Method and system for early breeding of rana nigromaculata and breeding of froglets

Abstract

The invention relates to the technical field of aquaculture, in particular to a rana nigromaculata early breeding and froglet breeding method and system. On the basis of temperature control and water body stimulation of'fullness, drying and refullness', awakening and delivery are promoted under the condition of no exogenous hormone; a stepped terrain is constructed in the same temperature control greenhouse, the water level and the water-land ratio are adjusted in a linkage mode according to a population metamorphosis rate threshold value, and continuous operation of incubation, cultivation, metamorphosis and food domestication is achieved in cooperation with a water inlet and outlet net bag with the replaceable mesh number, an anti-escape fence and moving / film covering food tables on the two sides. Compared with a conventional pond dividing mode, breeding can be advanced by more than or equal to 2 months, and froglets appear on the market to July; the survival rate of incubation and metamorphosis is improved, drowning is remarkably reduced, the success rate of domestication and the specification uniformity are improved, meanwhile, carrying stress is reduced, and the unit fry cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aquaculture technology, in particular to a method and system for early breeding of Pelophylax nigromaculatus and cultivation of young frogs. BACKGROUND

[0002] Pelophylax nigromaculatus is a common edible and medicinal amphibian in China, with wide distribution and strong adaptability. The breeding season usually starts after winter with rising temperature, and the eggs are laid in shallow water areas, with a clutch of several hundred to several thousand eggs. This species is widely distributed in eastern and central China, and has formed a coexistence breeding mode represented by rice field coexistence for a long time. However, it still faces the common problems of seasonal market concentration and the survival rate of fry being greatly affected by climate fluctuations.

[0003] The mainstream "rice-frog coexistence" mode of the existing industry constructs breeding pools, hatching pools, fry pools and breeding pools in different zones in rice fields, and matches micro-flow water, density and water level control to improve hatching and growing efficiency. The main disadvantages of this mode are: ① The initial investment of rice-frog coexistence mode is large, with a cost of 16000-18000 yuan per mu in the first year (including mechanized facilities), and the cost of young frogs is about 3500 yuan (directly purchasing young frog seeds). ② The breeding season of black-spotted frogs is seasonal. Young frogs are released in early July, and start to be marketed in September, and black-spotted frogs start to hibernate in November. The time of large-scale marketing of black-spotted frogs is only 2 months. Concentrated marketing will result in low prices and reduced profits. In addition, in recent years, climate change has been large, and spring temperature is fluctuating, which has a great impact on the hatching and survival rate of tadpoles.

[0004] Early breeding of black-spotted frogs can effectively solve the above problems. That is, in addition to natural breeding in March-April, a series of technical measures are taken to make part of the black-spotted frog parents lay eggs and hatch in January-February, so as to cultivate large-scale early breeding young frogs. The advantages are: first, the marketing time is greatly advanced, filling the lack of frog period in May-July. Second, early breeding can intensively breed tadpoles, and the temperature and other conditions can be controlled, which can effectively improve the survival rate of seeds. Third, the early breeding of black-spotted frogs is not synchronized with the natural breeding of black-spotted frogs, which is conducive to maintaining the purity of the breeding population, facilitating the further breeding of black-spotted frogs, and is conducive to the optimization of black-spotted frog germplasm resources, laying a foundation for the sustainable development of black-spotted frog industry.

[0005] Chinese patent CN114532294B proposes to divide the rice field into zones according to function and adopt "three-level single ditch" transformation, and clearly defines the area and ratio of each functional zone, and installs a micro-flow water pipe above the hatching pool to increase oxygen, so as to realize orderly breeding and moderate advance of marketing (80% of the commercial frogs are larger than or equal to 40g in size). This scheme also emphasizes the necessity of anti-escape infrastructure such as netting and netting.

[0006] In terms of feeding and domestication, some technologies gradually domesticate Pelophylax nigromaculatus from "motile feeding" to "static feeding" through long-term selection and bait distribution, so as to adapt to artificial feed and reduce the risk of disease transmission caused by artificial driving. Chinese patent CN107616142B gives the area ratio of rice and frogs, the size of water ditch and the key points of temperature control, and proposes a behavior domestication path of 3-5 generations to improve the efficiency and economy of feeding.

