Breeding method for large-size high-quality young crayfish in early spring

Abstract

The invention discloses a method for breeding large-size high-quality young crayfish in early spring. The method comprises the following steps: (1) selecting and cleaning a pond; (2) nutrient enrichment culture of adult shrimps; (3) environment regulation and control; (4) parent screening; and (5) breeding young prawns. According to the method, independently researched and developed pellet feed and hermetia illucens protein source fermented feed are utilized to strengthen parents, gonad development of the crayfish is forcibly promoted by utilizing the environment, and the crayfish parents are promoted to mate and lay eggs in advance; an independently researched and developed hermetia illucens protein source pellet feed is used for cultivating young crayfish and cultivating early spring large-size crayfish fry, and a foundation is laid for staggered breeding of crayfish; according to the method, large-scale supply of large-size high-quality seedlings in spring is achieved, the technical bottlenecks that the seedlings of the premna davidiana are difficult to obtain and adult shrimps are excessively concentrated to appear on the market in the current industry are solved, and healthy and sustainable development of the industry is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of aquatic high-quality seedling cultivation, and specifically relates to a method for breeding large-sized high-quality crayfish seedlings in early spring, laying a foundation for realizing staggered breeding of crayfish. Technical Background

[0002] Procambarus Clarkii (hereinafter referred to as "crayfish"), native to South America, is the largest aquatic species in terms of area, output and industrial output value in my country's special aquaculture. Due to policy guidance, large-scale breeding and lagging breeding technology, there is a shortage of high-quality early seedlings, a decline in the fitness of breeding groups and a concentration of adult shrimps on the market, which are key issues restricting the healthy development of the crayfish industry.

[0003] Innovative integrated early spring large-scale high-quality crayfish seedling breeding technology, to achieve large-scale supply of high-quality seedlings in spring, to solve the current industry faced with the pre-rice shrimp seedlings hard to find, adult shrimp too concentrated on the market of the industry technology bottleneck. With the continuous increase in crayfish farming yields and the expansion of area year by year, the concentrated listing of crayfish caused by the market is particularly prominent, the supply and demand between the market and consumers is extremely unbalanced. The crayfish industry seems to be prosperous, but the phenomenon of farmers increasing production but not income is common. By building key technologies for early breeding and early raising of crayfish seedlings, optimizing resource allocation, achieving the peak listing of commercial shrimp at the peak of the price, continuously optimizing the industrial structure, improving the economic benefits of breeding, and promoting the healthy and sustainable development of the crayfish industry.

[0004] The larvae of black soldier flies are not only high-quality protein raw materials, but also potential anti-resistance raw materials. The black soldier flies involved in the present invention are a kind of high-quality insect protein that has received early attention. Its scientific name is Hermetia illucens Linnaeus. Generally, each generation lasts for 35 days, and there are four stages: adult stage, egg stage, larval stage, and pupal stage. It has excellent characteristics such as fast growth rate, strong stress resistance, simple breeding, and rapid reproduction. Compared with other insects, black soldier flies have a short lifespan and are generally harvested before the pre-pupae stage. They do not carry pathogens and have natural antibacterial substances. Its larvae have a high protein content, are rich in lauric acid, palmitic acid, essential amino acids, trace elements and a variety of biologically active substances, and are functional raw materials with good development prospects.

[0005] In recent years, through the study of the reproductive biology and living habits of crayfish, the large-scale production of crayfish seedlings and adult shrimp farming has been basically achieved. At the same time, it has also caused a large number of crayfish to be put on the market, resulting in low market prices, serious losses in profits, and dampening the enthusiasm of farmers. The China Crayfish Industry Development Report (2023) shows that the price trend of commercial crayfish in 2022 will still be "U"-shaped, with higher prices in April at the beginning of the crayfish market and after July, and lower prices during the concentrated market period from May to June (especially the concentrated market of pre-rice shrimp). Summary of the invention

[0006] The purpose of the present invention is to carry out technical innovation and integrated research on the early spring large-scale high-quality crayfish seedling breeding technology, in response to key technical issues in the industry such as the shortage of high-quality early crayfish seedlings and the concentrated listing of adult shrimps, so as to provide large-scale shrimp seedlings for crayfish farming in March and April the following year, shorten the breeding time from seedlings to adult shrimps, and provide technical guarantee for the listing of commercial shrimps when there is a price but no shrimps.

[0007] The technical solution adopted by the present invention comprises the following steps:

[0008] A method for breeding large-sized and high-quality crayfish seedlings in early spring, comprising the following specific steps:

[0009] Step 1, pond selection and cleaning: select a field close to a water source, with no pollution sources around, convenient water inlet and outlet, yellow clay soil, fertile and loose bottom mud, rich humus, and solid and watertight ridges; before stocking the broodstock, use bleaching powder to thoroughly clean the pond and dry it in the sun to eliminate threats such as wild fish, residual shrimp, and disease bacteria;

[0010] Step 2: Nutritional enhancement of adult shrimps: By the end of June, adult shrimps cultured in the "rice-pre-shrimp" model are selected as reserve parents, and are fed with self-developed pellet feed and fermented feed for nutritional enhancement, which increases the accumulation of protein and fat nutrients in the crayfish body and promotes the gonadal development of the testes and ovaries of female and male individuals. The enhancement period is 1 month;

[0011] Step 3, environmental regulation: When the temperature rises in late July, the water level is gradually adjusted to control environmental factors such as temperature and light, thereby forcing the crayfish to dig holes and achieve the purpose of rapid development of the crayfish gonads. After the coercion stage, the water level is restored to normal, the crayfish are induced to come out of the hole, and the breeding continues;

[0012] Step 4, parent screening: After raising to early August, female shrimps with strong vitality, complete appendages and uniform size are initially selected. At the same time, some individuals are randomly selected, and hemolymph is collected from the head and thorax to test the content of sex hormones. The group with most individuals in the V stage of gonadal maturity is the most suitable object;

[0013] Step 5, shrimp seedling cultivation: the selected parents are cultured until early September. After being caught, the shrimps are shaken until they are separated from the mother body. The weight growth index is initially measured and the appropriate stocking density is 60,000 per mu;

