Batch artificial breeding method of rana nigromaculata tadpole

Abstract

The present application belongs to the technical field of aquaculture, and particularly relates to a batch artificial breeding method of early larvae of Pelophylax nigromaculatus, comprising the following steps: (1) the breeding frogs are selected from the Pelophylax nigromaculatus captured before hibernation in the previous year and temporarily bred in a room, or the Pelophylax nigromaculatus captured this year and removed from hibernation 30-45 days in advance; (2) in February, the breeding frogs are selected according to a male-female ratio of 1:1 to artificially induce spawning, and a single Pelophylax nigromaculatus is injected with a dose of 1.05-1.25 μg of LHRH-A2 and 40-45 IU of HCG; (3) the breeding frogs after induced spawning are placed in an oviposition pool to lay eggs, and the placement density of the breeding frogs is 30-60 pairs / m 2 , and a quiet and dark environment is provided for egg laying; and (4) after the breeding frogs lay eggs, the fertilized eggs are fished out and dispersed in a hatching net cage for hatching, and all the breeding frogs in the oviposition pool are removed. The present application solves the problems of a large time span of natural egg laying of the Pelophylax nigromaculatus, short breeding time, small size of adult frogs, and the like, and increases the breeding benefit.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aquaculture, and particularly relates to a batch artificial breeding method of Pelophylax nigromaculatus early fry. BACKGROUND

[0002] Pelophylax nigromaculatus, also known as black-spotted frog or green frog, belongs to amphibians of the order Anura, the family Ranidae and the genus Pelophylax. In China, Pelophylax nigromaculatus and small crayfish are both from unobtrusive paddy field aquatic animals and become delicacies on the dining table. With the continuous improvement of people's material living standards, the demand for Pelophylax nigromaculatus is also increasing, and it is obviously impossible to meet the market demand by catching in the wild, so artificial breeding of Pelophylax nigromaculatus has gradually emerged.

[0003] With the implementation of the rural revitalization strategy, in order to further adjust the agricultural industrial structure and develop efficient agriculture, the government encourages and supports the comprehensive planting and breeding in paddy fields. The net income of the rice-frog comprehensive planting and breeding mode is several times higher than that of the single rice mode, and has significant economic, ecological and social benefits, which is one of the directions of agricultural development in China. As the only amphibian in the comprehensive planting and breeding in paddy fields, Pelophylax nigromaculatus is attracting more and more attention, but it is still in the initial stage in terms of breeding and scientific research.

[0004] Chinese invention patent with publication number CN101543193A provides a breeding method of Pelophylax nigromaculatus in northern Guangdong, which controls the water temperature at 11-13℃ to let Pelophylax nigromaculatus naturally spawn and hatch tadpoles in the soil pool by providing a suitable spawning environment, aiming to develop a method for breeding northern Pelophylax nigromaculatus in the northern mountainous area of Guangdong. Chinese invention patent with publication number CN102388835A provides an early breeding method of Pelophylax nigromaculatus in the northeast, which builds a greenhouse spawning and hatching pool and an outdoor tadpole breeding pool, aiming to prolong the growth time of tadpoles and improve the maximum weight and metamorphosis rate of tadpoles. Compared with Pelophylax nigromaculatus, Pelophylax nigromaculatus has a long growth cycle, spawns at two years old, and reaches a body weight of about 35g at three years old. Pelophylax nigromaculatus is mainly bred in a semi-artificial way, i.e., artificial breeding of tadpoles and breeding of metamorphic frogs in the wild environment. Pelophylax nigromaculatus is currently bred artificially in the whole process, and can reach sexual maturity and a body weight of more than 50g in the same year. Pelophylax nigromaculatus has medicinal value, and its oviduct is a famous tonic and health food, commonly known as snow crab oil; while Pelophylax nigromaculatus is mainly used for food, so there are obvious differences between the two in breeding, breeding and application.

