Breeding method and application of ammonia-nitrogen-resistant river crabs

Abstract

The invention provides a breeding method and application of ammonia-nitrogen-resistant river crabs, and belongs to the technical field of river crab breeding. The breeding method provided by the invention comprises the following steps: S1, establishing a breeding base population, and performing ammonia nitrogen resistance evaluation; s2, after the larval crabs of the basic group are subjected to toxic substance counteracting breeding, the robust larval crabs are selected for adult crab breeding; s3, after adult crabs are harvested, robust adult crabs are selected as parent crabs, juvenile crabs are obtained after mating of the parent crabs, and after the juvenile crabs are bred into fifth-stage juvenile crabs, toxic substance counteracting breeding is conducted; s4, after the challenge culture in the step S3, selecting robust juvenile crabs for juvenile crab culture; s5, after the juvenile crabs are harvested, the steps S2 to S4 are repeated, and when the survival rate is larger than or equal to 90% after the juvenile crabs are subjected to toxic substance counteracting breeding, the ammonia-nitrogen-resistant river crabs are successfully bred. The method is simple and easy to implement, the river crabs with ammonia nitrogen resistance can be bred, and development and popularization of crab culture in the rice field are facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of river crab breeding, and in particular relates to a method for breeding river crabs resistant to ammonia nitrogen and application thereof. Background Art

[0002] River crab, scientifically known as Chinese mitten crab (Eriocheir sinensis), has tender meat, delicious crab roe and crab paste and rich nutrition. It is one of the main crustacean economic animals for freshwater farming, and the history of artificial breeding has exceeded 30 years. In recent years, with the adjustment of agricultural industrial structure and the improvement of environmental protection requirements, crab farming in rice fields has been rapidly promoted and has become an important means for farmers to increase their income and become rich. However, due to the need to take into account the growth of rice, the ammonia nitrogen level in the water of rice fields is generally high in the early stage of rice growth. Ammonia nitrogen is also a relatively sensitive water chemistry indicator for river crabs. Excessive ammonia nitrogen can cause river crab poisoning or even death. Therefore, how to take into account the ammonia nitrogen requirements of rice and river crabs is an urgent problem to be solved in rice field crab farming. The existing solution is mainly staggered breeding, that is, a large amount of ammonia nitrogen nutrients are needed before the end of rice tillering. At this time, river crabs are not released, and river crabs are released after the end of rice tillering and the demand for ammonia nitrogen is reduced. When staggered breeding is adopted, river crabs need to be temporarily raised in a centralized manner before being released into the rice fields. The breeding density is high, the water quality is easy to deteriorate, and the risk of disease is high.

[0003] Therefore, providing a method for breeding ammonia nitrogen-resistant river crabs is beneficial to the development and promotion of crab farming in rice fields. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for breeding ammonia-nitrogen-resistant river crabs, which can breed ammonia-nitrogen-resistant river crabs and promote the development of crab farming in rice fields.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A method for breeding ammonia nitrogen resistant river crabs comprises the following steps:

[0007] S1. Establish a breeding base population and evaluate ammonia nitrogen tolerance;

[0008] S2. After the basic group of crabs are subjected to virus-challenging culture, healthy crabs are selected for adult crab culture;

[0009] S3. After harvesting adult crabs, healthy adult crabs are selected as breeding crabs. After mating, crab seedlings are obtained. After the crab seedlings are raised to the fifth stage of juvenile crabs, they are subjected to virus attack breeding;

[0010] S4, step S3, after the virus attack and breeding, selecting healthy crablets for crab breeding;

[0011] S5. After harvesting the crabs, repeat steps S2 to S4. When the survival rate of the crablets after the poison-challenging culture is ≥ 90%, the breeding of ammonia-nitrogen-resistant river crabs is successful.

[0012] Preferably, the ammonia nitrogen resistance assessment is to assess the 96h half-lethal concentration of ammonium chloride to crabs in the basic population.

[0013] Preferably, the drug-challenging culture is to culture the crabs in an aqueous solution containing ammonium chloride, and the concentration of the ammonium chloride is the 96-hour half-lethal concentration of the crabs obtained by the ammonia nitrogen resistance assessment.

[0014] Preferably, the duration of the virus-challenging culture is 96 hours.

