Method for improving germplasm of procambarus clarkii on market in advance

Abstract

The invention discloses a method for improving germplasm of procambarus clarkii appearing on the market in advance, and belongs to the technical field of procambarus According to the method, a rice field project, a factory-like hatching workshop, a net cage and a plastic greenhouse facility are utilized, screening and breeding are carried out in the growth stages of breeding four crayfishes including egg-carrying crayfishes, larvae-carrying crayfishes, shrimp seeds and backup parents, a certain proportion of excellent individuals are preferably selected in each stage according to target characters, gathering of the target excellent characters is accelerated, and the survival rate of the crayfishes is increased. The population with strong fecundity, fast growth and early marketing can be quickly obtained, and the germplasm improvement process of the crayfish is accelerated. According to the method, through the technical steps of breeding the egg-carrying shrimps in the rice field, carrying out temperature control incubation on the baby shrimps in the incubation workshop, carrying out in-vitro cultivation on the baby seedlings in the net cage, marking the baby seedlings in the plastic greenhouse, cultivating the reserved parent shrimps in the rice field and the like, the egg-carrying shrimps, the baby shrimps, the baby seedlings, large-size shrimp seedlings and commercial shrimps can be obtained in batches in advance, so that the marketing time of the commercial crayfishes is advanced to early and middle April; compared with commercial shrimps cultured in a conventional rice field, the marketing time is advanced by more than 15 days.

Description

Technical Field

[0001] This invention belongs to the field of crayfish breeding technology, specifically relating to a method for improving the germplasm of crayfish that can be marketed earlier. Background Technology

[0002] Currently, with the rapid expansion of crayfish farming, market supply exhibits seasonal imbalances. Crayfish are concentrated on the market in May and June, leading to oversupply, high farming costs, and declining profits. Early-season crayfish, harvested before May, have limited supply, high demand, higher prices, fewer diseases, lower farming costs, and better profits. Currently, early-season crayfish mainly rely on a small amount of overwintered crayfish caught from rice paddies after seedling breeding, and their yield and market timing are unstable.

[0003] After years of closed-loop farming, selective harvesting of larger crayfish while leaving smaller ones to thrive, and adverse selection, the genetic quality of rice paddy crayfish has degenerated, mainly manifested in decreased reproductive capacity, slow growth, poor resistance to adverse conditions, and smaller body size. Currently, most private farmers improve the genetic quality by introducing crayfish from other regions each year to supplement their own crayfish farms. While this method has some effect on improving the genetic quality, it is extensive and lacks precision, making it easy to lose the superior traits of the population.

[0004] In view of this, the present invention selects superior individuals in four stages: autumn breeding of berried shrimp in rice paddies, temperature-controlled incubation in workshops, seedling growth in plastic greenhouses, and breeding of reserve broodstock in rice paddies. At each stage, berried shrimp with a large number of eggs, berried shrimp with a large number of offspring, large-sized shrimp larvae, and marketable shrimp are selected according to a selection ratio of 40-50%. After more than three generations of systematic breeding, a superior population with strong reproductive capacity, fast growth, and early market availability is cultivated, thereby improving the quality of crayfish germplasm. Summary of the Invention

[0005] To address the numerous problems currently existing in the breeding of superior crayfish varieties, this invention proposes a method for improving the germplasm of crayfish that allows for earlier market entry. This method overcomes the drawbacks of traditional crayfish breeding, which involves screening only once per generation at the broodstock stage and results in a slow breeding process. This invention allows for four screenings of superior individuals in each breeding generation, improving the efficiency of breeding, accelerating the aggregation of superior genes in crayfish, and speeding up the germplasm improvement process. Furthermore, the breeding objectives simultaneously consider growth rate and reproductive capacity, and establish superior populations for early market entry.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for improving the genetic quality of crayfish that can be marketed earlier involves using paddy fields, hatching workshops, net cages, and plastic greenhouses to screen and breed crayfish at four main growth stages: berried crayfish, juvenile crayfish, crayfish larvae, and reserve broodstock. At each stage, a certain proportion of superior individuals are selected according to the target traits to accelerate the aggregation of the target superior traits and quickly obtain a population with strong reproductive capacity, fast growth, and early market availability, thereby accelerating the process of crayfish genetic quality improvement.

[0008] As a preferred technical solution of the present invention, the specific steps of the berried shrimp breeding stage in the method for improving the germplasm quality of crayfish for early market launch are as follows:

[0009] (1) Paddy field engineering

[0010] The paddy field area is 10-20 mu. Dig "L", "U" or circular shrimp ditches around the paddy field. The ditches are 2-3m wide and 50-60cm deep. The embankments are 50-60cm high and 1-2m wide. Set up secondary embankments along the side of the shrimp ditches closest to the paddy field. The secondary embankments are 40-50cm wide and 10-20cm high. The slope ratio of the embankments to the ditches is 1:(1-2). The area of ​​the ditches should not exceed 10% of the paddy field area. Set up escape-proof nets 10-20cm below the embankment surface so that the parent shrimp can burrow 10-20cm below the embankment slope, which makes it easy to add water to stimulate the egg-bearing shrimp to come out of the burrow.

[0011] (2) Transplanting of aquatic plants

[0012] In mid-March, transplant two rows of Elodea in the shrimp ditches and two rows of aquatic plants every 8-10m on the field surface, with a spacing of 4-5m between plants. By mid-April, the aquatic plant coverage area is about 50%.

[0013] (3) Rice cultivation

[0014] The rice varieties selected are medium-grain indica rice varieties with a growth period of less than 135 days. Sowing and seedling raising are carried out in mid-to-late April, and the seedlings are transplanted by machine or manually in mid-to-late May. The rice harvest is completed in mid-to-late September.

