Method and system for high-density culture of rotifers

Abstract

The invention relates to a method and a system for high-density culture of rotifers. The method comprises the following steps: (1) providing a rotifer culture system, wherein the culture system comprises a conical culture barrel, a filter screen, a nano air stone, a water inlet pipe, a drain valve and an air delivery pipe; (2) disinfection treatment: carrying out disinfection treatment on a culture system and tools by using disinfection seawater; (3) inoculating and culturing rotifers: inoculating the domesticated rotifers into a culture system for culturing, feeding the rotifers by using concentrated chlorella with the particle size of 3-5 microns as bait, keeping the bait feeding period not more than 12 hours, keeping the water temperature of disinfected seawater used for culturing at 28-32 DEG C, the salinity at 13-17 per mill and the pH value at 7-9, and introducing pure oxygen through a microporous aeration device; sampling rotifers every day for microscopic examination, observing the water quality, measuring the density of the rotifers, and determining the dissolved oxygen, the water changing amount of the disinfected seawater and the bait feeding amount. According to the method, high-density rotifer culture can be achieved, cost is reduced, culture conditions are optimized, and stable supply of high-quality bait in aquaculture is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of ultramicrorotifer cultivation, and in particular relates to a method and system for high-density cultivation of rotifers. Background Art

[0002] Rotifers are tiny organisms of great value in aquaculture, serving as a high-quality starter feed for fry of aquatic species such as fish and shrimp. Their small size and slow movement make them easy to prey on, and they are nutritious, with a protein content of up to 57%. Their moderate size makes them easily digestible and absorbed by juvenile fish and shrimp. Their strong adaptability, rapid growth, and rapid reproduction make them an indispensable natural, high-quality feed for juveniles of many aquatic economic species. However, rotifer cultivation is susceptible to predators such as ciliates. Furthermore, rotifer cultivation requires low densities, requires large volumes of water, and is susceptible to environmental influences, leading to high costs and unstable yields. Therefore, a consistent and stable supply of rotifers has become an essential component of aquatic fry production. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method and system for culturing rotifers at a high density, so as to provide a scientific basis for optimizing rotifer culture conditions and improving rotifer yield and quality, thereby ensuring a stable supply of high-quality bait in aquaculture.

[0004] The present invention provides a method for high-density culturing rotifers, comprising:

[0005] (1) Provide rotifer culture system

[0006] The culture system includes a conical culture bucket, a filter screen, a nano air stone, a water inlet pipe, a drain valve and an air supply pipe;

[0007] (2) Disinfection

[0008] Sterilize the culture system and tools with sterile seawater;

[0009] (3) Rotifer inoculation and culture

[0010] The domesticated rotifers are inoculated into the culture system for cultivation, and concentrated Chlorella with a particle size of 3 to 5 μm is used as bait to feed the rotifers. The feeding cycle does not exceed 12 hours. The sterilized seawater used for cultivation is maintained at a temperature of 28 to 32°C, a salinity of 13‰ to 17‰, and a pH of 7 to 9. Pure oxygen is introduced through a microporous aeration device. Rotifers are sampled daily for microscopic examination, water quality is observed, and rotifer density is measured. The dissolved oxygen, bait feeding amount, and sterilized seawater water exchange amount are determined based on the microscopic examination results.

[0011] Preferably, the culture system in step (1) can be placed at an angle when in use to facilitate the overflow of foam.

[0012] Preferably, in step (1), the filter screen in the culture system should be replaced frequently. A 400-liter conical culture barrel uses 5 to 10 filter screens, and the filter screen cleaning frequency is 2 to 3 hours per time.

[0013] Preferably, the preparation process of disinfected seawater in step (2) is as follows: the seawater is first sand filtered, then dark precipitated for 1 to 2 days, and after precipitation is completed, it is transferred to a water storage tank and disinfected with bleaching powder, the amount of bleaching powder used is 7 to 15 g / m 3 Seawater, disinfection time is 5 to 7 days.

[0014] More preferably, the temperature of the disinfected seawater in step (3) is maintained at 28°C.

[0015] Preferably, the rotifer in step (3) is Brachionus plicatilis; the concentration of the concentrated Chlorella is 5×10 7 ~1×10 8 cells / ml.

[0016] Preferably, the specific operation of introducing pure oxygen in step (3) is to control the gas flow rate to 0.1 to 0.3 L / (m 3 ·min), output pressure 0.05~0.1MPa, forming a dense bubble flow with a diameter of 0.5~1.5mm, which diffuses and rises in the water body in the form of mist.

[0017] Preferably, the process of observing the water quality by microscopic examination in step (3) is as follows: taking water samples from the upper and lower layers of the conical culture bucket, and after settling for 3-7 minutes, taking the upper and lower water samples for microscopic examination respectively.