[0015] Preferably, the robust standard is: having healthy limbs and immediately fleeing and hiding after being touched.

[0016] Preferably, the basic population is composed of different families in the breeding population, and the number of the families is 5 to 10.

[0017] Preferably, the breeding group includes the Photosynthetic No. 1 breeding group.

[0018] Preferably, the breeding crabs are mated by self-pollination within the family between male and female crabs at a ratio of 1:2.

[0019] Another object of the present invention is to provide application of the breeding method in river crab breeding.

[0020] Another object of the present invention is to provide application of the breeding method in crab farming in rice fields.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides a method for breeding ammonia nitrogen-resistant river crabs, which can breed ammonia nitrogen-resistant river crabs with a survival rate of ≥90% in water bodies with high ammonia nitrogen levels. The method provided by the present invention is simple and easy to implement, can quickly breed new varieties of river crabs, and is applied to the process of raising crabs in rice fields, which is conducive to the development and promotion of raising crabs in rice fields. DETAILED DESCRIPTION

[0023] The invention provides a method for breeding ammonia nitrogen resistant river crabs, comprising the following steps: S1, forming a breeding basic group, and evaluating ammonia nitrogen resistance; S2, carrying out virus-challenging culture on the crabs of the basic group, and then selecting strong crabs for adult crab culture; S3, after harvesting the adult crabs, selecting strong adult crabs as breeding crabs, obtaining crab seedlings after mating the breeding crabs, and carrying out virus-challenging culture after the crab seedlings are raised to fifth-stage crablets; S4, after the virus-challenging culture in step S3, selecting strong crablets for crab culture; S5, after harvesting the crablets, repeating steps S2 to S4, and when the survival rate of the crablets after the virus-challenging culture is completed is ≥90%, the breeding of ammonia nitrogen resistant river crabs is successful.

[0024] In the present invention, the basic population is composed of different families in the breeding group, and the breeding group includes the photosynthetic No. 1 breeding group; the number of the families is 5 to 10; the survival rate of the families in rice field culture is ≥30%, and the survival rate refers to the survival rate of river crabs from the stage of releasing crab seedlings into the rice fields in early June to harvesting crabs in early October.

[0025] In the present invention, the ammonia nitrogen resistance assessment is to assess the 96h half-lethal concentration of ammonia nitrogen to crabs in the basic population through an acute toxicity test. The challenge culture is to culture the river crabs in an aqueous solution containing ammonia nitrogen prepared with ammonium chloride, the challenge culture is static water culture, the ammonia nitrogen concentration is the 96h half-lethal concentration of crabs obtained by the ammonia nitrogen resistance assessment, feed them in sufficient quantities every day, and detect the ammonia nitrogen content in the aqueous solution every 12 hours to ensure that the ammonia nitrogen content in the aqueous solution is a preset value.

[0026] In the present invention, the duration of the virus-challenging culture is 96 hours; the virus-challenging culture is preferably still water culture; after the virus-challenging culture is completed, healthy crabs are selected, and the standard of health is: healthy limbs and immediate escape and avoidance after being touched.

[0027] In the present invention, the mating of the breeding crabs is that the male crabs and the female crabs mate in a ratio of 1:2, and the mating is self-pollination within the family.

[0028] The invention also provides the application of the breeding method in river crab breeding. The method provided by the invention can obtain river crabs with stable inheritance and resistance to ammonia nitrogen, thus promoting the development of river crab breeding.

[0029] The invention also provides the application of the breeding method in crab farming in rice fields. The ammonia nitrogen-resistant river crabs bred by the invention can tolerate high ammonia nitrogen content, which is beneficial to promoting the development of crab farming in rice fields.