[0015] (4) Selection and stocking of broodstock shrimp

[0016] In April, in conjunction with the harvesting of reserve broodstock, with large size as the breeding target, the selection pressure is 40-50% to select superior broodstock. From the reserve broodstock, select superior individuals with a size of 25g or more, healthy and active, and with complete appendages as broodstock. The culled reserve broodstock can be sold as commercial shrimp. The selected broodstock are directly and evenly released into the shrimp ditches and surface of the rice paddies to establish a breeding population, with 40-60kg of broodstock per mu of rice paddy.

[0017] (5) Cultivation of broodstock shrimp

[0018] Starting the day after the broodstock shrimp are released, feed them with high-quality crayfish-specific pelleted feed (36% protein content, 2-3mm particle size) at a daily feeding rate of 2-4%. Feed them throughout the field before rice transplanting, and only in the shrimp ditches after rice transplanting. After July, when the temperature exceeds 30℃, reduce the daily feeding rate to 1-2%. When the temperature exceeds 33℃, halve the feeding or stop feeding altogether. Set up feeding platforms and adjust the feeding amount according to the shrimp's feeding behavior.

[0019] (6) Induced reproduction

[0020] In mid-to-late May, in conjunction with rice seedling transplanting, water is gradually drained into ditches to induce broodstock shrimp to enter burrows for mating and reproduction. In mid-to-late June, after the rice seedlings have finished tillering, water is drained into ditches again to induce broodstock shrimp to enter burrows for mating and reproduction. In mid-to-late August, before the rice reaches the waxy ripening stage, the paddy fields are kept in a state of alternating dry and wet conditions to induce crayfish to enter burrows for mating and reproduction. In mid-to-late September, before the rice reaches the yellow ripening stage, the paddy field and ditch water are completely drained to induce broodstock shrimp to enter burrows for ovulation, fertilization, egg-carrying, and hatching. After the rice is harvested, the straw is removed to keep the paddy fields dry. In mid-to-late October, the water level is gradually increased to a level higher than the bottom of the escape-proof nets, submerging all burrows and inducing egg-carrying shrimp to emerge from their burrows.

[0021] (7) Harvesting of berried shrimp

[0022] While adding water, two rows of flower basket traps are set along the shrimp ditches in the paddy fields, and one row of flower basket traps is set along the bottom of the embankment to catch berried shrimp. The fertilized eggs are then classified and incubated at controlled temperatures according to their development stage.

[0023] As a preferred technical solution of the present invention, the specific steps of the egg-bearing shrimp incubation stage in the method for improving the germplasm quality of crayfish for early market launch are as follows:

[0024] (1) Incubation facilities

[0025] Hatching pools are set up in the incubation room. These pools can be square, made of cement or PP material. The construction of the pools depends on the size of the room, with each pool ranging from 10 to 30 square meters. 2 Each hatchery is 0.8m deep and equipped with a water circulation and filtration system, an air source or boiler heating system, a Roots blower or vortex aeration system, and uses a three-dimensional mesh deaeration packing as hatching cover. The heating system controls the hatchery water temperature at 25~26℃; the aeration system controls the dissolved oxygen at above 5mg / L; and the water circulation and filtration system keeps the ammonia nitrogen, nitrite, and pH physicochemical indicators of the hatchery water within the normal range, maintaining the hatchery water quality.

[0026] (2) Screening and hatching of berried shrimp

[0027] From the berried shrimp bred in rice paddies, high-quality berried shrimp with large egg loads and no moldy eggs are selected under a selection pressure of 40-50%. According to the stage of egg development, they are classified and hatched in separate ponds. The water level in the hatching pond is maintained at 50-60cm, the water temperature at 25-26℃, and the dissolved oxygen at 5mg / L or above. After 20-30 days of temperature-controlled hatching, high-quality berried shrimp are obtained.

[0028] As a preferred technical solution of the present invention, the specific steps of in vitro culture of water fry in the method for improving the germplasm quality of crayfish for early market launch are as follows:

[0029] (1) In vitro culture of water lily seedlings

[0030] Cement or canvas ponds, net cages, and plastic greenhouses are used as in vitro culture facilities for fry. Two layers of net cages are installed inside and outside the cement or canvas ponds, and a plastic greenhouse is placed above the ponds to maintain water temperature, prevent rainwater from affecting water quality and brooding shrimp, and promote rapid fry release. Net cages are 2-4 meters in size. 2 A double-layered net cage system is used, with the inner cage accounting for 70-80% of the outer cage area. The inner cage uses a 3-5 mesh net to facilitate the passage of fry leaving the mother through the larger mesh into the outer cage. The outer cage uses a 40-60 mesh net to support the fry leaving the inner cage. The bottom of the outer cage is approximately 10cm below the bottom of the concrete pond, and the bottom of the inner cage is approximately 10cm below the bottom of the outer cage. At a selection pressure of 40-50%, brooding shrimp with a brood size of 200 or more are selected from the hatched shrimp and placed in the inner cage at a density of 20-30 brooding shrimp per square meter. 2 Release the seedlings and promptly remove any detached fry from the outer net cages;

[0031] (2) Temporary cultivation of water lily seedlings

[0032] The juvenile fry are temporarily raised in net cages with a mesh size of 40-60 mesh for 2-3 days, at a density of 100,000-150,000 fry / m². 2 They are mainly fed egg yolk water filtered through a 60-mesh silk screen, which is used to feed the seedlings.

[0033] As a preferred technical solution of the present invention, the specific steps for raising crayfish seedlings in the method for improving the germplasm quality of crayfish for early market launch are as follows:

[0034] (1) Roughing facilities

[0035] Standard coarse water tank: The required area is 1-2 acres, the length is 70-150m, the width is 8-10m, the depth is 0.8-1.0m, the slope ratio is 1:(1-2), the slope is protected by two layers of impermeable geomembrane and 40 mesh polyethylene netting, the bottom of the tank is flat and slightly inclined towards the outlet; and a complete inlet and outlet drainage system is built.

