Cultivation method for promoting growth of ictalurus punctatus juvenile fish

Abstract

The invention relates to a cultivation method for promoting growth of ictalurus punctatus juvenile fish, which comprises the following steps: starting a conventional cultivation photoperiod from 12-hour illumination and 12-hour darkness every day, increasing 30 minutes and reducing 30 minutes every day, and when the daily photoperiod is changed into 15-hour illumination and 9-hour darkness, continuously maintaining, using an LED lamp as a light source, and using cold white light as a light source, so that the growth of the ictalurus punctatus juvenile fish is promoted, and the growth of the ictalurus punctatus juvenile fish is promoted. The illumination intensity is 500 l *, so that the lipid metabolism is regulated, and the growth of the ictalurus punctatus seedlings is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of aquaculture, and in particular relates to a cultivation method for promoting the growth of channel catfish fry. Background Art

[0002] Photoperiod is an important factor in many biological processes of aquatic species, such as growth performance, metamorphosis, feeding behavior, survival and gonadal development. The entire life cycle of bony fish is affected by light. Photoperiod is very important for aquatic species in long-term culture in artificial culture systems. In general, for normal development and growth, an optimal photoperiod should be provided and differentiated according to the habits of fish. In the juvenile period, the synergistic effect of photoperiod on growth performance is crucial. Related studies have shown that photoperiod effects can affect the growth of juveniles and juveniles of different fish species. For example, a long photoperiod (16L:8D) can effectively increase the growth rate of juveniles of Lates calcarifer, but further extension of light will inhibit its growth. With the extension of light duration, the growth rate of California bass (Micropterus salmoides) juveniles shows an upward trend, and the growth efficiency is optimal under full light cycle conditions. The evaluation of the effect of photoperiod on the growth and development of young Oriental redfin pufferfish (Takifugu rubripes) showed that the length, weight and muscle biochemical composition of young fish under 16 hours of light were significantly higher than those under 12 hours of light. However, some studies have shown that the growth rate of young fish has no correlation with the length of photoperiod. For example, the photoperiod has no significant effect on the growth of young brown flounder (Paralichthys olivaceus). Yellow light can even have an adverse effect on organs such as the liver or heart of young rainbow trout, reducing their immune capacity and affecting their growth.

[0003] Channel catfish (lctalurus punctatus) is native to North America and is a large Siluriformes fish. It has become one of my country's important specialty economic fish because of its tender and delicious meat, lack of intramuscular spines, and strong environmental adaptability. The growth of its seedlings is crucial. Due to the limitations of regional climatic conditions, the breeding of channel catfish seedlings in the lower reaches of the Yangtze River is delayed by one month compared with the middle and upper reaches. Therefore, the production and cultivation of seedlings are at a disadvantage in the market, which directly affects the development of the channel catfish seedling industry in the region and prolongs the breeding cycle. Therefore, there is an urgent need for a breeding method that promotes the growth of channel catfish fry, accelerates the growth of seedlings, shortens the breeding cycle, and increases the marginal benefits of breeding. Summary of the invention

[0004] The invention aims to provide a cultivation method for promoting the growth of channel catfish fry.

[0005] The invention provides a cultivation method for promoting the growth of channel catfish fry, which comprises adjusting the daily light cycle, a first stage: starting from 12 hours of light and 12 hours of darkness per day, the daily light time is increased by 30 minutes and the darkness is reduced by 30 minutes, until the daily light cycle becomes 15 hours of light and 9 hours of darkness; a second stage: continuously maintaining 15 hours of light and 9 hours of darkness per day.

[0006] As a preferred solution of the cultivation method for promoting the growth of channel catfish fry described in the present invention: after placing channel catfish water flower seedlings in a seedling cultivation pond, the daily light cycle is adjusted to continuously maintain 15 hours of light and 9 hours of darkness per day for 8 to 10 weeks.

[0007] As a preferred embodiment of the method for promoting the growth of channel catfish fry of the present invention, the density of the fry is 50-70 g / m 3 .

[0008] As a preferred solution of the method for promoting the growth of channel catfish fry described in the present invention: the light source includes an LED lamp as a light source with a light intensity of 500l×.

