Fish feed for reducing fat deposition and promoting growth of snakeheads and preparation method of fish feed

Abstract

The invention belongs to but is not limited to the technical field of fish culture, and discloses a fish feed for improving growth performance and feed utilization of snakeheads and a preparation method of the fish feed, and 500-1000mg of hydrolyzed tannic acid is added into every 1000g of compound feed. The basic formula comprises 350g of fish meal; 110 g of soybean meal; 140 g of corn protein powder; 88 g of rapeseed meal; 60 g of high gluten flour; 120 g of cassava starch; 50 g of fish oil; 25 g of soybean oil; 30 g of a mineral premix; premixing 10 g of vitamin; 5 g of vitamin C; 1 g of choline chloride; and 1g of ethoxyquin. According to the invention, 500-1000mg / kg of tannic acid is added into the basal feed, so that the growth performance and feed efficiency of the snakeheads are improved, the body fat content of the snakeheads is reduced, and the oxidation resistance of livers and the health condition of the livers are improved. The snakehead feed has the effects of improving snakehead growth and feed utilization, improving liver health and improving meat quality.

Description

Technical Field

[0001] The present invention belongs to, but is not limited to, the technical field of fish farming, and particularly relates to a fish feed for reducing fat deposition in snakehead, improving the growth performance of snakehead and feed utilization, and a preparation method thereof. Background Art

[0002] Antibiotics are one of the common additives in aquaculture. They can prevent the invasion of pathogenic bacteria, improve the intestinal morphological structure, promote growth, and enhance the immunity of livestock and poultry. However, long-term addition of antibiotics in feed can lead to the generation of antibiotic resistance in pathogenic microorganisms, resulting in drug residue problems in aquatic products and the environment, seriously endangering human health. Therefore, finding new green feed additives to replace antibiotics has become one of the important research directions in current feed research. Natural plant extracts have the advantages of low toxicity and side effects, low residue, and high safety. Using plant extracts as functional feed additives has attracted more and more attention. Tannic acid is a natural polyphenolic small molecule compound with rich sources, widely present in the bark and fruits of plants such as pomegranate, raspberry, and schisandra chinensis. It has many important biological activities, such as antiviral, chemoprevention, neuroprotection, anti-inflammatory, and good free radical scavenging ability. At the same time, it also has the effects of reducing blood lipid, antioxidant, and regulating lipid metabolism, having a certain protective effect on liver and intestinal health, and having extremely high development value for feed use. Although tannic acid has unique biological characteristics, its application as a functional feed additive in aquaculture has not been systematically evaluated, and there are few reports on the research of the growth, metabolism, and antioxidant performance of fish.

[0003] Snakehead is an important freshwater economic fish in China. It has a fast growth rate, strong low-oxygen tolerance, and is suitable for high-density farming. The aquaculture output of snakehead in China has reached 6 million tons in 2023. However, the current aquaculture mode is prone to cause fatty liver and oxidative stress in snakehead, seriously affecting the aquaculture production efficiency of snakehead.

[0004] In view of the above analysis, the technical problems urgently to be solved in the prior art are: how to reduce the risk of fatty liver and oxidative stress in snakehead and improve the aquaculture production efficiency of snakehead. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention provides a functional additive feed for improving the growth performance, feed utilization of hybrid snakehead, and reducing body fat content, and a preparation method. By adding tannic acid to the feed, the growth performance of snakehead can be improved, the fat deposition and the risk of fatty liver can be reduced, which is of great significance for reducing the use of antibiotics and improving the production efficiency in aquaculture.

[0006] The present invention is implemented as follows. A fish feed for improving the growth performance and feed utilization of snakehead fish includes a compound feed and hydrolyzed tannic acid. 500 - 1000 mg of hydrolyzed tannic acid is added to every 1000 g of the compound feed (crude protein level: 43.65%).

