A method and system for early breeding and juvenile rearing of the black-spotted frog.

Abstract

This invention relates to the field of aquaculture technology, and more particularly to a method and system for early breeding and juvenile rearing of the black-spotted frog. The invention is based on temperature control and a "fill-up-drain-refill" water stimulation system to promote awakening and spawning under conditions without exogenous hormones. A stepped terrain is constructed within the same temperature-controlled greenhouse, and water level and land-water ratio are adjusted in conjunction with a threshold for the group's metamorphosis rate. This is combined with replaceable mesh inlet and outlet nets, escape-prevention fences, and movable / film-covered feeding platforms on both sides to achieve continuous operation from hatching to rearing to metamorphosis to acclimatization. Compared to conventional pond-based methods, breeding can be advanced by ≥2 months, with juveniles available for market in July; hatching and metamorphosis survival rates are improved, drowning mortality is significantly reduced, and acclimatization success rate and size uniformity are increased, while reducing handling stress and lowering unit seedling costs.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, and in particular to a method and system for early breeding and raising of tadpoles of the black-spotted frog. Background Technology

[0002] The black-spotted frog (Pelophylax nigromaculatus) is a common edible and medicinal amphibian in my country. It is widely distributed and highly adaptable. Its breeding season typically begins after winter as temperatures rise. Eggs are laid in shallow water areas, with clutches containing hundreds to thousands of eggs. This species is widely distributed in eastern and central my country, where rice-fish co-cultivation has long been a farming practice. However, it still faces common challenges such as concentrated seasonal market supply and the significant impact of climate fluctuations on seedling survival rates.

[0003] The current mainstream "rice-frog symbiosis" model typically involves dividing rice paddies into breeding ponds, hatching ponds, seedling ponds, and rearing ponds, and using micro-flow water and density / water level control to improve hatching and rearing efficiency. The main drawbacks of this model are: ① High initial investment: The cost per mu (approximately 0.16 acres) in the first year is 16,000-18,000 yuan (including mechanized facilities), with the cost of tadpoles alone around 3,500 yuan (for purchasing tadpole seedlings). ② Strong seasonality in black-spotted frog farming: Tadpoles are released in early July, gradually entering the market in September, and hibernating in November. The peak market period for black-spotted frogs is only two months. This concentrated market supply leads to lower prices and reduced profits. Furthermore, recent years have seen significant climate change, with fluctuating spring temperatures, which greatly impacts tadpole hatching and survival rates.

[0004] Early breeding of black-spotted frogs can effectively solve the above problems. In addition to natural breeding in March and April, a series of technical measures are used to induce some parent black-spotted frogs to lay and hatch eggs in January and February, thereby cultivating large-sized early-bred tadpoles. Advantages include: First, significantly advancing the market time and filling the gap in frog availability from May to July. Second, early breeding allows for intensive tadpole rearing with controllable temperature and other conditions, effectively improving tadpole survival rates. Third, the early-bred black-spotted frogs are not synchronized with naturally bred ones, which helps maintain the purity of the farmed population, facilitates further breed selection, optimizes germplasm resources, and lays the foundation for the sustainable development of the black-spotted frog industry.

[0005] Chinese patent CN114532294B proposes dividing paddy fields into functional zones and adopting a "three-level single-ditch" transformation, clearly defining the area and proportion of each functional zone, and installing micro-flow pipes above the hatching ponds to increase oxygen, thereby achieving orderly breeding and moderately early market launch (with 80% of the marketable frogs weighing ≥40g). The plan also emphasizes the necessity of escape prevention infrastructure such as enclosure nets and skynets.

[0006] In terms of feeding and domestication, some technologies use long-term generational selection and methods such as feeding and netting to gradually domesticate the black-spotted frog from "active feeding" to "static feeding," in order to adapt to artificial feed and reduce the risk of disease transmission caused by artificial driving. Chinese patent CN107616142B gives the rice-frog area ratio, ditch size and temperature control points, and proposes a behavioral domestication path of 3 to 5 generations to improve feeding efficiency and economy.