[0007] For the complete process management of breeding and growing, Chinese patent CN106106348A gives a more systematic "seed selection, cultivation, spawning, incubation, tadpole feeding, juvenile frog management, and adult frog management" steps and key water environment parameters (such as incubation water temperature 18-31℃, pH 6.8-8.0, water depth 20-30cm, dissolved oxygen ≥3mg / L), emphasizing that the water level should be controlled to the edge of the feeding table when the tadpole's forelimbs are out and the tail is shrinking, reducing stress and facilitating landing.

[0008] To alleviate the contradiction between seasonality and concentrated marketing, some early breeding technologies attempt to induce spawning in February through exogenous hormones. For example, Chinese patent CN116548374A proposes "batch artificial breeding method of early Pelophylax nigromaculatus", which uses LHRH-A2 about 1.05-1.25μg and HCG about 40-45IU per individual to induce spawning in February, and uses net cage micro-flow water to concentrate incubation under the condition of spawning above 16℃ and incubation above 14℃ to obtain early fry, thereby extending the growth cycle and marketing early.

[0009] Some practitioners attempt to use a spawning needle to promote early breeding of Pelophylax nigromaculatus, however, this approach is not ideal in subsequent fry cultivation process. In addition, the metamorphosis development process of tadpoles after breeding is inconsistent, such as not changing the water-land ratio in time, which can lead to the phenomenon of juvenile frog drowning, thereby adversely affecting the overall cultivation efficiency. SUMMARY

[0010] To solve the above technical problems, the technical purpose of the present application is to provide an early breeding and juvenile frog integrated cultivation method and system suitable for Pelophylax nigromaculatus, which uses engineering means to promote awakening and spawning through temperature control and "filling, drying, and refilling" water stimulation without exogenous hormones, and realizes continuous operation of incubation, tadpole cultivation, metamorphosis, and juvenile frog domestication in the same temperature-controlled greenhouse with a ladder-type terrain, combined with adjustable water level, replaceable mesh escape-proof net, and feeding table arrangement, to solve the problems of handling stress caused by existing dispersed multi-pool management, drowning caused by metamorphosis out of sync, difficulty in real-time matching of water-land ratio, and seasonal concentrated marketing, thereby improving the consistency of fry survival and domestication, reducing unit cost, and significantly advancing the marketing time.

[0011] To achieve the purpose of the present application, the following technical solutions are adopted:

[0012] A method for early breeding of Rana nigromaculata and cultivation of tadpoles, comprising the following steps:

[0013] S1, overwintering and awakening of parents: in a closed greenhouse with controllable ventilation and heating, the parents are kept in a water-free environment to maintain hibernation; in February-March of each year, the greenhouse temperature is raised to 13-17°C, and the water stimulation program of "filling up and draining, and filling up again the next day" is implemented in the frog pond, to induce the end of hibernation and trigger spawning under the condition of no exogenous hormone.

[0014] S2, fertilized egg collection and hatching: collect egg masses 2 hours after spawning and transfer them to the stepped cultivation area in the same greenhouse for hatching, with an egg laying density of 4x10 4 ~ 5x10 4 particles / m2, and maintain water temperature ≥15°C, pH 6.8-8.0, water depth 20-50 cm, and dissolved oxygen ≥3 mg / L;

[0015] S3, tadpole cultivation and water-land ratio linkage: tadpoles open their mouths one week after hatching, and the powder spraying, dough positioning, and 0.5-1.0 mm particle feeding programs are implemented according to the growth stage; the water level is linked and controlled according to the metamorphosis rate threshold value: when metamorphosis occurs, the water level is slowly lowered to expose a small amount of land, and when the metamorphosis rate reaches 70-80%, the water level is lowered to expose the feeding table, and then gradually lowered to the middle water channel as the metamorphosis rate and domestication rate increase;

[0016] S4, artificial domestication of juvenile frogs: feeding twice a day at 7:00-8:00 and 16:00-17:00, and retaining a small amount of food at night, using black-spotted frog special feed with crude protein content of 40-42% and particle size of 0.8-1.0 mm for 2-5 days of domestication;

[0017] S5, seedling release: when the body weight of juvenile frogs reaches ≥4 g / tail, they are released after screening or transferred to rice fields for further cultivation.

[0018] As a preferred embodiment, the stepped cultivation area is a plurality of steps formed along the ground surface, each step is 15-25 cm high, the horizontal width of adjacent steps is 0.6-1.5 m, and a continuous gentle slope is formed between the lowest step and the highest step, and high-stem plants can be planted above the steps to form a shade belt.

