Efficient bait feeding mode suitable for northern crassostrea gigas fry

Abstract

The invention relates to a bait feeding mode suitable for northern oyster larva breeding work, and in the D-type larva period of northern oysters, mixed bait of chrysophyceae and chlorella is fed. The crassostrea gigas larvae are fed with the mixed bait of the chrysophyceae and the chlorella, so that the growth rate and the survival rate of the larvae are remarkably improved, and the breeding period is shortened.

Description

Technical Field

[0001] The invention relates to aquaculture technology, and in particular to a high-efficiency bait feeding mode suitable for northern long oyster seedlings. Background Art

[0002] The giant oyster (Crassostrea gigas) is one of the important economic species in my country. It is a filter-feeding bivalve mollusc and is mainly distributed in the Yellow Sea, Bohai Sea and East China Sea. Liaoning's production accounts for about 70% of the country's total production. Seedling cultivation is the key to the sustainable development of the giant oyster aquaculture industry, and the stable production and supply of high-quality bait algae are essential to ensure the healthy and efficient growth of the larvae. In recent years, giant oyster seed production companies have been concentrated in southern regions such as Guangdong, Fujian and Zhejiang, where the water temperature is suitable, which is conducive to the breeding and seed production of giant oysters. However, the significant differences in the aquaculture environment between the north and the south, especially the temperature, have restricted the healthy development of the giant oyster aquaculture industry in the north, and have had a significant impact on the bait demand and growth conditions of giant oyster larvae.

[0003] In the south, Chlorella is the main feed in the cultivation of long oyster larvae, while in the north, Chlorella is mainly fed. Chlorella, with its characteristics of no cell wall and rich in polyunsaturated fatty acids, helps the growth and development of long oyster larvae. However, Chlorella grows slowly, especially during peak demand periods, and may not provide enough bait. In addition, the optimal growth temperature of Chlorella is 15℃-20℃. When the water temperature exceeds this range, its growth rate and stability will be adversely affected. Seedling cultivation in the northern Yellow Sea is usually carried out in mid-June, when the water temperature in the natural sea area is often above 20℃, which leads to a decrease in the reproduction rate of Chlorella, thereby affecting the stability of bait supply. In contrast, Chlorella has a wider temperature range of adaptation, especially growing rapidly at 25℃, which can ensure a continuous and stable supply of bait. In addition, Chlorella has a thin cell wall, which is easy for larvae to digest and absorb, and improves the utilization efficiency of bait. Chlorella is also rich in nutrients such as protein and multiple vitamins, which can meet the high nutritional needs of long oyster larvae and promote their healthy development.

[0004] Therefore, in view of the problems of unstable bait supply and high cost in the breeding process of long oysters in northern regions, an improved bait feeding mode is urgently needed to reduce the cost in the breeding process and improve the breeding efficiency and yield. This demand provides an important technical background and practical significance for the present invention. Summary of the invention

[0005] The invention aims to invent a bait feeding mode suitable for northern oyster larvae breeding.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a bait feeding mode suitable for the breeding of northern oyster larvae, feeding a mixed bait of golden algae and chlorella to the northern oyster D-type larvae during the period of larvae, thereby improving the growth rate and survival rate of the larvae and shortening their breeding cycle.

[0007] The D-type larvae are continuously fed with a mixed feed of golden algae and chlorella, and start to be fed only with chlorella in the middle stage of the shell top larvae.

[0008] In the present invention, during the initial feeding, the mixed bait of golden algae and chlorella has a quantity ratio of golden algae: chlorella = 1:5-10. As the larvae grow, the feeding ratio of golden algae is gradually reduced.

[0009] The D-type larvae are larvae that have a distinct "D" shape one day after fertilization.

[0010] When the mixed bait is fed, the water temperature is 22-25°C, the salinity is 25-35‰, and the pH value is 7.0-8.5.

[0011] The density of the larvae when the mixed bait is fed is 5 to 10 larvae / mL.

[0012] During the feeding process, the feed was fed three times a day and the water was changed every 4 days.

[0013] Advantages of the present invention:

[0014] 1. Effectiveness: The oyster larvae of the present invention are fed with a mixed feed of golden algae and chlorella, which significantly improves the growth rate and survival rate of the larvae and shortens the breeding cycle.

[0015] 2. Economical: By feeding mixed bait, it helps to reduce the production cost of long oyster farming.

[0016] 3. Easy to operate: The method of the present invention is simple and easy to operate, and is suitable for application in actual production.

