and application thereof, and relates to the technical field of aquaculture, the fish feed compound additive comprises the following components: 0.01-0.05 part of L-dopamine, 45-70 parts of broad bean extract, 10-25 parts of amino acid compound, 2-5 parts of bile acid, 10-20 parts of L-carnitine, 5-10 parts of Chinese herbal medicine composition and 3-8 parts of compound emulsifier. Through the neuroendocrine regulation and control effect of L-dopamine, the L-dopamine, the broad bean extract, the amino acid compound, the bile acid, the Chinese herbal medicine composition, the compound emulsifier and other components generate multiple synergistic effects, and multi-channel precise regulation and control of the tilapia mossambica muscle texture are achieved.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, and in particular to a compound fish feed additive based on L-dopamine, its preparation method, and its application. Background Technology

[0002] Tilapia, a globally important aquaculture species, is highly sought after due to its rapid growth and strong adaptability. However, ordinary tilapia has relatively soft flesh and a less than ideal taste, limiting its market value. To improve the quality of tilapia flesh, the cultivation of crispy-fleshed tilapia has become a research hotspot. Crispy-fleshed tilapia refers to tilapia whose muscle tissue is made firmer, more elastic, and chewier through special breeding techniques; its market value is 30%-50% higher than that of ordinary tilapia.

[0003] Currently, tilapia crisping farming mainly uses the method of feeding broad beans. Broad beans contain special components that can alter the muscle tissue structure of fish, increasing muscle firmness and chewiness. For example, patent CN113729128B discloses a feed additive that promotes tilapia meat crisping, whose main components are broad bean water extract and amino acid complex. Compared with feeding only broad beans, it can increase the growth rate of tilapia. However, this method has significant drawbacks: the crisping period is long (usually requiring more than 60 days), the meat quality is uneven, and long-term feeding of broad beans can lead to growth inhibition and increased liver burden in tilapia.

[0004] Another existing technology, CN107981103A, describes a functional additive for tilapia containing traditional Chinese medicinal herbs such as astragalus, eucommia, sea buckthorn, and honeysuckle. This additive improves the disease resistance and survival rate of tilapia and enhances the flavor of the meat. However, its direct effect on muscle crispness is limited, and it does not address the neuroendocrine regulatory mechanism.

[0005] Studies have shown that the formation and regulation of fish muscle texture involves complex physiological and biochemical processes, including muscle fiber type transformation, collagen deposition, and energy metabolism regulation. Traditional crisping methods mainly rely on unknown components in broad beans, which have a single effect and lack systematic regulation. In addition, current technologies do not pay enough attention to the stress response and health maintenance of fish during the crisping process, often leading to increased mortality during crisping.

[0006] Therefore, the market urgently needs a new technological solution that can quickly, efficiently, and safely improve the crispness of tilapia meat without affecting or even promoting its growth and health. Summary of the Invention

[0007] The purpose of this invention is to provide a fish feed compound additive based on L-dopamine, its preparation method and application. This invention introduces L-dopamine into the field of aquatic feed for the first time. Through its neuroendocrine regulatory effect, it produces multiple synergistic effects with components such as broad bean extract, amino acid complex, bile acid, traditional Chinese medicine composition and compound emulsifier, thereby achieving multi-pathway precise regulation of tilapia muscle texture.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: The present invention provides a fish feed compound additive based on L-dopamine, which comprises the following components by mass parts: 0.01-0.05 parts of L-dopamine, 45-70 parts of broad bean extract, 10-25 parts of amino acid complex, 2-5 parts of bile acid, 10-20 parts of L-carnitine, 5-10 parts of traditional Chinese medicine composition, and 3-8 parts of compound emulsifier.

[0009] Furthermore, based on the above technical solution, the composite emulsifier includes modified phospholipids and bile salts in a mass ratio of (2-4):1.

[0010] Furthermore, based on the above technical solution, the modified phospholipid is soybean lecithin treated with a pulsed electric field; And / or, the bile salts include glycocholate and taurocholate in a mass ratio of 2-3:1.

[0011] Furthermore, based on the above technical solution, the preparation method of the modified phospholipid includes the following steps: Soybean lecithin was dissolved in water to obtain a soybean lecithin solution. The soybean lecithin solution was preheated and then placed in a pulsed electric field for treatment to obtain modified phospholipids. The soybean lecithin solution has a mass percentage concentration of 2-5%. The preheating temperature is 70-80℃; And / or, the conditions for the pulsed electric field include: pulse intensity 10-30 kV / cm, pulse processing time 100-500 μs, and pulse frequency 300-350 Hz; And / or, the glycinecholate is sodium glycinecholate; And / or, the taurocholate salt is sodium taurocholate.