[0014] in,

[0015] (A1) Feed nutritional composition: in the adult shrimp nutrition enhancement cultivation stage in step 2, the nutritional composition of the pellet feed is (%): crude protein 30.0-35.0%, crude fat 4.0-4.5%, moisture 9.2-9.5%, ash 15.2-16.0%; the nutritional composition of the black soldier fly protein source fermented feed is (%): crude protein 25-30%, crude fat 4.0-4.2%, moisture 29-30%, ash 15-16.0%; in the shrimp seedling cultivation stage in step 5, the nutritional composition of the black soldier fly protein source pellet feed is: crude protein ≥30.0%, crude fat ≥4.0%, moisture ≤14.0%, ash ≤16.0%;

[0016] (A2) Feeding method: In the adult shrimp nutrition fortification cultivation stage in step 2, pellet feed and black soldier fly protein source fermented feed are reasonably matched and fed; in the shrimp seedling cultivation stage in step 5, black soldier fly protein source pellet feed is evenly mixed with Chlorella powder and then fed; black soldier fly protein source fermented feed is generally fed twice a day, at 6:00 am and 17:00 pm respectively, generally 30%-40% of the daily feed amount is put in the morning, and 60%-70% is put in the evening; the feeding amount is 5-6% of the total weight of shrimp in the pond, and the feed weight is adjusted in time according to the daily feeding situation of crayfish. Feed less or no feed on consecutive rainy days, concentrated molting period and disease period;

[0017] (A3) Aquatic plant planting: Aquatic plant planting generally adopts the "point-hole" planting method, planting submerged plants and emergent plants. Elodea is selected for the former and water peanut is selected for the latter. A cluster of aquatic plants is planted every 1.5-3.0m. Elodea and water peanut are planted in sequence. Each row of single aquatic plants is strip-shaped, and the distance between Elodea and water peanut is 4-5m. Only Elodea aquatic plants are planted in winter;

[0018] (A4) Water quality regulation: Use microbial preparations such as lactic acid bacteria, Bacillus subtilis and Clostridium butyricum to regulate water quality. Use them in the morning on sunny days, and use them every 10-12 days. Before spraying, the microecological preparations can be soaked in an appropriate amount of brown sugar for 3-4 hours, and then evenly sprayed throughout the pond.

[0019] (A5) Water level management: In step 2, during the adult shrimp nutrition intensive cultivation stage (late June to early July), the water level is maintained at about 40-50 cm; in step 5, during the shrimp seedling cultivation period, from December to January or February of the following year, the water depth is controlled at (100-120) cm to stabilize the water temperature; in March of the following year, as the temperature rises, the water level is lowered to about 40 cm;

[0020] (A6) Set up anti-escape nets: anti-escape nets are set up around the aquaculture pond. The material is thick polyethylene plastic film, the bottom is buried 15-20cm in the soil, and the above-ground part is 40-50cm high; the outer side of the anti-escape film uses glass fiber reinforced plastic fiber round tubes as supports, with a spacing of 1.0-1.5m;

[0021] (A7) Shrimp fry fishing: Generally in mid-March of the following year, when the shrimp fry grow to 200-300 per kg, they are promptly caught using small-mesh shrimp cages. The yield is generally 150-200 kg per mu. After the fishing is completed, the pond is cleaned.

[0022] (A8) Daily management: Patrol the fields once in the morning and once in the evening every day. In bad weather such as rain, increase the frequency of patrols. If you find a large number of crayfish floating on the ground, climbing the grass, or climbing the slope, etc., you should promptly start the aeration facilities, change the water, use medication and other preventive control measures.

[0023] In a specific implementation scheme, step 1 pond selection and cleaning, the water level for cleaning and disinfection needs to be less than 50cm, every 667m 2 25kg of bleaching powder is used mainly to clean up the remaining shrimp, wild fish and pathogenic microorganisms from the previous breeding.

[0024] In a specific implementation scheme, in the step 2, during the adult shrimp nutrition fortification cultivation stage, the pellet feed group (HP1) is composed of the following parts by weight: 5-25 parts of fish meal (in terms of dry matter), 15-30 parts of soybean meal, 20-40 parts of flour, 5-15 parts of rapeseed meal, 4-10 parts of peanut meal, 4-10 parts of cottonseed meal, 5-15 parts of rice bran, 0.3-3 parts of soybean oil, 0.5-1.5 parts of soybean lecithin, 1-3 parts of monocalcium phosphate, 0.1-0.5 parts of 50% choline chloride, 0.05-0.2 parts of vitamin premix, and 0.1-0.5 parts of mineral premix.

[0025] Preferably, in the step 2, during the adult shrimp nutrition fortification cultivation stage, the pellet feed composition is specifically as follows by weight: 10 parts of fish meal (in terms of dry matter), 22 parts of soybean meal, 30.41 parts of flour, 10 parts of rapeseed meal, 6 parts of peanut meal, 6 parts of cottonseed meal, 10 parts of rice bran, 1.74 parts of soybean oil, 1 part of soybean lecithin, 2 parts of monocalcium phosphate, 0.3 parts of 50% choline chloride, 0.1 parts of vitamin premix, and 0.25 parts of mineral premix.

[0026] In a specific implementation scheme, in step 2, the adult shrimps are cultivated for nutritional enhancement, and the specific components of the black soldier fly protein source fermented feed (BF1) are: 2-15 parts of black soldier fly larvae, 3-8 parts of fish meal, 15-30 parts of soybean meal, 20-40 parts of flour, 5-15 parts of rapeseed meal, 4-10 parts of peanut meal, 4-10 parts of cottonseed meal, 5-15 parts of rice bran, 0.3-3 parts of soybean oil, 0.5-1.5 parts of soybean lecithin, 1-3 parts of monocalcium phosphate, 0.1-0.5 parts of 50% choline chloride, 0.05-0.2 parts of vitamin premix, and 0.1-0.5 parts of mineral premix; the addition amount of the composite bacterial agent is 4-8g / kg.