[0007] The basic formula of the compound feed is as follows (per 1000 g): 350 g of fish meal; 110 g of soybean meal; 140 g of corn protein powder; 88 g of rapeseed meal; 60 g of high - gluten flour; 120 g of tapioca starch; 50 g of fish oil; 25 g of soybean oil; 30 g of mineral premix; 10 g of vitamin premix; 5 g of vitamin C; 1 g of choline chloride; 1 g of ethoxyquinoline.

[0008] Furthermore, the protein includes fish meal, corn protein powder, soybean meal and rapeseed meal.

[0009] Furthermore, the fat is fish oil and soybean oil.

[0010] Furthermore, the carbohydrates are high - gluten flour and tapioca starch.

[0011] Another object of the present invention is to provide a preparation method of a fish feed for improving the growth performance and feed utilization of snakehead fish, including:

[0012] (1) Respectively crush and sieve the above raw materials, accurately weigh the raw materials and tannic acid according to the ratio, and add them step by step from less to more and mix fully. Then, while stirring, add pure water to the surface of the mixed raw materials with a sprayer to make the raw materials into a wet powder state.

[0013] (2) Use an aquatic extruded feed machine to make the mixture into compact pellets and then dry the moisture, keeping the moisture content at 5% - 6%.

[0014] (3) After drying, weigh the fish oil and soybean oil according to the formula at a ratio of 2:1, mix them evenly and spray them under vacuum negative pressure.

[0015] Combined with the above - mentioned technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by the present invention are as follows:

[0016] First, the present invention takes hybrid snakehead fish as the research object, evaluates the effects of adding hydrolyzed tannic acid in the feed on the growth performance, feed utilization, intestinal health, liver oxidation / antioxidation ability and the ability to resist hybrid snakehead rhabdovirus infection of hybrid snakehead fish, and provides new ideas and references for the application of tannic acid as a functional feed additive in fish farming.

[0017] The present invention provides a green and efficient tannic acid additive feed. When the addition amount is 500 - 1000 mg / kg, it can significantly improve the growth and feed utilization rate of fish, significantly reduce the fish body fat content, relieve the formation of fatty liver and reduce the risk of liver oxidative stress, and improve the survival rate of resisting rhabdovirus infection.

[0018] Second, the expected benefits and commercial value after the transformation of the technical solution of the present invention are as follows:

[0019] It has significant economic benefits: 1) Reducing breeding costs: By improving feed utilization rate (reducing feed waste) and shortening the growth cycle (higher output per unit time), it directly reduces the input costs of farmers and increases the profit margin. 2) Product premium space: Low-fat and healthy fish meet the trend of consumption upgrading, can enter the high-end market or the field of health food, and obtain a higher selling price. 3) Reducing disease losses: Reducing the risks of fatty liver and oxidative stress means an increase in the survival rate of the fish population and a reduction in losses caused by diseases. Rhabdovirus is a major threat to the aquaculture industry, which can cause a fish mortality rate of over 70%. Improving the antiviral survival rate directly reduces the huge losses of farmers due to diseases.

[0020] It has significant environmental and ecological benefits: 1) Natural tannic acid replaces chemical additives, reducing water pollution and drug residues, conforming to the global policies of banning and reducing antibiotics, and is easy to obtain policy support. 2) Reducing the dependence on vaccines and drugs: Traditional prevention and control rely on costly vaccines or antibiotics, while this solution enhances innate immunity through feed, reduces the cost of medication, and avoids the risk of antibiotic resistance.

[0021] The technical solution of the present invention solves the technical problems that people have been eager to solve but have never succeeded in:

[0022] 1. Solving the difficulty of achieving both growth rate and health: Traditional feeds often lead to excessive fat deposition and metabolic diseases (such as fatty liver) in the pursuit of rapid weight gain. The present invention regulates lipid metabolism through tannic acid, improves the health of fish while promoting growth, and solves the long-existing contradiction in the industry of "growing fast but not being healthy".