[0036] Plastic greenhouse: A steel frame for a plastic greenhouse is erected above the standard fertilization tank. The steel frame is 80-160m long, 9-10m wide, and 2-3m high. A transparent plastic film can be laid on the greenhouse to increase the air and water temperature inside.

[0037] Concealment: Suspend brushes 70-80cm long in the water in the grading tank, with the bottom of the brushes 10-15cm from the bottom of the water. Set up 3 rows of brushes in the grading tank, with one row of brushes 100-150cm wide on each side and one row of brushes 250-300cm wide in the middle. The brushes are spaced about 20cm apart in each row and 150-200cm apart in each row.

[0038] Aeration facilities: In the pre-coagulation tank, between each row of brushes, install nano aeration discs with a diameter of 20-40cm, one disc every 2-3m, and configure Roots blowers or vortex aerators with a power of 0.4-0.5kw per acre;

[0039] (2) Pond cleaning, disinfection, and fertilization

[0040] 10-15 days before stocking the aquatic seedlings, remove excess silt, disinfect the pond with quicklime, and use bio-fertilizer and Chlorella to cultivate water quality.

[0041] (3) Release of water fry

[0042] After water quality improvement and fertilization, the water was detoxified using an organic acid detoxifying agent. Following a trial run of the aquatic seedlings, the seedlings were released at a density of [number] per m². 2 Stock 150-200 aquatic fry with a size of 80,000-100,000 fish / kg;

[0043] (4) Feeding

[0044] Feed twice daily (6:00-7:00 and 17:00-18:00), with 60% of the daily feeding occurring in the afternoon. Feeding process: shrimp milk powder + brine shrimp larvae (10 days) → crushed feed No. 1 (1mm particle size) (10-15 days) → feed No. 1 (1mm particle size) (30-35 days). Initially feed 40 g / day per 10,000 shrimp larvae, evenly distributed throughout the pond, with feeding platforms provided. Adjust the feeding amount promptly based on feeding behavior. Regularly mix Clostridium butyricum, lactic acid bacteria, or immunomodulatory polysaccharides into the feed to enhance the liver and intestinal health and disease resistance of the shrimp larvae.

[0045] (5) Water quality regulation

[0046] Use low-temperature resistant Bacillus subtilis once every 3-5 days, and potassium persulfate compound salt once every 5-7 days; change the water with well water once every 5-7 days, changing 10-20% of the water each time to maintain good water quality and promote rapid growth of shrimp larvae.

[0047] (6) Shrimp fry harvesting

[0048] After 50-60 days of careful cultivation, the shrimp fry in the nursery pond reach a size of 400-600 shrimp / kg. On consecutive sunny days, all the bristles are removed, and the shrimp fry are caught using knotless traps. The best individuals are selected and released into the prepared paddy fields for raising broodstock.

[0049] As a preferred technical solution of the present invention, the specific steps for breeding backup parents in the method for improving the germplasm quality of crayfish for early market launch are as follows:

[0050] (1) Paddy field preparation

[0051] After the rice is harvested, the straw is completely removed, and the paddy field is thoroughly tilled and exposed to the sun for more than 50 days. In early January, water is added and grass is planted, with the planting area of ​​aquatic grass accounting for 30-40% of the paddy field area. In February, when the temperature rises and stabilizes above 8℃, grass fertilizer is used to promote the rapid growth of aquatic grass.

[0052] (2) Shrimp larvae selection and stocking

[0053] After 50 to 60 days, combined with the harvesting and separate rearing of shrimp fry from the nursery pond, select large-sized shrimp fry (over 2.0g) from the harvested fry at noon on a sunny day, with a selection pressure of 40 to 50%, and release them into the prepared paddy fields at a rate of 15 to 20 kg per acre.

[0054] (3) Feeding

[0055] After the shrimp larvae are released, feed them according to the weather. When the temperature is above 10℃, feed them crayfish pellet feed (1.0~2.0mm in diameter, 36% protein content) once a day at noon on sunny days. Do not feed them when the temperature is below 10℃. After March, feed them once a day at a daily feeding rate of 1~3%. During the cultivation process, pay attention to regulating water quality and maintaining aquatic plants to keep the water quality excellent and the aquatic plants lush and green with a coverage area of ​​about 50%. Feed them evenly throughout the field, set up feeding platforms, and adjust the feeding amount according to their feeding behavior.

[0056] (4) Reservoir parent fish harvesting and selection

[0057] Shrimp larvae are carefully raised for 50-60 days until the broodstock reaches a size of 20g or more. The broodstock is then harvested using slug traps to provide a basic selection population for the selection of superior broodstock. The selected broodstock shrimp reach a size of 25g or more, and the selection pressure is 40-50%.

[0058] As a preferred technical solution of the present invention, the method for improving the germplasm of crayfish that is put on the market ahead of time involves entering the second generation of breeding. In this way, with strong reproductive capacity and fast growth as the breeding objectives, the crayfish are repeatedly selected in the four growth stages of crayfish: berried shrimp, larvae, shrimp larvae, and reserve broodstock, and the best are selected and the worst are eliminated. After 3 to 5 generations of breeding, a superior population of crayfish with strong reproductive capacity and fast growth can be established.

[0059] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0060] 1. This invention can make full use of facilities such as paddy fields, hatching workshops, net cages, and plastic greenhouses to screen and breed crayfish at four growth stages: berried shrimp, juvenile shrimp, shrimp larvae, and reserve broodstock. At each stage, 40-50% of the superior individuals are selected according to the target traits. The comprehensive selection pressure of each generation reaches 2.56-6.25%, which improves the selection efficiency, accelerates the aggregation of the target superior traits, and can quickly obtain populations with strong reproductive capacity, fast growth, and early market availability. This accelerates the process of crayfish germplasm improvement and creates a high-quality crayfish germplasm production and supply base.