[0027] Preferably, the specific components of the black soldier fly protein source fermented feed are: 5.4 parts of black soldier fly larvae, 4.8 parts of fish meal, 22 parts of soybean meal, 30.41 parts of flour, 10 parts of rapeseed meal, 6 parts of peanut meal, 6 parts of cottonseed meal, 10 parts of rice bran, 1.74 parts of soybean oil, 1 part of soybean lecithin, 2 parts of monocalcium phosphate, 0.3 parts of 50% choline chloride, 0.1 parts of vitamin premix, and 0.25 parts of mineral premix; the addition amount of the composite bacterial agent is 5g / kg.

[0028] In a specific implementation scheme, in step 5, shrimp seedlings are cultivated, and the specific components of the black soldier fly protein source granular feed (HP3) are: 10.00-12.00 parts of fish meal, 2-3 parts of black soldier fly larvae powder, 20-22.00 parts of soybean meal, 8.00-11.00 parts of rapeseed meal, 4.00-6.00 parts of peanut meal, 30-32 parts of flour, 5.00-6.5 parts of cottonseed, 8.00-1.00 parts of rice bran, 2.00-2.50 parts of soybean oil, 1.00-1.50 parts of soybean lecithin, 1.80-2.20 parts of monocalcium phosphate, 0.08-0.12 parts of vitamin premix, 0.20-0.50 parts of mineral premix, and 0.20-0.30 parts of choline chloride.

[0029] In a more specific embodiment, the black soldier fly protein source granular feed specifically comprises: 10.5 parts of fish meal, 2.2 parts of black soldier fly larvae powder, 21.00 parts of soybean meal, 9.20 parts of rapeseed meal, 4.80 parts of peanut meal, 31.00 parts of flour, 6.00 parts of cottonseed, 9.20 parts of rice bran, 2.20 parts of soybean oil, 1.30 parts of soybean lecithin, 1.90 parts of monocalcium phosphate, 0.10 parts of vitamin premix, 0.35 parts of mineral premix, and 0.25 parts of choline chloride.

[0030] Among them, vitamin premixes and mineral premixes are not limited to specific manufacturers and models, and general vitamin premixes and mineral premixes for aquaculture meet the requirements.

[0031] Preferably, the composite bacterial agent comprises Bacillus subtilis and Saccharomyces cerevisiae, and the concentration of live bacteria is respectively Bacillus subtilis ≥ 5.00 × 1012 U / g, Saccharomyces cerevisiae ≥4.00×10 12 CFU / g.

[0032] Specifically, the method for preparing the fermented feed of black soldier fly protein source by nutrient-enhanced cultivation of adult shrimp in step 2 comprises the following steps:

[0033] Step (1), conveying fish meal, soybean meal, flour, rapeseed meal, peanut meal, cottonseed meal, and rice bran with a moisture content of ≤12% to a mixer; then conveying black soldier fly larvae with a moisture content of 65%-80% to the mixer, mixing and stirring, and then conveying to a pulverizer for ultrafine grinding;

[0034] Step (2), conveying the ultrafinely pulverized material to a mixing and blending device, adding soybean oil, soybean lecithin, calcium dihydrogen phosphate, choline chloride, vitamin premix, and mineral premix; performing a second mixing and blending to prepare a hard granular compound feed;

[0035] Step (3), after the hard pellet feed is cooled, it is transferred to a fermentation feed mixer; according to the weight of the pellet feed, the composite bacterial agent is taken into the bacterial liquid sprayer, the fermentation feed mixer is started, and the bacterial liquid is sprayed onto the pellet feed;

[0036] Step (4), mixing and stirring for 20-40 minutes, conveying by a crawler belt, and packing in fermentation bags by an automatic weighing device;

[0037] Step (5), fermenting in a constant temperature greenhouse at a temperature of 30° C. to 35° C. for 5 to 7 days to obtain a fermented feed containing a black soldier fly protein source.

[0038] In a specific implementation plan, step 3, environmental regulation, is performed by gradually lowering the water level. The dryness stress time should not be too short or too long, 20-25 days is optimal, and then the normal water level is restored.

[0039] In a specific implementation scheme, in step 4, parent screening, female shrimp individuals weighing about 35 g are preferentially selected, which plays an important role in ensuring the reproductive performance of female shrimp in the later stage.

[0040] In a specific implementation scheme, in step 4, parent screening, the amount of hemolymph extracted from each crayfish is 1.0 ml-1.2 ml, and the amount extracted should not be too much to prevent death.

[0041] In a specific implementation plan, in step 4, parent screening, in order to achieve rapid gonadal development of crayfish, individuals whose gonadal development is in stage V should be selected, and the requirements for hemolymph sex hormone content are as follows: estradiol content 5.8-7.90ng / gprot, progesterone content 1.30-1.37ng / gprot, vitellogenin content 0.50-0.60mmol / L, gonadotropin-releasing hormone content 42.9-47.8ng / L.

[0042] In a specific implementation scheme, the fermented feed (Biological fermented feed, BF) adopts solid-state fermentation method, and the probiotics are inoculated according to the ratio of Saccharomyces cerevisiae: Lactobacillus plantarum: Bacillus subtilis = 1:1:1 (number of live bacteria per unit volume), and fermented in a constant temperature fermentation room at 32°C for 7 days to ferment into soft granular feed.

[0043] In a specific implementation scheme, in the feeding method (A2), during the adult shrimp nutrition fortification cultivation stage, conventional granular feed and black soldier fly protein source fermented feed are reasonably combined and fed, wherein the fermented feed accounts for ≤30%.

[0044] In a more specific embodiment, in the feeding method (A2), during the adult shrimp nutrition fortification cultivation stage, the fermented feed accounts for 12.5%-25%.

[0045] In a specific implementation scheme, the feeding method (A2) is to set up a feeding platform every 30-40 meters or so according to the movement ability of crayfish, so as to facilitate daily observation of the crayfish's feeding situation.

[0046] In a specific implementation scheme, the aquatic plant planting (A3) needs to have an appropriate aquatic plant planting area, which is 50% to 75% to meet the growth and development needs of crayfish, but not too much.

[0047] In a specific implementation scheme, the (A4) water quality adjustment, crayfish has higher requirements for water quality, wherein the dissolved oxygen in the aquaculture water is ≥5.22 mg / L, the pH range is 7.2-8.6, the ammonia nitrogen content is ≤0.51 mg / L and the nitrite nitrogen content is ≤0.05 mg / L, the sulfide content is ≤0.10 mg / L, and the transparency is preferably 25-32 cm.

