A high-protein and low-fat compound feed for juvenile gobiocypris rarus and a preparation method thereof

Abstract

The application discloses a high-protein and low-fat compound feed for juvenile Gymnocypris przewalskii and a preparation method thereof, and relates to the technical field of aquatic feed, wherein the crude protein content is 46-49%, the crude fat content is 6%, and the feed comprises the following raw materials: fish meal, chicken meal, pork meal, soybean protein concentrate, soybean meal, beer yeast, alpha-starch, fish oil, soybean oil, soybean lecithin, calcium dihydrogen phosphate, choline chloride, compound vitamin premix, compound mineral premix, microcrystalline cellulose and VC. The application optimizes the protein and fat ratio, improves the growth performance, feed utilization and liver health level of juvenile G. przewalskii, and determines the suitable protein and fat ratio according to the nutritional demand characteristics of juvenile G. przewalskii, so that the liver health is maintained while the rapid growth is promoted. The application solves the problems of lack of special feed for G. przewalskii, unreasonable nutritional ratio and high-fat induced liver damage, and is suitable for artificial domestication and large-scale breeding of G. przewalskii.

Description

Technical Field

[0001] This invention relates to the field of aquaculture feed technology, specifically to a high-protein, low-fat compound feed for juvenile naked carp and its preparation method. Background Technology

[0002] The sharp-skinned naked carp (Oxygymnocypris stewartii) is a cold-water carnivorous fish native to high-altitude areas. Its muscle protein content is as high as 74.40% (dry sample), containing 17 amino acids, including 25.96% of the total of the seven essential amino acids, 23.39% of the total umami amino acids, and a high content of n-3 polyunsaturated fatty acids (EPA and DHA) of 39.27%. It has extremely high edible and economic value. In recent years, due to overfishing, habitat destruction, and hydropower construction, the wild population of sharp-skinned naked carp has declined sharply. Currently, the artificial breeding technology for naked carp is not yet mature. One of the main reasons is the lack of specialized formulated feed for this fish species, and the existing technology also has the following technical problems: Lack of basic data on protein and fat requirements: Research on the nutritional requirements of naked carp is extremely limited. There are no reports on the appropriate requirements of feed protein and fat at different growth stages and the interaction between the two. The lag in nutritional requirement research has led to a lack of scientific basis for feed feeding in artificial breeding. Improper protein-to-fat ratio: In the current technology, commercial feeds of other fish are often used to feed naked carp directly. The protein-to-fat ratio is not suitable and cannot meet the specific nutritional needs of naked carp. Studies have shown that when the fat level in the feed increases from 6% to 10%, it will lead to a significant increase in the degree of fatty degeneration in the liver of naked carp, indicating that cold-water carnivorous fish in the plateau have a low tolerance threshold for fat. High-fat diet leads to liver damage: The naked carp has poor adaptability, strong stress and high incidence of disease in artificial breeding environment. High-fat diet can easily induce fatty degeneration of the liver of naked carp, leading to liver tissue damage and oxidative stress, which is manifested as dense and diffuse lipid droplets in hepatocytes, disordered hepatic cord structure and increased malondialdehyde content. Growth and health are difficult to balance: Current technologies cannot simultaneously meet the needs of rapid growth and maintaining liver health, and there is a lack of differentiated feed formulations for different breeding objectives.

[0003] Therefore, developing a formulated feed specifically for the nutritional needs of juvenile naked carp and determining the appropriate protein-to-fat ratio is of great significance for the artificial breeding and germplasm resource protection of naked carp. Summary of the Invention

[0004] This invention provides a high-protein, low-fat compound feed for juvenile naked carp and its preparation method, which can effectively solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high-protein, low-fat compound feed for juvenile naked carp, with a crude protein content of 46%-49% and a crude fat content of 6%, comprising the following raw materials by weight percentage: Fish meal 28%-34.5%, chicken meal 6%-8%, pork meal 5%, soy protein concentrate 9%-12%, soybean meal 5%-9%, brewer's yeast 4%, α-starch 19%, fish oil 0%-0.3%, soybean oil 0%-0.6%, soy lecithin 1%, calcium dihydrogen phosphate 1%, choline chloride 1%, compound vitamin premix 1%, compound mineral premix 1%, microcrystalline cellulose 4%-18.5%, vitamin C 0.5%.