[0061] 2. This invention prevents broodstock shrimp from escaping by setting up an escape-proof net 10-20cm below the embankment surface in paddy field engineering, allowing the broodstock shrimp to dig burrows at relatively low points on the embankment surface, making it easy to flood all the burrows; setting up secondary embankments can effectively reduce the damage to rice seedlings by the broodstock shrimp and increase the burrowing space for the broodstock shrimp; and by setting up flower basket traps at the bottom of the shrimp ditches and secondary embankments, the harvesting efficiency of egg-bearing shrimp is improved.

[0062] 3. This invention adopts the method of releasing broodstock shrimp before rice seedling transplanting in April. The broodstock shrimp can be released at low temperatures, which can improve the survival rate. Furthermore, the stress methods such as draining the water into the ditch before rice seedling transplanting in mid-to-late May, draining the water into the ditch again after the rice seedlings have completed tillering in mid-to-late June, alternating between dry and wet conditions in the paddy field in mid-to-late August, and draining the ditch water in mid-to-late September can induce the broodstock shrimp to enter the burrow for mating, spawning, fertilization, egg-carrying, and hatching in advance, thus obtaining high-quality egg-carrying shrimp in advance.

[0063] 4. This invention utilizes facilities such as temperature-controlled incubation in hatching workshops, in vitro cultivation of fry in net cages, growth-promoting of fry in plastic greenhouses, and cultivation of broodstock shrimp in paddy fields. This allows for the early production of juvenile shrimp, fry, large-sized shrimp seedlings, and marketable shrimp in bulk. As a result, the market time for marketable crayfish can be brought forward to early to mid-April, which is more than 15 days earlier than the market time for marketable shrimp raised in conventional paddy fields. This increases the selling price of marketable shrimp and boosts profits.

[0064] 5. This invention improves the efficiency of seedling removal from the body, increases the survival rate of seedlings after removal, and enhances the collection efficiency of seedlings after removal by setting up inner and outer net cages and adopting technical measures such as larger mesh size in the inner net cage and smaller mesh size in the outer net cage. Attached Figure Description

[0065] Figure 1 This is a flowchart illustrating the process of improving the genetic quality of crayfish that are brought to market earlier than usual.

[0066] Figure 2 This is a schematic diagram of the paddy field project.

[0067] Figure 3This is a schematic diagram of a factory-scale incubation facility for berried shrimp.

[0068] The meanings of the reference numerals in the figure are as follows:

[0069] 1-Shrimp ditch, 2-Ditch, 3-Field surface, 4-Field ridge, 5-Escape-proof net, 6-Hatching pond, 7-Three-dimensional mesh deaeration packing, 8-Nano aeration disc, 9-Water circulation treatment filter box, 10-Return water pipe, 11-Water pump, 12-Water well, 13-Boiler heating system, 14-Stainless steel pipe, 15-Vortex aeration system, 16-PE air pipe. Detailed Implementation

[0070] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0071] Example 1:

[0072] Please see Figure 1 As shown, in 2022, an experiment on the genetic improvement of crayfish for early market launch was conducted at Anhui Chunquan Agricultural Technology Co., Ltd. This included 100 mu of rice paddies for breeding broodstock, 50 mu of rice paddies for breeding berried crayfish, and an 800m² hatchery. 2 500 m² in vitro incubation cage 2 Ten standard greenhouses / ponds, covering an area of ​​8000 m². 2 .

[0073] 1. Rice paddy berried shrimp breeding

[0074] (1) Paddy field engineering

[0075] The paddy field covers an area of ​​50 mu (approximately 3.3 hectares), with individual plots ranging from 15 to 20 mu (approximately 1 hectares). A U-shaped shrimp ditch 1 is dug around the perimeter of the paddy field (3). The ditch is 2.5m wide and 60cm deep, with a 60cm high embankment and a 1.5m wide embankment. A secondary embankment 2 is constructed along the paddy field side of the ditch, 50cm wide and 20cm high, with a slope ratio of 1:1.2. A 30cm high escape-prevention net 5 is installed 20cm below the embankment surface (4), allowing the parent shrimp to burrow at lower points on the embankment slope (e.g., ...). Figure 2 (As shown).

[0076] (2) Transplanting of aquatic plants

[0077] In mid-March, two rows of Elodea were transplanted into the shrimp ditches, and two rows of aquatic plants were transplanted every 10m on the field surface, with a spacing of 5m between plants. By mid-April, the aquatic plant coverage area reached 50%.

[0078] (3) Rice cultivation

[0079] The rice variety selected was Fengliangyouxiang No. 1. Sowing and seedling raising were carried out on April 20, 2022, and the seedlings were machine-transplanted on May 18. The seedlings completed tillering on June 16, and the rice was harvested on September 30.

[0080] (4) Selection and stocking of broodstock shrimp

[0081] From April 15 to April 25, 2022, superior individuals weighing over 25g, healthy and active, with intact appendages were selected from the reserve broodstock shrimp cultivated in rice paddies as parent stock. A total of 2,500kg of superior broodstock shrimp were selected and released into the rice paddies, with 50kg of broodstock shrimp stocked per mu of breeding rice paddies to establish a breeding population.

[0082] (5) Cultivation of broodstock shrimp

[0083] Starting the day after stocking the broodstock, feed them with crayfish-specific feed (36% protein content, 2mm particle size) at a daily feeding rate of 2-4%. Feed them evenly throughout the field before transplanting the seedlings on May 18th. After transplanting the seedlings on May 18th, feed them along the shrimp ditches. After July, when the temperature exceeds 30℃, reduce the daily feeding rate to 1-2%. Stop feeding when the temperature exceeds 33℃. Set up feeding platforms and adjust the feeding amount according to the feeding situation.

