A compounded feed for juvenile leopard grouper epinephelus maculatus and a preparation method thereof

Abstract

This invention discloses a compound feed for juvenile leopard-gill sea bass and its preparation method, belonging to the field of aquatic feed technology. It comprises the following components by weight percentage: 50-70% red fish meal, 3-10% wheat gluten, 10-20% wheat flour, 0.5-1.5% yeast, 1-5% fish oil, 1-5% soybean oil, 0.5-3% soybean lecithin, sea buckthorn flavonoids, and neutral protease, etc. This invention creatively combines neutral protease with sea buckthorn flavonoids, achieving a synergistic effect of promoting digestion and regulating physiological functions. The synergistic effect of these two components promotes rapid growth of the leopard-gill sea bass while effectively enhancing its overall health and stress resistance.

Description

Technical Field

[0001] This invention belongs to the field of aquatic feed technology, specifically a compound feed for juvenile leopard gill sea bass and its preparation method. Background Technology

[0002] Leopard grouper (Plectropomus leopardus), commonly known as the Eastern Star Grouper or Seven-Star Grouper, is an important economic species in my country's high-end aquaculture industry. Its meat is delicious and nutritious, and its bright red body color is highly sought after in the consumer market. With the continuous growth of market demand, the intensive farming scale of Eastern Star Grouper has been expanding, forming a complete industrial chain and becoming one of the key species driving regional fishery economic development. However, the following problems still exist in its farming process:

[0003] 1. Due to its physiological characteristics, the East Star Grouper grows relatively slowly and has a long breeding cycle. This characteristic directly leads to the continuous accumulation and increase of various breeding costs such as feed, labor, and facilities. At the same time, the long breeding process also makes it more susceptible to multiple uncertain factors such as environmental fluctuations, disease attacks, and market changes, thus significantly increasing the overall risk and operating pressure of breeding.

[0004] 2. During the farming of grouper, the fish are highly susceptible to various parasites, bacteria, or viruses due to factors such as environment, density, and their own immunity. Once diseases and pests occur, they will not only directly damage the health of the fish, leading to reduced feeding activity, significantly decreased appetite, and stunted growth, but may also cause a large number of individuals to die in a short period of time, resulting in serious economic losses for farmers and increasing the complexity and uncertainty of subsequent management.

[0005] 3. In high-density aquaculture environments, eutrophication of water bodies intensifies, and the levels of ammonia nitrogen and nitrite exceed the tolerance of fish, causing farmed organisms to be in a state of sub-health or stress for a long time.

[0006] Neutral proteases are a class of proteases that exhibit the highest catalytic efficiency in a neutral pH environment (typically pH 6.0-8.0). They specifically hydrolyze peptide bonds in protein molecules, breaking them down into smaller polypeptides and amino acids. These enzymes are primarily derived from microbial fermentation (e.g., Bacillus) and are characterized by high activity, good stability, and high safety. They can promote digestion, improve feed efficiency, enhance immune nutrition, reduce intestinal burden, and lower the risk of disease. Currently, they are used in various aquaculture organisms (such as Litopenaeus vannamei and Nile tilapia).

[0007] Flavonoids from Hippophae rhamnoides L., an extract derived from sea buckthorn, possess beneficial properties such as lowering blood pressure, lowering blood lipids, anti-oxidation, and immune enhancement due to their diverse chemical structures and multi-target mechanisms of action. However, there are currently few reports on their application in aquaculture. Summary of the Invention

[0008] The purpose of this invention is to provide a compound feed for juvenile leopard-gill sea bass and its preparation method. It aims to significantly promote the growth performance of the sea bass through precise nutritional regulation and the addition of functional ingredients, effectively enhance its non-specific immunity and disease resistance, and improve the fish's adaptability and tolerance to stressful environments, thereby providing key technical support for achieving healthy, efficient and stable sea bass farming.