[0006] Preferably, the crude protein content is 46% and the crude fat content is 6%, and the raw material composition by weight percentage is as follows: Fish meal 33%, chicken meal 8%, pork meal 5%, soy protein concentrate 9%, soybean meal 8%, brewer's yeast 4%, α-starch 19%, soybean oil 0.2%, soy lecithin 1%, calcium dihydrogen phosphate 1%, choline chloride 1%, compound vitamin premix 1%, compound mineral premix 1%, microcrystalline cellulose 9.3%, and vitamin C 0.5%.

[0007] Preferably, the crude protein content is 49% and the crude fat content is 6%, and the raw material composition by weight percentage is as follows: Fish meal 34.5%, chicken meal 8%, pork meal 5%, soy protein concentrate 12%, soybean meal 9%, brewer's yeast 4%, α-starch 19%, soy lecithin 1%, calcium dihydrogen phosphate 1%, choline chloride 1%, compound vitamin premix 1%, compound mineral premix 1%, microcrystalline cellulose 4%, and vitamin C 0.5%.

[0008] A method for preparing a high-protein, low-fat compound feed for juvenile naked carp includes the following steps: Step S1: Grind and sieve the fish meal, chicken meal, pork meal, soy protein concentrate, and soybean meal separately. Step S2: Weigh the raw materials according to the proportions, mix them in a mixer to obtain a mixture; Step S3: Mix fish oil and soybean oil according to the specified ratio and add them to the mixture. Step S4: Condition the mixture in a conditioner. Step S5: The material is granulated using a ring die pellet mill; Step S6: Dry the pelleted feed, cool it to room temperature, and then package and store it.

[0009] Preferably, in step S1, fish meal, chicken meal, pork meal, soy protein concentrate, and soybean meal are respectively fed into a grinder for grinding, the fineness of grinding is controlled, and the mixture is passed through a 60-80 mesh sieve. Brewer's yeast is used as a live bacteria source and is passed through a 60 mesh sieve separately. In step S2, each component is weighed one by one using an electronic scale according to the raw material formula, as follows: The raw material formula for the rapid growth mode is: fish meal 33%, chicken meal 8%, pork meal 5%, soybean protein concentrate 9%, and soybean meal 8%. Liver health formula: 34.5% fish meal, 8% chicken meal, 5% pork meal, 12% soy protein concentrate, and 9% soybean meal; During the mixing and feeding process after weighing the raw materials, first add fish meal, chicken meal, pork meal, soybean protein concentrate, soybean meal, α-starch, and microcrystalline cellulose, then add brewer's yeast, calcium dihydrogen phosphate, choline chloride, compound vitamin premix, compound mineral premix, and vitamin C. Soybean lecithin needs to be premixed with soybean meal at a ratio of 1:3 before being added to the mixer. When using a twin-shaft paddle mixer, the amount of raw materials fed should be controlled at 60-75% of the rated volume of the equipment, the speed of the mixer should be controlled at 30-50 r / min, and the mixing time should be 15-30 minutes. When testing the uniformity of raw material mixing, multiple samples are taken at the discharge port of the mixer to determine the crude protein content and calculate the coefficient of variation (CV).

[0010] Preferably, in step S3, the fish oil and soybean oil are mixed evenly in a container according to the specified ratio, and the water temperature is controlled at 40-50℃. While the mixer is running continuously, gradually add the mixed oil to the mixture in step S2. After the mixed oil has been added, continue mixing for 3-5 minutes. After mixing, samples were taken to test the crude fat content of the feed, with a target value of 6-8%.

[0011] Preferably, in step S4, the oil mixture is fed into a conditioner, the conditioning temperature is adjusted to 80-95°C, and the conditioning time is controlled to 2-5 minutes. During the conditioning of the oil mixture, the temperature and moisture content need to be continuously monitored. After conditioning, the condition of the oil-oil mixture needs to be checked.

[0012] Preferably, in step S5, the conditioned material is fed into a ring die pellet mill. During the pelleting process, the pelleting temperature is controlled at 85-95℃, the die diameter of the ring die pellet mill is 1.5-2.5mm, and the ring die compression ratio of the ring die pellet mill is 1:8-1:10. During the granulation process, samples are taken every 30 minutes to test the particle length, powder content, and hardness.

[0013] Preferably, in step S6, the wet granules are evenly spread on the conveyor belt of the dryer to a thickness of 2-3 cm, the drying temperature of the dryer is controlled at 60-70℃, and the drying time is 15-20 minutes, so that the wet granules are dried to a target moisture content of ≤10%. After the granules are dried, they need to be cooled to room temperature. After cooling, the granules are passed through a vibrating screen to obtain granules with qualified particle size for packaging. When packaging and storing granules, the inner layer of the packaging bag is a vacuum-sealed PE food-grade plastic bag, and the outer layer is a woven bag. After granulation, store in a cool, dry, and well-ventilated place.