[0009] As a preferred solution of the cultivation method for promoting the growth of channel catfish fry described in the present invention: the dissolved oxygen in the seed cultivation pond is maintained above 6 mg / L.

[0010] As a preferred solution of the method for promoting the growth of channel catfish fry of the present invention: the daily feed feeding amount in the first stage is about 4% of the total fish body weight in the fry cultivation pond.

[0011] As a preferred solution of the method for promoting the growth of channel catfish fry described in the present invention: the feed includes floating granular feed, and the feed is fed twice a day.

[0012] As a preferred solution of the method for promoting the growth of channel catfish fry of the present invention: the daily feed feeding amount in the second stage is about 6% of the total fish body weight in the fry cultivation pond.

[0013] As a preferred solution of the method for promoting the growth of channel catfish fry of the present invention, feed is fed three times a day.

[0014] As a preferred embodiment of the method for promoting the growth of channel catfish fry described in the present invention, the body size of the channel catfish fry is 0.5-1.5g and the body length is 2.5-5.5cm.

[0015] Preferably, the technical solution adopted by the present invention is: placing channel catfish water flower seedlings of about 1g in size into a seedling cultivation pond at a density of 50-70g / m3 , use LED lamp as light source, the color is cold white light, the light intensity is 500l×, the light cycle is 12 hours light and 12 hours dark, flow water culture, keep dissolved oxygen at more than 6mg / L, the bait is floating particles and feed, regular bottom cleaning and partial water change; the light cycle starts with the regular daily 12 hours light and 12 hours dark, the daily light time increases by 30 minutes and the darkness decreases by 30 minutes, until the light cycle becomes 15 hours light and 9 hours dark, during this stage, floating particles and feed are fed at 7:00 in the morning and 16:00 in the afternoon, the protein mass fraction is 35%, and the daily feed amount is about 4% of the fish body weight; the light cycle continues to maintain 15 hours light and 9 hours dark, during this stage, feeding is increased once at 20:00, the daily feed amount is about 6% of the fish body weight, and the same feeding amount is given three times a day, and the seedling size is cultivated to 50g. DETAILED DESCRIPTION

[0016] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below.

[0017] Embodiment 1:

[0018] At the breeding base of the National Channel Catfish Breeding Center in Yangzhong, Jiangsu, six indoor breeding ponds (1m×3m×1.5m) were selected, and 60 channel catfish fingerlings were stocked in each pond, with a body size of 55±10g and a body length of 20±2cm. Three breeding ponds were used as a group, of which three breeding ponds were control groups and three breeding ponds were experimental groups. The breeding cycle was 10 weeks.

[0019] The control group used natural light to maintain a normal light cycle (12 hours of light and 12 hours of darkness per day). The experimental group used LED lights as light sources, with a color of cold white light and a light intensity of 500l×. The light cycle of the experimental group started with a regular daily 12 hours of light and 12 hours of darkness, and the light time increased by 30 minutes and the darkness decreased by 30 minutes every day. When the daily light cycle became 15 hours of light and 9 hours of darkness, it was maintained continuously.

[0020] During the breeding period, floating pellet compound feed (protein mass fraction of 35%) was fed at 7:00 am and 16:00 pm every day, and the daily feed amount was about 4% of the fish body weight. After the light cycle was continuously maintained to 15 hours of light and 9 hours of darkness, the experimental group and the control group were fed once more at 20:00, and the daily feed amount was about 6% of the fish body weight, and the three feeding amounts were the same. During the breeding period, micro-flow water was maintained, and the dissolved oxygen was maintained at more than 6 mg / L. The residual bait deposited in the breeding pond was sucked every two days, and the water in the breeding pond was changed every 5 days, and the water change amount was 1 / 3 of the total water volume. The water body and temperature were monitored daily, and the number of fish deaths was recorded.

[0021] After the experiment, the fish were stopped from eating for one day, and the final weight and length of each fish were recorded. The growth performance indicators of each group, survival rate (RS), fatness (K), weight gain rate (WGR), and specific growth rate (SGR) were calculated as follows:

[0022] RS=Nt / NO×100%

[0023] K=Wt / Lt 3

[0024] WGR=(Wt-W0) / W0

[0025] SGR=(LnWt-LnWO) / t

[0026] Where: Nt, NO are the final and initial numbers of channel catfish, respectively; Wt, WO are the final and initial average body weights of channel catfish, respectively (g); t is the culture time (d); Lt is the final body length of channel catfish (cm).