[0012] Furthermore, based on the above technical solution, the amino acid complex comprises lysine, methionine, and tryptophan in a mass ratio of (4-6):(2-4):(1-3); And / or, the herbal composition comprises Astragalus membranaceus, Eucommia ulmoides, Hippophae rhamnoides and Lonicera japonica in a mass ratio of (2-4):(1-3):(1-3):1.

[0013] The present invention also provides a method for preparing the L-dopamine-based fish feed compound additive as described above, comprising the following steps: S1: The broad bean extract, amino acid complex, L-carnitine and traditional Chinese medicine composition are pulverized and mixed to obtain a mixed powder; S2: Dissolve L-dopamine in water to obtain an L-dopamine solution, then add bile acids and a compound emulsifier and mix to obtain a pre-emulsion; S3: Place the mixed powder in a mixer, mix it, then spray the pre-emulsion onto the flowing powder, continue mixing, and dry to obtain the composite additive.

[0014] Furthermore, based on the above technical solution, in step S1, the average particle size of the mixed powder is ≤50μm; And / or, in step S2, L-dopamine is dissolved in water at 35-40°C; And / or, the mass percentage concentration of the L-dopamine solution is 0.3-0.5%; And / or, in step S2, the mixing is performed using a high-speed shear emulsifier, shearing and stirring at a speed of 4000-5000 rpm for 3-5 minutes.

[0015] Furthermore, based on the above technical solution, in step S3, the mixer speed is 15-25 rpm, the spraying time of the pre-emulsion is 10-15 min, then the spray gun is turned off, and mixing continues for 15-20 min, with a total mixing time of not less than 25 min; And / or, in step S3, the drying is performed at 40-45°C and a vacuum of -0.08 to -0.05 MPa for 12-24 hours.

[0016] The present invention also provides an application of the L-dopamine-based fish feed compound additive as described above, or the L-dopamine-based fish feed compound additive prepared by the preparation method described above, wherein the L-dopamine-based fish feed compound additive is used in the preparation of fish feed.

[0017] Furthermore, based on the above technical solution, the amount of the L-dopamine-based fish feed compound additive added is 1-5% of the total mass of the fish feed.

[0018] This invention provides a fish feed compound additive based on L-dopamine, its preparation method, and its application, with the following beneficial effects: This invention introduces L-dopamine as the core signal for neuroendocrine regulation, and, in conjunction with key components such as broad bean extract, bile acids, and a complex emulsifier, constructs a highly efficient multi-target muscle texture regulation system. Specifically, L-dopamine precisely activates the hypothalamus-pituitary-growth axis, guiding the targeted distribution of nutrients to muscle tissue; the active ingredients in broad bean extract directly act on muscle fibers, promoting myofibril proliferation and collagen cross-linking; while the stable emulsification system formed by bile acids and the complex emulsifier significantly improves the bioavailability of lipid-soluble active ingredients such as L-dopamine, and optimizes lipid metabolism by activating farnesol X receptors (FXR). Each component has a clear function and works synergistically to jointly drive muscle fiber structural remodeling and improve muscle quality, thereby significantly shortening the traditional brittleness cycle of over 60 days to 30 days. This greatly improves brittleness efficiency and product uniformity while ensuring the health of the fish. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0020] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0021] According to a first aspect of the present invention, a fish feed compound additive based on L-dopamine is provided, comprising, by weight parts: 0.01-0.05 parts of L-dopamine (e.g., 0.02 parts, 0.03 parts, 0.04 parts, etc.), 45-70 parts of broad bean extract (e.g., 50 parts, 55 parts, 60 parts, 65 parts, 67 parts, etc.), 10-25 parts of amino acid complex (e.g., 15 parts, 17 parts, 20 parts, 23 parts, etc.), 2-5 parts of bile acid (e.g., 3 parts, 4 parts, etc.), 10-20 parts of L-carnitine (e.g., 12 parts, 14 parts, 16 parts, 18 parts, etc.), 5-10 parts of traditional Chinese medicine composition (e.g., 6 parts, 7 parts, 8 parts, 9 parts, etc.), and 3-8 parts of compound emulsifier (e.g., 4 parts, 5 parts, 6 parts, 7 parts, etc.).