[0030] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0031] Example 1

[0032] A method for breeding ammonia nitrogen resistant river crabs comprises the following steps:

[0033] S1. Select 10 families (survival rate ≥ 30%) from the photosynthetic No. 1 breeding population to form a basic breeding population, and conduct ammonia nitrogen tolerance assessment: conduct an acute toxicity test on the crabs in the basic population to obtain the 96-hour half-lethal concentration of ammonia nitrogen to the crabs;

[0034] S2. Performing a virus-challenging culture on the basic group of crabs: adjusting the ammonia nitrogen concentration in the water to a semi-lethal concentration for crabs in 96 hours by adding ammonium chloride, placing the crabs in the above water, and culture the crabs in static water for 96 hours; after the virus-challenging culture, selecting the crabs with intact limbs and able to escape and hide immediately after being touched for adult crab culture;

[0035] S3. After harvesting adult crabs, healthy (with healthy limbs and able to escape and hide immediately after being touched) adult crabs are selected from each family as breeding crabs for self-pollination within the family, wherein the ratio of male crabs to female crabs is 1:2, and crab seedlings are obtained after mating. The crab seedlings are raised to stage 5 crablets and then subjected to poison culture: the ammonia nitrogen concentration in the water is adjusted to a half-lethal concentration for crab detaining for 96 hours by adding ammonium chloride, and the crablets are placed in the above water for static water culture for 96 hours;

[0036] S4, step S3, after the virus attack and breeding, select healthy (with healthy limbs and able to escape and hide immediately after being touched) crabs for crab-holding breeding;

[0037] S5. After harvesting the crabs, repeat steps S2 to S4. When the survival rate of the crablets after the poison-challenging culture is ≥ 90%, the breeding of ammonia-nitrogen-resistant river crabs is successful.

[0038] Test Example 1

[0039] The method for breeding ammonia nitrogen-resistant river crabs in Example 1 is adopted to breed ammonia nitrogen-resistant river crabs, and the steps are as follows:

[0040] S1. In the spring of 2017, 10 families (survival rate ≥ 30%) were selected from the Photosynthetic No. 1 breeding population to form a basic breeding population. The conditions of the 10 families are shown in Table 1.

[0041] Table 1 Basic population crab family situation

[0042] Family number Survival rate (%) Quantity (pcs) Specifications (g / piece) 1 36.57 3600 5.1 2 34.89 3400 5.0 3 32.60 3100 4.9 4 34.88 2900 4.8 5 33.95 2700 5.1 6 33.89 2500 4.9 7 36.18 2300 5.0 8 38.88 3100 5.1 9 38.34 3700 5.2 10 37.05 3800 4.8

[0043] Acute toxicity test on crabs in the base population:

[0044] Use 20g of analytical grade ammonium chloride to dissolve in 1L of distilled water to prepare a mother solution; add the mother solution to 50L of aerated tap water to make its ammonia nitrogen concentration reach the preset value, then accurately measure 3 portions of 30L of the prepared solution and put them into a 50L plastic water tank for standby use. The preset ammonia nitrogen concentration gradient is shown in Table 2; put 30 crabs in each test water tank (3 crabs are randomly selected from each family), record the number of dead crabs every 24 hours as shown in Table 2, detect ammonia nitrogen once every 12 hours, and use the mother solution to adjust and maintain the preset value; count the number of crab deaths in each water tank test within 96 hours, and calculate the mortality rate.

[0045] The average mortality results are shown in Table 3. According to the mortality of crabs at various concentrations, the data fitting equation can be obtained: y=1.8461x-5.1192, where y is the mortality rate and x is the ammonia nitrogen concentration. Substituting y=50, the 96-hour half-lethal concentration is 29.86 mg / L. For the convenience of experimental operation, the 96-hour half-lethal concentration is selected as 30 mg / L.

[0046] Table 2 Death record of crabs in the experiment

[0047]

[0048] Table 3 Statistics of average mortality rate in the experiment

[0049]

[0050]

[0051] S2. Conduct virus-challenging culture on the basic group of crabs: adjust the ammonia nitrogen concentration in the water to 30 mg / L by adding ammonium chloride, place the crabs in the above water, and culture the crabs in static water for 96 hours; 2,000 crabs are challenged with viruses for each family. After the virus-challenging culture, 800 crabs with intact limbs that can escape and hide immediately after being touched are selected from each family for adult crab culture.

[0052] S3. After harvesting adult crabs, healthy (with healthy limbs and able to escape and hide immediately after being touched) adult crabs are selected from each family as breeding crabs for self-pollination within the family. The ratio of male to female breeding crabs is 1:2. Egg-bearing crabs are obtained after mating of the breeding crabs.