[0023] 2. Solving the problem of chemical additive residues: In the past, the prevention and treatment of fatty liver may rely on synthetic drugs (such as choline, betaine) or antibiotics, which have the risk of residues. Tannic acid, as a natural plant extract, is safe and non-toxic, and solves the problem of balancing safety and efficacy. Description of the Drawings

[0024] Figure 1 It is a flowchart of the preparation method of a fish feed for improving the growth performance and feed utilization of snakehead provided by an embodiment of the present invention;

[0025] Figure 2 It is a schematic diagram of the influence of adding tannic acid to the feed on the body composition of snakehead fish provided by an embodiment of the present invention;

[0026] Figure 3 It is a schematic diagram of the influence of adding tannic acid to the feed on the antioxidant enzyme activity of the liver of snakehead provided by an embodiment of the present invention;

[0027] Figure 4 Schematic diagram of the effect of feed tannic acid levels on the liver tissue morphology of Channa provided by an embodiment of the present invention. Figure 5 Schematic diagram of the effect of feed tannic acid levels on the cumulative survival rate of hybrid snakehead provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] The embodiment of the present invention provides a fish feed for improving the growth performance and feed utilization of Channa, comprising a compound feed and hydrolyzed tannic acid, wherein 500-1000 mg of hydrolyzed tannic acid is added to every 1000 g of compound feed (crude protein level: 43.65%);

[0030] The basic formula of the compound feed is as follows (per 1000g): 350g fish meal; 110g soybean meal; 140g corn gluten meal; 88g rapeseed meal; 60g high-gluten flour; 120g cassava starch; 50g fish oil; 25g soybean oil; 30g mineral premix; 10g vitamin premix; 5g vitamin C; 1g choline chloride; 1g ethoxyquinoline.

[0031] Furthermore, the protein includes fish meal, corn gluten meal, soybean meal and rapeseed meal.

[0032] Furthermore, the fat is fish oil and soybean oil.

[0033] Furthermore, the sugars are high-gluten flour and tapioca starch.

[0034] like Figure 1 As shown, an embodiment of the present invention provides a method for preparing fish feed for improving the growth performance and feed utilization of Channa, comprising:

[0035] (1) The above raw materials are crushed and sieved separately, and the raw materials and tannic acid are accurately weighed according to the ratio. After adding them step by step from less to more and mixing them thoroughly, pure water is added to the surface of the mixed raw materials with a spray bottle while stirring until the raw materials are in a wet powder state.

[0036] (2) Use an aquaculture extruder to make the mixture into compact particles and then dry them to keep the moisture at 5%-6%.

[0037] (3) After drying, the granular material is weighed with fish oil and soybean oil in a ratio of 2:1 and mixed evenly, and then vacuum-pressure sprayed.

[0038] (1) Experimental feed: Taking fish meal, corn gluten meal, soybean meal and rapeseed meal as the main protein sources, fish oil and soybean oil as the fat sources, and high-gluten flour and tapioca starch as the sugar sources, a basic feed was formulated. Hydrolyzed tannic acid was added to the basic feed at 0, 0.05%, 0.1%, 0.2%, and 0.4% (i.e., 0, 500, 1000, 2000, 4000 mg / kg) respectively to prepare 5 gradient tannic acid additive feeds. The feed raw materials were accurately weighed according to the ratio, then put into a blender and mixed evenly. The pulverized raw materials were slowly sprayed with an appropriate amount of pure water and stirred evenly to obtain a mixture, which was processed into pellet feeds with a diameter of 2 mm using an aquatic extruder, dried, and then accurately weighed the mixed oil and evenly sprayed and mixed it in a blender.