[0014] A method for raising juvenile naked carp involves feeding them with formulated feed. The raising steps include pre-raising preparation, control of raising conditions, daily feeding management, and determination of the raising cycle and objectives. Preparation before breeding: Select juvenile naked carp, with an initial weight controlled at 4.5-5.0g; Choose an indoor recirculating aquaculture pond with a water depth of 0.8-1.2m. The pond should be equipped with a constant temperature device, an aerator, a filtration and circulation device, a temperature control probe, and an online pH monitor. When selecting feed, different methods should be chosen, as follows: Rapid growth formula: 46% protein + 6% fat, 33% fish meal; Liver health formula: 49% protein + 6% fat, fish meal 34.5%; Balanced growth and health: 43% protein + 6% fat; Aquaculture conditions control: Aquaculture water temperature: 11-17℃, dissolved oxygen ≥5mg / L; pH: 7.4-7.8, monitored twice daily, ammonia nitrogen <0.02 mg / L, nitrite <0.1 mg / L; Change 20-30% of the water daily; Daily feeding management: Feeding frequency after stocking: 2-3 times a day; Daily feeding amount: Weigh 2-3% of the total weight of the fish and feed in 2-3 times. Take samples and weigh them weekly and adjust the feeding amount according to the weight gain. Determine the breeding cycle and objectives: When the breeding objective is a rapid growth mode: weight gain rate 86.23%, specific growth rate 0.83% / day, feed conversion ratio 2.13, survival rate 94.17%; When the breeding target is liver health mode: weight gain rate 73.55%, specific growth rate 0.79% / day, feed conversion ratio 2.04, survival rate 100%; When the breeding objective is a balanced model: weight gain rate 64.25%, specific growth rate 0.71% / day, and survival rate 95.83%.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This study clarifies for the first time the appropriate protein and fat requirements of juvenile *Gymnocypris lanceolatus*. Through a systematic 4×3 two-factor experimental design with 4 protein levels × 3 fat levels, it elucidates for the first time the appropriate protein and fat requirements of juvenile *Gymnocypris lanceolatus* and the interaction mechanism between the two, filling a gap in the nutritional physiology research of *Gymnocypris lanceolatus*. This study provides important theoretical support and data reference for the artificial conservation, healthy breeding, and precise feed formulation of cold-water protected fish species in high-altitude areas. Under 6% low-fat conditions, growth performance continuously improved with increasing protein levels. After feeding juvenile *Gymnocypris lanceolatus* with a feed ratio of 46% protein + 6% fat for 10 weeks, the weight gain rate reached 86.23%, and the specific growth rate reached 0.83% / day, significantly better than other feed ratios. The visceral-to-body ratio remained at a low level, indicating that this combination met the protein synthesis requirements while avoiding excessive fat deposition.

[0016] 2. Optimized formulation can effectively prevent hepatic steatosis and maintain liver health. Juvenile naked carp have a low tolerance threshold for high-fat diets. When the fat level exceeds 6%, the visceral-to-body ratio increases significantly. When the fat level reaches 10%, obvious steatosis occurs in the liver. The diet with a 49% protein + 6% fat ratio showed significantly fewer lipid droplets in the hepatocytes, with only a few scattered small red particles and a lightly stained background. The hepatic cords were neatly arranged, and the cell nuclei were mostly located in the center of the cells. The liver tissue structure was significantly better than other formulations, which can significantly enhance the liver's antioxidant capacity. The malondialdehyde content in the liver of the 49% protein + 6% fat ratio group was the lowest in the entire study, significantly lower than that of the 43% protein group. The total antioxidant capacity was at a high level, significantly higher than that of the 43% and 46% protein groups. The lysozyme activity reached 8.05 U / mL, significantly higher than other groups, indicating that the 49% protein level can enhance the non-specific immunity of juvenile naked carp.

[0017] 3. The feed conversion ratio of the feed was 2.04-2.13, which was significantly better than that of the high-fat control group. The FCR of the low-fat group was significantly lower than that of the medium-fat group, indicating that the feed utilization efficiency was higher under low-fat conditions. The survival rate was 94.17%-100%, indicating that the feed was suitable for the growth and development of juvenile naked carp and no large-scale mortality due to nutritional inadequacy occurred.