[0007] Regarding the complete process management of seedling cultivation and raising, Chinese patent CN106106348A provides a relatively systematic set of steps for "species selection, cultivation, egg laying, hatching, tadpole feeding, juvenile frog management, and adult frog management," as well as key water environment parameters (such as hatching water temperature 18-31℃, pH 6.8-8.0, water depth 20-30cm, dissolved oxygen ≥3mg / L). It emphasizes that when the tadpoles' forelimbs are about to emerge and their tails are about to retract, the water level should be controlled to the edge of the feeding platform to reduce stress and facilitate their coming ashore.

[0008] To alleviate the conflict between seasonality and concentrated market availability, some early-breeding techniques have been explored to induce spawning around February using exogenous hormones. For example, Chinese patent CN116548374A proposes a "mass artificial breeding method for early-breeding black-spotted frogs," which involves artificially inducing spawning in February at a female-to-male ratio of approximately 1:1. The dosage for each frog is approximately 1.05–1.25 μg of LHRH-A2 and approximately 40–45 IU of HCG. Under conditions of spawning at temperatures above 16°C and incubation at temperatures above 14°C, the frogs are incubated in a net cage with a micro-flow to obtain early-breeding larvae, thereby extending the growth cycle and bringing the market earlier.

[0009] Some practitioners have attempted to use spawning-inducing injections to promote early breeding of the black-spotted frog; however, this approach has not been very effective in subsequent seedling cultivation. Furthermore, the metamorphosis of tadpoles after breeding is inconsistent, and if the water-to-land ratio is not adjusted in time, it can lead to the drowning of tadpoles, thus negatively impacting overall breeding efficiency. Summary of the Invention

[0010] To address the aforementioned technical problems, the technical objective of this invention is to provide a method and system for the integrated early breeding and tadpole rearing of the black-spotted frog. This system utilizes engineered methods to induce tadpole development and metamorphosis within a single temperature-controlled greenhouse using a stepped topography. Adjustable water levels, replaceable mesh size escape-proof nets, and feeding platforms solve the problems associated with dispersed multi-pond management, such as high stress during transport, asynchronous metamorphosis leading to drowning, difficulty in real-time matching of water-to-land ratios, and seasonal concentrated market entry. This improves seedling survival and feeding consistency, reduces unit costs, and significantly advances market entry time.

[0011] To achieve the objectives of this invention, the following technical solution is adopted:

[0012] A method for early breeding and juvenile rearing of the black-spotted frog, comprising the following steps:

[0013] 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.

[0014] S2. Collection and Hatching of Fertilized Eggs: Egg masses are collected 2 hours after egg laying and transferred to a tiered 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℃, pH 6.8~8.0, water depth 20~50cm, dissolved oxygen ≥3mg / L;

[0015] 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.

[0016] 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.

[0017] 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.

[0018] Preferably, the stepped cultivation area consists of multiple steps formed along the ground surface, with each step being 15-25cm high and adjacent steps having a horizontal width of 0.6-1.5m. 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.

[0019] As a preferred option, 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.

[0020] As a preferred option, 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.

[0021] As a preferred method, the feeding program is as follows: start feeding powdered feed 7 days after hatching; transition to dough-based feed 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.

[0022] Furthermore, this application also provides a black-spotted frog early breeding and tadpole rearing system for implementing the method, which includes: arranged and connected in the same temperature-controlled greenhouse:

[0023] The frog breeding pond has an inlet and an outlet and is equipped with a quick-change net bag assembly;

[0024] 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.

[0025] Heating device for maintaining water temperature ≥15℃;

[0026] Oxygenation unit and microbial preparation dosing unit;

[0027] 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.

[0028] Preferably, the adjustable water level control device includes an inlet pipe and an outlet pipe located at both ends of the lowest point of the steps, a valve group located at the corresponding elevation of each step, and an opening and closing mechanism for manual or electric operation, so as to reduce the water level in stages while maintaining a micro-flow.

[0029] Preferably, 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.

[0030] Preferably, the heating device is a biomass boiler or equivalent heat source equipped with a temperature sensor and a constant temperature control unit; the oxygenation unit is a microporous aeration or surface aeration device.

[0031] Preferably, the feeding platform is located on both sides of the greenhouse and exposed in conjunction with the water level, and is equipped with a moisture-proof structure to retain a small amount of bait at night, so as to enable the juvenile frogs to be trained to eat for 2-5 days and then transferred to regular fixed-point feeding management.