[0009] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0010] The purpose of this invention is to provide a formulated feed for juvenile leopard gill sea bass, comprising the following components by weight percentage:

[0011] The formula consists of 50-70% red fish meal, 3-10% wheat gluten, 10-20% wheat flour, 0.5-1.5% yeast, 1-5% fish oil, 1-5% soybean oil, 0.5-3% soybean lecithin, 0.1-0.8% premix I, 0.1-0.5% premix II, 0.5-3% calcium dihydrogen phosphate, 0.1-1% sodium carboxymethyl cellulose, 1.5-3% corn starch, and 0.1-0.5% growth promoter; the growth promoter includes sea buckthorn flavonoids and neutral protease in a mass ratio of 1:1.25-10.

[0012] Furthermore, it includes the following components by weight percentage:

[0013] The formula consists of 60-70% red fish meal, 3-5% wheat gluten, 15-20% wheat flour, 1-1.5% yeast, 1-3% fish oil, 1-3% soybean oil, 0.5-1% soybean lecithin, 0.1-0.5% premix I, 0.1-0.5% premix II, 1-2% calcium dihydrogen phosphate, 0.1-1% sodium carboxymethyl cellulose, 1.5-2% corn starch, and 0.1-0.4% growth promoter; the growth promoter includes sea buckthorn flavonoids and neutral protease in a mass ratio of 1:1.25-10.

[0014] Furthermore, the mass ratio of sea buckthorn flavonoids to neutral protease is 1:3~4.

[0015] Furthermore, premix I is a vitamin premix, purchased from Guangzhou Yuequn Biotechnology Co., Ltd.

[0016] Furthermore, premix II is a mineral premix, purchased from Guangzhou Yuequn Biotechnology Co., Ltd.

[0017] Another object of the present invention is to provide a method for preparing the above-mentioned compound feed for juvenile leopard gill sea bass, which includes the following steps:

[0018] (1) Mix and crush the solid raw materials according to the formula to make their particle size ≤250μm;

[0019] (2) Mix the product obtained in step (1) with soybean lecithin, soybean oil and soybean oil, mix at 200-300 rpm for 5-10 min, then add water to adjust the total moisture content to 28-32%, and continue stirring and mixing for 10-15 min;

[0020] (3) The product of step (2) is placed in a twin-screw extruder for extrusion and then dried to obtain the compound feed.

[0021] Furthermore, the process parameters of the twin-screw extruder in step (3) are as follows:

[0022] Barrel temperature: Zone 1 45℃, Zone 2 55℃, Zone 3 65℃;

[0023] Head temperature: 70℃;

[0024] Screw speed: 180~200 rpm;

[0025] Feeding rate: 12~15 kg / h;

[0026] Cutting speed: 800~1000 rpm.

[0027] Furthermore, the drying process in step (3) is as follows:

[0028] Under conditions of 25±1℃ and relative humidity of 40-50%, the particles were dried in layers with ventilation for 48 hours, turning them over every 12 hours, until the moisture content of the extruded particles from the twin-screw extruder was reduced to below 10%.

[0029] The present invention has the following beneficial effects:

[0030] 1. In this invention, neutral protease and sea buckthorn flavonoids work synergistically through the following pathways: Neutral protease improves protein digestibility, providing sufficient amino acids for fish growth; simultaneously, it reduces the digestive burden on the intestines, working with sea buckthorn flavonoids to maintain intestinal health. Sea buckthorn flavonoids, through their powerful antioxidant and immunomodulatory functions, protect fish cells (especially hepatocytes and intestinal mucosal cells) from damage caused by metabolic waste and external stressors. The two work synergistically to achieve a balance between 'promoting growth' and 'maintaining health'. This invention creatively combines neutral protease and sea buckthorn flavonoids, achieving a dual synergistic effect of promoting digestion and regulating physiological functions. Their synergistic effect effectively enhances the overall health and resilience of the grouper while promoting rapid growth.

[0031] 2. The formula of this invention provides precise nutritional design to address specific aquaculture challenges of grouper, such as slow growth, susceptibility to diseases, and sensitivity to environmental stress. By adding functional ingredients, it directly strengthens the fish's non-specific immune barrier and antioxidant defense system, improving its tolerance to adverse environmental factors such as ammonia nitrogen, thereby reducing losses and risks during the aquaculture process.