[0019] As a preferred embodiment, the water stimulation program of S1 is: after the temperature is raised and stabilized, the frog pond is filled with water to the working water level and kept for 1-2 hours, then completely drained and kept dry for 12-24 hours, then filled with water to the working water level again and kept for 12-24 hours, then maintained at a constant temperature of 15±2°C and reduced light disturbance to induce spawning.

[0020] As preferred, the inlet and outlet of the incubation and cultivation stage are respectively equipped with 60-80 mesh replaceable mesh bags, which are gradually replaced by 20 mesh mesh bags with the metamorphosis process; a 1.0-1.2 m high escape-proof fence is provided around the greenhouse, and support posts are provided at an interval of 1 m.

[0021] As preferred, the feeding program is as follows: opening feeding of powder after 7 days after membrane rupture; transition to dough fixed point from the 8th to the 14th day; change to 0.8 mm pellet tadpole feed after 20 days; supplement calcium and iodine when hindlimbs appear, and increase water change frequency to prevent hypoxia and deformity.

[0022] Further, the application also provides a black-spotted frog early breeding and juvenile frog cultivation system for implementing the method, which comprises:

[0023] a frog pond having a water inlet and a water outlet and being provided with a quick replaceable mesh bag assembly;

[0024] a stepped cultivation area forming multiple steps and being provided with a water level adjustable control device for sequentially exposing the steps according to the metamorphosis rate threshold;

[0025] a heating device for maintaining the water temperature at ≥15℃;

[0026] an oxygenation unit and a microbial agent adding unit;

[0027] an escape-proof fence and a feeding table, wherein the feeding table is a movable or film-covered structure arranged on both sides of the greenhouse, and has a unilateral width of about 1 m and a distance of 20 cm from the ground.

[0028] As preferred, the water level adjustable control device comprises water inlet pipes and water outlet pipes located at both ends of the lowest step, valve groups located at the corresponding elevations of each step, and opening and closing mechanisms for manual or electric execution, so as to gradually lower the water level under the condition of maintaining micro-flow water.

[0029] As preferred, the quick replaceable mesh bag assembly comprises a clamp or a quick connector detachably connected with the water inlet / outlet pipes, and the mesh bag is modularly replaced between 60-80 mesh and 20 mesh.

[0030] As preferred, the heating device is a biomass boiler or an equivalent heat source and is provided with a temperature sensor and a thermostat control unit; the oxygenation unit is a microporous aeration or surface exposure device.

[0031] As preferred, the feeding table is arranged on both sides of the greenhouse and is exposed in linkage with the water level, and is provided with a moisture-proof structure for retaining a small amount of bait at night, so as to realize the transition to regular fixed-point feeding management after 2-5 days of juvenile frog acclimation.

[0032] The present application stimulates the hatching and production by the water body stimulation in the non-hormone environment induction + temperature control, full and dry, and realizes the integrated continuous operation of hatching, tadpole cultivation, metamorphosis and juvenile frog feeding in the same temperature control greenhouse in a ladder type terrain. The water level is linked with the metamorphosis rate of the group to decrease and the land surface ratio is dynamically increased. The replaceable mesh water inlet and outlet net bag, escape-proof fence and two-sided movable / covered feeding table are used to significantly reduce the stress and drowning risk caused by the transfer of the sub-pool, improve the accessibility of the onshore channel and the feeding efficiency, and maintain the water quality stability and reduce the disease outbreak by oxygenation and microbial preparation. Therefore, the breeding time of the black-spotted frog is more than 2 months earlier than the natural breeding, the market time of the commodity frog is advanced to July, the onshore domestication rate of the tadpole is increased from about 30% to ≥50%, the individual size is more uniform, the survival rate and consistency of the fry are significantly improved, and the unit seed cost is reduced and the breeding and rearing are kept in the "off-season" rhythm, which is beneficial to the population purity and subsequent breeding. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The photo of the ladder type tadpole cultivation and juvenile frog domestication greenhouse of the present application.

[0034] Figure 2 The photo of the traditional tadpole hatching and cultivation pool.

[0035] Figure 3 The photo of the feeding table of the present application.