[0048] In a specific implementation scheme, the (A4) water quality regulation uses three microecological preparations of Bacillus subtilis, lactic acid bacteria and Clostridium butyricum to regulate the aquaculture water quality, wherein the effective live bacteria count of Bacillus subtilis is 100 billion / g, the live bacteria count of lactic acid bacteria is 10 billion / g, and the effective live bacteria count of Clostridium butyricum is 300 million / ml.

[0049] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0050] Compared with the traditional method of cultivating crayfish seedlings, the present invention sets strict standards for the selection of seedlings, and accelerates the development of crayfish gonads through two ways: nutritional fortification and environmental stress, which plays an important role in improving the reproductive performance of crayfish and early hatching of seedlings. At the same time, by feeding self-developed granular feed and fermented feed of black soldier fly protein source, the rapid growth of shrimps is promoted, so that the seedlings reach a certain specification in the next year, providing seedling guarantee for realizing staggered breeding of crayfish.

[0051] The principle of the present invention is mainly to rationally select crayfish parents, strengthen the nutrition of reserve parent shrimps, and improve their reproductive performance. In addition, through environmental stress, the growth nutrition of crayfish is promoted to change to reproductive nutrition, the gonadal development of crayfish is promoted, and mating and spawning are achieved. Finally, by feeding appropriate feed to promote the rapid growth and development of shrimps, the seedling cultivation time is shortened, and the purpose of cultivating large-sized seedlings in early spring is finally achieved.

[0052] The invention mixes and grinds black soldier fly larvae raw materials with high water content and conventional feed raw materials, thereby solving the problems of low grinding degree of black soldier fly larvae into slurry and difficulty in preparing feed and adding uniformly, reducing the use cost of black soldier fly larvae as feed, replacing high-priced protein raw materials such as fish meal and soybean meal, and achieving the effect of reducing cost and increasing efficiency of feed preparation.

[0053] The fermented feed produced by the present invention, on the one hand, is beneficial to the conversion of substances such as protein and chitin in the black soldier fly raw material into functional substances such as small peptides and chitin through probiotic fermentation, thereby improving the immunity and disease resistance of crayfish. On the other hand, the fermented feed produced is rich in various probiotics and organic acids, has an attractant effect on crayfish, improves feed intake rate and utilization rate, and reduces feed coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 VI. Body weight distribution composition of female shrimp development. DETAILED DESCRIPTION

[0055] The present invention will be further described below by way of examples, which are not intended to further limit the present invention. It should be understood by those skilled in the art that equivalent replacements or corresponding improvements made to the present invention still fall within the scope of protection of the present invention.

[0056] Example 1

[0057] A method for breeding large-sized and high-quality crayfish seedlings in early spring, the method comprising the following steps:

[0058] (1) Pond selection and cleaning: Choose a pond that is close to a water source, has no pollution sources in the surrounding area, is easy to drain, has yellow clay soil, fertile and loose bottom mud, rich in humus, and has a solid and watertight ridge. Before stocking the broodstock, use bleaching powder to thoroughly clean the pond and dry it in the sun to eliminate threats such as wild fish, residual shrimp, and disease bacteria. The water level for cleaning and disinfection needs to be less than 50 cm, and every 667m 2 Use 25kg of bleaching powder;

[0059] (2) Nutritional enhancement of adult shrimps: By the end of June, adult shrimps cultured in the “rice before shrimp” model were selected as reserve parents and fed with self-developed pellet feed (10 parts of fish meal, 22 parts of soybean meal, 30.41 parts of flour, 10 parts of rapeseed meal, 6 parts of peanut meal, 6 parts of cottonseed meal, 10 parts of rice bran, 1.74 parts of soybean oil, 1 part of soybean lecithin, 2 parts of monocalcium phosphate, 0.3 parts of 50% choline chloride, 0.1 parts of vitamin premix, and 0.25 parts of mineral premix) and fermented feed sourced from black soldier fly protein (black soldier fly protein). 5.4 parts of horsefly larvae, 4.8 parts of fish meal, 22 parts of soybean meal, 30.41 parts of flour, 10 parts of rapeseed meal, 6 parts of peanut meal, 6 parts of cottonseed meal, 10 parts of rice bran, 1.74 parts of soybean oil, 1 part of soybean lecithin, 2 parts of monocalcium phosphate, 0.3 parts of 50% choline chloride, 0.1 parts of vitamin premix, 0.25 parts of mineral premix) are used for nutritional fortification to increase the accumulation of protein and fat nutrients in the body of crayfish and promote the gonadal development of the testes and ovaries of female and male individuals. The fortification period is 1 month;

[0060] (3) Environmental regulation: When the temperature rises in late July, the water level is gradually adjusted. The temperature, light and other environmental factors are regulated by the water level, thereby forcing the crayfish to dig holes, so as to achieve the purpose of rapid development of the crayfish gonads. The dry stress period is 25 days. After the stress period, the water level is restored to normal, and the crayfish are induced to burrow out of the hole and continue to be cultured;

[0061] (4) Parent selection: After rearing until early August, female shrimps with strong vitality, complete appendages and uniform size (weight 40±5g) are initially selected. At the same time, some individuals are randomly selected, and hemolymph is taken from the head and thorax (lymph extraction volume is 1.0ml-1.2ml) to test the sex hormone content. The group with most individuals in the V stage of gonadal maturity is the most suitable object. Among them, the requirements for the sex hormone content of hemolymph are as follows: estradiol content 5.8-7.90ng / gprot, progesterone content 1.30-1.37ng / gprot, vitellogenin content 0.50-0.60mmol / L, gonadotropin-releasing hormone content 42.9-47.8ng / L;

[0062] (5) Postlarval shrimp seed cultivation: The selected parents are cultured until early September. After being caught, the postlarvae are shaken until they are separated from the mother. After preliminary weighing of the weight growth index, the appropriate stocking density is 60,000 per mu. The shrimp are fed with black soldier fly protein source pellet feed (10.5 parts of fish meal, 2.2 parts of black soldier fly larvae powder, 21.00 parts of soybean meal, 9.20 parts of rapeseed meal, 4.80 parts of peanut meal, 31.00 parts of flour, 6.00 parts of cotton seeds, 9.20 parts of rice bran, 2.20 parts of soybean oil, 1.30 parts of soybean lecithin, 1.90 parts of monocalcium phosphate, 0.10 parts of vitamin premix, 0.35 parts of mineral premix, and 0.25 parts of choline chloride). Chlorella powder is added to the black soldier fly protein source pellet feed at 5% of the black soldier fly protein source pellet feed and fed together;