[0022] Specifically, L-dopamine, as a neurotransmitter precursor, can cross the blood-brain barrier and enter the central nervous system of tilapia, where it is converted into dopamine by dopa decarboxylase. Dopamine binds to D1 and D2 receptors, activating the hypothalamus-pituitary-growth axis and promoting growth hormone secretion. Simultaneously, the dopaminergic system regulates feeding behavior and energy allocation, promoting the targeted deposition of nutrients into muscle tissue, and accelerating the breakdown of muscle glycogen and energy supply, providing the impetus for rapid muscle metabolism and remodeling. This invention has discovered that extremely low doses (0.01-0.05 parts) of L-dopamine can activate tilapia muscle-specific growth pathways without causing neurotoxicity. This dose is far below the pharmacological dose for mammals, ensuring feeding safety. Compared to traditional crisping methods, the introduction of L-dopamine can significantly improve the crisping efficiency of fish meat.

[0023] As an optional embodiment of the present invention, the preparation method of the broad bean extract includes the following steps: after the broad beans are crushed, water is added at a material-to-liquid ratio of 1:10, and the extract is soaked at 55°C for 2-3 hours. Then, a compound enzyme (cellulase and pectinase mixed at a ratio of 1:1) is added and enzymatically hydrolyzed at pH 5.5 and 45°C for 1-2 hours. Finally, the extract is separated by an ultrafiltration membrane (molecular weight cutoff of 5000 Da), the filtrate is collected and spray-dried.

[0024] Specifically, broad bean extract contains special protease inhibitors and phytohemagglutinins, which can mildly inhibit excessive protein degradation in the intestine and promote the overall absorption of oligopeptides. These components can also bind to specific receptors on the myofibril membrane, altering myofibril structure and promoting sarcomere proliferation and increased myofibril density. L-dopamine activates neuroendocrine pathways, creating a favorable physiological environment for the myofibril remodeling effect of broad bean extract; while broad bean extract provides the material basis for myofibril structural modification, and the two work synergistically to achieve dual regulation of "signal-structure".

[0025] Furthermore, L-carnitine is a key transporter in the β-oxidation process of fatty acids, functioning to transport long-chain fatty acids from outside the mitochondria to inside the mitochondria for oxidation and energy supply. L-carnitine ensures that fatty acids can be efficiently utilized under high metabolic conditions, providing sufficient and continuous energy for muscle fiber remodeling and contraction, avoiding muscle fatigue or degradation caused by energy shortage. In addition, L-carnitine promotes fat burning, resulting in a significant reduction in intramuscular fat in fish meat and a firmer texture.

[0026] As an optional embodiment of the present invention, the amino acid complex comprises lysine, methionine and tryptophan in a mass ratio of (4-6):(2-4):(1-3).

[0027] Specifically, lysine, as the main limiting amino acid for collagen synthesis, directly supports increased muscle fiber density and strengthened connective tissue due to its high proportion; methionine, as an initiating amino acid for protein synthesis and a precursor to glutathione, regulates protein metabolism and antioxidant processes; and tryptophan, by converting into serotonin, regulates feeding behavior and stress response, creating a stable physiological environment for muscle remodeling. Through the functional complementarity and metabolic synergy of these three amino acids, they jointly promote the targeted improvement of muscle texture towards firmness and resilience.

[0028] As an optional embodiment of the present invention, the herbal composition comprises Astragalus membranaceus, Eucommia ulmoides, Hippophae rhamnoides and Lonicera japonica in a mass ratio of (2-4):(1-3):(1-3):1.

[0029] Specifically, the polysaccharides, flavonoids, and glycosides in the traditional Chinese medicine composition (Astragalus membranaceus, Eucommia ulmoides, Hippophae rhamnoides, and Lonicera japonica) possess antioxidant, anti-stress, and immunomodulatory functions. These components can alleviate mild stress responses that may be caused by L-dopamine, maintain liver metabolic homeostasis, and provide a healthy physiological basis for efficient fragility. The traditional Chinese medicine composition alleviates stress responses that may be caused by L-dopamine, protects liver and gastrointestinal function, and provides a "shock-absorbing" effect for efficient fragility. It also plays a positive intervention and alleviating role against the risks of intestinal tissue fragility, intestinal mucosal damage, and enteritis that may occur during the fragility process, thereby comprehensively ensuring the physiological safety and body tolerance of the fragility process.