[0032] 3. The preparation process described in this invention, by controlling key processing parameters such as fineness of grinding, mixing conditions, extrusion temperature and low-temperature drying, maximizes the protection of the stability of heat-sensitive functional components (such as protease activity and flavonoids) during processing, and ensures the expected efficacy of the additive in the final product.

[0033] 4. The core functional components are derived from natural extracts or bio-fermentation, avoiding the risks of chemical drug residues and drug resistance, and meeting the requirements of green, ecological, and sustainable development in aquaculture. The application of this feed can comprehensively improve aquaculture efficiency in many ways, such as increasing feed efficiency, reducing disease incidence, and shortening the breeding cycle.

[0034] In summary, this invention, through scientific formula design and rigorous process control, provides a specialized feed that can simultaneously improve the growth rate, health status, and environmental adaptability of the Chinese starfish, offering an effective technical solution to address key bottlenecks in its breeding. Detailed Implementation

[0035] The technical solutions will now be clearly and completely described in conjunction with embodiments of the present invention. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] A formulated feed for juvenile leopard gill sea bass includes red fish meal, wheat gluten, flour, yeast, fish oil, soybean oil, soybean lecithin, vitamin premix, mineral premix, calcium dihydrogen phosphate, sodium carboxymethyl cellulose, corn starch, neutral protease, and sea buckthorn flavonoids. The specific dosages are shown in Group PB of Table 1. The preparation method is as follows:

[0038] (1) Raw material pretreatment and crushing

[0039] After accurately weighing all solid ingredients in the formula (including red fish meal, wheat gluten, flour, yeast, vitamin and mineral premix, calcium dihydrogen phosphate, sodium carboxymethyl cellulose, corn starch, etc.), they are fed into a powder mill for grinding. The ground powder is then filtered through a 60-mesh standard sieve to ensure uniform particle size (particle size ≤ 250 micrometers) to meet the requirements of subsequent mixing and granulation processes. Coarse particles on the sieve are returned for re-grinding.

[0040] (2) Mixing process

[0041] Add the sieved powder to the SLH-5 dual-motion mixer. Add soybean lecithin, soybean oil, and fish oil in sequence according to the formula. Start the mixer and dry mix at 200 rpm for 5 minutes. Then slowly add 25-30% (w / w) of purified water (i.e., 250-300g of water per kilogram of dry material) to adjust the total moisture content to 28-32%. Wet mix for 10-15 minutes until the material forms a uniform, moist clump that can be formed into a ball when squeezed but crumbles easily when released.

[0042] (3) Granulation and molding

[0043] The mixture is transferred to the hopper of a twin-screw extruder. Process parameters are set:

[0044] Barrel temperature: Zone 1 45℃, Zone 2 55℃, Zone 3 65℃;

[0045] Die head temperature: 70℃;

[0046] Screw speed: 180-220 rpm;

[0047] Feeding rate: 12-15 kg / h;

[0048] Cutting speed: 800-1000 rpm;

[0049] Under a system pressure of 0.8-1.2 MPa, the material is extruded through a die (orifice diameter 3.00 mm) and simultaneously cut into cylindrical particles with a length of 3-5 mm by a cutter.

[0050] (4) Drying and ripening

[0051] Fresh granules are spread evenly on stainless steel sieve trays (thickness ≤ 2 cm) and transferred to a constant temperature drying room. They are dried in layers with ventilation for 48 hours at 25±1℃ and relative humidity 40-50%, turning them over every 12 hours. The final moisture content of the granules is reduced to below 10%.

[0052] Comparative Example 1

[0053] Compared with Example 1, the difference is that only neutral protease is used in the formulation, while the rest of the process is the same as in Example 1. The specific formulation ratio is shown in Table 1, PR group.

[0054] Comparative Example 2

[0055] Compared with Example 1, the difference is that only sea buckthorn flavonoids are used in the formula, while the rest of the process is the same as in Example 1. The specific formula ratio is shown in Group BH in Table 1.