[0084] (6) Induced reproduction

[0085] From May 15th to 18th, 2022, water was gradually drained into ditches to induce the parent shrimp to enter their burrows for the first time to mate and reproduce. From June 16th to 18th, after the rice seedlings had finished tillering, water was drained into ditches to induce the parent shrimp to enter their burrows for the second time to mate and reproduce. After August 29th, the paddy fields were kept in a state of alternating dry and wet conditions to induce the crayfish to enter their burrows for mating and reproduction. On September 20th, the paddy field water and ditch water were completely drained to induce the parent shrimp to enter their burrows for ovulation, fertilization, egg carrying, and hatching. On October 20th, the water level was gradually increased to a level higher than the bottom of the escape-proof nets, submerging all the burrows and inducing the egg-carrying shrimp to emerge from their burrows.

[0086] (7) Harvesting of berried shrimp

[0087] On October 20, two rows of flower basket traps were set along the shrimp ditches in the rice paddies, and one row of flower basket traps was set along the bottom of the embankment to catch berried shrimp. When collecting berried shrimp, it is necessary to handle them gently and operate them in the water to prevent injury to the berried shrimp and loss of eggs. The collection of berried shrimp ended on October 26, 2022, with a total of 30,000 berried shrimp collected.

[0088] 2. Selection and industrialized hatching of berried shrimp

[0089] (1) Incubation facilities

[0090] Set up an 800 m² incubation facility. 2 The incubation facility includes 6 cement pools as incubation pools, with a total of 25 incubation pools, each 20m². 2Each hatchery is 0.8m deep and equipped with a water circulation and filtration box 9, a boiler heating system 13, and a vortex aeration system 15. A three-dimensional mesh deaeration packing material 7 is used as the hatching cover. The vortex aeration system 15 is connected to several nano-aeration discs 8 arranged in the hatchery via PE air pipes 16. The boiler heating system 13 is circulated repeatedly in each hatchery via stainless steel pipes 14. The water circulation and filtration box 9 is connected to a water pump 11 via a return water pipe 10, forming a water treatment system. It is also connected to a water well 12 via pipelines to provide fresh water to the hatchery (e.g., water from a well). Figure 3 (As shown).

[0091] During incubation, maintain the water temperature in the incubation tank at 25-26℃ and control dissolved oxygen above 5 mg / L. Keep the physicochemical indicators of the incubation water, such as ammonia nitrogen, nitrite, and pH, within normal ranges, and maintain clear incubation water quality.

[0092] (2) Screening and hatching of berried shrimp

[0093] From October 21st to 26th, 2022, 15,000 superior berried shrimp with more than 400 eggs were selected from the breeding berried shrimp population. These shrimp were then classified and hatched in separate ponds according to their egg development stages, with a stocking density of 30 shrimp / m². 2 By maintaining a water level of 60cm, a water temperature of 25-26℃, and dissolved oxygen above 5mg / L in the hatching pond, a total of 12,000 high-quality juvenile shrimp were obtained from November 15 to November 25, 2022.

[0094] 3. In vitro culture and temporary culture of aquatic seedlings

[0095] (1) In vitro culture of water lily seedlings

[0096] In November 2022, facilities for the in vitro cultivation of fry were set up, including cement ponds, net cages, and plastic greenhouses. Two layers of net cages were set up in the cement ponds, and a plastic greenhouse was set up above the cement ponds to help maintain water temperature, prevent rainwater from affecting water quality and brooding shrimp, and promote the rapid release of fry.

[0097] Set up a 500 m³ cement pond for in vitro culture of water fry. 2 Two layers of wire mesh cages, inner and outer, are installed in the cement pool, with each inner cage measuring 3m in length. 2 Mesh size: 5 mesh; External mesh box: 4m in length. 2 The netting had a mesh size of 40 meshes; a total of 100 inner and 100 outer net cages were set up. From November 15 to November 25, 2022, in conjunction with the hatching of brooding shrimp, and with a selection pressure of 50%, 6,000 brooding shrimp with an average number of over 200 brooding shrimp were selected from the hatched brooding shrimp and released into the inner net cages, with 60 brooding shrimp in each inner net cage. The detached fry in the outer net cages were also removed in a timely manner. By November 28, 2022, a total of 1.5 million fry had been obtained.

[0098] (2) Temporary cultivation of water lily seedlings

[0099] A 4m diameter cement pool is installed. 2 Three net cages with a mesh size of 40 are used, each temporarily holding 500,000 shrimp larvae. They are mainly fed egg yolk water filtered through a 60-mesh silk screen, with 3-5 egg yolks given to each cage daily. After 2-3 days of temporary holding, they are transferred to nursery ponds for larger-sized shrimp rearing.

[0100] 4. Thickening of water lily seedlings in plastic greenhouse

[0101] (1) Plastic greenhouse facilities

[0102] Standardization ponds: From October 10th to 20th, 2022, a total of 10 standardization ponds were set up, each with an area of ​​800 m². 2 The pool is 80m long, 8m wide, and 1.0m deep, with a slope ratio of 1:(1~2). It utilizes two layers of slope protection: an impermeable geomembrane and 40-mesh polyethylene mesh. The bottom of the pool is flat and slopes slightly towards the outlet. A complete inlet and outlet system is also provided. The silt in the standard coarse-grained pool is thoroughly removed using a slurry suction machine. 100kg of quicklime is applied per acre, and the entire pool is covered with a slurry and thoroughly exposed to sunlight for at least 15 days.

[0103] Plastic greenhouse: A steel frame greenhouse is constructed above the standard coagulation pool. The steel frame is 90m long, 9m wide, and 2m high. A plastic film is laid on the greenhouse to increase the air and water temperature inside.