[0005] The main problem faced by Pelophylax nigromaculatus in artificial breeding is that the natural breeding time of Pelophylax nigromaculatus is from April to June, and the natural breeding time span is relatively large. In order to collect enough egg masses in the wild, a long time span is required. The egg masses collected at different times are concentrated for hatching, which not only causes the hatching batches to be out of sync, but also causes large tadpoles to eat small tadpoles. In addition, the metamorphosis of tadpoles of different sizes is concentrated for breeding, and large Pelophylax nigromaculatus will eat small Pelophylax nigromaculatus, which greatly reduces the survival rate. After the temperature drops at the end of September every year, Pelophylax nigromaculatus will start to hibernate, so the feeding time of Pelophylax nigromaculatus breeding can only be before September. Therefore, due to the influence of weather factors, if the natural spawning time is too late, the breeding time of the year will be shortened, and the size of the adult frog will be small and cannot be marketed in the year. SUMMARY

[0006] In order to solve the problems of low natural spawning rate of Pelophylax nigromaculatus, large size difference of adult frogs caused by different batches of natural spawning, short breeding time caused by too late natural spawning time, and small size of adult frogs that cannot be marketed in the year, the present application provides a batch artificial breeding method for early Pelophylax nigromaculatus seedlings.

[0007] Specifically, the batch artificial breeding method for early Pelophylax nigromaculatus seedlings of the present application comprises:

[0008] (1) Selection of breeding frogs

[0009] The breeding frogs are Pelophylax nigromaculatus captured before hibernation in the previous year and temporarily bred indoors, or Pelophylax nigromaculatus captured in the current year and hibernated for 30-45 days in advance;

[0010] (2) Breeding frog induction

[0011] The breeding frogs are selected according to a female to male ratio of 1:1 for artificial induction, and the dose of the induction agent injected into each Pelophylax nigromaculatus is 1.05-1.25 μg of LHRH-A2 and 40-45 IU of HCG;

[0012] (3) Breeding frog spawning and fertilization

[0013] The induced breeding frogs are placed in a spawning pool for spawning, and the placement density of the breeding frogs is 30-60 pairs / m 2 , and a quiet and dark environment is provided for spawning;

[0014] (4) Fertilized egg hatching

[0015] After the breeding frogs spawn, the fertilized eggs are removed and dispersed in a hatching net cage for hatching, and all the breeding frogs in the spawning pool are removed. For female Pelophylax nigromaculatus that do not spawn, the next batch of induction and spawning is performed after re-injection of the induction agent.

[0016] The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects:

[0017] The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects: 2 The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects:

[0018] The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects:

[0019] The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects:

[0020] The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects: 2 .

[0021] The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects:

[0022] The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects:

[0023] The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects:

[0024] The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects:

[0025] The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects:

[0026] The batch artificial breeding method of the Pelophylax nigromaculatus tadpole has the following beneficial effects:

[0027] (2) The batch artificial breeding method of the Pelophylax nigromaculatus tadpole solves the problems of large time span of natural spawning of the Pelophylax nigromaculatus, short breeding time caused by late natural spawning, small size of adult frogs, and the like, and increases the breeding benefit;

[0028] (3) The batch artificial breeding method of the Pelophylax nigromaculatus tadpole can achieve the same batch by using artificial induction of spawning, and the spawning rate of the Pelophylax nigromaculatus injected in the same batch reaches more than 80%, thereby greatly improving the spawning efficiency;

[0029] (4) The batch artificial breeding method of the Pelophylax nigromaculatus tadpole can achieve the same batch by using artificial induction of spawning, and the spawning rate of the Pelophylax nigromaculatus injected in the same batch reaches more than 80%, thereby greatly improving the spawning efficiency; BRIEF DESCRIPTION OF DRAWINGS

[0030] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not intended to limit the scope of the application.

[0031] Figure 1 The figure is a schematic diagram of the composition of the batch artificial breeding system of the Pelophylax nigromaculatus tadpole adopted by the present application.

[0032] Figure 2 The figure is a perspective view of the temporary breeding pond.

[0033] Figure 3 The figure is a perspective view of the spawning pond.

[0034] Figure 4 The figure is a perspective view of the hatching pond.

[0035] Symbol explanation: 1 is the temporary breeding pond, 2 is the spawning pond, 3 is the hatching pond, 11 is the ordinary greenhouse, 12 is the sterilized straw, 13 is the spraying system, 21 is the heat preservation greenhouse, 22 is the EVA foam board, 31 is the heat preservation greenhouse, 32 is the hatching net cage, and 33 is the water inlet valve. DETAILED DESCRIPTION

[0036] In order to fully understand the purpose, features and effects of the present application, the following specific embodiments are used to describe the present application in detail. The process method of the present application adopts the conventional method or device in the art except for the following content. Unless otherwise specified, the following terms have the meanings commonly understood by those skilled in the art.