[0030] As an optional embodiment of the present invention, the composite emulsifier comprises modified phospholipids and bile salts in a mass ratio of (2-4):1 (e.g., 2.5:1, 3:1, 3.5:1, etc.).

[0031] Specifically, L-dopamine is a fat-soluble active ingredient. If the emulsion is unstable, the fat droplets will re-aggregate and enlarge, preventing the effective release of the encapsulated L-dopamine and its absorption by intestinal cells. Therefore, ensuring a stable emulsion system can promote the absorption of L-dopamine. This invention utilizes the synergistic effect of bile acids and a complex emulsifier to ensure the long-term physical stability of the emulsion system. Once in the intestines, bile acids, as potent ionic surfactants, rapidly adsorb onto the interface between large fat droplets and lipid-soluble active ingredients (such as L-dopamine and lipid-soluble components in broad bean extract) in the feed. Leveraging their strong interfacial activity, they drastically reduce the oil-water interfacial tension, breaking down large oil droplets into numerous, smaller micron-sized droplets. Further, modified phospholipids (possessing excellent emulsifying stability) and bile salts from the emulsifier begin to migrate to the interface. Modified phospholipid molecules and bile acid molecules co-align at the droplet interface, forming a dense, stable, and bioactive composite interfacial film. This effectively prevents the droplets from re-aggregating due to collisions during intestinal peristalsis, ensuring the long-term physical stability of the emulsion system.

[0032] Furthermore, bile acids and compound emulsifiers can synergistically promote digestion, absorption, and metabolic activation: the mixed micelles formed by bile acids and compound emulsifiers have a more complete structure and larger capacity, enabling them to more efficiently transport lipid-soluble active ingredients across the "water layer" covering the surface of the emulsion droplets, directly reaching the brush membrane of intestinal epithelial cells, significantly improving the bioavailability of components such as L-dopamine; in addition, bile acids themselves are natural ligands of farnesol X receptors (FXR). Appropriate amounts of bile acids can activate the FXR signaling pathway in the fish gut, helping to regulate lipid metabolism homeostasis and promoting the allocation of nutrients to muscle tissue rather than their accumulation in the viscera, which aligns with the nutritional goals of crispy tilapia.

[0033] Furthermore, if there is too little bile acid (<2 parts) or too much compound emulsifier (>8 parts), the dispersion of fats and fat-soluble components will be poor, making it difficult to form an ideal microemulsion system even with a large amount of compound emulsifier. If there is too much bile acid (>5 parts) or too little compound emulsifier (<3 parts), the excess bile acid will competitively occupy the interface, crowding out modified phospholipids, resulting in a less dense interfacial film with poor mechanical strength. The emulsion droplets are prone to rupture and aggregate in the intestinal environment, which in turn reduces absorption efficiency.

[0034] As an optional embodiment of the present invention, the modified phospholipid is soybean lecithin treated with a pulsed electric field. By treating soybean lecithin with a pulsed electric field, its molecular spatial conformation is changed and its particle size is reduced, so as to enhance its synergistic effect with proteins and improve the stability of the emulsion system.

[0035] As an optional embodiment of the present invention, the preparation method of the modified phospholipid includes the following steps: Soybean lecithin was dissolved in water to obtain a soybean lecithin solution. The soybean lecithin solution was preheated and then placed in a pulsed electric field for treatment to obtain modified phospholipids. The soybean lecithin solution has a mass percentage concentration of 2-5%. The preheating temperature is 70-80℃; The conditions for the pulsed electric field include: pulse intensity 10-30 kV / cm, pulse processing time 100-500 μs, and pulse frequency 300-350 Hz.

[0036] As an optional embodiment of the present invention, the bile salts include glycinecholate and taurocholate in a mass ratio of 2-3:1 (e.g., 2.2:1, 2.5:1, 2.7:1, etc.). Glycinecholate has slightly stronger hydrophilicity and can be adsorbed onto the oil-water interface more quickly, reducing interfacial tension and initiating initial emulsification. The emulsion film formed by taurocholate has higher stability and can better resist external disturbances. The two work together to achieve a seamless transition from "rapid demulsification" to "long-term stability".

[0037] The glycinecholate salt is sodium glycinecholate (manufacturer: Beyotime Biotechnology, model number Y026830-10mg). The taurocholate is sodium taurocholate (manufacturer: Shanghai Guyan, model: GOY-13236).