[0039] Table 1 Feed formula and nutritional components

[0040]

[0041]

[0042] (2) Feeding process: The hybrid snakehead fry bred in the same batch was used in this invention. Before the formal feeding started, all the fish were temporarily raised in an indoor cement pond (6.0 m × 3.0 m × 1.0 m) and domesticated with commercial feed for 2 weeks, feeding twice a day. The breeding experiment was carried out in the indoor recirculating water breeding system of the Pearl River Fisheries Research Institute. Five concentration gradients were set, with 3 replicates in each group. 40 hybrid snakehead fry (about 16 g) were placed in each tank (256 L), and a breeding experiment was carried out for 8 weeks. During the breeding period, apparent satiation feeding was carried out at 8:00 and 17:00 every day, the feeding amount was recorded daily, the water temperature was controlled at 25 - 27 °C, the dissolved oxygen content was greater than 5.0 mg / L, the pH was 7.5 - 8.0, the ammonia and nitrite contents were lower than 0.1 mg / L, and natural light was used.

[0043] (3) After the breeding experiment ended, all the fish were fasted for 24 h, and the fish in each net cage were fished out separately, counted and weighed after anesthesia. 3 hybrid snakeheads were randomly selected from each breeding tank, and their body lengths and weights were measured respectively. Then, the internal organs and livers were dissected and weighed to calculate the viscerosomatic ratio and hepatosomatic ratio. One portion of liver and intestinal tissues was stored in a -80 °C refrigerator for enzyme activity determination, and at the same time, one portion of liver and intestine was placed in 4% paraformaldehyde for histological section observation.

[0044] (5) Challenge experiment: After the breeding experiment ended, 20 hybrid snakeheads were selected from each group and injected with rhabdovirus culture solution through intraperitoneal injection. The virus concentration was 1 × 106 cfu mL -1 , and the injection dose was 1000 μl / kg of the virus culture solution. The mortality of hybrid snakeheads within 14 days after the challenge was recorded.

[0045] (4) One-way ANOVA was performed using SPSS 23.0 statistical analysis software. A significant difference was considered when P < 0.05, and a highly significant difference was considered when P < 0.01.

[0046] The experimental results are shown in Table 2.

[0047] Table 2 Effects of adding tannic acid to the feed on the growth performance and feed utilization of hybrid snakehead

[0048]

[0049]

[0050] Different lowercase letters superscripted on the same-row data indicate significant differences (P < 0.05).

[0051] It can be seen from Table 2 that through an 8-week feeding experiment, compared with the TA0 (control group), adding 500 and 1000 mg / kg of tannic acid to the feed significantly increased the weight gain rate, specific growth rate, and feed efficiency of juvenile hybrid snakehead (P < 0.05), while adding excessive tannic acid (4000 mg / kg) inhibited the growth of snakehead and reduced the feed efficiency. There were no significant differences in the viscerosomatic index and hepatosomatic index among the groups. The results show that adding 500 - 1000 mg / kg of tannic acid to the feed can significantly improve the growth performance and feed efficiency of snakehead.

[0052] From Figure 2 it can be obtained that compared with the control group TA0, adding tannic acid to the feed significantly reduced the body fat content of snakehead (P < 0.05). There were no significant differences in the fish body protein, moisture, and ash contents among the groups. It shows that adding tannic acid to the feed can alleviate fish body fat deposition and improve the meat quality.

[0053] From Figure 3 it can be known that adding 500 - 1000 mg / kg of ellagic acid to the feed significantly increased the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GHS-Px) in the liver of snakehead, while significantly reducing the content of malondialdehyde (MDA), a lipid peroxidation product in the liver. The results show that adding 500 - 1000 mg / kg of ellagic acid to the feed significantly improved the antioxidant activity of the liver, reduced the oxidative damage of tissues, and maintained liver health.

[0054] From Figure 4It can be seen that adding tannic acid to the feed significantly improves the histological morphology of snakehead liver and reduces liver fat deposition. From HE staining, it can be seen that tannic acid at 500 - 1000 mg / kg significantly reduces the vacuolization of hepatocytes, and oil red staining significantly shows that adding tannic acid significantly reduces the number of lipid droplets in liver cells. Compared with the control group, adding 500 - 1000 mg / kg of tannic acid can reduce the fat content in the liver by 40%, indicating that appropriate supplementation of tannic acid can effectively improve liver morphology and fat deposition.