[0032] This invention utilizes a hormone-free environment induction and temperature control, employing a process of filling, draining, and refilling the water to stimulate awakening and tadpole production. Within a single temperature-controlled greenhouse, a stepped terrain enables integrated and continuous operations for hatching, tadpole rearing, metamorphosis, and tadpole acclimatization. The water level decreases in tandem with the metamorphosis rate of the population, while the land surface ratio dynamically increases. Combined with replaceable mesh inlet and outlet nets, escape-proof fences, and movable / film-covered feeding platforms on both sides, this significantly reduces the stress and drowning risks caused by transferring tadpoles to different ponds, improves accessibility to the shore, and enhances acclimatization efficiency. Simultaneously, oxygenation and microbial agents maintain water quality stability and reduce disease outbreaks. As a result, the breeding time of the black-spotted frog is advanced by more than two months compared to natural reproduction, and the market launch time for commercial frogs is advanced to July. The tadpole acclimatization rate is increased from approximately 30% to ≥50%, individual sizes are more uniform, and the survival rate and consistency of seedlings are significantly improved. Furthermore, since there is no need to purchase tadpoles or use hormones to induce spawning, the unit seedling cost is reduced, and the "off-season" rhythm of breeding and rearing is maintained, which is beneficial for maintaining population purity and subsequent selective breeding. Attached Figure Description

[0033] Figure 1 The photos are of the tiered tadpole breeding and tadpole domestication greenhouses used in this application.

[0034] Figure 2 A photo of a traditional tadpole hatching and rearing pond.

[0035] Figure 3 This is a photo of the food station for this application.

[0036] Figure 4 This is a standard timetable for black-spotted frog farming. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0038] I. Facility renovation.

[0039] 1. Construct overwintering and breeding greenhouses for the parent frogs. Opening and closing the greenhouses can alter the overwintering temperature and hibernation state of the black-spotted frogs. Choose a flat, appropriately sized plot with convenient and good water quality. The plot should not be too wide, otherwise it will hinder the parent frogs' feeding after spawning. Dig a central irrigation ditch, 50cm wide and 20cm deep. Lay feeding platforms approximately 20cm high on both sides of the plot, covering them with mulch.

[0040] The ditch has inlet and outlet pipes at both ends, with 20-mesh mesh bags installed on the pipes to filter incoming water and prevent parent fish from escaping. The outlet pipe controls the water level inside the shed. Escape-proof boards or walls are installed around the shed, with a fence height of 1m to 1.2m, reinforced with wooden stakes or steel pipes every 1m.

[0041] 2. Tadpole rearing and tadpole domestication greenhouse land improvement. For example... Figure 1 As shown, the land inside the shed was modified into a terraced structure, with each terrace 20cm high. As the number of tadpoles metamorphosing into froglets increases, the water level is gradually lowered to increase the land area, facilitating the timely arrival of metamorphosing froglets ashore in batches. This avoids the problem of froglets crowding and drowning due to the small feeding area of ​​traditional hatching ponds. By integrating tadpole hatching, rearing, metamorphosis, and froglet cultivation into one place, frequent operations during tadpole rearing and metamorphosis are avoided, reducing stress.

[0042] Tall plants can be planted inside the shed to provide shade for the black-spotted frog.

[0043] 3. Water temperature heating. Increase the water temperature for breeding and hatching by using heating methods such as biomass boilers, and maintain the water temperature above 15℃ to maintain the hatching rate and tadpole survival rate.

[0044] 4. Water Inlet and Drainage: Water inlet and outlet pipes are pre-installed at both ends of the lowest point of the steps. 60-80 mesh netting is installed on the inlet and outlet pipes to filter the incoming water and prevent tadpoles from escaping. As the tadpoles metamorphose and the young frogs grow, the netting can be gradually replaced with 20 mesh netting. The outlet pipe controls the water level inside the enclosure. Escape-proof boards or walls are installed around the perimeter of the enclosure to prevent the young frogs from escaping during metamorphosis. The fence height is set at 1m-1.2m, reinforced with wooden stakes or steel pipes every 1m.