[0038] Specifically, modified phospholipids are excellent amphiphilic molecules, suitable for forming oil-in-water (O / W) emulsions. They can form a dense, ordered liquid crystal film with high mechanical strength at the oil-water interface. This film, like the steel skeleton of a building, provides long-term physical stability and prevents emulsion droplets from re-aggregating. Furthermore, bile salts are potent ionic surfactants that rapidly reduce interfacial tension and quickly encapsulate lipid droplets during dynamic processes (such as when feed mixes with digestive fluids in the fish intestines), achieving initial emulsification. In addition, due to their small molecular size and charged nature, they can penetrate phospholipid membranes, increasing their fluidity and permeability.

[0039] Furthermore, when modified phospholipids and bile salts are mixed at a mass ratio of (2-4):1, the modified phospholipids and bile salts are arranged together at the oil-water interface, which can stably achieve rapid emulsification. If there is too little bile salt (e.g., ratio >4:1), the bile salts lack the ability to quickly penetrate and reduce interfacial tension, and the emulsion system forms more slowly. Although the stability is good, it may slightly affect the contact efficiency of lipase and the release and absorption of lipid digestion products in the intestinal environment. If there is too much bile salt (e.g., ratio <2:1), the excess bile salts will partially replace the modified phospholipids in the interfacial membrane. Since the monomolecular membrane formed by bile salts has low mechanical strength, the emulsion is more likely to break down and separate during storage or processing. Moreover, high concentrations of bile salts may irritate the intestinal mucosa of fish and increase the burden on the liver.

[0040] According to a second aspect of the present invention, a method for preparing the L-dopamine-based fish feed compound additive as described above is provided, comprising the following steps: S1: The broad bean extract, amino acid complex, L-carnitine and traditional Chinese medicine composition are pulverized and mixed to obtain a mixed powder; S2: Dissolve L-dopamine in water to obtain an L-dopamine solution, then add bile acids and a compound emulsifier and mix to obtain a pre-emulsion; S3: Place the mixed powder in a mixer, mix it, then spray the pre-emulsion onto the flowing powder, continue mixing, and dry to obtain the composite additive.

[0041] As an optional embodiment of the present invention, in step S1, the average particle size of the mixed powder is ≤50μm. By crushing the broad bean extract, amino acid complex, L-carnitine, and traditional Chinese medicine composition into particles with an average particle size of ≤50μm, the specific surface area of ​​the material is increased, which helps the active ingredients to dissolve and come into contact more quickly and fully in the animal digestive tract, thereby significantly improving bioavailability.

[0042] As an optional embodiment of the present invention, in step S2, L-dopamine is dissolved in water at 35-40°C; The mass percentage concentration of the L-dopamine solution is 0.3-0.5% (e.g., 0.35%, 0.4%, 0.45%, etc.). In step S2, the mixing is performed using a high-speed shear emulsifier, which shears and stirs at a speed of 4000-5000 rpm for 3-5 minutes to form a uniform and stable milky white pre-emulsion.

[0043] Specifically, warm water can accelerate the dissolution of L-dopamine, preventing it from clumping due to static electricity during subsequent solid mixing. It first forms a liquid phase system, which can fully disperse and encapsulate trace amounts of L-dopamine molecules in micelles formed by bile acids and composite emulsifiers. This not only improves the uniform dispersion of trace amounts of L-dopamine but also provides initial protection for L-dopamine through emulsification.

[0044] As an optional embodiment of the present invention, in step S3, the mixer speed is 15-25 rpm, the spraying time of the pre-emulsion is 10-15 min, then the spray gun is turned off, and mixing continues for 15-20 min, with a total mixing time of not less than 25 min; In step S3, the drying is carried out at 40-45℃ and a vacuum of -0.08 to -0.05 MPa for 12-24 hours.

[0045] According to a third aspect of the present invention, an application of the L-dopamine-based fish feed compound additive as described above is provided, wherein the L-dopamine-based fish feed compound additive is used in the preparation of fish feed.

[0046] As an optional embodiment of the present invention, the amount of the L-dopamine-based fish feed compound additive added is 1-5% of the total mass of the fish feed.