[0018] In summary, by optimizing the protein-to-fat ratio, the growth performance, feed utilization, and liver health of juvenile naked carp can be improved. Specifically, a 46% protein to 6% fat ratio can significantly improve weight gain and specific growth rate, while a 49% protein to 6% fat ratio can effectively reduce hepatic lipid droplet deposition and oxidative stress levels. This approach allows for the determination of an appropriate protein-to-fat ratio based on the nutritional needs of juvenile naked carp, promoting rapid growth while maintaining liver health. It addresses the issues of insufficient specialized feed for naked carp, unreasonable nutritional ratios, and high-fat-induced liver damage, and is suitable for the artificial domestication and large-scale farming of naked carp. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0020] In the attached diagram: Figure 1 This is a flowchart of the feed preparation method of the present invention; Figure 2 This is a flowchart illustrating the feed preparation process of the present invention; Figure 3 This is a graph showing the effects of different protein and fat levels on the weight gain rate and specific growth rate of juvenile naked carp according to the present invention. Figure 4 This is an image showing the results of oil red O staining of the liver of juvenile naked carp at different protein and fat levels according to the present invention; Figure 5 This is a graph showing the effects of different protein and fat levels on the antioxidant index of the liver of juvenile naked carp. Detailed Implementation

[0021] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] like Figure 3-5 As shown in Example 1: For rapid growth mode, the raw material components are weighed according to the following parts by weight: Fish meal 33%, chicken meal 8%, pork meal 5%, soy protein concentrate 9%, soybean meal 8%, brewer's yeast 4%, α-starch 19%, soybean oil 0.2%, soy lecithin 1%, calcium dihydrogen phosphate 1%, choline chloride 1%, compound vitamin premix 1%, compound mineral premix 1%, microcrystalline cellulose 9.3%, and vitamin C 0.5%.

[0023] like Figure 1-2 As shown, a method for preparing a high-protein, low-fat compound feed for juvenile naked carp includes the following steps: Step S1: Grind and sieve the fish meal, chicken meal, pork meal, soy protein concentrate, and soybean meal separately. Step S2: Weigh the raw materials according to the proportions, mix them in a mixer to obtain a mixture; Step S3: Mix fish oil and soybean oil according to the specified ratio and add them to the mixture. Step S4: Condition the mixture in a conditioner. Step S5: The material is granulated using a ring die pellet mill; Step S6: Dry the pelleted feed, cool it to room temperature, and then package and store it.

[0024] S1. Respectively feed five protein raw materials, namely fish meal, chicken meal, pork meal, soy protein concentrate, and soybean meal, into a pulverizer, start the pulverizer for pulverization, control the pulverization fineness, and sieve through a 70-mesh sieve. Use brewer's yeast as the live bacteria source and sieve it through a 60-mesh sieve alone to avoid killing yeast live cells due to excessive heat generation during pulverization. α-starch and microcrystalline cellulose are powder accessories and can be directly used without pulverization. S2. Weigh each component one by one with an electronic balance according to the raw material formula, with a weighing accuracy of ±0.1%. The specific formula is as follows: The raw material formula for the rapid growth mode is: fish meal 33%, chicken meal 8%, pork meal 5%, soy protein concentrate 9%, soybean meal 8%. Liver health mode: fish meal 34.5%, chicken meal 8%, pork meal 5%, soy protein concentrate 12%, soybean meal 9%. During the mixed feeding process after weighing the raw materials, first feed seven bulk raw materials, namely fish meal, chicken meal, pork meal, soy protein concentrate, soybean meal, α-starch, and microcrystalline cellulose, and then feed brewer's yeast, calcium dihydrogen phosphate, choline chloride, compound vitamin premix, compound mineral premix, and VC. Since soybean lecithin is prone to moisture absorption and caking due to containing phospholipids, it needs to be premixed with soybean meal at a ratio of 1:3 first, and then fed into the mixer after premixing. Use a double-shaft paddle mixer, control the raw material feeding amount at 65% of the rated volume of the equipment to avoid affecting the mixing uniformity at full load, control the mixer speed at 40 r / min, and the mixing time at 20 minutes. When detecting the mixing uniformity of the raw materials, take samples at five points, namely in front of, in the middle of, behind, on the left, and on the right of the mixer discharge port, with each point not less than 100 g, measure the crude protein content, calculate the coefficient of variation CV, CV = standard deviation / mean × 100%. If CV ≤ 5% is qualified, otherwise extend the mixing time by 5 minutes and then conduct a re-inspection.

