In-vitro hatching method for fertilized eggs of cherax quadricarinatus

Abstract

The invention discloses an in-vitro hatching method for fertilized eggs of cherax quadricarinatus. The hatching method comprises the following steps: stripping fertilized eggs of cherax quadricarinatus from a parent body, cleaning and disinfecting, putting the fertilized eggs into a hatching cup, and putting the hatching cup into a hatching liquid tank with prepared hatching liquid for in-vitro hatching. According to the hatching method, hatching conditions of fertilized eggs of cherax quadricarinatus in a parent body can be simulated, the conditions in the hatching process are controllable, the death rate of the fertilized eggs is greatly reduced, and the hatching rate of the cherax quadricarinatus is increased; and the fertilized eggs are stripped from the parent for in-vitro incubation, so that the carrying time of the fertilized eggs in the parent can be shortened, the mating and egg carrying times of female shrimps are increased, and the breeding quantity is increased on a large scale. Wide market application prospects are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of aquatic animal breeding, and in particular relates to an in vitro hatching method for fertilized eggs of red claw crayfish. Background Art

[0002] Red claw crayfish (Cherax quadricarinatus), native to Australia, is one of the world's most valuable freshwater economic shrimps. Because of its appearance similar to sea lobsters, it is commonly known as Australian freshwater lobsters in China. Red claw crayfish belongs to tropical shrimps. The water temperature for mating and hatching is generally 22-32℃, and the best water temperature is 24-30℃. They begin to mate in this temperature season every year. After mating, fertilization is completed within 24 hours. The female shrimp holds the fertilized eggs in her abdomen. After 35-42 days, the shrimp fry are hatched, with a body length of 0.6-0.8cm.

[0003] At present, the main way of hatching fertilized eggs in the seedling rearing process is that the female shrimps carry the fertilized eggs to hatch naturally. There are three main ways to manage the hatching of egg-bearing shrimps in production management: one is to pick out the female shrimps carrying eggs at different stages in the mating pond of the broodstock, put them in the hatching pond for hatching, and collect the shrimp fry from the hatching pond to the breeding pond for cultivation every day; the second is to pick out the egg-bearing shrimps of the same egg color from the mating pond and hatch them separately in the hatching pond. After all the shrimps are hatched, the female shrimps are picked out and the shrimp fry are cultivated in the original hatching pond; the third is that the egg-bearing shrimps hatch naturally in the mating pond, and the hatched shrimp fry are collected from the mating pond and cultivated in the breeding pond. The above three hatching methods all use natural hatching of egg-carrying shrimps. The female shrimps carry fertilized eggs for a long time, and cannot mate for the second time during the egg-carrying period. The fertilized eggs are affected by natural conditions such as water quality and temperature, and are prone to problems such as egg drop, mold and dead eggs. The first two methods require picking egg-carrying shrimps every day. The egg-carrying shrimps bounce, causing some fertilized eggs to fall off. At the same time, hatching pools are required, which consumes a lot of manpower and increases space. Picking egg-carrying shrimps every day will cause stress to the parent shrimps in the mating pool. The seedlings hatched by the third method are easily attacked and eaten by the parent shrimps, affecting the survival rate. These problems will seriously affect the efficiency and scale of seedling cultivation, and restrict industrial development. Summary of the invention

[0004] The purpose of the invention is to provide an in vitro hatching method for fertilized eggs of red claw crayfish. The invention hatches the fertilized eggs of red claw crayfish in vitro, overcomes the defect of natural hatching of the mother's eggs, realizes the full control of the hatching of the fertilized eggs, greatly improves the hatching rate, saves space, and improves the efficiency and amount of seedling cultivation.

[0005] To achieve the purpose of the present invention, the present invention provides the following technical solutions: The present invention provides a method for in vitro hatching of fertilized eggs of red claw crayfish, comprising the following steps: (1) Peeling, cleaning and disinfecting the fertilized eggs from the mother: Pick up the fertilized female shrimp, hold it tightly with your hands, and gently collect the fertilized eggs from the abdomen with curved forceps disinfected with 75% alcohol. Clean and disinfect them, record the number of eggs, and then put them into the hatching cup; (2) Preparation of fertilized egg hatching solution: Filter and disinfect underground fresh water or water from shrimp ponds, then add 1-2ppm formalin solution to make fertilized egg hatching solution, which is then poured into the hatching solution tank. The solution is filtered, sterilized and disinfected in a circulating water system in the hatching solution tank for at least 24 hours before use; (3) In vitro incubation of fertilized eggs: The incubation place is a relatively closed incubation room. The incubation cups containing fertilized eggs are fixed on the incubation tank where the incubation device is located, and the incubation liquid completely immerses the fertilized eggs. A constant temperature controller is used during the incubation process to control the water temperature of the incubation liquid to be relatively constant. The incubation tank is connected to a variable frequency motor to drive the entire incubation tank to swing, causing the fertilized eggs in the incubation cup to swing. A circulating water system with an internal ultraviolet lamp is used to circulate and filter the incubation liquid for 24 hours. The incubation period is 35-42 days.