[0047] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0048] Example 1

[0049] This embodiment provides a fish feed compound additive based on L-dopamine, which includes the following components by mass: 0.03 parts of L-dopamine (manufacturer: Xinfan Biotechnology, model: L-DOPA), 60 parts of broad bean extract, 18 parts of amino acid complex, 3 parts of bile acid, 15 parts of L-carnitine, 8 parts of traditional Chinese medicine composition, and 6 parts of compound emulsifier.

[0050] The preparation method of the broad bean extract includes the following steps: after the broad beans are crushed, water is added at a material-to-liquid ratio of 1:10, and the mixture is extracted at 55°C for 2.5 hours. Then, a compound enzyme (cellulase and pectinase mixed at a ratio of 1:1) is added and the mixture is enzymatically hydrolyzed at pH 5.5 and 45°C for 1.5 hours. Finally, the mixture is separated by an ultrafiltration membrane (molecular weight cutoff of 5000 Da), the filtrate is collected and spray-dried to obtain the broad bean extract.

[0051] The method for preparing the modified phospholipid includes the following steps: dissolving soybean lecithin in water to obtain a soybean lecithin solution with a mass percentage concentration of 5%; preheating the soybean lecithin solution at 80°C and then treating it in a pulsed electric field to obtain the modified phospholipid. The conditions for the pulsed electric field include: pulse intensity 20 kV / cm, pulse processing time 400 μs, and pulse frequency 350 Hz.

[0052] The composite emulsifier comprises modified phospholipids and bile salts (sodium glycocholate and sodium taurocholate in a mass ratio of 3:1) in a mass ratio of 3:1.

[0053] The amino acid complex comprises lysine, methionine, and tryptophan in a mass ratio of 5:3:2. The herbal composition comprises Astragalus membranaceus, Eucommia ulmoides, Hippophae rhamnoides, and Lonicera japonica in a mass ratio of 3:2:2:1.

[0054] This embodiment provides a method for preparing the L-dopamine-based fish feed compound additive as described above, comprising the following steps: S1: Pulverize the broad bean extract, amino acid complex, L-carnitine and traditional Chinese medicine composition to an average particle size ≤50μm, mix well, and obtain a mixed powder (average particle size ≤50μm). S2: Dissolve L-dopamine in water at 40°C to obtain an L-dopamine solution with a mass percentage concentration of 0.5%. Then add bile acids and a composite emulsifier. Use a high-speed shear emulsifier to shear and stir at 4000 rpm for 5 minutes to obtain a pre-emulsion. S3: Place the mixed powder in a mixer and mix at a speed of 20 rpm for 5 minutes. Then spray the pre-emulsion onto the flowing powder for 13 minutes. Continue mixing at 20 rpm for 20 minutes. Dry at 40℃ and -0.08MPa vacuum for 24 hours to obtain the composite additive.

[0055] Example 2

[0056] The main difference between this embodiment and Example 1 is that the L-dopamine-based fish feed compound additive provided in this embodiment includes the following components by mass parts: 0.05 parts of L-dopamine, 70 parts of broad bean extract, 25 parts of amino acid complex, 5 parts of bile acid, 20 parts of L-carnitine, 10 parts of traditional Chinese medicine composition, and 8 parts of compound emulsifier. The composite emulsifier comprises modified phospholipids and bile salts (sodium glycocholate and sodium taurocholate in a mass ratio of 2:1) in a mass ratio of 3:1.

[0057] The remaining steps and technical parameters are the same as in Example 1.

[0058] Example 3

[0059] The main difference between this embodiment and Example 1 is that the L-dopamine-based fish feed compound additive provided in this embodiment includes the following components by mass parts: 0.01 parts of L-dopamine, 45 parts of broad bean extract, 10 parts of amino acid complex, 2 parts of bile acid, 10 parts of L-carnitine, 5 parts of traditional Chinese medicine composition, and 3 parts of compound emulsifier. The composite emulsifier comprises modified phospholipids and bile salts (sodium glycocholate and sodium taurocholate in a mass ratio of 4:1) in a mass ratio of 3:1.

[0060] The remaining steps and technical parameters are the same as in Example 1.

[0061] Comparative Example 1 The main difference between this comparative example and Example 1 is that L-dopamine is not added in this comparative example, while the remaining steps and technical parameters are the same as in Example 1.

[0062] Comparative Example 2 The main difference between this comparative example and Example 1 is that no composite emulsifier is added in this comparative example, while the remaining steps and technical parameters are the same as in Example 1.

[0063] Comparative Example 3 The main difference between this comparative example and Example 1 is that bile acids are not added in this comparative example, while the remaining steps and technical parameters are the same as in Example 1.