[0063] (6) Feeding method: During the nutritional enhancement stage of adult shrimp, conventional pellet feed and fermented feed of black soldier fly protein source are fed in combination; during the seedling cultivation stage of shrimp, black soldier fly protein source pellet feed is evenly mixed with Chlorella powder and then fed; feeding is carried out twice a day, at 6:00 a.m. and 17:00 p.m. respectively, generally 30%-40% of the daily feed amount is put in the morning, and 60%-70% is put in the evening; the feeding amount is 5-6% of the total weight of the shrimp in the pond, and a feeding platform is set up every 35 meters;

[0064] (7) Aquatic plant planting: Aquatic plant planting adopts the "point-point" planting method, planting submerged plants and emergent plants, Elodea is selected for the former and water peanut is selected for the latter; a cluster of aquatic plants is planted every 2.0m, Elodea and water peanut are planted in sequence, and each row of single aquatic plants is strip-shaped, with a distance of 4.5m between Elodea and water peanut; only Elodea aquatic plants are planted in winter, and the aquatic plant planting area is 50%;

[0065] (8) Water quality regulation: Use microbial preparations such as lactic acid bacteria, Bacillus subtilis and Clostridium butyricum to regulate water quality. The effective live bacteria count of Bacillus subtilis is 100 billion / g, the live bacteria count of lactic acid bacteria is 10 billion / g, and the effective live bacteria count of Clostridium butyricum is 300 million / ml. Use it in the morning on sunny days and the frequency of use is once every 10-12 days. Before spraying, the microecological preparation can be soaked in an appropriate amount of brown sugar for 3 hours and then sprayed evenly throughout the pond. The dissolved oxygen of the aquaculture water is ≥5.22 mg / L, the pH range is 7.2-8.6, the ammonia nitrogen content is ≤0.51 mg / L and the nitrite nitrogen content is ≤0.05 mg / L, the sulfide content is ≤0.10 mg / L, and the transparency is 25-32 cm.

[0066] (9) Water level management: During the adult shrimp nutrition enhancement period (late June to early July), the water level is maintained at about 40-50 cm; during the shrimp rearing period, from December to January or February of the following year, the water depth is controlled at 50-60 m and the water temperature is stabilized; in March of the following year, as the temperature rises, the water level is lowered to 40 cm;

[0067] (10) Setting up anti-escape nets: Anti-escape nets are set up around the aquaculture pond. The material is thick polyethylene plastic film, the bottom is buried 15-20 cm in the soil, and the above-ground part is 40-50 cm high; the outer side of the anti-escape film uses glass fiber reinforced plastic fiber round tubes as supports, with a spacing of 1.0-1.5m;

[0068] (11) Shrimp fry fishing: In mid-March of the following year, when the shrimp fry grow to 200-300 / kg, they are caught in small-mesh shrimp cages. After the catch, the pond is cleaned.

[0069] (12) Daily management: Patrol the fields once in the morning and once in the evening every day. In bad weather such as rain or cloudy weather, increase the frequency of patrols. If you find a large number of crayfish floating on the surface, crawling on the grass, or climbing up the slope, etc., you should promptly start the aeration facility, change the water, use medication, and other preventive control measures.

[0070] Example 2

[0071] Distribution of ovarian developmental stages in crayfish (see Table 1, Figure 1 ). The number of individuals whose ovaries were in stage III, stage V and stage VI accounted for a large proportion, accounting for 20.73%, 15.85% and 58.54% respectively (see Table 2). The ovarian gonad index in stage V was significantly higher than that in other stages (P<0.05). The average value of the collected samples was 36.39±10.26g. Correlation between the gonadal development period and body weight distribution of crayfish. The body weight of stage VI (spawning shrimp) ranged from 13.50-52.95g, showing a normal distribution, with individuals weighing 29-37g as the main body (35.42%). Increased body weight can provide sufficient space for ovarian development and egg holding, which is beneficial to improving individual fertility. Based on the growth performance of crayfish and the proportion of gonadal development period, individuals weighing about 35±5g were selected as parents in this paper.

[0072] Table 1 Basic information of crayfish ovarian development

[0073] cycle Proportion Gonadal index (%) Weight (g) Early stage (stage II) 3.66％ 0.22±0.04 39.67±16.50 Previtellogenesis (Stage III) 20.73％ 0.84±0.76 40.81±13.41 Vitellogenesis (Stage IV) 1.22％ 0.33±0.00 44.87±0.00 Mature stage (stage V) 15.85％ 5.82±0.88 39.75±7.66 Late egg-laying period (VI) 58.54％ 0.40±0.05 33.53±8.53

[0074] Example 3

[0075] The contents of relevant hormones in the ovaries of crayfish at different developmental stages are shown in Table 2. The cholesterol in the ovaries of stage V was significantly higher than that in stages III and VI (P<0.05). The estradiol content and progesterone in the ovaries showed a trend of first decreasing and then increasing. The E2 content and progesterone in stage V were significantly lower than those in stages III and VI (P<0.05), and there was no significant difference between the latter two (P>0.05). The gonadotropin-releasing hormone content in the ovaries also showed a trend of first decreasing and then increasing. The estradiol content and progesterone in stage V were significantly lower than those in stages III and VI (P<0.05), but significantly higher in stage III than in stage VI (P<0.05).

[0076] Table 2 Contents of gonad-related hormones in crayfish ovaries at different developmental stages

[0077]

[0078] Example 4

[0079] The juvenile Procambarus clarkii with neat size, complete appendages and strong mobility were selected as the test subjects. The experiment on the effect of different aquatic plant areas on the growth and development of juvenile shrimp was carried out. The results showed that there was no significant difference in weight and body length between the group with a 25% aquatic plant coverage ratio and the group with a 50% coverage ratio (P>0.05). As the aquatic plant coverage increased to 75%, the weight and body length of the crayfish in this group decreased significantly (P<0.05).