[0104] Concealment: Suspend brushes 70cm long in the water in the grading tank, with the bottom of the brush 10cm above the bottom of the water. Set up 3 rows of brushes in the grading tank: one row of brushes 120cm wide on each side and one row of brushes 240cm wide in the middle, with each row of brushes spaced about 20cm apart. The spacing between each row of brushes is 160cm.

[0105] Oxygenation facilities: In the pre-coagulation tank, nano-aeration discs with a diameter of 40cm are installed between each row of brushes, with one disc every 3m. A 5.5kw Roots blower is provided, and air is delivered into the nano-aeration discs through PVC pipes and hoses to increase the oxygen in the water.

[0106] (2) Water quality cultivation

[0107] On November 8, 2022, 80cm of water was added to the standard coarse water tank. 2.5kg of amino acid fertilizer paste and 2.5kg of potassium humate were used in each tank. After fertilization, 1L of Chlorella seed was sprinkled to enrich the water quality.

[0108] (3) Release of water fry

[0109] From November 15th to 28th, 2022, a total of 1.5 million fry (80,000-100,000 fry / kg) were stocked, with 150,000 fry released into each nursery pond. One hour before stocking, the entire pond was treated with a stress-relief vitamin C solution.

[0110] (4) Feeding

[0111] Feed twice daily (6:00-7:00 and 17:00-18:00), with 60% of the daily feeding occurring in the afternoon. The feeding process is as follows: shrimp milk powder (48% protein) + brine shrimp larvae for 10 days → crushed feed (36% protein, 1mm particle size) for 15 days → feed (36% protein, 1mm particle size) for 35 days. Initially, feed 6kg / day, increasing to 65kg / day in the later stages of rearing. Adjustments are made dynamically based on the remaining feed on the feeding platform. Regularly mix Clostridium butyricum, lactic acid bacteria, or immunomodulatory polysaccharides into the feed (twice a week) to maintain hepatobiliary health and enhance the shrimp larvae's disease resistance.

[0112] (5) Water quality regulation

[0113] Use low-temperature resistant Bacillus every 3-5 days, 1-1.5 kg per nursery pond each time; use potassium persulfate compound salt (20%) every 5-7 days, 200-300 g per nursery pond each time; change the water with well water every 5-7 days, 10-20% each time, to maintain good water quality and promote rapid growth of shrimp larvae.

[0114] (6) Shrimp fry harvesting

[0115] From January 20 to February 10, 2023, on consecutive sunny days, the brushes in the nursery ponds were removed, and 30 knotless traps were set in each nursery pond to catch shrimp larvae. A total of 2,000 kg of shrimp larvae with a size of 400-600 shrimp / kg were caught.

[0116] 5. Cultivation of broodstock shrimp in paddy fields

[0117] (1) Paddy field preparation

[0118] Set up 100 mu of paddy fields. After the rice is harvested, the paddy fields are thoroughly tilled and exposed to the sun for more than 50 days. On December 12, 2022, water is added and Elodea is transplanted. The planting area of ​​aquatic plants accounts for 30-40% of the paddy field area.

[0119] (2) Shrimp larvae selection and stocking

[0120] From January 20 to February 10, 2023, in conjunction with the harvesting and separate rearing of shrimp fry from the nursery ponds, and with size as the selection target, and with a selection pressure of 50%, large-sized shrimp fry weighing 2g or more were selected from the harvested shrimp fry and released into the prepared paddy fields. A total of 1,000 kg of shrimp fry were released, with 10 kg released per mu.

[0121] (3) Feeding

[0122] From January to February, shrimp larvae are released and fed. When the temperature is above 10℃, feed the crayfish once a day at midday on sunny days with crayfish pellet feed (1.0-2.0mm in diameter, 36% protein content); do not feed when the temperature is below 10℃. From March onwards, feed once a day at a rate of 1-3%, with a daily feed intake of 10-150kg. Set up feeding platforms and adjust the feeding amount according to the feeding situation. During the cultivation process, pay attention to regulating water quality and maintaining aquatic plants to keep the water quality excellent and the aquatic plants lush and green with a 50% coverage area.

[0123] (4) Fishing of reserve parent stock

[0124] From April 10 to 28, 2023, reserve parent stock was harvested using slug traps, with a total of 4,750 kg of reserve parent stock harvested, providing reserve parent stock for the selection of superior parent stock.

[0125] 6. Breeding Results

[0126] By November 2025, after four generations of systematic breeding, 5,000 kg of superior crayfish populations were preserved at Anhui Chunquan Agricultural Technology Co., Ltd. The average number of eggs carried by crayfish reached 415 per crayfish, and the average size of 80-day-old crayfish reached 32g, which were 18.6% and 28% higher than before the breeding, respectively.

Claims

1. A method for improving the germplasm quality of crayfish to facilitate earlier market entry, characterized in that, By utilizing paddy field engineering, factory-style hatching workshops, net cages, and plastic greenhouse facilities, selection and breeding are carried out at four growth stages of crayfish: berried shrimp breeding, broodstock hatching, in vitro culture and rearing of shrimp larvae, and breeding of reserve broodstock. At each stage, according to the target traits, superior individuals are selected with a selection pressure of 40-50%, which accelerates the aggregation of the target superior traits, quickly obtains a population with strong reproductive capacity and fast growth, and speeds up the process of crayfish germplasm improvement.