[0064] Comparative Example 4 The main difference between this comparative example and Example 1 is that the mass fraction of the composite emulsifier is 2 parts, while the remaining steps and technical parameters are the same as in Example 1.

[0065] Comparative Example 5 The main difference between this comparative example and Example 1 is that the mass fraction of bile acids is 1 part, while the remaining steps and technical parameters are the same as in Example 1.

[0066] Performance testing The compound additives obtained in Examples 1-3 and Comparative Examples 1-5 were added to the tilapia basal feed (the basal feed included 100g fish meal, 200g soybean meal, 120g rapeseed meal, 80g cottonseed meal, 120g wheat middlings, 80g rice bran, 60g extruded soybean meal, 30g peanut meal, 50g germ meal, 20g soybean oil and 20g calcium dihydrogen phosphate). The amount of compound additive added was 3% of the weight of the basal feed. A total of 8 groups of experimental feeds were obtained in Examples 1-3 and Comparative Examples 1-5. At the start of the experiment, healthy tilapia of uniform size (50±3g) were randomly grouped and stocked in nine fiberglass tanks (water volume: 1000L) in an indoor recirculating aquaculture system at a stocking density of 100 fish / tank. The nine tanks were fed with experimental feeds (Examples 1-3), comparative examples 1-5, and a basal feed (without compound additives, i.e., the blank group), respectively. Fish were fed twice daily (once at 08:00 AM and once at 18:00 PM), with the same total feed weight added to each tank daily. Aerated tap water was used for the experiment. One-fifth of the total water volume was replaced daily in each fiberglass tank. The water temperature was 25-30℃, and the pH was 6-7.6. One hour before each feeding, feces were siphoned off from the bottom of the tanks. The experiment lasted 30 days. The results were averaged and are shown in Table 1.

[0067] Test method: 1. Growth performance test: Weigh the animals at the beginning and end of the test and calculate the weight gain rate (WGR, %), specific growth rate (SGR, % / d) and feed conversion ratio (FCR). Specific growth rate (SGR, % / d) = (ln(total weight of fish in each bucket after 30 days) - ln(initial total weight of fish in each bucket before the experiment) / number of days of the experiment × 100%). The larger the SGR value, the faster the absolute growth rate of the fish, the higher the feed conversion rate, and the better the growth performance. Weight gain rate = (Total weight of fish in each bucket after 30 days - Initial total weight of fish in each bucket before the experiment) / Initial total weight of fish in each bucket before the experiment × 100%.

[0068] Survival rate = (Number of surviving fish / Initial total number of fish) × 100%.

[0069] 2. Collagen content in fish muscle: Hydroxyproline is a unique amino acid in collagen, which is present in very small amounts in other muscle proteins. Its content in collagen is relatively constant. Therefore, by measuring the content of hydroxyproline in muscle samples, the collagen content can be determined. For specific reference, refer to GB / T 9695.23-2008. In this invention, a hydroxyproline content of 0.4% or higher is considered as the standard for muscle fragility.

[0070] Results data Table 1

[0071] As shown in Table 1, compared with Example 1, Comparative Example 1 did not contain L-dopamine, resulting in a lower collagen content in the tilapia muscle after 30 days of feeding. This indicates that Comparative Example 1 could not effectively achieve muscle crisping in tilapia within 30 days.

[0072] As shown in Table 1, compared with Example 1, Comparative Example 2 did not contain a composite emulsifier. The monomolecular interfacial film formed by bile acids had poor stability and could not maintain the long-term stability of the emulsion system. As a result, the absorption of components such as L-dopamine and broad bean extract was poor, and the muscle crisping of tilapia could not be effectively achieved within 30 days.

[0073] As shown in Table 1, compared with Example 1, Comparative Example 3 did not contain bile acids, resulting in poor dispersion of components such as L-dopamine and broad bean extract, making it difficult to form an ideal microemulsion system. This further affected the absorption capacity of components such as L-dopamine and broad bean extract, and the muscle crisping of tilapia could not be effectively achieved within 30 days.

[0074] As shown in Table 1, compared with Example 1, Comparative Example 4 had a lower mass fraction of 2 parts of composite emulsifier. This resulted in excessive bile acids competitively occupying the interface and displacing the modified phospholipids, leading to an insufficiently dense interfacial film with poor mechanical strength. The emulsion droplets were prone to rupture and aggregation in the intestinal environment, which reduced the absorption efficiency of components such as L-dopamine and broad bean extract. Ultimately, the muscle crisping of tilapia could not be effectively achieved within 30 days.