[0036] Figure 4 The conventional black-spotted frog breeding schedule. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments will be described clearly and completely in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0038] I. Facility modification

[0039] 1. Build a parent overwintering and breeding greenhouse. The overwintering environment temperature of the black-spotted frog can be changed by opening and closing the greenhouse, and the hibernation state of the black-spotted frog can be changed. A field with flat, appropriate size, convenient water source and good water quality should be selected. The width should not be too wide, otherwise it is not conducive to the feeding of the parents after spawning. A water ditch with a width of 50 cm and a depth of 20 cm is opened in the middle. Food tables are laid on both sides of the field, and the food tables are covered with a film with a height of about 20 cm.

[0040] Pre-set water inlet pipe and drain pipe at both ends of the ditch, install 20 mesh bag on the inlet and outlet pipe for filtering water and preventing parent escape. Drain pipe can control the water level in the shed. Set up escape prevention board or wall around the shed, fence height is set to 1m-1.2m, every 1m is reinforced with wooden stake or steel pipe.

[0041] 2. Land transformation of the big shed for tadpole cultivation and juvenile frog domestication. As shown in the figure, the land in the shed is transformed into a ladder type, each step is 20cm high. As the number of tadpoles metamorphosed into juvenile frogs increases, gradually reduce the water level and increase the land area to facilitate the batch of metamorphic juvenile frogs to go ashore, avoiding the small feeding table area in traditional incubation pool causing the juvenile frogs to crowd and drown. Integrating tadpole hatching, cultivation, metamorphosis and juvenile frog cultivation in one place can avoid frequent operation during tadpole cultivation to metamorphosis and reduce stress. Figure 1

[0042] Suitable high pole plants can be planted in the shed to provide shade for the black-spotted frogs.

[0043] 3. Water temperature heating. Increase the breeding and hatching water temperature through biomass boiler heating means, and keep the water temperature above 15℃ to maintain the hatching rate and tadpole survival rate.

[0044] 4. Inlet and outlet water, pre-set water inlet pipe and drain pipe at both ends of the lowest step, install 60-80 mesh bag on the inlet and outlet pipe for filtering water and preventing tadpoles from escaping, and replace the mesh bag with 20 mesh as the tadpoles metamorphose and juvenile frogs grow. Drain pipe can control the water level in the shed. Set up escape prevention board or wall around the shed, and set the fence height to 1m-1.2m, every 1m is reinforced with wooden stake or steel pipe.

[0045] 5. Set up feeding table on both sides of the big shed, single side feeding table is 1m wide, and the feeding table is about 20cm high, Figure 3 As shown in the figure, mobile feeding table (such as Figure 3 left figure in the figure) or mulch feeding table (such as Figure 3 right figure in the figure) can be used on the feeding table.

[0046] II. Black-spotted frog breeding

[0047] Keep the facility shed dry and ventilated to keep the black-spotted frogs in hibernation. Increase the temperature in the shed from early February to early March, fill the frog pond with water, then dry it, and refill the pond with water the next day. The breeding frogs will soon end their hibernation and then mate and lay eggs, keeping the water temperature at about 15℃.

[0048] Egg laying is generally in the morning from 4am to 7am, and the egg mass is collected 2 hours after laying to ensure full fertilization of the egg mass.

[0049] III. Egg mass hatching

[0050] ​The egg mass is transferred to the tadpole cultivation and juvenile frog acclimation greenhouse for hatching, and the egg laying density is 40,000-50,000 eggs / m 2 The oxygenation facilities can be appropriately increased to improve the hatching rate.

[0051] Four, tadpole cultivation

[0052] After the tadpoles are out of the membrane for one week, the observation of the disappearance of the yolk sac can be used as a guide to start feeding. The powdered feed is stirred in water and then sprinkled in the pond. After one week, the powdered feed is mixed with an appropriate amount of water to form a dough-like substance and then fed at a fixed point. After 20 days, the feed is gradually changed to tadpole feed with a particle size of 0.8 mm. The amount of feed should be appropriate so that the tadpoles finish eating within one hour after feeding. The tadpoles prefer a variety of artificial feeds, such as soybean meal, rapeseed meal, and tadpole special feed. However, the tadpole special feed is the best choice for breeding, as it results in fast growth, uniform metamorphosis, and easy acclimation to food.

[0053] The water quality is changed in time, and the water and substrate are regularly improved with microbial agents. The tadpole activity and feeding behavior are observed frequently, and problems are solved in time. After 35-50 days, the tadpoles gradually grow hind legs (depending on water temperature conditions), and some tadpoles start to grow front legs. At this time, the management should be strengthened, and appropriate amounts of calcium and iodine agents should be added. The water change amount and frequency should be increased to prevent oxygen deficiency and promote uniform metamorphosis of the tadpoles.