[0018] More preferably, when microscopic examination in step (3) shows that the lower layer of water sample contains a lot of garbage, the water volume is changed by 100%, and the gas is stopped before the water is changed. After settling for 3-7 minutes, the garbage on the bottom layer is discharged and the rotifers are collected.

[0019] Preferably, the process of determining the rotifer density by microscopic examination in step (3) is as follows: taking 100 μl of seawater from the conical culture bucket, counting using a counter under a dissecting microscope, and calculating the average of three times as the rotifer density.

[0020] Preferably, the dissolved oxygen in step (3) is greater than 2 ppm.

[0021] More preferably, the dissolved oxygen in step (3) is 7 ppm.

[0022] Preferably, the theoretical value of the bait feeding amount in step (3) is Y,

[0023]

[0024] Case 1: When the rotifer density is less than 5000 / ml, X = 0.4;

[0025] Case 2: When the rotifer density is 5000-8000 / ml, X = 0.8;

[0026] Case 3: When the rotifer density is greater than 8000 / ml, X=1.

[0027] Preferably, the bait feeding cycle in step (3) is 12 hours, each feeding is carried out after changing the water, and the bait feeding amount is the theoretical value Y.

[0028] Preferably, the amount of water changed in step (3) is as follows: the water change cycle is 5 days, the water change frequency is 1 time / day in the first four days, and the water change amount is 30% each time; on the fifth day, the culture system is replaced and the water change amount is 100%; when the rotifer density is greater than 5000 / ml, the water change frequency is 2 times / day, and the water change amount is 30% each time; after the water change, a microscopic examination is performed, and the amount of bait fed is determined according to the rotifer density.

[0029] Preferably, the egg holding rate is calculated based on the microscopic examination results in step (3), wherein the number of rotifers examined under the microscope is A, the number of eggs is B, the egg holding rate = B / A%, and the average is calculated by recording more than three times.

[0030] The present invention also provides a rotifer culture system, which includes: a conical culture barrel, a filter screen, a nano-air stone, a water inlet pipe, a drain valve and an air supply pipe; the filter screen is horizontally placed in a cross shape inside the barrel body of the conical culture barrel, the nano-air stone is arranged inside the bottom of the conical culture barrel and below the filter screen, the water inlet pipe is horizontally connected to the top of the barrel body of the conical culture barrel, the pipe mouth of the water inlet pipe is at 45 degrees to the bottom of the conical culture barrel, and the drain valve is vertically connected to the bottom of the conical culture barrel; the bottom end of the air supply pipe is connected to the nano-air stone.

[0031] Preferably, the conical culture barrel is made of glass, and its barrel body is cylindrical and its bottom is conical.

[0032] Preferably, the filter is installed 20 to 30 cm away from the lowest point of the bottom of the conical culture barrel.

[0033] Preferably, the nano air stone is fixed on the vertical central axis of the conical culture barrel, 15 cm ± 0.5 cm away from the lowest point of the barrel bottom, and a three-dimensional coordinate positioning method is adopted (with the center of the barrel bottom circle as the coordinate origin and vertically upward as the positive direction of the Z axis) to ensure that the nano air stone forms a uniform aeration area in the middle and lower layers of the water body.

[0034] Preferably, the drain valve collects rotifers by opening the valve.

[0035] Preferably, the gas pipeline transports pure oxygen.

[0036] Beneficial effects

[0037] The present invention utilizes a dedicated rotifer cultivation system and cultivation method to realize high-density cultivation of rotifers, reduce the use of cultivation water, lower the cultivation cost, optimize the rotifer cultivation conditions, and ensure the stable supply of high-quality bait in aquaculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the structure of the rotifer culture system of the present invention.

[0039] Figure numerals: 1-conical culture bucket, 2-filter, 3-nano air stone, 4-water inlet pipe, 5-drain valve, 6-air supply pipe. DETAILED DESCRIPTION

[0040] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0041] Example

[0042] The rotifer culture system in this embodiment is as follows Figure 1 As shown, it includes: a conical culture barrel 1, a filter 2, a nano-air stone 3, a water inlet pipe 4 and a drain valve 5; the conical culture barrel 1 is made of glass; the filter 2 is placed horizontally in a cross shape inside the barrel body of the conical culture barrel 1, 20 to 30 cm away from the lowest point of the bottom of the conical culture barrel 1; the nano-air stone 3 is arranged inside the bottom of the conical culture barrel 1 and below the filter 2. The optimal installation distance is 15 cm from the lowest point of the bottom of the conical culture barrel 1, which can fully oxygenate the interior of the conical culture barrel 1 and facilitate some particulate garbage to sink to the bottom of the barrel through centrifugation or gravity; the water inlet pipe 4 is horizontally connected to the top of the barrel body of the conical culture barrel 1, and the mouth of the water inlet pipe 4 is at 45° to the bottom of the conical culture barrel 1; the drain valve 5 is vertically connected to the bottom of the conical culture barrel 1, and rotifers are collected by opening the valve; the bottom end of the air supply pipe 6 is connected to the nano-air stone 3 for transporting pure oxygen.