[0037] When a numerical range is disclosed herein, the range is to be construed as having been measured continuously along the range, and including each and every value within the range. Further, when a range is provided, it is intended to include the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Additionally, multiple ranges provided herein can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein.

[0038] Specifically, the application provides a batch artificial breeding method of Pelophylax nigromaculatus early fry, comprising:

[0039] (1) Selection of breeding frogs

[0040] The breeding frogs are Pelophylax nigromaculatus captured before hibernation in the previous year and temporarily raised indoors, or Pelophylax nigromaculatus captured this year and de-hibernated 30-45 days in advance;

[0041] (2) Induction of breeding frogs

[0042] The breeding frogs are selected according to a female to male ratio of 1:1 for artificial induction, and the dose of the induction agent injected into each Pelophylax nigromaculatus is 1.05-1.25 μg of LHRH-A2 and 40-45 IU of HCG, and the injection dose of the induction agent is 85-110 μL per frog;

[0043] (3) Oviposition and fertilization of breeding frogs

[0044] The induced breeding frogs are placed in an oviposition pool for oviposition, and the placement density of the breeding frogs is 30-60 pairs / m 2 , and a quiet and dark environment is provided for oviposition;

[0045] (4) Hatching of fertilized eggs

[0046] After the breeding frogs oviposit, the fertilized eggs are fished out and dispersed in a hatching shed for hatching, all the breeding frogs in the oviposition pool are removed, and for the female Pelophylax nigromaculatus that does not oviposit, the next batch of oviposition is performed after re-injection of the induction agent.

[0047] The inventor found through research that the earlier the Pelophylax nigromaculatus is bred in the year, the more time it has for breeding, i.e., early frog emergence, early market, and large size. The application studies the minimum oviposition temperature and the minimum hatching temperature suitable for Pelophylax nigromaculatus, so that Pelophylax nigromaculatus can be bred as early as February, and the Pelophylax nigromaculatus tadpoles become metamorphic frogs 30-45 days in advance. At this time, the weather is fine outdoors, which is the best time to start rice field Pelophylax nigromaculatus breeding. Through practice, the method of the application not only increases the breeding time of Pelophylax nigromaculatus by 30-45 days, achieves early frog emergence, early market, and large size, but also maximizes the cost savings of Pelophylax nigromaculatus breeding and improves economic efficiency.

[0048] In some preferred embodiments, the application provides a method for batch artificial breeding of Rana nigromaculata tadpoles, which is carried out by using the artificial breeding system as shown in Figure 1 and specifically comprises the following steps:

[0049] Selection of breeding frogs

[0050] In order to prolong the growth time of Rana nigromaculata, the spawning can be carried out about 30 days earlier than the natural spawning time of the local Rana nigromaculata. In general, the artificial breeding in central China is started in February.

[0051] In some embodiments, the breeding frogs are Rana nigromaculata captured in September of the previous year and temporarily kept indoors. As shown in Figure 2 The Rana nigromaculata is temporarily kept in a cement pond or other hard temporary keeping pond 1, and the temporary keeping density is 50-100 / m 2 . The temporary keeping pond 1 is arranged in a greenhouse 11 without a heat preservation function, the temporary keeping pond 1 is covered with disinfected straw 12 with a thickness of more than 30 cm, a spraying system 13 sprays tap water every week to keep the straw wet, and no feeding is performed during the temporary keeping period, so that the temperature in the pond differs from the outdoor temperature by 0-1℃, thereby promoting the breeding frogs to quickly burrow into the straw and hibernate.

[0052] In yet some embodiments, the breeding frogs are obtained by digging out the Rana nigromaculata hibernating in the rice frog field at the beginning of February, or by filling the rice frog field with water to force the Rana nigromaculata hibernating in the rice frog field out of the burrows.

[0053] One frog induced to oviposit

[0054] In the method, the breeding frogs with a weight of 50 g or more, bright color, intact body surface, full abdomen and powerful jumping are selected.

[0055] Preferably, the dosage of the ovulation agent injected into a single Rana nigromaculata is 1.1 μg of LHRH-A2 and 45 IU of HCG, and the injection dosage of the ovulation agent is 100 μL per frog.