[0056] Comparative Example 3

[0057] Compared with Example 1, the difference is that sea buckthorn flavonoids and neutral protease are not used in the formula, but the rest of the process is the same as in Example 1. The specific formula ratio is shown in the CO group in Table 1.

[0058] Table 1 Feed Design (g / kg, dry matter)

[0059] Element Conventional control group (CO) Neutral proteome (PR) Sea buckthorn flavonoid group (BH) Protease + Seabuckthorn Flavonoids Group (PB) Red Fish Powder 680.0 680.0 680.0 680.0 Wheat gluten 50.0 50.0 50.0 50.0 flour 160.0 160.0 160.0 160.0 yeast 10.0 10.0 10.0 10.0 fish oil 20.0 20.0 20.0 20.0 Soybean oil 20.0 20.0 20.0 20.0 Soy lecithin 10.0 10.0 10.0 10.0 Vitamin premix 3.0 3.0 3.0 3.0 Mineral premix 5.0 5.0 5.0 5.0 calcium dihydrogen phosphate 15.0 15.0 15.0 15.0 Sodium carboxymethyl cellulose 5.0 5.0 5.0 5.0 corn starch 22.0 20.0 21.5 19.5 protease 0 2.0 0 2.0 Sea buckthorn flavonoids 0 0 0.5 0.5 total 1000 1000 1000 1000

[0060] Test case

[0061] 360 juvenile grouper (22.04±0.36g) were temporarily held in a 5 m×6 m×1.5 m pond, with 60% of the water replaced daily. The water temperature was maintained at 27.8-31.3 ℃, salinity at 23-28, pH at 7.8-8.0, and dissolved oxygen at a level greater than 6.5 mg / L. The holding period was 10 days.

[0062] After the initial rearing period, healthy and uniformly sized leopard gill perch were randomly divided into four groups and placed in 1m × 1m × 1m net cages for a nutritional experiment. Each group had three replicates, with 30 fish per replicate. Initial body weight was measured and recorded. The groups were randomly numbered and fed twice daily (8:00 AM and 5:00 PM) to their satiated state. Feed intake was observed after each feeding, and the feed amount was adjusted accordingly. Feed consumption was measured daily. Wastewater was removed twice daily, morning and evening, and continuous oxygen supply was maintained. The rearing period was eight weeks.

[0063] After the aquaculture experiment, the remaining fish from each group were placed in 120 L water tanks for ammonia nitrogen stress (10 fish per tank, 3 tanks per group). The stress concentration of 96 hLC50 obtained in the preliminary experiment was used. After 24 h of stress, the survival rate and immune enzyme activity were counted, and the results are shown in Tables 2 to 5. Other experimental conditions were set as follows: temperature 29.7±2.7 ℃, pH 7.8±0.5, salinity 23-28, phosphate <0.05 mg / L, and nitrite <0.2 mg / L.

[0064] Table 2 Growth Efficiency

[0065] index CO PR BH PB Initial average weight IBW (g) 22.04±0.36 22.64±0.71 22.52±0.53 22.40±0.22 Final average weight (FBW) (g) <![CDATA[66.36±2.67 c ]]> <![CDATA[71.05±3.03 ab ]]> <![CDATA[70.29±3.53 b ]]> <![CDATA[73.2±3.05 a ]]> Survival rate (SR) in aquaculture (%) 96.67±1.00 97.78±1.15 98.89±0.58 100.00±0.00 Weight gain rate (WGR) (%) <![CDATA[204.15±7.66 c ]]> <![CDATA[225.69±4.06 ab ]]> <![CDATA[222.21±1.05 b ]]> <![CDATA[235.59±3.71 a ]]> Specific growth rate (SGR) (% / d) <![CDATA[1.92±0.04 c ]]> <![CDATA[2.04±0.02 ab ]]> <![CDATA[2.02±0.01 b ]]> <![CDATA[2.09±0.02 a ]]> Fatness CF (%) 2.27±0.03 2.40±0.08 2.24±0.02 2.28±0.10 Liver body ratio HSI (%) <![CDATA[0.70±0.04 b ]]> <![CDATA[0.77±0.05 ab ]]> <![CDATA[1.02±0.22 a ]]> <![CDATA[1.03±0.07 a ]]> Visceral body ratio VSI (%) 4.11±0.25 5.40±1.03 4.55±0.44 4.67±0.21 Feed conversion ratio (FCR) <![CDATA[1.07±0.04 a ]]> <![CDATA[0.98±0.02 b ]]> <![CDATA[1.01±0.01 a ]]> <![CDATA[1.02±0.02 a ]]> Stress survival rate SR (%) <![CDATA[58.33±0.03 c ]]> <![CDATA[66.67±0.03 bc ]]> <![CDATA[76.67±0.01 a ]]> <![CDATA[83.33±0.04 ab ]]>