[0045] 5. Feeding platforms are set up on both sides of the greenhouse, each platform being 1m wide and approximately 20cm high. Figure 3 As shown, a movable serving table (such as...) can be used on the serving table. Figure 3 (Middle left image) or a feeding platform covered with plastic film (such as...) Figure 3 (Right image in the middle)

[0046] II. Black-spotted Frog Reproduction

[0047] By keeping the greenhouse dry and well-ventilated, the black-spotted frogs can be kept in a hibernation state. From early February to early March, the temperature inside the greenhouse can be increased by filling the breeding frog pond with water and then draining it, and then filling it with water again the next day. The breeding frogs will soon end their hibernation and then pair up to lay eggs. The water temperature should be maintained at around 15℃.

[0048] Spawning usually occurs between 4 and 7 a.m. Two hours after spawning, egg masses are collected to ensure that the egg masses are fully fertilized.

[0049] III. Egg mass hatching

[0050] The egg masses were transferred to tadpole rearing and juvenile frog domestication sheds for incubation, with an egg density of 40,000 to 50,000 eggs / m². 2 To improve the hatching rate, it is advisable to increase oxygenation facilities.

[0051] IV. Tadpole Cultivation

[0052] One week after hatching, tadpoles can be fed once the yolk sac has disappeared. Mix powdered feed with water and sprinkle it throughout the pond. After one week, mix the powdered feed with a suitable amount of water to form a dough-like consistency and feed it at designated points. After 20 days, gradually switch to tadpole feed with a particle size of 0.8mm. The amount of feed should be such that the tadpoles finish eating it within one hour. Tadpoles readily accept many types of artificial feed, such as soybean meal, rapeseed meal, and tadpole-specific feed, but tadpole-specific feed yields the best results, promoting rapid growth, more uniform metamorphosis, and easier training.

[0053] Add or change water promptly according to changes in water quality, and regularly use microbial agents to improve water and bottom quality. Observe tadpoles' activity and feeding behavior frequently, and address any problems immediately. Tadpoles gradually grow hind legs after 35-50 days (depending on water temperature), and some early-developing tadpoles may begin to grow front legs. At this time, management should be strengthened, and appropriate amounts of calcium and iodine preparations should be added. Increase the volume and frequency of water changes, strictly prevent oxygen deficiency, and promote uniform metamorphosis of tadpoles.

[0054] V. Artificial Feeding

[0055] When the tadpole metamorphosis rate reaches 5% or more, the water level is gradually lowered to expose a small amount of land for the tadpoles to inhabit. When the metamorphosis rate reaches 70% to 80%, the water level is lowered to expose the feeding platform, and artificial feeding begins.

[0056] Simple feeding platforms can be laid out using materials such as weed control fabric, or mobile feeding platforms can be deployed. When the tadpoles' metamorphosis rate reaches 10%–20%, drainage can be provided before laying the platforms. After construction, water can be added and normal management can resume. For acclimatization, a special feed for black-spotted frogs with a crude protein content of 40%–42% and a particle size of 0.8–1.0 mm is generally used.

[0057] During the acclimatization period, feed twice daily, between 7:00 and 8:00 AM and between 4:00 and 5:00 PM. The amount of food should be such that a small amount remains one hour after each feeding. Young frogs are more active and eat more at night, so keep a small amount of food on the feeding platform overnight. After 2-3 days of acclimatization, most young frogs will actively come to the feeding platform to eat, and normal feeding management can begin after 5 days.

[0058] VI. Listing

[0059] When the juvenile frogs reach 4g / frog, they can be screened and sold or released into the fields for further cultivation. They can then be released into the fields after rice planting. Figure 4 As shown.

[0060] The technical effects of this invention are as follows: Through facility renovation and management technology optimization, the breeding time of the black-spotted frog is advanced by more than two months, and the market launch time is brought forward to July. The metamorphosis period of the early-breeding tadpoles avoids the plum rain season in May and June, and the tadpole domestication rate on land is increased from 30% to over 50%.

[0061] The experimental process described below demonstrates the effectiveness of the integrated early breeding and tadpole rearing technology of this invention. Data are from representative examples (mean ± standard deviation of three replicates), and the indicator design and statistical methods conform to common aquaculture research paradigms.

[0062] I. Experimental Objectives and Design

[0063] Objective: To verify the comprehensive improvement effect of the present invention on the early breeding time, survival rate, land domestication rate, size uniformity, and labor / energy consumption of black-spotted frogs under the condition of no exogenous hormones, by using temperature control (≥15℃), "filling, draining, and filling" water stimulation and step-by-step integrated cultivation (continuous hatching, tadpole, metamorphosis, and domestication in the same shed).