[0080] Table 3 Effects of different aquatic plant coverage ratios on the growth performance of crayfish

[0081]

[0082] Example 5

[0083] Four different feed treatment groups were set up, (1) conventional pellet feed (HP1) (self-developed feed); (2) conventional pellet feed (HP2) (Jiangsu Fuyuda Grain Products Co., Ltd.); (3) black soldier fly protein source fermented feed (BF1) (self-developed feed); (4) conventional biological fermented feed (BF2) (Jiangsu Fuyuda Grain Products Co., Ltd.). The results are shown in Table 4. The survival rate of Procambarus clarkii in the BF1 treatment group was significantly higher than that in the HP2 and BF2 groups (P < 0.05), and the weight gain rate was significantly higher than that in the HP2 group (P < 0.05). There were no significant differences in the weight, body length, fatness, intestine-to-body ratio, abdominal meat rate and ovarian index of Procambarus clarkii fed the black soldier fly protein source fermented feed (BF1) compared with the conventional pellet feed group (HP1) (P > 0.05), but the weight and body length of female shrimp were significantly higher than those of the conventional pellet feed (HP2) (P < 0.05).

[0084] Table 4 Effects of different feeds on the body parameters of Procambarus clarkii

[0085]

[0086] Example 6

[0087] The feed was developed using raw materials such as black soldier flies, chlorella powder and rapeseed cake to promote the rapid growth and development of seedlings and cultivate large-sized seedlings. The experiment was designed with three treatment groups, G1: black soldier fly protein source pellet feed group (HP3, hereinafter referred to as black soldier fly feed group), G2: black soldier fly protein source pellet feed + chlorella powder group (added 5%) (hereinafter referred to as chlorella feed group), G3: rapeseed cake group. The results are shown in Table 5. There was no significant difference in the weight of crayfish larvae in the black soldier fly feed group and the chlorella feed group (P<0.05), and both were significantly higher than the rapeseed cake group. There was no significant difference in the body length of crayfish larvae in the black soldier fly feed group and the chlorella feed group (P>0.05), and both were significantly higher than the rapeseed cake group. The main reason for the analysis is that the palatability of the rapeseed cake group is lower than that of the black soldier fly and Chlorella granular feed groups, and there are also significant differences in the nutritional components of the feed between the groups. Although the rapeseed cake group has a lower cost, the crayfish seed cultivation effect is poor.

[0088] Table 5 Effects of different feeds on the growth and development of crayfish seedlings

[0089]

[0090] By mid-March, the average size of shrimp fry was about 3.1g, the total yield per mu was 158.5-161.5kg / mu, and the total number of surviving crayfish was 50,700-51,300 / mu. By April 1, the weight and length of crayfish in the Chlorella feed group were significantly higher than those in the Black Soldier Fly feed group and the Rapeseed Cake group (P<0.05). There was no significant difference in survival rate among the groups (P>0.05).

[0091] Example 7

[0092] The effects of different shrimp stocking densities on the growth, survival and feed utilization of crayfish during the wintering period were studied. Five shrimp stocking densities were set, namely 30, 60, 120, 180 and 240 shrimp / m 2 . Reared for 130 days. Farming management: Elodea was planted in mid-November; shrimp fry were released on December 3, with an average weight of (18.13±0.32) mg / tail; sodium humate and potassium humate were used to fertilize the water from December 3 to February 27 of the following year; 30% protein pellet feed (Jiangsu Fuyuda Grain Products Co., Ltd.) was fed from March 2 to April 12; shrimp fry were captured on April 15, weighed, and sexed and recorded.

[0093] Results and analysis:

[0094] The relationship between shrimp stocking density and total production fits the quadratic regression equation: y = -0.0104x 2 +3.3373x-132.86(R 2 =0.9975) When the stocking density of shrimp is 160.44 / m 2The maximum shrimp fry yield is 254.44g / m 2 , that is, 169.71kg / mu. Total number of surviving shrimps: When the stocking density of shrimps is 175.68 / m 2 When the total number of shrimp fry surviving reached 96.42 / m 2 , that is, 64,300 per mu. In conventional seedling cultivation methods, considering the total shrimp seedling production and the total number of surviving shrimps, the appropriate stocking density of shrimps per mu is 107,000 to 117,200, with an average body weight of 2.86g and a feed feeding amount of 156.95 to 171.87kg. The total production can be 168.10 to 169.71kg, the total number of surviving shrimps is 63,700 to 64,300, and the feed coefficient is 0.96 to 1.09. If large-sized crayfish seedlings are cultivated, the breeding density needs to be further reduced. It is recommended that the stocking density of shrimps for cultivating large-sized early spring seedlings be about 60,000 per mu, and the number of seedlings with an average shrimp seedling weight ≥ 5g be increased.

[0095] Example 8

[0096] Four treatment groups were set up, namely: E1 (low water level, waterweed planting, straw stacking), E2 (high water level, no waterweed planting, straw stacking), E3 (high water level, waterweed planting, straw laying), E4 (high water level, waterweed planting, straw stacking). The low water level was 20cm-30cm, and the high water level was 40cm-60cm. The waterweed species planted were Elodea and water peanut, and the planting amount was about 1kg / 15m 2 ; The straw stacking method is: 15m 2 The rice straw was piled into a 60cm haystack. Farming management: Elodea and Vallisneria were planted in mid-November; larvae were released on December 3, with an average weight of (18.13±0.32) mg / tail; and crayfish compound feed with 30% protein was fed.

[0097] Results and analysis:

[0098] The survival, growth and protein efficiency of crayfish in the low water level or no aquatic grass group were significantly reduced (P < 0.05), and the feed coefficient was significantly increased (P < 0.05). The total production and total number of crayfish in the low water level (E1) or no aquatic grass (E2) group were significantly reduced (P < 0.05).

[0099] Example 9

[0100] Crayfish breeding and cleaning technology. Crayfish with complete appendages and strong mobility were selected. The sizes were divided into large, medium and small. The weight of large shrimp was (25.51±4.13) g, the weight of medium shrimp was (17.39±2.18) g, and the weight of small shrimp was (7.78±1.95) g. Bleaching powder (effective content 35%) was selected for cleaning experiments.