[0066] Table 3 Liver oxidative immune indicators

[0067] index CO PR BH PB Malondialdehyde (MDA (nmol / ml)) <![CDATA[10.01±0.56 a ]]> <![CDATA[7.06±0.40 b ]]> <![CDATA[6.15±0.28 b ]]> <![CDATA[5.98±0.51 b ]]> Reactive oxygen species (ROS) (ng / ml) <![CDATA[124.29±4.22 a ]]> <![CDATA[97.49±2.95 bc ]]> <![CDATA[104.36±1.17 b ]]> <![CDATA[85.27±3.47 c ]]> Total antioxidant capacity (T-AOC) (U / ml) <![CDATA[15.87±0.50 c ]]> <![CDATA[17.80±0.53 b ]]> <![CDATA[23.68±0.75 a ]]> <![CDATA[25.77±1.21 a ]]> Alkaline phosphatase (ALP) (IU / L) <![CDATA[184.90±3.67 c ]]> <![CDATA[193.24±3.67 b ]]> <![CDATA[220.40±6.83 a ]]> <![CDATA[226.25±3.43 a ]]> Acid phosphatase (ACP) (IU / L) <![CDATA[9.8±0.36 b ]]> <![CDATA[9.23±0.29 b ]]> <![CDATA[12.13±0.45 a ]]> <![CDATA[14.34±0.39 a ]]>

[0068] Table 4 Intestinal Digestive and Immune Indicators

[0069] index CO PR BH PB Malondialdehyde (MDA) (nmol / mL) <![CDATA[10.54±0.28 a ]]> <![CDATA[7.70±1.15 a ]]> <![CDATA[6.77±0.45 b ]]> <![CDATA[7.17±0.30 b ]]> Reactive oxygen species (ROS) (ng / ml) <![CDATA[130.28±5.76 a ]]> <![CDATA[105.56±7.39 b ]]> <![CDATA[101.87±7.39 b ]]> <![CDATA[91.23±1.92 b ]]> Total antioxidant capacity (T-AOC) (U / ml) <![CDATA[16.73±0.50 b ]]> <![CDATA[15.03±0.95 b ]]> <![CDATA[23.24±0.45 a ]]> <![CDATA[22.64±0.31 a ]]> Alkaline phosphatase (ALP) (IU / L) <![CDATA[150.64±4.07 b ]]> <![CDATA[214.66±3.26 a ]]> <![CDATA[220.30±5.35 a ]]> <![CDATA[230.84±12.74 a ]]> Acid phosphatase (ACP) (IU / L) <![CDATA[9.12±0.52 a ]]> <![CDATA[12.45±0.47 b ]]> <![CDATA[11.75±0.57 b ]]> <![CDATA[14.56±0.34 c ]]> Amylase (IU / ml) <![CDATA[246.94±6.27 b ]]> <![CDATA[323.25±13.46 a ]]> <![CDATA[381.26±32.54 a ]]> <![CDATA[454.44±42.27 a ]]> Lipase (U / L) <![CDATA[285.43±69.34 c ]]> <![CDATA[558.07±97.71 ab ]]> <![CDATA[671.35±67.74 bc ]]> <![CDATA[836.90±52.09 a ]]> Trypsin (U / ml) <![CDATA[728.91±62.52 b ]]> <![CDATA[1015.38±16.72 a ]]> <![CDATA[1182.80±173.07 a ]]> <![CDATA[1202.31±44.33 a ]]>