[0043] The method for high-density culturing rotifers in this embodiment comprises the following steps:

[0044] (1) Provide rotifer culture system

[0045] When using the culture system, it can be tilted at 15° to 20°. This tilt angle can effectively utilize the effect of gravity to quickly collect the generated foam to the overflow port, achieve efficient overflow discharge, and avoid foam accumulation affecting the culture environment. The maintenance of the filter in the culture system is very important. This time, a 500-liter conical culture barrel is used as an example, and 8 filter screens are configured to form a multi-layer filtration barrier. The filter is cleaned every 2.5 hours to ensure that the filter always maintains good permeability, prevent impurities from clogging and affecting the water circulation and rotifer growth environment, and reduce the risk of water quality deterioration due to filter clogging.

[0046] (2) Disinfection

[0047] The culture system and tools were disinfected with sterilized seawater. The preparation process of sterilized seawater is as follows: the filtered seawater is injected into a sedimentation tank with a volume of 10 cubic meters, and then allowed to settle for 36 hours in the dark, and the suspended particles are allowed to settle naturally by gravity; finally, the supernatant is transferred to a dedicated water storage tank by a water pump and the concentration is adjusted to 10g / m3. 3 Bleach with an effective chlorine content of ≥28% was added to the water at a ratio of 1:1, stirred thoroughly, and disinfected for 6 days. On the 6th day, the residual chlorine content was less than 0.05 mg / L, fully meeting safety standards for rotifer cultivation. This not only completely killed pathogenic bacteria such as Vibrio parahaemolyticus and Vibrio harveyi in seawater, but also prevented residual disinfectant from toxic effects on rotifer growth.

[0048] (3) Rotifer inoculation and culture

[0049] The domesticated Brachionus plicatilis rotifer was inoculated into the culture system for cultivation. The concentrated Chlorella with a particle size of 3-5 μm was used as bait to feed the rotifer. The feeding cycle did not exceed 12 hours, and the rotifer was not allowed to starve. The sterilized seawater used for cultivation was kept at a temperature of 28-32°C, where the most suitable water temperature for rotifer growth was 28°C, a salinity of 15‰, and a pH of 7-9. Pure oxygen was introduced through a microporous aeration device, and the gas flow rate was controlled at 0.1-0.3 L / (m 3 ·min), output pressure 0.05~0.1MPa, forming a fine bubble flow with a diameter of 0.5~1.5mm, which diffuses and rises in the water body in a mist-like manner, and the dissolved oxygen in the water body is greater than 2ppm, which is adjusted according to the measured rotifer density;

[0050] Daily rotifer sampling for microscopic examination was performed to observe water quality and measure rotifer density. This was used to determine dissolved oxygen, feed intake, and the amount of disinfected seawater to be exchanged. Water quality was observed by microscopic examination: water samples were collected from the upper and lower layers of a conical culture bucket. After settling for 5 minutes, a drop of each sample was taken from the upper and lower layers for microscopic examination. If microscopic examination revealed excessive debris in the lower layer, a 100% water exchange was performed. Before the water exchange, the air was stopped. After settling for 5 minutes, the debris on the bottom layer was removed and the rotifers were collected. Rotifer density was determined by microscopic examination: 100 μL of seawater was collected from the conical culture bucket and counted using a counter under a dissecting microscope. The average of the three counts was used as the rotifer density.

[0051] Theoretical value of bait feeding amount Y:

[0052]

[0053] Case 1: When the rotifer density is less than 5000 / ml, X = 0.4;

[0054] Case 2: When the rotifer density is 5000-8000 / ml, X = 0.8;

[0055] Case 3: When the rotifer density is greater than 8000 / ml, X=1.

[0056] The culture cycle operation and specific values ​​(taking 5 days as an example) are shown in Table 1.

[0057] Day 1: The initial inoculation density of rotifers was set at 2500 / ml, a 500L culture tank (400L effective water volume) was selected, the dissolved oxygen content of the water was maintained at 5-7ppm, and the pH value was stably controlled in the range of 7.5-8.2.