2. The method for improving the germplasm quality of crayfish for earlier market launch as described in claim 1, characterized in that, The specific steps of the berried shrimp's reproductive stage are as follows: (1) Paddy field engineering The paddy field area is 10-20 mu. "L", "U" or circular shrimp ditches are dug around the paddy field. The ditches are 2-3m wide and 50-60cm deep. The embankments are 50-60cm high and 1-2m wide. Sub-embankments are set up along the side of the shrimp ditches closest to the paddy field. The sub-embankments are 40-50cm wide and 10-20cm high. The slope ratio of the embankments to the ditches is 1:(1-2). The area of ​​the ditches should not exceed 10% of the paddy field area. An escape-proof net is set up 10-20cm below the embankment surface so that the parent shrimp can burrow 10-20cm below the embankment slope, making it easier to add water to stimulate the egg-bearing shrimp to come out of the burrow. (2) Transplanting of aquatic plants In mid-March, transplant two rows of Elodea in the shrimp ditches, and transplant two rows of aquatic plants every 8-10m on the field surface, with a spacing of 4-5m between plants. By mid-April, the aquatic plant coverage area reaches 50%. (3) Rice cultivation The rice varieties selected are medium-grain indica rice varieties with a growth period of less than 135 days. Sowing and seedling raising are carried out in mid-to-late April, and the seedlings are transplanted by machine or manually in mid-to-late May. The rice harvest is completed in mid-to-late September. (4) Selection and stocking of broodstock shrimp In April, in conjunction with the harvesting of reserve broodstock, with large size as the breeding target, the selection pressure is 40-50% to select superior broodstock. From the reserve broodstock, superior individuals with a size of 25g or more, healthy and active, and with complete appendages are selected as broodstock. The culled reserve broodstock are sold as commercial shrimp. The selected broodstock are evenly released along the shrimp ditches and surface of the rice paddies. A breeding population is established, with 40-60kg of broodstock stocked per acre. (5) Cultivation of broodstock shrimp Starting the day after stocking the broodstock, feed them with high-quality crayfish-specific pelleted feed (36% protein content, 2-3mm particle size) at a daily feeding rate of 2-4%. Feed them throughout the field before rice transplanting, and only in the shrimp ditches after rice transplanting. After July, when the temperature exceeds 30℃, reduce the daily feeding rate to 1-2%. When the temperature exceeds 33℃, halve the feeding or stop feeding altogether. Set up feeding platforms and adjust the feeding amount promptly according to the feeding situation. (6) Induced reproduction In mid-to-late May, in conjunction with rice seedling transplanting, gradually drain water into ditches to induce broodstock shrimp to enter burrows for mating and reproduction; in mid-to-late June, after the rice seedlings have sufficiently tillered, drain water into ditches to induce broodstock shrimp to enter burrows again for mating and reproduction; in mid-to-late August, during the early waxy ripening stage of rice, maintain a state of alternating dry and wet conditions in the paddy fields to induce broodstock shrimp to enter burrows for mating and reproduction; in mid-to-late September, during the early yellow ripening stage of rice, completely drain the paddy fields and ditches to induce broodstock shrimp to enter burrows for spawning, fertilization, egg-carrying, and hatching; after rice harvesting, remove straw and keep the paddy fields dry; in mid-to-late October, gradually increase the water level to above the bottom of the escape-proof nets to submerge all burrows and induce egg-carrying shrimp to emerge from their burrows; (7) Harvesting of berried shrimp While adding water, two rows of flower basket traps are set along the shrimp ditches in the paddy fields, and one row of flower basket traps is set along the bottom of the embankment to catch berried shrimp; and the fertilized eggs are classified and incubated at controlled temperatures according to their development stage.

3. The method for improving the germplasm quality of crayfish for earlier market launch as described in claim 2, characterized in that, The specific steps of the berried shrimp incubation stage are as follows: (1) Incubation facilities Hatching pools are set up in the incubation room. The incubation pools are square pools made of cement or PP material. The construction of the incubation pools depends on the size of the room, with each incubation pool ranging from 10 to 30 square meters. 2 Each hatchery is 0.8m deep and equipped with a water circulation and filtration system, an air source or boiler heating system, a Roots blower or vortex aeration system, and uses a three-dimensional mesh deaeration packing as a concealment. The heating system controls the hatchery water temperature at 25~26℃; the aeration system controls the dissolved oxygen at above 5mg / L; and the water circulation and filtration system controls the ammonia nitrogen, nitrite, and pH physicochemical indicators of the hatchery water within the normal range, maintaining high-quality and clear hatchery water. (2) Screening and hatching of berried shrimp From the berried shrimp bred in rice paddies, high-quality berried shrimp with large egg loads and no moldy eggs are selected under a selection pressure of 40-50%. According to the stage of egg development, they are classified and hatched in separate ponds. The water level in the hatching pond is maintained at 50-60cm, the water temperature at 25-26℃, and the dissolved oxygen at 5mg / L or above. After 20-30 days of temperature-controlled hatching, high-quality berried shrimp are obtained.

4. The method for improving the germplasm quality of crayfish for earlier market launch as described in claim 3, characterized in that, The specific steps for the in vitro culture of the shrimp larvae are as follows: (1) In vitro culture of water lily seedlings Cement or canvas ponds, net cages, and plastic greenhouses are used as in vitro culture facilities for fry. Two layers of net cages are installed inside and outside the cement or canvas ponds, and a plastic greenhouse is placed above the ponds to maintain water temperature, prevent rainwater from affecting water quality and brooding shrimp, and promote rapid fry release. Net cages are 2-4 meters in size. 2 A double-layered net cage system is used, with the inner cage accounting for 70-80% of the outer cage area. The inner cage uses a 3-5 mesh net to facilitate the passage of fry leaving the mother through the larger mesh into the outer cage. The outer cage uses a 40-60 mesh net to support the fry leaving the inner cage. The bottom of the outer cage is 10cm from the bottom of the concrete pond, and the bottom of the inner cage is 10cm from the bottom of the outer cage. At a selection pressure of 40-50%, brooding shrimp with more than 200 brooding shrimp are selected from the hatched shrimp and released into the inner cage at a density of 20-30 brooding shrimp per square meter. 2 Release the seedlings and promptly remove any detached fry from the outer net cages; (2) Temporary cultivation of water lily seedlings The juvenile fry are temporarily raised in net cages with a mesh size of 40-60 mesh for 2-3 days at a density of 100,000-150,000 fry / m². 2 They are mainly fed egg yolk water filtered through a 60-mesh silk screen, which is used to feed the seedlings.