[0055] Figure 5 It can be seen that after injection with rhabdovirus, supplementing 1000 mg / kg of tannic acid in the feed significantly increases the cumulative survival rate of hybrid snakehead, and the cumulative survival rate at 11 days after virus challenge is 50%, while the mortality rate of the control group is 100%.

[0056] I. The specific application field or related products of the present invention.

[0057] Application example: Additive feed for the high - density culture mode of hybrid snakehead

[0058] Core claim of the technical solution: Tannic acid (derived from gallnut extract) is added at a dosage of 1000 mg / kg to make an expanded pellet feed.

[0059] Embodiment:

[0060] (1) Raw material treatment:

[0061] Pretreatment of tannic acid: Using β - cyclodextrin inclusion technology, tannic acid and β - cyclodextrin are mixed at a ratio of 1:3, and spray - dried to form microcapsules (particle size ≤ 50 μm) to improve its stability in high - temperature extrusion processing (retention rate ≥ 95%).

[0062] (2) Feed preparation:

[0063] Formulation composition: 35% fish meal, 10% soybean meal, 14% corn protein powder, 9% rapeseed meal, 18% starch, 5% fish oil, 3% soybean oil, 7% premix, 1% encapsulated tannic acid, 3% others.

[0064] Processing technology: After mixing, granulated by a twin - screw extruder, with a particle diameter of 3 mm, an expanded feed.

[0065] (3) Breeding experiment:

[0066] Experimental design: 1000 hybrid snakeheads (initial weight 50 ± 2 g) are randomly divided into 2 groups:

[0067] Control group: Commercially available feed (containing 150 mg / kg of chemical antioxidant BHT);

[0068] Experimental group: The feed of the present invention.

[0069] Cultivation conditions: Recirculating water system (water temperature 26 °C), feeding twice a day until satiation, for 8 weeks continuously.

[0070] Virus challenge test: In the 9th week, add the virus suspension of hybrid snakehead rhabdovirus (HSHRV) (titer 10^ 5 TCID50 / mL) into the water bodies of the two groups, and observe the mortality rate within 14 days.

[0071] (4) Technical effects:

[0072] Growth performance: The feed conversion ratio (FCR) of the experimental group decreased to 1.15 (1.32 for the control group), and the weight gain rate increased by 23%;

[0073] Disease resistance: The cumulative mortality rate of the experimental group was 8.2% (67.5% for the control group), and the viral load (detected by qPCR) decreased by 99%;

[0074] Health indicators: The liver fat content decreased by 31%, the activity of superoxide dismutase (SOD) increased by 40%, and the serum IgM level increased by 2.3 times.

[0075] II. Evidence related to the technical effects obtained in the embodiments of the present invention.

[0076] 1. Growth performance data

[0077]

[0078] Note: The data are mean ± standard deviation (n = 3 replicates, 150 fish per replicate), and the significance was analyzed by t-test (α = 0.05).

[0079] 2. Health and metabolic indicators

[0080]

[0081] Interpretation:

[0082] ● Alleviation of fatty liver: The liver fat content and hepatosomatic index decreased significantly, indicating that tannic acid effectively inhibited lipid accumulation;

[0083] ● Protection of liver function: The decrease in serum ALT (alanine aminotransferase) indicates a reduction in hepatocyte damage;

[0084] ● Enhancement of antioxidant capacity: The increase in the activity of SOD (superoxide dismutase) and the decrease in the content of MDA (malondialdehyde) confirmed the alleviation of oxidative stress.