[0006] Furthermore, in step (1), the method for cleaning and disinfecting the fertilized eggs is: soaking the fertilized eggs in 3% saline for 3-5 minutes.

[0007] Furthermore, in the step (1), the hatching cup is provided with uniform gaps, the size of which is large enough to allow water to pass through but not the fertilized eggs to pass through, and the appropriate width of the gap is 0.1-0.15 mm.

[0008] Furthermore, after the fertilized eggs in step (1) are separated from the mother, cleaned and disinfected, the fertilized eggs of each female shrimp are placed in a separate hatching cup.

[0009] Furthermore, the fertilized egg hatching liquid in step (2) is disinfected by using 15-20 ppm bleaching powder and then aerated until the residual chlorine disappears.

[0010] Furthermore, in step (3), two ultraviolet lamps are installed inside the fertilized egg incubation room, and the ultraviolet light can cover the entire room and remain on after the person leaves the room.

[0011] Furthermore, the incubation device in step (3) is the utility model "a device for in vitro incubation of fertilized eggs of red claw crayfish CN 215380838 U", comprising an incubation tank, an incubation cup rack, a circulating water system and incubation cups, wherein the incubation tank is slidably connected to the incubation cup rack; the bottom of the incubation tank is connected to the circulating water system; the incubation cup rack is provided with incubation cups; and the incubation cups are evenly provided with gaps.

[0012] Furthermore, in step (3), the hatching cup is 1-2 cm away from the bottom of the hatching liquid tank.

[0013] Furthermore, in step (3), the fertilized eggs in the hatching cup should be completely immersed in the hatching liquid, and the water level of the hatching liquid should preferably be 3-5 cm higher than the fertilized eggs in the hatching cup.

[0014] Furthermore, in step (3), the water temperature of the hatching liquid is controlled at 27-30°C.

[0015] Furthermore, in step (3), the hatching liquid tank is swung once every 3-5 seconds to keep the fertilized eggs swaying slightly in the hatching cup.

[0016] Furthermore, in step (3), the water flow rate of the circulating water system is based on the condition that the fertilized eggs in the hatching cup can swing slightly without being squeezed against the cup wall.

[0017] Furthermore, in step (3), the fertilized eggs are incubated in vitro, and the incubation fluid is supplemented with 1-2 ppm formalin solution once a week.

[0018] Furthermore, in step (3), the fertilized eggs are incubated in vitro, and dead and moldy eggs in the incubation cup are cleaned every day with tweezers disinfected with 75% alcohol, and the number is recorded.

[0019] Compared with the existing technology, the effects and advantages of the present invention are: 1. The in vitro hatching technology of fertilized eggs adopted by the present invention saves space for the management and hatching of brooding shrimps, and the hatched shrimp fry have uniform specifications and have good market application prospects.

[0020] 2. The in vitro hatching technology of fertilized eggs adopted by the present invention ensures that the conditions of the whole process of hatching fertilized eggs are controllable, and avoids the problems of dead eggs, dropped eggs and moldy eggs caused by the shrimps with eggs under unfavorable conditions such as high temperature, low temperature and water quality; the natural hatching conditions of fertilized eggs are simulated throughout the process, and the hatching space and hatching fluid are disinfected to ensure the normal development of fertilized eggs, greatly reduce the infection of pathogenic microorganisms, and improve the hatching rate and the amount of shrimp seedlings.

[0021] 3. The in vitro hatching technology of fertilized eggs adopted by the present invention reduces the burden of egg-carrying shrimps. After the fertilized eggs are separated from the mother shrimps, the mother shrimps can quickly enter into secondary mating, thereby increasing the annual egg production and shrimp seedling quantity and improving the scale of seedling cultivation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 These are fertilized eggs collected from red claw crayfish mothers in hatching cups that have just completed fertilization.

[0023] Figure 2 These are fertilized eggs of red claw crayfish with eye spots appearing during hatching.

[0024] Figure 3 These are fertilized eggs of red claw crayfish with eyespots and appendages showing during hatching.

[0025] Figure 4 Fully hatched juvenile shrimp. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods, but the scope of protection claimed by the present invention is not limited to the scope described in the examples.