[0058] Table 1 Culture cycle operations and specific values

[0059]

[0060] After 5 days of culture, the density of rotifers reached 10,000 / ml, and the total number of rotifers harvested from the entire culture system was 4×10 9 Compared with the traditional culture method, in the same 400L water, the density of rotifers cultured by the traditional method for 5 days can usually only reach about 2000 / ml, and the number of rotifers harvested is about 8×10 8 The number of rotifers harvested by the high-density culture method of the present invention is five times that of the traditional method.

Claims

1. A method for high-density culturing rotifers, comprising: (1) Provide rotifer culture system The culture system comprises a conical culture bucket (1), a filter (2), a nano-gas stone (3), a water inlet pipe (4), a drain valve (5) and an air supply pipe (6); (2) Disinfection Sterilize the culture system and tools with sterile seawater; (3) Rotifer inoculation and culture The domesticated rotifers are inoculated into the culture system for cultivation, and concentrated Chlorella with a particle size of 3-5um is used as bait to feed the rotifers. The feeding cycle does not exceed 12 hours. The sterilized seawater used for cultivation is maintained at a temperature of 28-32°C, a salinity of 13‰-17‰, and a pH of 7-9. Pure oxygen is introduced through a microporous aeration device. Rotifers are sampled daily for microscopic examination, water quality is observed, and rotifer density is measured. The dissolved oxygen, bait feeding amount, and water exchange amount of sterilized seawater are determined based on the microscopic examination results.

2. The method for high-density culturing rotifers according to claim 1, wherein The preparation process of disinfected seawater in step (2) is as follows: the seawater is first sand filtered, then dark precipitated for 1 to 2 days, and then transferred to a water storage tank after the precipitation is completed, and disinfected with bleaching powder, the amount of bleaching powder used is 7 to 15 g / m 3 Seawater, disinfection time is 5 to 7 days.

3. The method for high-density culturing rotifers according to claim 1, wherein The rotifer in step (3) is Brachionus plicatilis; the concentration of the concentrated Chlorella is 5×10 7 ~1×10 8 cells / ml.

4. The method for high-density culturing rotifers according to claim 1, wherein The specific operation of introducing pure oxygen in step (3) is to control the gas flow rate to 0.1-0.3 L / (m 3 ·min), output pressure 0.05~0.1MPa, forming a dense bubble flow with a diameter of 0.5~1.5mm, which diffuses and rises in the water body in the form of mist.

5. The method for high-density culturing rotifers according to claim 1, wherein The process of observing the water quality by microscopic examination in step (3) is as follows: taking water samples from the upper and lower layers of the conical culture bucket (1), and after settling for 3-7 minutes, taking the upper and lower water samples for microscopic examination respectively.

6. The method for high-density culturing rotifers according to claim 1, wherein: The process of determining the rotifer density by microscopic examination in step (3) is as follows: taking 100 microliters of seawater from the conical culture bucket (1), counting with a counter under a dissecting microscope, and calculating the average of three times as the rotifer density.

7. The method for high-density culturing rotifers according to claim 1, wherein: The theoretical value of the bait feeding amount in step (3) is Y, Case 1: When the rotifer density is less than 5000 / ml, X = 0.4; Case 2: When the rotifer density is 5000-8000 / ml, X = 0.8; Case 3: When the rotifer density is greater than 8000 / ml, X=1.

8. The method for high-density culturing rotifers according to claim 7, wherein: The feeding cycle of the bait in step (3) is 12 hours, and each feeding is done after changing the water, and the bait feeding amount is the theoretical value Y.

9. The method for high-density culturing rotifers according to claim 1, wherein: The amount of water changed in step (3) is specifically as follows: the water change cycle is 5 days, the water change frequency is 1 time / day in the first four days, and the water change volume is 30% each time; on the fifth day, the culture system is replaced and the water change volume is 100%; when the rotifer density is greater than 5000 / ml, the water change frequency is 2 times / day, and the water change volume is 30% each time; after the water change, a microscopic examination is performed, and the feed amount is determined according to the rotifer density.

10. A rotifer culture system according to claim 1, characterized in that: The culture system comprises a conical culture barrel (1), a filter screen (2), a nano-gas stone (3), a water inlet pipe (4), a drain valve (5) and an air supply pipe (6); the filter screen (2) is horizontally placed in a cross shape inside the barrel body of the conical culture barrel (1); the nano-gas stone (3) is arranged inside the bottom of the conical culture barrel (1) and below the filter screen (2); the water inlet pipe (4) is horizontally connected to the top of the barrel body of the conical culture barrel (1); the pipe mouth of the water inlet pipe (5) is at a 45-degree angle to the bottom of the conical culture barrel (1); the drain valve (5) is vertically connected to the bottom of the conical culture barrel (1); and the bottom end of the air supply pipe (6) is connected to the nano-gas stone (3).

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