5. The method for improving the germplasm quality of crayfish for earlier market launch as described in claim 4, characterized in that, The specific steps for raising shrimp larvae are as follows: (1) Roughing facilities Standard coarse water tank: The required area is 1-2 acres, the length is 70-150m, the width is 8-10m, the depth is 0.8-1.0m, the slope ratio is 1:(1-2), the slope is protected by two layers of impermeable geomembrane and 40 mesh polyethylene netting, the bottom of the tank is flat and slightly inclined towards the outlet; and a complete inlet and outlet drainage system is built. Plastic greenhouse: A steel frame for a plastic greenhouse is erected above the standard fertilization pool. The steel frame is 80-160m long, 9-10m wide, and 2-3m high. A transparent plastic film is laid on the greenhouse to increase the air and water temperature inside. Concealment: Suspend brushes 70-80cm long in the grading tank, with the bottom of the brush 10-15cm above the bottom of the water. Set up 3 rows of brushes in the grading tank, with one row of brushes 100-150cm wide on each side and one row of brushes 250-300cm wide in the middle. The brushes are spaced 20cm apart in each row and 150-200cm apart in each row. Aeration facilities: In the pre-breeding tank, nano-aeration discs with a diameter of 20-40cm are installed between each row of brushes, with one disc every 2-3m. Roots blowers or vortex aerators with a power of 0.4-0.5kw are provided per acre. (2) Pond cleaning, disinfection, and fertilization 10-15 days before stocking the aquatic seedlings, remove excess silt, disinfect the pond with quicklime, and use bio-fertilizer and Chlorella to cultivate water quality. (3) Release of water fry After water quality improvement and fertilization, the water was detoxified using an organic acid detoxifying agent. Following a trial run of the aquatic seedlings, the seedlings were released at a density of [number] per m². 2 Stock 150-200 aquatic fry with a size of 80,000-100,000 fish / kg; (4) Feeding Feed twice daily (6:00-7:00 and 17:00-18:00), with 60% of the daily feeding occurring in the afternoon. Feeding process: shrimp milk powder + brine shrimp larvae (10 days) → crushed feed No. 1 (1mm particle size) (10-15 days) → feed No. 1 (1mm particle size) (30-35 days). Initially feed 40 g / day per 10,000 shrimp larvae, evenly distributed throughout the pond, with feeding platforms provided. Adjust the feeding amount promptly based on feeding behavior. Regularly mix Clostridium butyricum, lactic acid bacteria, or immunomodulatory polysaccharides into the feed to enhance the liver and intestinal health and disease resistance of the shrimp larvae. (5) Water quality regulation Use low-temperature resistant Bacillus subtilis once every 3-5 days, and potassium persulfate compound salt once every 5-7 days; change the water with well water once every 5-7 days, changing 10-20% of the water each time to maintain good water quality and promote rapid growth of shrimp larvae. (6) Shrimp fry harvesting After 50-60 days of careful cultivation, the shrimp fry in the nursery pond reach a size of 400-600 shrimp / kg. On consecutive sunny days, all the bristles are removed, and the shrimp fry are caught using knotless traps. The best individuals are selected and released into the prepared paddy fields for raising broodstock.

6. The method for improving the germplasm quality of crayfish for earlier market launch as described in claim 5, characterized in that, The specific steps for breeding the backup parent lines are as follows: (1) Paddy field preparation After the rice is harvested, the straw is completely removed, the paddy field is thoroughly tilled and exposed to the sun for more than 50 days. In early December, water is added and aquatic plants are transplanted. The planting area of ​​aquatic plants accounts for 30-40% of the paddy field area. In February, when the temperature rises and stabilizes above 8℃, grass fertilizer is used to promote the rapid growth of aquatic plants. (2) Shrimp larvae selection and stocking Combined with the separate rearing of shrimp fry harvested from the nursery ponds, with the selection target being large size, and with a selection pressure of 40-50%, large-sized shrimp fry weighing over 2g are selected from the reared shrimp fry and released into the prepared paddy fields at a rate of 15-20kg per acre. (3) Feeding After the shrimp larvae are released, feed them according to the weather. If the temperature is above 10℃, feed them crayfish pellet feed (1.0~2.0mm in diameter, 36% protein content) once a day on a sunny midday. Do not feed them if the temperature is below 10℃. After March, feed them once a day at a daily feeding rate of 1~3%. During the cultivation process, pay attention to regulating water quality and maintaining aquatic plants to keep the water quality excellent and the aquatic plants lush and green with a coverage area of ​​50%. (4) Reservoir parent fish harvesting and selection Shrimp larvae are carefully raised for 50-60 days until the broodstock reaches a size of 20g or more. The broodstock are then caught using knotless traps to provide a basic selection population for the selection of superior broodstock. The selected broodstock are 25g or more in size, with a selection pressure of 40-50%. The selected broodstock are then released into rice paddies where berried shrimp are bred.

7. The method for improving the germplasm quality of crayfish for earlier market launch as described in claim 6, characterized in that, In the second generation of breeding, selection is carried out repeatedly at the four growth stages of crayfish: berried shrimp, juvenile shrimp, shrimp larvae, and replacement broodstock, with the principle of survival of the fittest. After 3 to 5 generations of breeding, a high-quality population of crayfish with strong reproductive capacity and fast growth can be established.

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