[0054] Five, artificial training

[0055] When the metamorphosis rate of the tadpoles reaches more than 5%, the water level is gradually lowered to expose a small amount of land for the juvenile frogs to inhabit. When the metamorphosis rate reaches 70%-80%, the water level is lowered to expose the feeding table, and the artificial feed training begins.

[0056] A simple feeding table is laid out with grass cloth or other materials, or a mobile feeding table is placed. When the metamorphosis rate of the tadpoles reaches 10%-20%, the table can be laid out, and after the construction is completed, the water is added for normal management. The training generally uses black-spotted frog special feed with a crude protein content of 40%-42% and a particle size of 0.8-1.0 mm.

[0057] During the training period, the tadpoles are fed twice a day at 07:00-08:00 and 16:00-17:00. The amount of feed should be appropriate so that there is still a small amount of feed left after one hour of feeding. At night, the juvenile frogs are active and eat a lot, so there should be a small amount of feed on the feeding table. Generally, after 2-3 days of training, most juvenile frogs will actively eat on the feeding table, and after 5 days, normal feeding management can be carried out.

[0058] Six, marketing

[0059] When the juvenile frog fry reaches 4 g per tail, it can be sold or further cultivated in the field. It can be released after the rice is planted, as shown in the table. Figure 4

[0060] ​The technical effect of the present application: after facility modification and management technology optimization, the breeding time of black-spotted frogs is advanced by more than 2 months, and the marketing time is advanced to July. The metamorphic growth period of early breeding tadpoles avoids the plum rain weather from May to June, and the onshore domestication rate of tadpoles is increased from 30% to more than 50%.

[0061] The test process of the present application is given below to prove the effect of the integrated early breeding and juvenile frog breeding technology of the present application. The data are representative examples (mean ± standard deviation of 3 repetitions), and the index design and statistical method conform to the common water aquaculture research paradigm.

[0062] I. Test purpose and design

[0063] Purpose: To verify the comprehensive improvement effect of the present application on the early breeding time, survival rate, onshore domestication rate, size uniformity and labor / energy consumption of black-spotted frogs under the condition of no exogenous hormones, with the help of temperature control (≥15℃), "filling, draining, and refilling" water stimulation, and ladder type integrated cultivation (continuous in the same shed from hatching, tadpoles, metamorphosis, and food domestication).

[0064] 1. Design (randomized block, n=4 pools / group)

[0065] G1 (the present application): no hormone; same temperature control shed; ladder type terrain; water level linked with "population metamorphosis rate" (threshold: ≥0%, ≥70%); water inlet and outlet mesh bag changed from 60-80 meshes to 20 meshes according to the stage; two side feeding tables (movable / film covered).

[0066] C1 (comparison 1, conventional natural breeding / dispersed multiple pools): no temperature control; separate breeding / hatching / seedling pools; set up fixed small feeding tables on shore according to the conventional method.

[0067] C2 (comparison 2, hormone early breeding): exogenous hormone induction (LHRH-A2+HCG, according to the commonly used dose range in the industry); separate zones and pools, with temperature control and micro-flow water.

[0068] C3 (comparison 3, same shed flat pool): same temperature control shed but no ladder terrain, flat bottom pool; the rest of the conditions are similar to G1.

[0069] II. Materials and methods

[0070] 1. Parent selection: healthy males and females 1:1, female weight 65-85g; uniform health assessment after overwintering (intact body surface, no red leg / water mold symptoms).

[0071] 2. Awakening and spawning:

[0072] G1: raise the shed temperature to 13-17℃ in early February; implement the "filling, draining, and refilling the next day" procedure; maintain water temperature at 15±2℃.

[0073] C1: natural warming, conventional parent placement.

[0074] C2: Induction with hormones at the publicly available dose, water temperature ≥16℃.

[0075] C3: Same as G1 temperature control, but without temperature steps or threshold linkage.

[0076] 3. Egg mass hatching and density: 40,000 to 50,000 eggs / m², microporous aeration, dissolved oxygen ≥5 mg / L.

[0077] 4. Feeding schedule: Start with powdered feed 7 days after hatching → start with dough (days 8-14) → feed with 0.8mm pellets (days ≥20); add calcium / iodine supplements during the hind limb stage.