[0025] S3. Stir and mix fish oil and soybean oil evenly in a container in advance, control the water temperature at 45°C to reduce the viscosity of the oil and improve its fluidity. Under the condition of continuous operation of the mixer, gradually add the mixed oil to the mixed material in step S2, and control the addition time at 6 minutes to avoid local oil enrichment. After adding the mixed oil, continue to stir for 4 minutes to make the oil evenly adsorbed on the surface of the powder particles. After mixing, take samples to detect the crude fat content of the feed, with a target value of 7%, ensure uniform oil distribution, consistent color of the material, and no obvious oil spots.

[0026] S4. Feed the oil mixture into the conditioner. The conditioner is a double-jacketed conditioner equipped with a steam injection system. Start the steam valve, introduce saturated steam at a pressure of 0.4 MPa, and adjust the conditioning temperature to 85°C. Controlling the conditioning time to 3 minutes ensures that the material temperature rises uniformly to 85℃, the moisture content increases to 16%, the α-starch is fully gelatinized, and the protein is moderately denatured, thereby improving particle adhesion and digestibility. During the conditioning of oil mixtures, it is necessary to continuously monitor temperature and moisture, and adjust the steam valve opening immediately when the temperature fluctuates by ±2℃. After conditioning, the condition of the oil mixture needs to be checked to ensure that the material is soft to the touch, can be kneaded into a ball, and can be easily crumbled when twisted, without any raw powdery feel or burnt texture.

[0027] S5, the conditioned material is fed into the ring die pellet mill, and a stainless steel ring die is selected to avoid metal ions catalyzing fat oxidation at high temperature; During the pelleting process, the pelleting temperature is controlled at 90℃, and the die diameter of the ring die pellet mill is 2.0mm, which makes it easy for juvenile fish to swallow and prevents the pellets from scattering. The ring die compression ratio of the ring die pellet mill is 1:9, and its spindle speed is determined according to the machine model and output, maintaining a pellet forming rate of ≥95%. During the granulation process, it is necessary to closely monitor the current, the gap between the pressure rollers and the discharge status. Every 30 minutes, samples should be taken to test the particle length, powder content and hardness. Among them, the particle length should be 6mm, the powder content should be ≤5%, and the hardness should be stable in water for ≥10 minutes without disintegrating.

[0028] S6. Spread the wet granules evenly on the conveyor belt of the dryer to a thickness of 2.5cm. Control the drying temperature of the dryer at 65℃ and the drying time at 18 minutes to dry the wet granules to the target moisture content ≤10%. After the particles are dried, they need to be cooled. The dried particles are cooled to room temperature (≤25℃) by a counter-current cooling tower. After the granules are cooled, they are passed through a vibrating screen to remove powder and broken particles, and granules with qualified particle size are obtained to enter the packaging process. The qualified granules have a particle size of 2.0 mm and a length of 6 mm. When packaging and storing the granules, the inner layer of the packaging bag is a vacuum-sealed PE food-grade plastic bag, and the outer layer is a woven bag, with a capacity of 22kg per bag. After granulation, store in a cool, dry, and well-ventilated place at a temperature ≤25℃ and a relative humidity ≤60%. The nutritional levels of the feed in Example 1 were tested and found to be: crude protein 46.04%, crude fat 6.44%, moisture 8.25%, and crude ash 9.79%. Breeding results: weight gain rate 86.23%, specific growth rate 0.83% / day, feed conversion ratio 2.13, survival rate 94.17%, liver oil red O staining showed that lipid droplets were scattered and the liver tissue structure was relatively clear; Example 2: For liver health mode, weigh each raw material component according to the following weight proportions: Fish meal 34.5%, chicken meal 8%, pork meal 5%, soy protein concentrate 12%, soybean meal 9%, brewer's yeast 4%, α-starch 19%, soy lecithin 1%, calcium dihydrogen phosphate 1%, choline chloride 1%, compound vitamin premix 1%, compound mineral premix 1%, microcrystalline cellulose 4%, and vitamin C 0.5%.