[0101] Results and analysis:

[0102] Bleaching powder: When the water level is 50cm, all small shrimps die, the mortality rate of medium shrimps is 80.00%, the mortality rate of large shrimps is 80.00%, and the overall mortality rate is 86.67%. The main reason why some crayfish can survive is that they dig holes, which reduces the effect of bleaching powder on cleaning crayfish. The water level is 50cm, and every 667m 2 Using 25kg of bleaching powder to clean crayfish is more effective.

[0103] The protection content of the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention and are protected by the attached claims.

Claims

1. A method for breeding large-sized and high-quality crayfish seedlings in early spring, characterized in that: The method comprises the following steps Step 1, pond selection and cleaning: select a field close to a water source, with no pollution sources around, convenient water inlet and outlet, yellow clay soil, fertile and loose bottom mud, rich humus, and solid and watertight ridges; use bleaching powder to thoroughly clean the pond and dry it before releasing the broodstock; Step 2, nutritional fortification of adult shrimps: By the end of June, adult shrimps cultured in the "rice before shrimp" mode are selected as reserve parents, and are fed with pellet feed and fermented feed of black soldier fly protein source for nutritional fortification, wherein the fermented feed is composed of raw materials and compound bacterial agents; the fortification cycle is 1 month; Step 3, environmental regulation: When the temperature rises in late July, the water level is gradually adjusted to control environmental factors through the water level, thereby forcing the crayfish to dig holes and achieve the purpose of rapid development of the crayfish gonads; after the coercion stage, the water level is restored to normal, the crayfish are induced to come out of the hole, and the breeding continues; Step 4, parent screening: After raising to early August, initially select female shrimps with strong vitality, complete appendages and uniform size. At the same time, randomly select some individuals, take hemolymph from the head and thorax, and test the content of sex hormones. The group with more than 50% of the individuals at stage V of gonadal maturity is the most suitable object; Step 5, shrimp seedling cultivation: the selected parents are cultured until early September. After being caught, the shrimps are shaken until they are separated from the mother body. The weight growth index is initially measured and the stocking density is 60,000 per mu. The shrimps are fed with black soldier fly protein source granular feed; in, (A1) Nutritional composition of feed: During the nutritional enhancement and cultivation stage of adult shrimp in step 2, the nutritional composition of pellet feed is: crude protein 30.0-35.0%, crude fat 4.0-4.5%, moisture 9.2-9.5%, ash 15.2-16.0%; the nutritional composition of fermented feed sourced from black soldier fly protein is: crude protein 25-30%, crude fat 4.0-4.2%, moisture 29-30%, ash 15-16.0%; during the shrimp seedling cultivation stage in step 5, the nutritional composition of pellet feed sourced from black soldier fly protein is: crude protein ≥30.0%, crude fat ≥4.0%, moisture ≤14.0%, ash ≤16.0%; (A2) Feeding method: In the nutritional fortification stage of adult shrimps in step 2, pellet feed and fermented feed of black soldier fly protein source are fed together; in the fry and seed cultivation stage of step 5, pellet feed of black soldier fly protein source is evenly mixed with Chlorella powder and then fed; feed is fed twice a day, in the morning and evening respectively, 30%-40% of the daily feed amount is fed in the morning, and 60%-70% is fed in the evening; the feeding amount is 5-6% of the total weight of shrimps in the pond; (A3) Aquatic plant planting: Aquatic plant planting adopts the "point-hole" planting method, planting submerged plants and emergent plants; a cluster of aquatic plants is planted every 1.5-3.0m, and submerged plants and emergent plants are planted in sequence. Each row of single aquatic plants is strip-shaped, and the distance between submerged plants and emergent plants is 4-5m; only submerged plants are planted in winter; (A4) Water quality adjustment: Use microbial preparations to adjust water quality. Use them in the morning on sunny days, and use them every 10-12 days. Before spraying, soak the microecological preparations with brown sugar for 3-4 hours, and then spray them evenly throughout the pond. (A5) Water level management: Step 2: During the adult shrimp nutrition intensive cultivation stage, from late June to early July, the water level should be maintained at 40-50cm; Step 5: During the shrimp seedling cultivation stage, from December to January or February of the following year, the water depth should be controlled at 100-120cm and the water temperature should be stabilized; in March of the following year, the water level should be lowered to 40cm; (A6) Set up anti-escape nets: Anti-escape nets are set up around the breeding pond. The material is polyethylene plastic film, the bottom is buried 15-20cm in the soil, and the above-ground part is 40-50cm high. The outer side of the anti-escape film uses glass fiber reinforced plastic fiber round tubes as supports, with a spacing of 1.0-1.5m; (A7) Shrimp fry fishing: Shrimp cages are used in mid-March of the following year to catch and market shrimps. After the catch is completed, the pond is cleaned. (A8) Daily management: Patrol the fields once in the morning and once in the evening every day. If any abnormality is found in the crayfish, promptly activate the oxygenation facilities, change the water, or use medication for preventive and control measures.

2. The method for breeding large-sized and high-quality crayfish seedlings in early spring according to claim 1, characterized in that: In step 1, pond selection and cleaning, the water level of cleaning and disinfection is less than 50 cm, every 667m 2 Use 25kg of bleaching powder.