[0027] Survival rate and growth tests were conducted at the end of the culture period, and the specific results are shown in Table 1.

[0028] Table 1 Comparison of survival and growth performance between the control group and the experimental group

[0029]

[0030] As can be seen from Table 1, after 10 weeks of culture of channel catfish fry fingerlings, there were no significant differences in body weight, body length, survival rate, fatness, weight gain rate and specific growth rate between the experimental group and the control group.

[0031] Embodiment 2:

[0032] At the breeding base of the National Channel Catfish Breeding Center in Yangzhong, Jiangsu, six indoor breeding ponds (1m×3m×1.5m) were selected, and 300 Channel Catfish fry were stocked in each pond, with a body size of 1±0.5g and a body length of 4±1.5cm. Three breeding ponds were set as a group, of which three breeding ponds were control groups and three breeding ponds were experimental groups. The breeding cycle was 10 weeks.

[0033] The control group used natural light to maintain a normal light cycle (12 hours of light and 12 hours of darkness per day). The experimental group used LED lights as light sources, with a color of cold white light and a light intensity of 500l×. The light cycle of the experimental group started with a regular daily 12 hours of light and 12 hours of darkness, and the light time increased by 30 minutes and the darkness decreased by 30 minutes every day. When the daily light cycle became 15 hours of light and 9 hours of darkness, it was maintained continuously.

[0034] During the breeding period, floating pellet compound feed (protein mass fraction of 35%) was fed at 7:00 am and 16:00 pm every day, and the daily feed amount was about 4% of the fish body weight. After the light cycle was continuously maintained to 15 hours of light and 9 hours of darkness, the experimental group and the control group were fed once more at 20:00, and the daily feed amount was about 6% of the fish body weight, and the three feeding amounts were the same. During the breeding period, micro-flow water was maintained, and the residual bait deposited in the breeding pond was sucked out every two days. The water in the breeding pond was changed once every 5 days, and the water change amount was 1 / 3 of the total water volume. The water body and temperature were monitored daily, and the number of fish deaths was recorded.

[0035] After the experiment, the fish were stopped from feeding for one day, and the final weight and length of each fish were recorded. The survival rate, fatness, weight gain rate, and specific growth rate of each group were calculated. Survival rate and growth test were conducted at the end of the culture period. The specific results are shown in Table 2:

[0036] Table 2 Comparison of survival and growth performance between the control group and the experimental group

[0037]

[0038]

[0039] Note: ＊＊ Indicates P < 0.01.

[0040] As can be seen from Table 2, after 10 weeks of extended photoperiod culture of channel catfish seedlings, the survival rate, fatness, weight gain rate and specific growth rate of the experimental group were higher than those of the control group. In particular, the final body weight, weight gain rate and specific growth rate were significantly higher than those of the control group (P < 0.01), that is, long photoperiod culture can significantly promote the growth of channel catfish seedlings.

[0041] At the same time, after the breeding experiment, the fish were fasted for 24 hours, and 6 individuals were randomly caught from each breeding pond for dissection. Before dissection, the instruments were disinfected with alcohol, and the liver was removed with dissecting scissors and collected in a 1.5 ml centrifuge tube. One liver tissue was one sample, and a total of 18 intestinal content samples were obtained. The samples were quickly frozen in liquid nitrogen and stored in an ultra-low temperature refrigerator at -80°C for liver metabolomics analysis.

[0042] Metabolic pathway enrichment analysis of the differential metabolites between the experimental group and the control group was performed by KEGG (Table 3), and the hypergeometric distribution algorithm was used to obtain the significantly enriched pathways of metabolites (P<0.05). The pathways with the top 20 enrichment values ​​were made into bubble charts, and a total of 4 significantly enriched pathways were screened out, namely PPAR signaling pathway, riboflavin metabolism, beta-Alanine metabolism, and arachidonic acid metabolism (P<0.05).