[0027] Example 1 The in vitro hatching method of fertilized red claw crayfish eggs provided by the present invention specifically comprises the following steps: 1. Peel, clean and disinfect the fertilized eggs from the mother: Pick 30 fertilized female red claw crayfish. The fertilized eggs are khaki in color. Grasp the female shrimp with your hands and gently collect the fertilized eggs from the abdomen with elbow tweezers disinfected with 75% alcohol. Soak them in 3% salt water for 3 minutes for cleaning and disinfection. After recording the number, put the fertilized eggs into the hatching cup. Put the fertilized eggs of each female shrimp in a separate hatching cup.

[0028] 2. Preparation of fertilized egg hatching solution: Collect underground fresh water, filter it with filter cotton, disinfect it with 15ppm bleaching powder and aerate it until the residual chlorine disappears, then add 1ppm formalin solution to make fertilized egg hatching solution, and then pour it into the hatching solution tank. It will be filtered, sterilized and disinfected by the circulating water system in the hatching solution tank for 24 hours before use.

[0029] 3. In vitro hatching of fertilized eggs: using an incubator (the incubator is the utility model "In vitro incubator for fertilized eggs of red claw crayfish CN 215380838 U") set at 20m 2 The incubation room has doors and windows, and there are two ultraviolet lamps installed on the wall, each 20W, which are always turned on after the personnel leave the room.

[0030] The hatching cup containing the fertilized eggs is fixed on the hatching liquid tank where the hatching device is located, the bottom of the hatching cup is 1 cm away from the hatching liquid tank, the hatching liquid completely immerses the fertilized eggs, and the hatching liquid surface is 3 cm higher than the fertilized eggs in the hatching cup; a constant temperature controller is used during the hatching process to control the temperature of the hatching liquid at 27°C; the hatching liquid tank is connected to a variable frequency motor to drive the entire hatching liquid tank to swing, and the swing frequency is once every 3 seconds, so that the fertilized eggs in the hatching cup swing; a circulating water system containing an ultraviolet lamp is used to circulate and filter the hatching liquid for 24 hours, and the water flow rate of the circulating water system is based on the fertilized eggs in the hatching cup can be slightly turned over and not squeezed against the cup wall; 1ppm formalin solution is added to the hatching liquid once a week; dead eggs and moldy eggs in the hatching cup are cleaned with tweezers disinfected with 75% alcohol every day, and the number is recorded.

[0031] At the beginning of the experiment, 8040 fertilized eggs were collected from 30 brooding shrimps. During the incubation period, 749 dead and moldy eggs were cleaned. After 42 days, all juvenile shrimps were hatched, with a total of 7291. The experimental results are as follows: the elimination rate of fertilized eggs is 9.3%, the hatching rate is 90.7%, and the highest hatching rate is 93.5%.

[0032] Example 2 The in vitro hatching method of fertilized eggs of red claw crayfish described in this embodiment specifically comprises the following steps: 1. Peel, clean and disinfect the fertilized eggs from the mother: Pick 30 fertilized female shrimps. The fertilized eggs are khaki in color. Grasp the female shrimps with your hands and gently collect the fertilized eggs from the abdomen with elbow tweezers disinfected with 75% alcohol. Soak them in 3% salt water for 5 minutes for cleaning and disinfection. After recording the number, put the fertilized eggs into the hatching cups. Put the fertilized eggs of each female shrimp into a separate hatching cup.

[0033] 2. Preparation of fertilized egg hatching fluid: The water in the mating pool for female shrimps is filtered with filter cotton, disinfected with 20ppm bleaching powder, and then aerated until the residual chlorine disappears. Then, 2ppm formalin solution is added to make fertilized egg hatching fluid, which is then poured into the hatching fluid tank. It is filtered, sterilized, and disinfected in the circulating water system in the hatching fluid tank for 28 hours before use.

[0034] 3. In vitro hatching of fertilized eggs: The hatching device (the hatching device is the utility model "In vitro hatching device for fertilized eggs of red claw crayfish CN 215380838 U") is set at 20m 2 The hatching room is equipped with doors and windows. Two ultraviolet lamps are installed on the wall, each with a power of 20W. They are turned on after the personnel leave the room. The hatching cup containing fertilized eggs is fixed on the hatching tank where the hatching device is located. The bottom of the hatching cup is 2 cm away from the hatching tank. The hatching liquid completely immerses the fertilized eggs, and the hatching liquid surface is 5 cm higher than the fertilized eggs in the hatching cup. During the hatching process, a constant temperature controller is used to control the hatching liquid temperature at 30°C. The hatching tank is connected to a variable frequency motor to drive the entire hatching tank to swing. The swing frequency is once every 5 seconds, so that the fertilized eggs in the hatching cup swing. A circulating water system containing ultraviolet lamps is used to circulate and filter the hatching liquid for 24 hours. The water flow rate of the circulating water system is based on the fertilized eggs in the hatching cup can be slightly turned over and not squeezed against the cup wall. The hatching liquid is supplemented with 2ppm formalin solution once a week. The dead and moldy eggs in the hatching cup are cleaned with tweezers disinfected with 75% alcohol every day, and the number is recorded. The incubation period is 40 days.