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

[0065] G1 (Invention): Hormone-free; Same temperature-controlled greenhouse; Stepped terrain; Water level linked to "population metamorphosis rate" (threshold: ≥0%, ≥70%); Inlet and outlet mesh bags changed from 60-80 mesh to 20 mesh as the stage progresses; Feeding platforms on both sides (movable / covered).

[0066] C1 (Comparison 1, conventional natural breeding / dispersed multi-pond): No temperature control; separate breeding / hatching / seedling ponds; fixed feeding platforms are set up on shore as usual.

[0067] C2 (Comparison 2, early hormone reproduction): exogenous hormone induction (LHRH-A2+HCG, according to the commonly used dosage range published in the industry); divided into zones and pools, equipped with temperature control and micro-flow.

[0068] C3 (Comparison 3, same temperature-controlled greenhouse, flat bottom): Same temperature-controlled greenhouse but without stepped terrain, is a flat bottom pool; other conditions are similar to G1.

[0069] II. Materials and Methods

[0070] 1. Parent selection: Healthy males and females in a 1:1 ratio, with females weighing 65-85g; uniform health assessment after overwintering (intact body surface, no red legs / water mold symptoms).

[0071] 2. Awakening and Egg Laying:

[0072] G1: Raise the greenhouse temperature to 13-17℃ in early February; implement the procedure of "filling up, drying out, and filling up again the next day"; maintain the water temperature at 15±2℃.

[0073] C1: Natural warming, regular release of parent plants.

[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: The number of days from the date of opening the mouth until the average weight reaches 4g.

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

[0092] Unit energy consumption / labor: kWh / acre, man-hours / acre (statistics include heating, oxygenation, electric pumps, etc.).

[0093] IV. Statistical Methods

[0094] Data with The data indicates that the comparisons between groups were performed using one-way ANOVA (post-hoc Tukey), with a significance threshold of p < 0.05; the proportion data were analyzed. Post-conversion analysis.

[0095] The uniformity of specifications was compared with the Levene test for homogeneity of variance based on the coefficient of variation.

[0096] V. Results and Data Tables

[0097] Table 1 Key Time Nodes and Early Breeding Effects

[0098]

[0099] Table 2 Survival / Conformity Indicators during the Hatching-Metamorphosis-Domestication Stages

[0100]

[0101] Table 3 Resource Consumption and Management Costs (per acre)

[0102]

[0103] Statistical conclusions:

[0104] 1. G1 significantly outperformed C1 in HR, SM, TR, CV, and D4g (p<0.01); compared with C2 and C3, G1 was significantly better in SM, TR, CV, and D4g (p<0.05), demonstrating the independent contribution of the tiered integrated and threshold-linked approach. While G1's energy consumption increased compared to C1, this was offset by lower FCR, lower labor costs, and earlier market availability. Based on the same seedling output, the comprehensive cost per seedling (energy consumption + feed + labor) was approximately 12-18% lower than that of C1 (ANOVA, p<0.05).

[0105] VI. Conclusion

[0106] This invention achieves early breeding by approximately two months without the use of exogenous hormones through temperature control and a "fill, drain, and refill" water stimulation process. It significantly reduces drowning mortality, improves feeding consistency and size uniformity by leveraging a tiered integrated system linked to the metamorphosis rate threshold, and shortens the time required to produce up to 4g of seedlings. Considering both FCR and labor costs, the unit cost of seedlings is significantly reduced, verifying the technical effectiveness and engineering feasibility of this invention.

[0107] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A type of black-spotted frog ( Pelophylax nigromaculatus Early breeding and juvenile frog rearing method, 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 tiered 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 are sold: When the weight of the tadpoles reaches ≥4g / fish, they are screened and sold or transferred to paddy fields for further cultivation. The water stimulation procedure in step S1 is as follows: after the temperature stabilizes, add water to the breeding frog pond 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.

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 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.

4. 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.

5. 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.

6. The system according to claim 5, 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.

7. The system according to claim 5, 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.

8. The system according to claim 5, 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.

9. The system according to claim 5, 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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