[0070] Table 5 Serum metabolic indicators

[0071] Index (nmol / L) CO PR BH PB Triglycerides (TG) <![CDATA[7.23±0.12 a ]]> <![CDATA[6.14±0.13 b ]]> <![CDATA[5.10±0.02 c ]]> <![CDATA[5.70±0.24 bc ]]> Total cholesterol (TC) <![CDATA[9.64±0.13 a ]]> <![CDATA[8.93±0.38 ab ]]> <![CDATA[9.25±0.38 b ]]> <![CDATA[7.34±0.11 c ]]> High-density lipoprotein (HDL-C) <![CDATA[1.84±0.35 b ]]> <![CDATA[2.34±0.09 a ]]> <![CDATA[3.30±0.25 ab ]]> <![CDATA[3.74±0.15 a ]]> Low-density lipoprotein (LDL-C) <![CDATA[8.13±0.40 a ]]> <![CDATA[6.60±0.46 b ]]> <![CDATA[6.00±0.31 b ]]> <![CDATA[4.00±0.49 b ]]> Blood urea nitrogen (BUN) <![CDATA[19.70±0.36 a ]]> <![CDATA[17.63±0.38 a ]]> <![CDATA[14.1±1.58 b ]]> <![CDATA[15.41±0.99 b ]]>

[0072] Experimental data showed that the groups containing neutral protease (PR group and PB group) performed excellently in key growth indicators. The PB group (neutral protease + sea buckthorn flavonoid compound group) exhibited the best growth performance among all groups, with the highest final average weight, weight gain rate, and specific growth rate (73.2±3.05g, 235.59±3.71%, and 2.09±0.02% / d, respectively) (see Table 2), significantly better than the control group (P<0.05). Neutral protease directly improved feed conversion efficiency. The PR group, with neutral protease added alone, had a feed conversion ratio (FCR) of 0.98±0.02, significantly lower than all other groups (P<0.05), demonstrating its most effective conversion of feed into fish weight gain, directly reducing feed costs. Although the PB group was slightly higher than the PR group, the slight increase in FCR due to higher feed intake is normal.

[0073] The addition of sea buckthorn flavonoids (BH and PB groups) systematically enhanced the antioxidant and immune functions of fish. Oxidative damage in the liver and intestines was significantly reduced. The levels of malondialdehyde (MDA) and reactive oxygen species (ROS) in the liver and intestines of both the BH and PB groups were significantly lower than those of the control and PR groups (P<0.05), indicating that cell membrane lipid peroxidation damage was effectively inhibited. Total antioxidant capacity (T-AOC) was significantly increased (P<0.05). The BH and PB groups, which were supplemented with sea buckthorn flavonoids, showed the highest T-AOC levels in the liver and intestines, indicating a systematic enhancement of the fish's ability to scavenge free radicals. Immunoenzyme activity was increased. The activities of acid phosphatase (ACP) and alkaline phosphatase (ALP), reflecting non-specific immune function, were significantly increased in the groups supplemented with sea buckthorn flavonoids (especially the PB group) (P<0.05) (Tables 3 and 4).

[0074] The formulated feed comprehensively improved the digestive physiology and metabolic status of grouper. Digestive enzyme activity was enhanced; the PB group showed the highest levels of intestinal amylase, lipase, and trypsin activity (P<0.05), indicating a comprehensive improvement in feed digestibility and absorption. Lipid metabolism was healthier: serum triglyceride (TG) levels in all experimental groups were significantly lower than in the control group (P<0.05). The PB group had the lowest serum total cholesterol (TC) (7.34±0.11 nmol / mL), and a significantly higher high-density lipoprotein cholesterol (HDL-C / LDL-C) ratio (P<0.05), indicating healthier lipid metabolism and a reduced risk of cardiovascular disease. Protein metabolism efficiency was improved: the BH and PB groups, supplemented with sea buckthorn flavonoids, showed significantly lower serum urea nitrogen (BUN) levels (Table 5) (P<0.05), indicating enhanced protein synthesis, reduced catabolism, and more efficient use of feed protein for growth.