[0035] At the beginning of the experiment, 9780 fertilized eggs were collected from 30 brooding shrimps. During the incubation period, 854 dead and moldy eggs were cleaned. After 40 days, all juvenile shrimps were hatched, with a total of 8926. The experimental results are as follows: the elimination rate of fertilized eggs is 8.7%, the hatching rate is 91.3%, and the highest hatching rate is 94.6%.

[0036] The above factual cases only represent the technical solutions of the present invention, rather than limiting the experiments. Although we have improved the experimental solutions, researchers in the same field can still make further improvements to the experimental solutions described above or make scientific equivalent replacements for the experimental links. These changes do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed to be protected by the present invention.

Claims

1. A method for in vitro hatching of fertilized eggs of red claw crayfish, characterized in that: The incubation method comprises the following steps: (1) Peeling, cleaning and disinfecting fertilized eggs from the mother: Pick the fertilized female red claw crayfish, gently collect the fertilized eggs from the abdomen with sterilized elbow tweezers, clean and disinfect them, record the number and place the fertilized eggs into the hatching cup; (2) Preparation of fertilized egg hatching solution: Take underground fresh water or water from the mother shrimp pond and filter it for disinfection, then add 1-2ppm formalin solution to make fertilized egg hatching solution; then pour it into the hatching solution tank, and use it after filtering, sterilizing and disinfecting it in the circulating water system in the hatching solution tank for at least 24 hours; (3) In vitro incubation of fertilized eggs: The incubation place is an incubation room. The incubation cups containing fertilized eggs are fixed on the incubation liquid tank where the incubation device is located, and the incubation liquid completely immerses the fertilized eggs. The water temperature of the incubation liquid is controlled to be relatively constant during the incubation process. The incubation liquid tank is connected to a variable frequency motor to drive the entire incubation liquid tank to swing, causing the fertilized eggs in the incubation cup to swing. A circulating water system containing ultraviolet lamps is used to circulate and filter the incubation liquid for 24 hours. The incubation period is 35-42 days.

2. The in vitro hatching method of fertilized eggs of red claw crayfish according to claim 1, characterized in that: In step (1), the method for cleaning and disinfecting the fertilized eggs is: soaking the fertilized eggs in 3% saline for 3-5 minutes.

3. The in vitro hatching method of fertilized eggs of red claw crayfish according to claim 1, characterized in that: In the step (1), the hatching cup is provided with uniform gaps, the size of which is large enough to allow water to pass through but not the fertilized eggs to pass through, and the width of the gaps is 0.1-0.15 mm.

4. The in vitro hatching method of fertilized eggs of red claw crayfish according to claim 1, characterized in that: In the step (2), the fertilized egg hatching liquid is disinfected by using 15-20 ppm bleaching powder and then aerating until the residual chlorine disappears.

5. The in vitro hatching method of fertilized eggs of red claw crayfish according to claim 1, characterized in that: In step (3), the hatching cup is 1-2 cm away from the bottom of the hatching liquid tank.

6. The in vitro hatching method of fertilized eggs of red claw crayfish according to claim 1, characterized in that: The fertilized eggs in the hatching cup should be completely immersed in the hatching fluid, and the water level of the hatching fluid should be 3-5cm higher than the fertilized eggs in the hatching cup.

7. The in vitro hatching method of fertilized eggs of red claw crayfish according to claim 1, characterized in that: The water temperature of the hatching liquid in step (3) is controlled at 27-30°C.

8. The in vitro hatching method of fertilized eggs of red claw crayfish according to claim 1, characterized in that: In the step (3), the hatching liquid tank is swung once every 3-5 seconds to keep the fertilized eggs swaying slightly in the hatching cup.

9. The in vitro hatching method of fertilized eggs of red claw crayfish according to claim 1, characterized in that: In the step (3), the fertilized eggs are incubated in vitro, and the incubation fluid is supplemented with 1-2 ppm formalin solution once a week.

10. The in vitro hatching method of fertilized eggs of red claw crayfish according to claim 1, characterized in that: In step (3), the fertilized eggs are incubated in vitro, and dead and moldy eggs in the incubation cup are cleaned every day with tweezers disinfected with 75% alcohol, and the number is recorded.

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