[0029] The preparation method is the same as in Example 1; The nutritional levels of the feed in Example 2 were tested and found to be: crude protein 49.73%, crude fat 6.46%, moisture 7.63%, and crude ash 10.01%. Breeding effects: weight gain rate 73.55%, specific growth rate 0.79% / d, feed conversion ratio 2.04, survival rate 100%, liver MDA content 2.59U / mg, T-AOC 21.73U / mg, lysozyme 8.05U / mL, Oil Red O staining showed the fewest lipid droplets, with only a few scattered fine red granules, liver cords were neatly arranged, and cell nuclei were mostly located in the center of the cell; Example 3: To balance growth and health, weigh the raw material components according to the following weight proportions: Fish meal 30%, chicken meal 7%, pork meal 5%, soy protein concentrate 9%, soybean meal 7%, brewer's yeast 4%, α-starch 19%, fish oil 0.2%, soybean oil 0.4%, soy lecithin 1%, calcium dihydrogen phosphate 1%, choline chloride 1%, compound vitamin premix 1%, compound mineral premix 1%, microcrystalline cellulose 13.9%, vitamin C 0.5%; The preparation method is the same as in Example 1; The nutritional levels of the feed in Example 3 were tested and found to be: crude protein 43.38%, crude fat 6.40%, moisture 8.38%, and crude ash 9.98%. Breeding results: weight gain rate 64.25%, specific growth rate 0.71% / day, feed conversion ratio 2.24, survival rate 95.83%; The feed composition and nutrient levels are shown in the table below:

[0030] Comparative Example 1: High-fat control; The feed was prepared in the same manner as in Example 1, except that the fat level was increased to 8%, the fish oil content was adjusted to 1%, the soybean oil content was adjusted to 1.2%, and the microcrystalline cellulose content was adjusted to 7.3%. Breeding results: weight gain rate 76.39%, specific growth rate 0.81% / d, feed conversion ratio 2.11, offal-to-body ratio increased to 10.11%, Oil Red O staining showed that liver lipid droplet density increased and distribution was more dense than in Example 1; Comparative Example 2: High-fat, high-protein control; The feed was prepared in the same manner as in Example 2, except that the fat level was increased to 8%, the amount of fish oil was adjusted to 0.9%, the amount of soybean oil was adjusted to 1.1%, and the amount of microcrystalline cellulose was adjusted to 2%. Breeding results: weight gain rate 73.43%, specific growth rate 0.79% / d, feed conversion ratio 2.21, offal to body ratio increased to 10.47%, Oil Red O staining showed that lipid droplet density was moderate and distribution was relatively uniform, with a significant increase in lipid droplets compared to Example 2; Comparative Example 3: High-fat, high-protein, high-fat control; The feed was prepared in the same manner as in Example 2, except that the fat level was increased to 10%, the amount of fish oil was adjusted to 1.8%, the amount of soybean oil was adjusted to 2.2%, and the amount of microcrystalline cellulose was adjusted to 0 parts. Breeding results: weight gain rate 75.33%, specific growth rate 0.80% / d, feed conversion ratio 2.09, visceral-to-body ratio increased to 10.68%, Oil Red O staining showed a significant increase in lipid droplets, with lipid droplets of varying sizes mixed and distributed, some large vesicles fused, and the hepatic cord structure blurred; Example 4: A method for raising juvenile naked carp is provided, which involves feeding the juvenile naked carp with formulated feed. The raising steps include pre-raising preparation, raising condition control, daily feeding management, and determining the raising cycle and objectives. Preparation before breeding: Select juvenile naked carp that are uniform in size, robust in physique, strong in swimming, free from injury or disease, and with intact scales. The initial weight should be controlled at 4.76±0.04g. Choose an indoor recirculating aquaculture pond with a water transparency of ≥50cm and a water depth of 1.0m. The pond should be equipped with a constant temperature device, an aerator, a filtration and circulation device, a temperature control probe, and an online pH monitor. When initially feeding juvenile naked carp, the feed from Example 1 was used. Subsequent feedings were then adjusted according to different feeding patterns, as detailed below: Rapid growth mode: Use the feed from Example 1, which contains 46% protein + 6% fat and 33% fish meal; Liver health mode: Use the feed from Example 2, 49% protein + 6% fat, 34.5% fish meal; Balanced growth and health: Use the feed from Example 3, which contains 43% protein and 6% fat; Aquaculture conditions control: Aquaculture water temperature: 12℃, dissolved oxygen (DO) ≥ 5mg / L, continuous aeration for 24 hours, dissolved oxygen (DO) ≥ 7mg / L when density is high; pH: 7.4-7.8, weakly alkaline, monitored twice daily, ammonia nitrogen <0.02 mg / L, nitrite <0.1 mg / L; Change 20-30% of the water daily and remove uneaten food and feces promptly; Daily feeding management: Feeding frequency after stocking: 2-3 times a day, increasing to 3 times a day under high density and low water temperature conditions; Daily feeding amount: Weigh 2-3% of the total fish weight and feed in 2-3 portions. Calculation formula: Daily feeding amount (kg) = Total fish weight (kg) × 2%-3%; Each feeding should be completed within 5-10 minutes, with an uneaten feed rate of ≤5%. Weekly sampling and weighing should be conducted, and the feeding amount should be adjusted according to the weight gain. Determine the breeding cycle and objectives: When the breeding objective is a rapid growth mode, select the compound feed of Example 1: weight gain rate 86.23%, specific growth rate 0.83% / day, feed conversion ratio 2.13, survival rate 94.17%, cycle 8-10 weeks, suitable for commercial fattening stage; When the breeding target is a liver health mode, the compound feed of Example 2 was selected: weight gain rate 73.55%, specific growth rate 0.79% / d, feed conversion ratio 2.04, survival rate 100%, liver MDA: 2.59U / mg, T-AOC: 21.73U / mg, lysozyme: 8.05U / mL, significantly reducing liver lipid deposition and oxidative stress; When the breeding goal is a balanced mode, the compound feed of Example 3 is selected: weight gain rate of 64.25%, specific growth rate of 0.71% / day, and survival rate of 95.83%, which takes into account both growth rate and liver burden, and is suitable for the transition from rapid growth to liver health.