[0056] In the method, the injection of the ovulation agent is performed in the thigh muscle, and the dosage of the ovulation agent injected into the male and female breeding frogs is the same. After the injection of the drug, the breeding frogs are placed in a foam box for observation for 0.5-1 h to confirm that there is no problem, and then the breeding frogs are placed in the spawning pond for spawning at a spawning density of 30 pairs / m 2 .

[0057] According to the method of the application, the ovulation can be achieved, the spawning rate of the Rana nigromaculata injected in the same batch reaches more than 80%, and the spawning efficiency is greatly improved.

[0058] One frog ovipositing and fertilizing

[0059] After induced spawning, the breeding frogs are placed in a special spawning pond to lay their eggs. Generally, the breeding frogs will pair up after the injection of the spawning agent, and most of them will complete the egg-laying process by the third day.

[0060] Among them, such as Figure 3 As shown, the spawning pond 2 of the present invention is set in a heat-insulating greenhouse 21, thereby making the water temperature of the spawning pond suitable for the breeding frogs to lay eggs and fertilize.

[0061] Preferably, the spawning pond 2 has a water depth of 10-15cm and a water temperature of 16℃ or above (such as 16-18℃, 18-20℃, 20-22℃, 22-24℃, 24-26℃). EVA foam boards 22 are placed on the water, and the foam boards 22 occupy more than half of the entire spawning pond area to facilitate mating and spawning of the breeding frogs.

[0062] Preferably, to ensure a quiet environment, the spawning pond 2 can be covered with a black cloth or the doors and windows of the insulated greenhouse 21 can be closed to create a continuously dark environment for spawning.

[0063] Fertilized eggs hatching

[0064] After the fertilized eggs are collected and dispersed, they are incubated in the hatching shed. All breeding frogs are removed from the spawning pond. Female breeding frogs that have not laid eggs are injected with an oxytocin agent again to induce spawning in the next batch. The method for checking whether a female breeding frog has laid eggs is as follows: A female breeding frog with a shriveled abdomen that will indent when touched indicates that she has laid eggs; a female breeding frog with a full abdomen that is elastic and does not indent when touched indicates that she has not laid eggs.

[0065] like Figure 4 As shown, the hatching pool 3 is set in the heat-insulating greenhouse 31. Hatching net cages 32 are placed in the hatching pool 3. The water depth in the hatching net cages 32 is more than 50cm, and the water temperature is 14℃ or above (such as 14-16℃, 16-18℃, 18-20℃, 20-22℃, 22-24℃, 24-26℃). The hatching pool 3 is equipped with a water inlet valve 33 so that the water body has a continuous flow to ensure excellent water quality.

[0066] Preferably, the insulated greenhouse 31 is 200m². 2 The plastic insulated greenhouse on the left and right has a dissolved oxygen content of 8.1 mg / L in the incubation pool water.

[0067] Generally, fertilized eggs develop into tadpole-like shapes on the 5th day of incubation, moving inside the egg membrane. By the 6th day, many tadpoles hatch and attach to the side walls. By the 7th day, most tadpoles have completed hatching. Unfertilized eggs and poor-quality eggs should be removed promptly to prevent contamination of the water.

[0068] The present application provides good hatching conditions by hatching the fertilized eggs of the same batch, and the survival rate after overall hatching reaches more than 50%, the same batch hatching ensures that the tadpoles and adult frogs have consistent specifications, reduces mutual predation, and improves the survival rate.

[0069] EMBODIMENT

[0070] The present application will be further described by way of examples without thereby limiting the present application to the examples described. The experimental methods in the following examples are not specified, and are carried out according to conventional methods and conditions.