[0017] 4. Scientific research value: The present invention provides new technical support for the development of Crassostrea gigas aquaculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention provides the survival rate of oyster larvae after three feeding methods. The mixed feeding group of golden algae and chlorella (1:10) is marked as "A", the mixed feeding group of golden algae and chlorella (1:5) is marked as "B", the group fed with chlorella is marked as "C", and the group fed with golden algae is marked as "D".

[0019] Figure 2The shell length data after three feeding methods are provided in the embodiments of the present invention. The mixed feeding group of golden algae and chlorella (1:10) is marked as "A", the mixed feeding group of golden algae and chlorella (1:5) is marked as "B", the group fed with chlorella is marked as "C", and the group fed with golden algae is marked as "D". The ordinate represents the shell length in μm. The p value <0.05 indicates a significant difference, and the significant difference is marked with letters.

[0020] Figure 3 The proportion of eyed oyster larvae after three feeding methods provided in the embodiment of the present invention. The mixed feeding group of golden algae and chlorella (1:10) is marked as "A", the mixed feeding group of golden algae and chlorella (1:5) is marked as "B", the group fed with chlorella is marked as "C", and the group fed with golden algae is marked as "D".

[0021] Figure 4 The average number of attachments on the attachment substrate after three feeding methods provided in the embodiment of the present invention. The mixed feeding group of golden algae and chlorella (1:10) is marked as "A", the mixed feeding group of golden algae and chlorella (1:5) is marked as "B", the group fed with chlorella is marked as "C", and the group fed with golden algae is marked as "D". DETAILED DESCRIPTION

[0022] The specific implementation modes of the present invention are further described below in conjunction with examples. It should be noted that the specific implementation modes described here are only for illustrating and explaining the present invention, and are not limited to the present invention.

[0023] Example 1 Survival rate of oyster larvae under different feeding modes

[0024] 1. Experimental materials: Type D larvae were obtained from the seed farm of Zhangzidao Group in Dalian, Liaoning Province, and golden algae and chlorella were provided by the seed farm of Zhangzidao Group.

[0025] 2. Experimental methods: D-type larvae were collected and randomly divided into four groups, A, B, C, and D. The mortality of larvae in each group was measured from 0 to 15 days. Group A: Golden algae and Chlorella were mixed and fed continuously. The initial feeding concentrations were 500 cells / mL of golden algae and 5000 cells / mL of Chlorella, respectively. As the larvae grew, the feeding ratio of golden algae was gradually reduced by 50 cells / mL per day. After 11 days, only Chlorella was fed, and 4L of Chlorella was fed each time. Group B: Golden algae and Chlorella were mixed and fed continuously. The initial feeding concentrations were 500 cells / mL of golden algae and 2500 cells / mL of Chlorella, respectively. As the larvae grew, the feeding ratio of golden algae was gradually reduced by 50 cells / mL per day. After 11 days, only Chlorella was fed, and 4L of Chlorella was fed each time. Group C: Only Chlorella was fed, and 4L of Chlorella was fed each time. Group D: Only golden algae were fed, 200 ml each time. Each culture box contained 150L of seawater, the larval density was 5-10 / mL, the seawater temperature was 23-25℃, the salinity was 25-35‰, and the pH value was 7.0-8.5. The water was changed every 4 days and fed twice a day. The five-point counting method was adopted, 2 ml of water was taken at each location, and the counting was performed under a microscope. The water was mixed before sampling.

[0026] 3. Experimental results: After 15 days of experiment, the survival rate of larvae in group A was 50.1%; the survival rate in group B was 54%; the survival rate in group C was 37%; and the survival rate in group D was 16%. The experimental results show that if the number of water changes is reduced, Figure 1 As shown, the mixed feeding mode of golden algae and Chlorella can significantly improve the survival rate of long oyster larvae.

[0027] Example 2 Growth of oyster larvae under different feeding modes

[0028] 1. Experimental materials: Type D larvae were obtained from the seed farm of Zhangzidao Group in Dalian, Liaoning Province, and golden algae and chlorella were provided by the seed farm of Zhangzidao Group.

[0029] 2. Experimental method: On 0 days, 2 days, 4 days, 10 days and 15 days, the long oyster larvae cultivated under different feeding modes were sampled. During sampling, the larvae were collected from 50 mL of water using a 500-mesh filter, and then observed and photographed under a microscope. Shell length measurements were analyzed using ImageJ software. The culture conditions and methods used during the experiment were consistent with those in Example 1.