[0075] As shown in Table 1, compared with Example 1, Comparative Example 5 had a lower concentration of bile acids (1 part by mass), resulting in poor dispersion of components such as L-dopamine and broad bean extract. Even with a relatively large amount of compound emulsifier, it was difficult to form an ideal microemulsion system, which further affected the absorption capacity of components such as L-dopamine and broad bean extract. Consequently, it was not possible to effectively achieve muscle crisping of tilapia within 30 days.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A compound additive for fish feed based on L-dopamine, characterized in that, By weight, it includes the following components: 0.01-0.05 parts L-dopamine, 45-70 parts broad bean extract, 10-25 parts amino acid complex, 2-5 parts bile acid, 10-20 parts L-carnitine, 5-10 parts traditional Chinese medicine composition, and 3-8 parts compound emulsifier.

2. The L-dopamine-based fish feed compound additive according to claim 1, characterized in that, The composite emulsifier comprises modified phospholipids and bile salts in a mass ratio of (2-4):

1.

3. The L-dopamine-based fish feed compound additive according to claim 2, characterized in that, The modified phospholipid is soybean lecithin treated with a pulsed electric field; And / or, the bile salts include glycocholate and taurocholate in a mass ratio of 2-3:

1.

4. The L-dopamine-based fish feed compound additive according to claim 3, characterized in that, The preparation method of the modified phospholipid includes the following steps: Soybean lecithin was dissolved in water to obtain a soybean lecithin solution. The soybean lecithin solution was preheated and then placed in a pulsed electric field for treatment to obtain modified phospholipids. The soybean lecithin solution has a mass percentage concentration of 2-5%. The preheating temperature is 70-80℃; And / or, the conditions for the pulsed electric field include: pulse intensity 10-30 kV / cm, pulse processing time 100-500 μs, and pulse frequency 300-350 Hz; And / or, the glycinecholate is sodium glycinecholate; And / or, the taurocholate salt is sodium taurocholate.

5. The L-dopamine-based fish feed compound additive according to claim 1, characterized in that, The amino acid complex comprises lysine, methionine, and tryptophan in a mass ratio of (4-6):(2-4):(1-3); And / or, the herbal composition comprises Astragalus membranaceus, Eucommia ulmoides, Hippophae rhamnoides and Lonicera japonica in a mass ratio of (2-4):(1-3):(1-3):

1.

6. A method for preparing an L-dopamine-based fish feed compound additive as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: The broad bean extract, amino acid complex, L-carnitine and traditional Chinese medicine composition are pulverized and mixed to obtain a mixed powder; S2: Dissolve L-dopamine in water to obtain an L-dopamine solution, then add bile acids and a compound emulsifier and mix to obtain a pre-emulsion; S3: Place the mixed powder in a mixer, mix it, then spray the pre-emulsion onto the flowing powder, continue mixing, and dry to obtain the composite additive.

7. The method for preparing the L-dopamine-based fish feed compound additive according to claim 6, characterized in that, In step S1, the average particle size of the mixed powder is ≤50μm; And / or, in step S2, L-dopamine is dissolved in water at 35-40°C; And / or, the mass percentage concentration of the L-dopamine solution is 0.3-0.5%; And / or, in step S2, the mixing is performed using a high-speed shear emulsifier, shearing and stirring at a speed of 4000-5000 rpm for 3-5 minutes.

8. The method for preparing the L-dopamine-based fish feed compound additive according to claim 6, characterized in that, In step S3, the mixer speed is 15-25 rpm, the spraying time of the pre-emulsion is 10-15 min, then the spray gun is turned off, and mixing continues for 15-20 min, with a total mixing time of not less than 25 min; And / or, in step S3, the drying is performed at 40-45°C and a vacuum of -0.08 to -0.05 MPa for 12-24 hours.

9. The application of an L-dopamine-based fish feed compound additive prepared by the preparation method of the L-dopamine-based fish feed compound additive as described in any one of claims 1-5 or as described in any one of claims 6-8, characterized in that, The L-dopamine-based fish feed compound additive is used in the preparation of fish feed.

10. The application according to claim 9, characterized in that, The amount of the L-dopamine-based fish feed compound additive added is 1-5% of the total mass of the fish feed.

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