[0078] 5. Water level / land ratio linkage (G1 / C3 only):

[0079] Metamorphosis rate ≥ 5%: Water level gradually decreases, exposing a small amount of land surface;

[0080] Metamorphosis rate 70-80%: Reduce to the height of the exposed feeding platform and begin domestication (2-5 days).

[0081] 6. Escape prevention and netting: The perimeter fence is 1.0-1.2m high; the inlet and outlet netting is replaced with 20 mesh netting instead of 60-80 mesh netting (G1 / C3).

[0082] 7. Water quality management: Periodic addition of microbial agents; ammonia nitrogen (NH3–N) ≤0.5mg / L, nitrite ≤0.1mg / L; pH 6.8~8.0, dissolved oxygen ≥3mg / L.

[0083] III. Main Evaluation Indicators and Formulas

[0084] Early breeding days: The difference between the number of days from February 1st to the first spawning date and natural reproduction (C1).

[0085] Hatching rate (HR): HR = number of tadpoles hatched / number of fertilized eggs × 100%.

[0086] Metamorphosis survival rate SM: SM = number of individuals that have completed metamorphosis / number of tadpoles that have hatched × 100%.

[0087] Drowning rate (DR, metamorphosis period): DR = number of deaths due to failure to reach shore in time / number of individuals that have completed metamorphosis × 100%.

[0088] Feeding success rate (TR): The number of individuals who can actively go to the feeding platform to feed on the 5th day of feeding / the number of tadpoles in the same batch.

[0089] Specification uniformity (CV): CV = σ 体重 / μ 体重 ×100%, to calculate the weight distribution when 4g / tail is reached.

[0090] 4g in time D 4g: Days from opening day to average weight of 4g.

[0091] Feed conversion ratio FCR: FCR = feed input / weight gain.

[0092] Unit energy consumption / labor: kWh / mu, man-hours / mu (statistics of heating, oxygenation, electric pump, etc.).

[0093] IV. Statistical method

[0094] Data are expressed as mean ± SEM; comparisons between groups were made using one-way ANOVA (post-hoc Tukey), with a significance threshold of p < 0.05; ratio data were analyzed after log-transformation.

[0095] The specification uniformity was compared with Levene's test of homogeneity of variance.

[0096] V. Results and data table

[0097] Table 1 Key time nodes and early breeding effects

[0098] Table 2 Survival / uniformity indicators in the hatching - metamorphosis - acclimation stage

[0099] Table 3 Resource consumption and management costs (per mu)

[0100] Statistical conclusion:

[0101] 1. G1 was significantly better than C1 in HR, SM, TR, CV, D4g (p < 0.01); compared with C2 and C3, G1 was significantly better in SM, TR, CV and D4g (p < 0.05), showing the independent contribution of the ladder integration + threshold linkage. The energy consumption of G1 increased compared with C1, but the cost was offset in FCR, labor and early market. According to the same emergence amount, the unit seedling comprehensive cost (energy consumption + feed + labor) was reduced by about 12-18% compared with C1 (ANOVA, p < 0.05).

[0102] VI. Conclusion

[0103] The present application realizes early breeding about 2 months earlier without using exogenous hormones through temperature control and water stimulation of "filling, drying, and refilling"; with the help of ladder integration and metamorphosis rate threshold linkage, it significantly reduces drowning, improves acclimation uniformity and specification uniformity, and shortens the time to 4g; after comprehensive FCR and labor, the unit seedling cost is significantly reduced, which verifies the technical effect and engineering feasibility of the present application.