[0043] Further analysis of the differential metabolites corresponding to the differential metabolic pathways between the two groups (Table 3) revealed that compared with the control group, the relative contents of luminol, malonic acid semialdehyde and histidine in the experimental group were significantly upregulated (P<0.05), and the riboflavin in the riboflavin metabolic pathway was significantly downregulated (P<0.05). At the same time, the metabolites in the PPAR signaling pathway and arachidonic acid metabolic pathway of the experimental group were significantly downregulated (P<0.01).

[0044] Table 3 Differential metabolite pathways between the experimental group and the control group

[0045]

[0046] Note: ↑ indicates up-regulation of differential metabolites; ↓ indicates down-regulation of differential metabolites.

[0047] Among them, the PPAR signaling pathway, riboflavin metabolism and arachidonic acid metabolism pathway are closely related to liver fat formation and lipid metabolism regulation, indicating that compared with the control group, the experimental group used more energy for growth, and never reduced fat accumulation, and finally the metabolites regulating lipid metabolism and accumulation function decreased significantly. At the same time, compared with the control group, the experimental group had significantly increased levels of malonic semialdehyde and histidine in the β-alanine metabolic pathway. Malonic semialdehyde and histidine can increase the body's carnosine content, enhance exercise and anti-fatigue ability, thereby improving growth, improving tissue antioxidant and muscle quality, and ultimately increasing the growth rate and feeding rate of fish.

[0048] In the present invention, the adjustment of light intensity and light cycle has a significant effect on the growth performance and metabolism of channel catfish seedlings. Starting from 12 hours of light per day, the daily light time increases by 30 minutes until the daily light time becomes 15 hours. The best mode is to adjust the light cycle faster or slower, or the light cycle maintained in the second stage is significantly longer than 15 hours or shorter than 15 hours, which will lead to reduced metabolism and growth performance of the seedlings. In summary, the cultivation light cycle of the present invention starts from the conventional daily 12 hours of light and 12 hours of darkness, and the daily light time increases by 30 minutes and the darkness decreases by 30 minutes. When the daily light cycle becomes 15 hours of light and 9 hours of darkness, it is continuously maintained, and the total cultivation period is 10 weeks. LED lamps are used as light sources, the color is cold white light, and the light intensity is 500l×, so as to regulate lipid metabolism and promote the growth of channel catfish seedlings.

[0049] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for promoting the growth of channel catfish fry, characterized in that: It includes adjusting the daily light cycle. The first stage: starting from 12 hours of light and 12 hours of darkness per day, the daily light time increases by 30 minutes and the darkness decreases by 30 minutes, until the daily light cycle becomes 15 hours of light and 9 hours of darkness. The second stage: continue to maintain 15 hours of light and 9 hours of darkness per day.

2. The method for promoting the growth of channel catfish fry according to claim 1, characterized in that: After placing channel catfish seedlings into the seedling cultivation pond, the daily light cycle is adjusted to continuously maintain 15 hours of light and 9 hours of darkness per day for 8 to 10 weeks.

3. The method for promoting the growth of channel catfish fry according to claim 2, characterized in that: The density of the seedlings is 50-70 g / m 3 .

4. The method for promoting the growth of channel catfish fry according to claim 2 or 3, characterized in that: The light source includes an LED lamp as a light source with a light intensity of 500l×.

5. The method for promoting the growth of channel catfish fry according to claim 2 or 3, characterized in that: The dissolved oxygen in the seedling cultivation pond is maintained above 6 mg / L.

6. The method for promoting the growth of channel catfish fry according to claim 2 or 3, characterized in that: The daily feed feeding amount in the first stage is about 4% of the total fish body weight in the seed cultivation pond.

7. The method for promoting the growth of channel catfish fry according to claim 6, characterized in that: The feed includes floating pellet feed, which is fed twice a day.

8. The method for promoting the growth of channel catfish fry according to claim 2 or 3, characterized in that: The daily feed feeding amount in the second stage is about 6% of the total fish body weight in the seed cultivation pond.

9. The method for promoting the growth of channel catfish fry according to claim 8, characterized in that: Feed three times a day.

10. The method for promoting the growth of channel catfish fry according to claim 2 or 3, characterized in that: The fish body specifications of the channel catfish fry are 0.5-1.5g and the body length is 2.5-5.5cm.

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