[0053] After the egg-bearing crabs hibernate, three egg-bearing crabs were randomly selected from each family in 2018 to cultivate crab seedlings and carry out crab culture. After the crab seedlings were raised to the fifth-stage crabs, they were cultured with poison: the ammonia nitrogen concentration in the water was adjusted to 30 mg / L by adding ammonium chloride, and the crabs were placed in the above water and cultured in static water for 96 hours.

[0054] S4. After the virus-infected culture in step S3, 100,000 healthy crablets (those with intact limbs and able to escape and hide immediately after being touched) were selected from each family for crab culture.

[0055] S5. After harvesting crabs in autumn, continue to repeat steps S2 to S4. When the survival rate of crablets after the poison-challenging culture is ≥ 90%, the breeding of ammonia-nitrogen-resistant river crabs is successful.

[0056] After breeding until 2021, the crab seedlings were raised to the fifth stage of crab larvae and then subjected to virus attack breeding. Among them, the survival rate of three families reached more than 90%. These three families were supplied to production as successfully bred ammonia-nitrogen-resistant river crab varieties.

[0057] Test Example 2

[0058] The resistance of the ammonia-nitrogen-resistant river crab lineage selected in Experimental Example 1 was verified.

[0059] In Experimental Example 1, 30 crab families were obtained by breeding in 2021, and the ammonia nitrogen resistance of each family was verified as follows:

[0060] The experiment was conducted in a 50L plastic container. The aerated tap water was adjusted to an ammonia nitrogen concentration of 30 mg / L with ammonium chloride. Thirty crabs from one family were placed in each tank. Three parallel tanks were tested for each family. The ammonia nitrogen concentration in the tank was adjusted once every 12 hours to maintain it at 30 mg / L. Dead crabs were picked out and recorded every 24 hours. After 96 hours, the number of surviving crabs was recorded and the average survival rate was calculated. The ammonia nitrogen resistance of each family was compared. The results are shown in Table 4.

[0061] Table 4 Resistance verification results of different families

[0062]

[0063]

[0064] According to the results in Table 5, the survival rate of crabs with family numbers 1, 2 and 3 after 96 hours is greater than 90%, which meets the breeding requirements. The present invention can effectively breed river crabs resistant to ammonia nitrogen.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for breeding ammonia nitrogen resistant river crabs, characterized in that: The steps include: S1. Establish a breeding base population and evaluate ammonia nitrogen tolerance; S2. After the basic group of crabs are subjected to virus-challenging culture, healthy crabs are selected for adult crab culture; S3. After harvesting adult crabs, healthy adult crabs are selected as breeding crabs. After mating, crab seedlings are obtained. After the crab seedlings are raised to the fifth stage of juvenile crabs, they are subjected to virus attack breeding; S4, step S3, after the virus attack and breeding, selecting healthy crablets for crab breeding; S5. After harvesting the crabs, repeat steps S2 to S4. When the survival rate of the crablets after the poison-challenging culture is ≥ 90%, the breeding of ammonia-nitrogen-resistant river crabs is successful.

2. The breeding method according to claim 1, characterized in that: The ammonia nitrogen resistance assessment is to evaluate the 96-hour half-lethal concentration of ammonium chloride to crabs in the basic population.

3. The breeding method according to claim 1, characterized in that: The drug-challenging culture is to culture the crabs in an aqueous solution containing ammonium chloride, and the concentration of the ammonium chloride is the 96-hour half-lethal concentration of the crabs obtained by the ammonia nitrogen resistance assessment.

4. The breeding method according to claim 1, characterized in that: The time of the virus-challenging culture was 96 h.

5. The breeding method according to claim 1, characterized in that: The standard of being strong is: having healthy limbs and being able to escape and hide immediately after being touched.

6. The breeding method according to claim 1, characterized in that: The basic population is composed of different families in the breeding population, and the number of the families is 5 to 10.

7. The breeding method according to claim 6, characterized in that: The breeding group includes the photosynthetic No. 1 breeding group.

8. The breeding method according to claim 1, characterized in that: The breeding crabs are mated by self-pollination within the family between male and female crabs at a ratio of 1:

2.

9. Application of the breeding method according to any one of claims 1 to 8 in river crab breeding.

10. Use of the breeding method according to any one of claims 1 to 8 in crab farming in rice fields.

Images