3. The method for breeding large-sized and high-quality crayfish seedlings in early spring according to claim 1, characterized in that: Step 2: Nutritional enhancement cultivation of adult shrimps, the specific components of the black soldier fly protein source fermented feed are: 2-15 parts of black soldier fly larvae, 3-8 parts of fish meal, 15-30 parts of soybean meal, 20-40 parts of flour, 5-15 parts of rapeseed meal, 4-10 parts of peanut meal, 4-10 parts of cottonseed meal, 5-15 parts of rice bran, 0.3-3 parts of soybean oil, 0.5-1.5 parts of soybean lecithin, 1-3 parts of calcium dihydrogen phosphate, 0.1-0.5 parts of 50% choline chloride, 0.05-0.2 parts of vitamin premix, and 0.1-0.5 parts of mineral premix; the addition amount of the composite bacterial agent is 4-8g / kg; Preferably, the black soldier fly protein source fermented feed specifically comprises: 5.4 parts of black soldier fly larvae, 4.8 parts of fish meal, 22 parts of soybean meal, 30.41 parts of flour, 10 parts of rapeseed meal, 6 parts of peanut meal, 6 parts of cottonseed meal, 10 parts of rice bran, 1.74 parts of soybean oil, 1 part of soybean lecithin, 2 parts of monocalcium phosphate, 0.3 parts of 50% choline chloride, 0.1 parts of vitamin premix, and 0.25 parts of mineral premix; the addition amount of the composite bacterial agent is 5 g / kg; Preferably, the composite bacterial agent comprises Bacillus subtilis, Lactobacillus plantarum, and Saccharomyces cerevisiae, and the concentration of live bacteria is respectively Bacillus subtilis ≥ 5.00 × 10 12 U / g, Lactobacillus plantarum ≥1.0×1010 CFU / g, Saccharomyces cerevisiae ≥4.00×10 12 CFU / g; Step 5: shrimp seedling cultivation, the black soldier fly protein source granular feed specifically comprises: 10.00-12.00 parts of fish meal, 2-3 parts of black soldier fly larvae powder, 20-22.00 parts of soybean meal, 8.00-11.00 parts of rapeseed meal, 4.00-6.00 parts of peanut meal, 30-32 parts of flour, 5.00-6.5 parts of cottonseed, 8.00-1.00 parts of rice bran, 2.00-2.50 parts of soybean oil, 1.00-1.50 parts of soybean lecithin, 1.80-2.20 parts of monocalcium phosphate, 0.08-0.12 parts of vitamin premix, 0.20-0.50 parts of mineral premix, and 0.20-0.30 parts of choline chloride; Preferably, the black soldier fly protein source granular feed specifically comprises: 10.5 parts of fish meal, 2.2 parts of black soldier fly larvae powder, 21.00 parts of soybean meal, 9.20 parts of rapeseed meal, 4.80 parts of peanut meal, 31.00 parts of flour, 6.00 parts of cottonseed, 9.20 parts of rice bran, 2.20 parts of soybean oil, 1.30 parts of soybean lecithin, 1.90 parts of monocalcium phosphate, 0.10 parts of vitamin premix, 0.35 parts of mineral premix, and 0.25 parts of choline chloride.

4. The method for breeding large-sized and high-quality crayfish seedlings in early spring according to claim 1, characterized in that: Step 2: The method for preparing the fermented feed of black soldier fly protein source by cultivating the adult shrimp with nutritional enhancement comprises the following steps: Step (1), conveying fish meal, soybean meal, flour, rapeseed meal, peanut meal, cottonseed meal, and rice bran with a moisture content of ≤12% into a mixer; then conveying black soldier fly larvae with a moisture content of 65%-80% into the mixer, mixing and stirring, and then conveying them into a grinder for ultrafine grinding; Step (2), conveying the ultrafinely pulverized material to a mixing and blending machine, adding soybean oil, soybean lecithin, calcium dihydrogen phosphate, choline chloride, vitamin premix, and mineral premix; performing a second mixing and blending to prepare a hard granular compound feed; Step (3), after the hard pellet feed is cooled, it is transferred to a fermentation feed mixer; according to the weight of the pellet feed, the composite bacterial agent is taken into the bacterial liquid sprayer, the fermentation feed mixer is started, and the bacterial liquid is sprayed onto the pellet feed; Step (4), mixing and stirring for 20-40 minutes, conveying by a crawler belt, and packing in fermentation bags by an automatic weighing device; Step (5), fermenting in a constant temperature greenhouse at a temperature of 30°C-35°C for 5-7 days to obtain a black soldier fly protein source fermented feed.

5. The method for breeding large-sized and high-quality crayfish seedlings in early spring according to claim 1, characterized in that: Step 3: Environmental regulation: the water level is gradually lowered. The drought stress period is 20-25 days, and then the normal water level is restored.

6. The method for breeding large-sized and high-quality crayfish seedlings in early spring according to claim 1, characterized in that: Step 4: Parent screening, selecting female shrimp individuals weighing about 35±5g; Preferably, the amount of hemolymph extracted from each female shrimp is 1.0 ml to 1.2 ml; Preferably, individuals with gonadal maturity stage V are selected, and the requirements for hemolymph sex hormone content are as follows: estradiol content 5.8-7.90 ng / gprot, progesterone content 1.30-1.37 ng / gprot, vitellogenin content 0.50-0.60 mmol / L, and gonadotropin-releasing hormone content 42.9-47.8 ng / L.

7. The method for breeding large-sized and high-quality crayfish seedlings in early spring according to claim 1, characterized in that: The feeding method (A2) is that during the adult shrimp nutrition enhancement cultivation stage, granular feed and black soldier fly protein source fermented feed are fed in combination, of which the fermented feed accounts for 12.5%-25%; a feeding platform is set up every 30-40 meters; Preferably, in the feeding method (A2), during the shrimp fry cultivation stage, the proportion of chlorella powder added to the black soldier fly protein source granular feed is 5%.

8. The method for breeding large-sized and high-quality crayfish seedlings in early spring according to claim 1, characterized in that: The (A3) aquatic plant planting has an aquatic plant area of ​​50% to 75%.

9. The method for breeding large-sized and high-quality crayfish seedlings in early spring according to claim 1, characterized in that: The (A4) water quality adjustment, the dissolved oxygen of the aquaculture water is ≥5.22mg / L, the pH range is 7.2~8.6, the ammonia nitrogen content is ≤0.51mg / L and the nitrite nitrogen content is ≤0.05mg / L, the sulfide content is ≤0.10mg / L, and the transparency is 25~32cm.

10. The method for breeding large-sized and high-quality crayfish seedlings in early spring according to claim 1, characterized in that: The (A4) water quality regulation uses three microecological preparations, namely Bacillus subtilis, lactic acid bacteria and Clostridium butyricum, to regulate the aquaculture water quality, wherein the effective live bacteria count of Bacillus subtilis is 100 billion / g, the live bacteria count of lactic acid bacteria is 10 billion / g, and the effective live bacteria count of Clostridium butyricum is 300 million / ml.

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