[0031] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-protein, low-fat formulated feed for juvenile naked carp, characterized in that: The crude protein content is 46%-49%, and the crude fat content is 6%, comprising the following raw materials by weight percentage: Fish meal 28%-34.5%, chicken meal 6%-8%, pork meal 5%, soy protein concentrate 9%-12%, soybean meal 5%-9%, brewer's yeast 4%, α-starch 19%, fish oil 0%-0.3%, soybean oil 0%-0.6%, soy lecithin 1%, calcium dihydrogen phosphate 1%, choline chloride 1%, compound vitamin premix 1%, compound mineral premix 1%, microcrystalline cellulose 4%-18.5%, vitamin C 0.5%.

2. The high-protein, low-fat formulated feed for juvenile naked carp according to claim 1, characterized in that: The crude protein content is 46% and the crude fat content is 6%. The raw material composition, by weight percentage, is as follows: Fish meal 33%, chicken meal 8%, pork meal 5%, soy protein concentrate 9%, soybean meal 8%, brewer's yeast 4%, α-starch 19%, soybean oil 0.2%, soy lecithin 1%, calcium dihydrogen phosphate 1%, choline chloride 1%, compound vitamin premix 1%, compound mineral premix 1%, microcrystalline cellulose 9.3%, and vitamin C 0.5%.

3. The high-protein, low-fat formulated feed for juvenile naked carp according to claim 1, characterized in that: The crude protein content is 49% and the crude fat content is 6%. The raw material composition, by weight percentage, is as follows: Fish meal 34.5%, chicken meal 8%, pork meal 5%, soy protein concentrate 12%, soybean meal 9%, brewer's yeast 4%, α-starch 19%, soy lecithin 1%, calcium dihydrogen phosphate 1%, choline chloride 1%, compound vitamin premix 1%, compound mineral premix 1%, microcrystalline cellulose 4%, and vitamin C 0.5%.

4. A method for preparing a high-protein, low-fat compound feed for juvenile naked carp according to claim 1, characterized in that: Includes the following steps: Step S1: Grind and sieve the fish meal, chicken meal, pork meal, soy protein concentrate, and soybean meal separately. Step S2: Weigh the raw materials according to the proportions, mix them in a mixer to obtain a mixture; Step S3: Mix fish oil and soybean oil according to the specified ratio and add them to the mixture. Step S4: Condition the mixture in a conditioner. Step S5: The material is granulated using a ring die pellet mill; Step S6: Dry the pelleted feed, cool it to room temperature, and then package and store it.

5. The method for preparing a high-protein, low-fat compound feed for juvenile naked carp according to claim 4, characterized in that: In step S1, fish meal, chicken meal, pork meal, soy protein concentrate, and soybean meal are respectively fed into a pulverizer for pulverization, the fineness of the pulverization is controlled, and the mixture is passed through a 60-80 mesh sieve. Brewer's yeast is used as a live bacteria source and is passed through a 60 mesh sieve separately. In step S2, each component is weighed one by one using an electronic scale according to the raw material formula, as follows: The raw material formula for the rapid growth mode is: fish meal 33%, chicken meal 8%, pork meal 5%, soybean protein concentrate 9%, and soybean meal 8%. Liver health formula: 34.5% fish meal, 8% chicken meal, 5% pork meal, 12% soy protein concentrate, and 9% soybean meal; During the mixing and feeding process after weighing the raw materials, first add fish meal, chicken meal, pork meal, soybean protein concentrate, soybean meal, α-starch, and microcrystalline cellulose, then add brewer's yeast, calcium dihydrogen phosphate, choline chloride, compound vitamin premix, compound mineral premix, and vitamin C. Soybean lecithin needs to be premixed with soybean meal at a ratio of 1:3 before being added to the mixer. When using a twin-shaft paddle mixer, the amount of raw materials fed should be controlled at 60-75% of the rated volume of the equipment, the speed of the mixer should be controlled at 30-50 r / min, and the mixing time should be 15-30 minutes. When testing the uniformity of raw material mixing, multiple samples are taken at the discharge port of the mixer to determine the crude protein content and calculate the coefficient of variation (CV).