[0030] 3. Experimental results: On the 15th day, the average shell length of group A was 248 μm, the average shell length of group B was 218 μm, the average shell length of group C was 210 μm, and the average shell length of group D was 190 μm. Figure 2As shown, the mixed feeding pattern of golden algae and Chlorella can significantly increase the growth rate of long oyster larvae.

[0031] Example 3 Eye spot occurrence rate of oyster larvae under different feeding modes

[0032] 1. Experimental materials: Type D larvae were obtained from the seed farm of Zhangzidao Group in Dalian, Liaoning Province, and golden algae and chlorella were provided by the seed farm of Zhangzidao Group.

[0033] 2. Experimental methods: Groups A and B were fed with a mixture of golden algae and chlorella from 0 to 10 days, 4L of chlorella each time from 11 to 15 days, and 6L of chlorella each time from 15 to 20 days. Group C was fed only 4L of chlorella from 0 to 15 days, and 6L of chlorella each time from 15 to 20 days. Group D was fed only with golden algae, 200mL of golden algae each time from 0 to 15 days, and 400mL of golden algae each time from 11 to 20 days. Groups A, B, C, and D were fed twice a day. Each culture box contained 150L of seawater, the larval density was 1 to 3 / mL, the seawater temperature was 23 to 25℃, the salinity was 25 to 35‰, and the pH value was 7.0 to 8.5. The water was changed every 4 days and fed twice a day. The oyster larvae fed under different culture modes for 20 days were collected in 50 ml of water using a 300-mesh filter. The appearance of eye spots was observed under a 10× objective lens, the number of eye spots was counted, and the eye spot rate was calculated.

[0034] 3. Experimental results: Figure 3 As shown, the mixed feeding pattern of Chlorella and Golden Algae can significantly increase the rate of eye spot emergence. During the growth of long oysters, once the eye spots are formed, the larvae begin to look for a base for attachment. The earlier the eye spots appear, the less likely the seedlings will lose.

[0035] Example 4 Attachment rate of oyster larvae under different feeding modes

[0036] 1. Experimental materials: Type D larvae were obtained from the seed farm of Zhangzidao Group in Dalian, Liaoning Province, and golden algae and chlorella were provided by the seed farm of Zhangzidao Group.

[0037] 2. Experimental method: After 20 days of feeding with different culture modes, 50 pieces of uniform substrate were added to each of the four groups A, B, C, and D. After the larvae attached for 5 days, the number of spat on each substrate was counted, and the attachment metamorphosis rate was calculated using the formula: attachment metamorphosis rate = total number of spat on the substrate / total number of larvae. The culture conditions and methods were consistent with those in Example 3.

[0038] 3. Experimental results: The experimental results show that Figure 4 As shown, during the same cultivation period and using the same specifications of attachment substrate, the larval attachment and metamorphosis rate of the mixed feeding group of golden algae and Chlorella was significantly better than that of the other two groups.

[0039] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement modes and shall be included in the protection scope of the present invention.

Claims

1. A feeding mode suitable for breeding northern oyster larvae, characterized in that During the D-type larvae stage of northern oysters, a mixed feed of golden algae and chlorella is fed.

2. The bait feeding mode suitable for breeding of northern oyster larvae according to claim 1 is characterized in that: The D-type larvae are continuously fed with a mixed feed of golden algae and chlorella, and start to be fed only with chlorella in the middle stage of the shell top larvae.

3. The bait feeding mode suitable for breeding of northern oyster larvae according to claim 1 is characterized in that: In the mixed bait of golden algae and chlorella, the quantity ratio of the golden algae to the chlorella is 1:5-10.

4. The bait feeding mode suitable for breeding of northern oyster larvae according to claim 3 is characterized in that: As the larvae grow, gradually reduce the proportion of golden algae fed.

5. The bait feeding mode suitable for breeding of northern oyster larvae according to claim 1 is characterized in that: The D-type larvae are larvae that have a distinct "D" shape one day after fertilization.

6. The bait feeding mode suitable for breeding of northern oyster larvae according to claim 1 is characterized in that: When the mixed bait is fed, the water temperature is 22-25°C, the salinity is 25-35‰, and the pH value is 7.0-8.

5.

7. The bait feeding mode suitable for breeding of northern oyster larvae according to claim 1 is characterized in that: The density of the larvae when the mixed bait is fed is 5 to 10 larvae / mL.

8. The bait feeding mode suitable for breeding northern oyster larvae according to any one of claims 1 to 7, characterized in that: During the feeding process, the feed was fed three times a day and the water was changed every 4 days.

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