[0075] Compound feed significantly improved the survival ability of grouper in harsh environments. The highest survival rate was observed under ammonia nitrogen stress: In subsequent ammonia nitrogen stress experiments, the PB group had the highest survival rate after stress (83.33±0.04%), significantly higher than the control group (P<0.05). The survival rate of the BH group, which was supplemented with sea buckthorn flavonoids alone, was also significantly improved, demonstrating that sea buckthorn flavonoids play a key role in enhancing stress resistance.

[0076] The data from Tables 2-5 show that the combined addition of neutral protease and sea buckthorn flavonoids (PB group) produced a synergistic effect of "1+1>2". In terms of growth promotion, the combination of the protease's ability to improve digestion and absorption and the sea buckthorn flavonoids' ability to improve metabolic health resulted in optimal growth performance. Regarding health protection, the combination of the protease's ability to reduce digestive burden and the sea buckthorn flavonoids' ability to directly enhance antioxidant and immune functions enabled the fish to exhibit the strongest survival ability when facing ammonia nitrogen stress.

[0077] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A formulated feed for juvenile leopard-gill sea bass, characterized in that, Includes the following components by weight percentage: The formula consists of 50-70% red fish meal, 3-10% wheat gluten, 10-20% wheat flour, 0.5-1.5% yeast, 1-5% fish oil, 1-5% soybean oil, 0.5-3% soybean lecithin, 0.1-0.8% premix I, 0.1-0.5% premix II, 0.5-3% calcium dihydrogen phosphate, 0.1-1% sodium carboxymethyl cellulose, 1.5-3% corn starch, and 0.1-0.5% growth promoter; the growth promoter includes sea buckthorn flavonoids and neutral protease in a mass ratio of 1:1.25-10.

2. The formulated feed for juvenile leopard-gill sea bass according to claim 1, characterized in that, Includes the following components by weight percentage: The formula consists of 60-70% red fish meal, 3-5% wheat gluten, 15-20% wheat flour, 1-1.5% yeast, 1-3% fish oil, 1-3% soybean oil, 0.5-1% soybean lecithin, 0.1-0.5% premix I, 0.1-0.5% premix II, 1-2% calcium dihydrogen phosphate, 0.1-1% sodium carboxymethyl cellulose, 1.5-2% corn starch, and 0.1-0.4% growth promoter; the growth promoter includes sea buckthorn flavonoids and neutral protease in a mass ratio of 1:1.25-10.

3. The formulated feed for juvenile leopard-gill sea bass according to claim 1 or 2, characterized in that, The mass ratio of sea buckthorn flavonoids to neutral protease is 1:3~4.

4. The formulated feed for juvenile leopard-gill sea bass according to claim 1 or 2, characterized in that, Premix I is a vitamin premix.

5. The formulated feed for juvenile leopard-gill sea bass according to claim 1 or 2, characterized in that, Premix II is a mineral premix.

6. A method for preparing a formulated feed for juvenile leopard-gill sea bass according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Mix and crush the solid raw materials according to the formula to make their particle size ≤250μm; (2) Mix the product obtained in step (1) with soybean lecithin, soybean oil and fish oil at 200-300 rpm for 5-10 min, then add water to adjust the total moisture content to 28-32%, and continue stirring for 10-15 min; (3) The product of step (2) is placed in a twin-screw extruder for extrusion and then dried to obtain the compound feed.

7. The preparation method according to claim 6, characterized in that, The process parameters for the twin-screw extruder in step (3) are as follows: Barrel temperature: Zone 1 45℃, Zone 2 55℃, Zone 3 65℃; Head temperature: 70℃; Screw speed: 180~200 rpm; Feeding rate: 12~15 kg / h; Cutting speed: 800~1000 rpm.

8. The preparation method according to claim 6, characterized in that, The drying process in step (3) is as follows: Under conditions of 25±1℃ and relative humidity of 40-50%, the particles were dried in layers with ventilation for 48 hours, turning them over every 12 hours, until the moisture content of the extruded particles from the twin-screw extruder was reduced to below 10%.