[0085] 3. Disease resistance data (HSHRV virus challenge test)

[0086]

[0087]

[0088] 4. Economic benefit calculation (based on 1 ton of feed)

[0089]

[0090] Example 1: The addition amount of hydrolyzed tannic acid is 500 mg / kg

[0091] In every 1000 g of compound feed with a crude protein level of 43.65%, 500 mg of hydrolyzed tannic acid is added. The feed composition is as follows:

[0092] Fish meal: 350 g

[0093] Soybean meal: 110 g

[0094] Corn gluten meal: 140 g

[0095] Rapeseed meal: 88 g

[0096] High-gluten flour: 60 g

[0097] Cassava starch: 120 g

[0098] Fish oil: 50 g

[0099] Soybean oil: 25 g

[0100] Mineral premix: 30 g

[0101] Vitamin premix: 10 g

[0102] Vitamin C: 5 g

[0103] Choline chloride: 1 g

[0104] Ethoxyquinoline: 1 g

[0105] Hydrolyzed tannic acid: 0.5 g

[0106] Example 2: The addition amount of hydrolyzed tannic acid is 700 mg / kg

[0107] In every 1000 g of compound feed with a crude protein level of 43.65%, 700 mg of hydrolyzed tannic acid is added. Its formula remains unchanged, and only the dosage of hydrolyzed tannic acid is adjusted to:

[0108] Hydrolyzed tannic acid: 0.7 g

[0109] Example 3: The addition amount of hydrolyzed tannic acid is 800 mg / kg

[0110] In every 1000 g of compound feed with a crude protein level of 43.65%, 800 mg of hydrolyzed tannic acid is added. The formula is as follows:

[0111] Hydrolyzed tannic acid: 0.8 g

[0112] Example 4: The addition amount of hydrolyzed tannic acid is 1000 mg / kg

[0113] In every 1000 g of compound feed with a crude protein level of 43.65%, 1000 mg of hydrolyzed tannic acid is added, which is the upper limit dose of the present invention:

[0114] Hydrolyzed tannic acid: 1.0 g

[0115] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention by those skilled in the art within the technical scope disclosed by the present invention shall be covered by the protection scope of the present invention.

Claims

1. A fish feed for improving the growth performance and feed utilization of snakehead fish, characterized in that, The invention comprises compound feed and hydrolyzed tannic acid, wherein 500-1000 mg of hydrolyzed tannic acid is added to each 1000 g of compound feed having a crude protein level of 43.65%; The basic formula of the compound feed is as follows: 350g fish meal; 110g soybean meal; 140g corn gluten meal; 88g rapeseed meal; 60g high-gluten flour; 120g cassava starch; 50g fish oil; 25g soybean oil; 30g mineral premix; 10g vitamin premix; 5g vitamin C; 1g choline chloride; 1g ethoxyquinoline.

2. The fish feed for improving the growth performance and feed utilization of snakehead fish as claimed in claim 1, wherein The proteins include fish meal, corn gluten meal, soybean meal and rapeseed meal.

3. The fish feed for improving the growth performance and feed utilization of snakehead fish according to claim 1, characterized in that, The fats are fish oil and soybean oil.

4. The fish feed for improving the growth performance and feed utilization of snakehead fish as claimed in claim 1, wherein The sugars are high-gluten flour and tapioca starch.

5. A method for preparing a fish feed for improving the growth performance and feed utilization of snakehead fish according to any one of claims 1 to 4, characterized in that, include: (1) The above raw materials are crushed and sieved respectively, the raw materials and tannic acid are accurately weighed according to the ratio, and added step by step from less to more and mixed thoroughly, and purified water is added to the surface of the mixed raw materials with a spray bottle while stirring until the raw materials are in a wet powder state; (2) Use an aquaculture extruder to make the mixed material into compact particles and then dry them to keep the moisture content at 5%-6%; (3) After drying, the granular material is weighed with fish oil and soybean oil in a ratio of 2:1 and mixed evenly, and then vacuum-pressure sprayed.

Images