[0071] Test 1: Determination of the minimum spawning temperature

[0072] In order to determine the minimum spawning temperature of Rana nigromaculata, we counted the mating, calling and spawning of Rana nigromaculata in the natural environment of the frog pond from the end of March to the beginning of April 2021, and measured the water temperature. The test lasted for 2 weeks, and the final determination was made by whether or not spawning. The results are shown in the following table:

[0073] Temperature Embrace situation Male frog croaking situation Oviposition situation 9.7℃ Very few embraces Not croaking Not ovipositing 12.8℃ Few embraces Croaking Very few ovipositing 13.4℃ Few embraces Croaking Very few ovipositing 14.4℃ Embrace Croaking Few ovipositing 15.6℃ Embrace Croaking Ovipositing

[0074] We measured the water temperature, and when the natural water temperature was only 9.7℃, we could only see a very small amount of mating, and could not hear any Rana nigromaculata calling, and the mating Rana nigromaculata did not spawn; when the water temperature was 12.8-13.4℃, we could see Rana nigromaculata mating, Rana nigromaculata calling continuously, but there were very few mating Rana nigromaculata spawning; when the water temperature reached 14.4℃, we could see more Rana nigromaculata mating, and some mating Rana nigromaculata spawning; when the water temperature rose to 15.6℃, we could see a lot of Rana nigromaculata mating, Rana nigromaculata calling continuously, and a lot of egg masses. Therefore, we recommend that the minimum water temperature for spawning should be above 16℃.

[0075] Test 2: Determination of the optimum dose of labor induction

[0076] In order to determine the optimum dose of labor induction of Rana nigromaculata, we conducted an artificial labor induction test in December 2021 when the weather was the coldest, at which time the Rana nigromaculata in the natural environment were hibernating, and our frogs were from Rana nigromaculata that were temporarily raised in a cement pond in September 2021 and hibernated. The test water temperature was heated by a heating rod, the test lasted for 3 days, the labor induction agent was prepared as LHRH-A 20.022μg / μL, HCG 0.9IU / μL, 50μL or 25μL of each of the two labor induction agents were mixed, and the corresponding total injection volume was 100μL or 50μL, and the results are shown in the following table:

[0077]

[0078] We used three injection doses, namely only male, male half and female and male. Only male injection has no effect on labor induction; the effect of male half is general; the best way is to inject the same dose of female and male, and the labor induction efficiency can reach 80%, which is much higher than the natural egg laying rate (about 35.2%).

[0079] Test 3: Determination of the minimum incubation temperature

[0080] In order to determine the minimum incubation temperature of Rana nigromaculata, we recorded the incubation and temperature of the egg mass after labor induction in natural environment and incubation shed in February 2022. The test lasted for 7 days, and the results are shown in the following table:

[0081] Days 1 2 3 4 5 6 7 Result Greenhouse water temperature / °C 15.5 16.7 16.1 19.5 16.9 14.0 14.2 Hatching success Natural water temperature / °C 14.8 18.1 15.6 15.7 13.4 7.3 13.1 Hatching failure

[0082] Through observation, at lower water temperature, the fertilized egg mass develops slowly, and the tadpoles need 6-7 days to emerge. During the 5th-7th day of the test, the temperature decreased, and it could be clearly seen that the tadpoles in the shed were in poor condition before or after emerging. In contrast, the egg mass in natural environment failed to hatch due to too low temperature. Therefore, we suggest that the minimum water temperature for incubation should be above 14℃.

[0083] Test 4: Comparison of natural spawning and artificial labor induction

[0084] In order to determine the effect of natural spawning and artificial labor induction, we conducted a comparative test in late March 2022, in which both artificial labor induction and natural spawning were under natural water temperature without temperature increasing facilities. The results are shown in the following table:

[0085] Item 1 2 3 4 5 Average weight g Natural oviposition single egg mass g 143 56 31 155 89 94.8 Artificial induced oviposition single egg mass g 101 70 172 131 200 134.8

[0086] We selected the egg mass of single pair of Rana nigromaculata for artificial labor induction and natural spawning for comparison by weighing. Overall, the weight of the egg mass of artificial labor induction was generally larger, while the collected natural egg mass was generally smaller. Finally, the weight of the egg mass of each pair of Rana nigromaculata for natural spawning was about 94.8g, while that for artificial labor induction was much higher, reaching 134.8g.