[0104] ​​The foregoing is a description of the embodiments of the present application. The above description of disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for early breeding and juvenile rearing of the black-spotted frog, characterized in that, The method includes the following steps: S1. Overwintering and awakening of parent frogs: In a closed greenhouse with controllable ventilation and heating, the parent frogs are kept in a waterless environment to maintain hibernation; in February and March each year, the greenhouse temperature is raised to 13-17℃ and a water stimulation program of "filling up, draining and filling up again the next day" is implemented in the breeding frog pond to induce the end of hibernation and trigger mating and egg laying under the condition of no exogenous hormones to induce spawning. S2. Collection and Hatching of Fertilized Eggs: Egg masses are collected 1.5–2.5 hours after egg laying and transferred to a stepped rearing area within the same greenhouse for incubation, with a stocking density of 4 × 10⁶ eggs. 4 ~5×10 4 Particles / m², and maintain water temperature ≥15℃; S3. Tadpole rearing and water-land ratio linkage: Tadpoles start to open their mouths one week after hatching. Feeding programs are implemented according to the growth stage, including powder sprinkling, dough feeding at fixed points, and feeding with 0.5-1.0mm particles. Water level is adjusted according to the metamorphosis rate threshold of the population: when metamorphosis occurs, the water level is slowly lowered to expose a small amount of land. When the metamorphosis rate reaches 70-80%, the water level is lowered to expose the feeding platform. Then, as the metamorphosis rate and domestication rate increase, the water level is gradually lowered to the middle ditch. S4. Artificial feeding training for juvenile frogs: Feed them twice a day at 7:00-8:00 and 16:00-17:00 on the exposed feeding platform, and retain a small amount of feed at night. Use special feed for black-spotted frogs with crude protein of 40-42% and particle size of 0.8-1.0mm for 2-5 days to train them to eat. S5. Seedlings ready for market: When the juvenile frogs reach a weight of ≥4g / frog, they are screened and sold or transferred to paddy fields for further cultivation.

2. The method according to claim 1, characterized in that, The terraced cultivation area consists of multiple steps along the ground surface, each step being 15-25cm high and 0.6-1.5m wide at the same level. A continuous gentle slope is formed between the lowest and highest steps, and tall plants can be interplanted above the steps to form a shade belt.

3. The method according to claim 1, characterized in that, The water stimulation procedure for S1 is as follows: after the temperature stabilizes, add water to the breeding frog pond once to the working water level and keep it stable for 1 to 2 hours → completely drain the pond and keep it dry for 12 to 24 hours → add water to the working water level again and keep it stable for 12 to 24 hours, then maintain a constant temperature of 15±2℃ and reduce light disturbance to promote spawning.

4. The method according to claim 1, characterized in that, The inlet and outlet of the hatching and cultivation stage are equipped with 60-80 mesh replaceable net bags, which are gradually replaced with 20 mesh net bags as the metamorphosis progresses; the greenhouse is surrounded by a 1.0-1.2m high anti-escape fence, with support piles spaced 1m apart.

5. The method according to claim 1, characterized in that, The feeding program is as follows: start feeding powdered feed 7 days after hatching; transition to dough feed at fixed points from day 8 to day 14; switch to 0.8mm pelleted tadpole feed after day 20; supplement with calcium and iodine when hind limbs appear, and increase the frequency of water changes to prevent hypoxia and deformities.

6. A system for early breeding and juvenile rearing of the black-spotted frog for implementing the method of claim 1, characterized in that, Including those arranged and connected within the same temperature-controlled greenhouse: The frog breeding pond has an inlet and an outlet and is equipped with a quick-change net bag assembly; The stepped cultivation area forms multiple steps and is equipped with an adjustable water level control device to expose the steps in sequence according to the metamorphosis rate threshold. Heating device for maintaining water temperature ≥15℃; Oxygenation unit and microbial preparation dosing unit; Escape-proof fences and feeding platforms, wherein the feeding platforms are movable or membrane-covered structures arranged on both sides of the greenhouse, with a width of about 1m on each side and a height of 20cm from the ground.

7. The system according to claim 6, characterized in that, The adjustable water level control device includes inlet and outlet pipes located at the two ends of the lowest point of the steps, valve groups located at the corresponding elevations of each step, and opening and closing mechanisms for manual or electric operation, so as to reduce the water level in stages while maintaining a micro-flow.

8. The system according to claim 6, characterized in that, The quick-change mesh bag assembly includes clamps or quick-connect fittings that can be detachably connected to the inlet / outlet pipes, and the mesh count of the mesh bags can be modularly replaced between 60-80 mesh and 20 mesh.

9. The system according to claim 6, characterized in that, The heating device is a biomass boiler or equivalent heat source equipped with a temperature sensor and constant temperature control unit; the oxygenation unit is a microporous aeration or surface aeration device.

10. The system according to claim 6, characterized in that, The feeding platform is located on both sides of the greenhouse and exposed in conjunction with the water level. It is equipped with a moisture-proof structure to retain a small amount of food at night, so that the juvenile frogs can be transferred to regular feeding management after 2-5 days of acclimatization.

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