6. The method for preparing a high-protein, low-fat compound feed for juvenile naked carp according to claim 5, characterized in that: In step S3, fish oil and soybean oil are mixed evenly in a container according to the specified ratio, and the water temperature is controlled at 40-50℃. While the mixer is running continuously, gradually add the mixed oil to the mixture in step S2. After the mixed oil has been added, continue mixing for 3-5 minutes. After mixing, samples were taken to test the crude fat content of the feed, with a target value of 6-8%.

7. The method for preparing a high-protein, low-fat compound feed for juvenile naked carp according to claim 6, characterized in that: In step S4, the oil mixture is fed into a conditioner, the conditioning temperature is adjusted to 80-95℃, and the conditioning time is controlled to 2-5 minutes. During the conditioning of the oil mixture, the temperature and moisture need to be continuously monitored. After conditioning, the condition of the oil-oil mixture needs to be checked.

8. The method for preparing a high-protein, low-fat compound feed for juvenile naked carp according to claim 7, characterized in that: In step S5, the conditioned material is fed into a ring die pellet mill. During the pelleting process, the pelleting temperature is controlled at 85-95℃, the die diameter of the ring die pellet mill is 1.5-2.5mm, and the ring die compression ratio of the ring die pellet mill is 1:8-1:

10. During the granulation process, samples are taken every 30 minutes to test the particle length, powder content, and hardness.

9. The method for preparing a high-protein, low-fat compound feed for juvenile naked carp according to claim 8, characterized in that: In step S6, the wet granules are evenly spread on the conveyor belt of the dryer to a thickness of 2-3 cm. The drying temperature of the dryer is controlled at 60-70℃, and the drying time is 15-20 minutes to dry the wet granules to a target moisture content of ≤10%. After the granules are dried, they need to be cooled to room temperature. After cooling, the granules are passed through a vibrating screen to obtain granules with qualified particle size for packaging. When packaging and storing granules, the inner layer of the packaging bag is a vacuum-sealed PE food-grade plastic bag, and the outer layer is a woven bag. After granulation, store in a cool, dry, and well-ventilated place.

10. A method for raising juvenile naked carp, characterized in that: Juvenile naked carp were fed with formulated feed. The breeding steps included pre-breeding preparation, breeding condition control, daily feeding management, and determination of the breeding cycle and objectives. Preparation before breeding: Select juvenile naked carp, with an initial weight controlled at 4.5-5.0g; Choose an indoor recirculating aquaculture pond with a water depth of 0.8-1.2m. The pond should be equipped with a constant temperature device, an aerator, a filtration and circulation device, a temperature control probe, and an online pH monitor. When selecting feed, different methods should be chosen, as follows: Rapid growth formula: 46% protein + 6% fat, 33% fish meal; Liver health formula: 49% protein + 6% fat, fish meal 34.5%; Balanced growth and health: 43% protein + 6% fat; Aquaculture conditions control: Aquaculture water temperature: 11-17℃, dissolved oxygen ≥5mg / L; pH: 7.4-7.8, monitored twice daily, ammonia nitrogen <0.02 mg / L, nitrite <0.1 mg / L; Change 20-30% of the water daily; Daily feeding management: Feeding frequency after stocking: 2-3 times a day; Daily feeding amount: Weigh 2-3% of the total weight of the fish and feed in 2-3 times. Take samples and weigh them weekly and adjust the feeding amount according to the weight gain. Determine the breeding cycle and objectives: When the breeding objective is a rapid growth mode: weight gain rate 86.23%, specific growth rate 0.83% / day, feed conversion ratio 2.13, survival rate 94.17%; When the breeding target is liver health mode: weight gain rate 73.55%, specific growth rate 0.79% / day, feed conversion ratio 2.04, survival rate 100%; When the breeding objective is a balanced model: weight gain rate 64.25%, specific growth rate 0.71% / day, and survival rate 95.83%.

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