[0087] Through tests 1-4, we can determine the minimum spawning temperature, the minimum incubation temperature and the most suitable labor induction dose for early breeding of Rana nigromaculata. We believe that it is feasible to induce labor 30-45 days earlier to end hibernation and thus increase the breeding time of Rana nigromaculata and improve the size of adult frogs. Therefore, the inventors conducted the following experiments:

[0088] Test 5: Artificial labor induction and natural spawning breeding test

[0089] In 2022, we carried out comparative breeding experiments of artificial induced spawning and natural breeding in Meijiandun Modern Agricultural Science and Technology Demonstration Park in Huanggang City, Hubei Province, wherein the artificial induced spawning breeding experiments were all carried out according to the method of the present application. The results are shown in the following table:

[0090]

[0091] Through the comparative experiment, we found that artificial induced spawning can make black-spotted frogs go on sale one month earlier, and they can be sold in early July. At this time, there are few black-spotted frogs on the market, and the price is very good, and the demand exceeds the supply. As a comparison, the earliest market time of natural breeding is in early August. Even in September, the artificially induced black-spotted frogs generally grow to 1.5 liang, while the naturally bred black-spotted frogs only grow to 1 liang. The batch artificial breeding method of early black-spotted frog seedlings can achieve the purposes of early frog, early market and large size, and it is better than others, has strong market competitiveness.

[0092] The present application has been disclosed in the foregoing by preferred embodiments, but those skilled in the art should understand that these embodiments are only used to depict the present application, and should not be understood as limiting the scope of the present application. It should be noted that any changes and substitutions equivalent to these embodiments should be considered as covered by the scope of the claims of the present application. Therefore, the protection scope of the present application should be limited by the scope defined in the claims.

Claims

1. A method for mass artificial breeding of Rana nigromaculata early larvae, characterized in that, The method comprises the following steps: (1) selecting a frog The black-spotted frog is captured in the previous year before hibernation and temporarily kept indoors, or the black-spotted frog is captured in the current year and is de-hibernated 30-45 days in advance; The black-spotted frog is captured in September of the previous year, and the black-spotted frog is de-hibernated in February; (2) inducing spawning of the frog The frog is selected according to a female-male ratio of 1:1 for artificial induction of spawning, and the dose of the single black-spotted frog injected with the inducer is LHRH-A 21.05-1.25 μg and HCG 40-45 IU; (3) spawning and fertilization of the frog The induced spawn frogs are placed in the spawning pool for spawning, and the placement density of the spawn frogs is 30-60 pairs / m 2 and provide a quiet and dark environment for spawning. The water depth of the spawning pool is 10-15 cm, the water temperature is 16℃ or above, and an EVA foam plate is placed on the water; (4) hatching of the fertilized eggs After the frog spawns, the fertilized eggs are collected and dispersed in a hatching net cage for hatching, and the frog in the spawning pool is removed, and the female black-spotted frog that does not spawn is injected with the inducer again, and then the next batch of induction, spawning is performed; The water depth of the hatching net cage is more than 50 cm, the water is kept slightly flowing, and the water temperature is 14℃ or above.

2. The method for mass artificial breeding of Rana nigromaculata early larvae according to claim 1, characterized in that, The temporary breeding method of black-spotted frogs in step (1) is as follows: temporary breeding is carried out in a cement pool or other hard temporary breeding pool, and the temporary breeding density is 50-100 per m 2 In the temporary breeding pool, sterilized straw is fully laid, the thickness of the straw is more than 30 cm, tap water is sprayed every week to ensure that the straw is wet, no feeding is carried out during the temporary breeding period, and the temperature in the pool is ensured to be 0-1℃ different from the outdoor temperature.

3. The method for mass artificial breeding of Rana nigromaculata early larvae according to claim 1, characterized in that, The method for de-hibernating the black-spotted frog in advance in step (1) is that the black-spotted frog hibernating in the rice frog field is dug out, or the rice frog field is filled with water, and the hibernating black-spotted frog is forced out of the cave.

4. The method for mass artificial breeding of Rana nigromaculata early larvae according to claim 1, characterized in that, In step (2), the selected frog has a weight of 50 g or above, bright color, no damage on the body surface, full abdomen, and powerful jumping.

5. The method for mass artificial breeding of Rana nigromaculata early larvae according to claim 1, characterized in that, The dose of the single black-spotted frog injection of the oxytocic agent was LHRH-A2 1.1 μg, HCG 45 IU, and the density of the breeding frogs was 30 pairs / m 2 .

6. The method for mass artificial breeding of Rana nigromaculata early larvae according to claim 5, characterized in that, The injection dose of the inducer is 100 μL per frog, and the injection method is thigh muscle injection.

7. The method of claim 1, wherein the Rana nigromaculata tadpoles are raised in batches. The spawning pool is covered with black cloth and / or the doors and windows are closed tightly.

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