WO2026005040A1 - Method for producing crustaceans, method for improving survival rate of crustaceans, crustacean feed, and agent for improving survival of crustaceans - Google Patents

Abstract

[Problem] To improve production efficiency in the breeding and farming of crustaceans.　[Solution] Provided are a method for improving the survival rate of crustaceans, a method for producing crustaceans, etc., in which a soybean-isoflavone-containing crustacean feed is fed to crustaceans. In the breeding and farming of crustaceans, a high survival rate during the breeding period can be maintained by feeding a soybean-isoflavone-containing crustacean feed to the crustaceans. Specifically, the number of deaths of crustaceans introduced into breeding and farming can be reduced, and, for example, the number of crustaceans that grow to a level suitable for shipping can be increased; therefore, the production efficiency in the breeding and farming of crustaceans can be improved.

Description

Crustacean production method, crustacean survival rate improvement method, crustacean feed, and crustacean survival rate improver

The present invention relates to a method for producing crustaceans, which includes a step of feeding crustaceans feed containing soy isoflavones, a method for improving the survival rate of crustaceans, feed for crustaceans, and an agent for improving the survival rate of crustaceans.

Crustaceans are a taxonomic group of arthropods, including shrimp, crabs, mysids, and daphnia. Their entire bodies are covered by a hard shell, and most live in water and breathe through gills.

Shrimp is a general term for crustaceans in the Decapoda order (order Decapoda) other than crabs and hermit crabs. Approximately 3,000 species are known, of which shrimps belonging to the families Penaeidae, Primateae, Palaemonidae, and Palaemonidae are widely edible. Crabs are a general term for crustaceans in the Decapoda order (infraorder Brachyura), but red king crabs and coconut crabs in the Decapoda order (infraorder Anomura), are also considered crabs. Widely edible species include snow crab, spider crab, red snow crab, and red snow crab from the spider crab family, hairy crab and chestnut crab from the Clethridae family, mitten crab from the Grass Crabs family, blue crab from the Portunidae family, and red king crab and flower crab from the Palaemonidae family. Other crustaceans are also used for food and some are cultivated artificially.

Among crustaceans, shrimp generally hatch from fertilized eggs, which then undergo repeated molting and metamorphosis as larvae, and then continue molting to grow into adults. For example, shrimp of the Penaeidae and Primarinidae families lay and release eggs, which hatch as nauplii larvae and metamorphose into zoeal larvae through repeated molting. Other shrimp species hatch as zoeal larvae. The zoeal larvae molt repeatedly during their planktonic life to become mysis larvae, which then molt again to metamorphose into postlarvae, which are almost identical in form to adults. The postlarva is the final metamorphosis, and the shrimp grow into adults through further molting. Females of Penaeidae and Primarinidae shrimp are larger than males. Shrimp of the Palaemonidae family, for example, undergo protoandrogenous sex change, so all large individuals are female. Crabs also develop in a similar way, although it differs depending on the species: fertilized eggs hatch and become larvae that float in the ocean, undergoing repeated molting and metamorphosis before transforming into zoea larvae, which pass through the megalopa stage and drift to a suitable habitat, where they become juvenile crabs and begin a benthic lifestyle.

Edible shrimp have traditionally been caught through fishing in accordance with their habitats, but while consumption is increasing year by year, catches are in decline in many cases due to landfilling and pollution of the shallow coastal waters where shrimp live. Edible crab catches are also becoming unstable and declining due to increased consumption and overfishing.

For this reason, in recent years, attempts have been made to produce edible shrimp through aquaculture, and for some species, aquaculture is becoming the primary method of production. For example, kuruma prawns have been successfully cultivated and managed in land-based ponds from artificial hatching to adulthood, and other species of the Penaeidae family are also cultivated around the world. Some attempts have also been made to produce crabs through aquaculture, but because most crabs are cannibalistic (see Patent Document 1, Non-Patent Documents 1 and 2), high-density rearing is difficult, and so it has rarely been commercialized.

There are various known methods for farming and raising shrimp, but the most common farming method used for kuruma shrimp farming is intensive farming, in which artificially produced juvenile shrimp are released at high densities and raised on large amounts of food. Furthermore, Patent Document 2 describes a farming system for shrimp farming, and Patent Document 3 describes a method for raising aquaculture shrimp by feeding them feed containing carotenoids.

Here, soy isoflavones will be explained as a topic related to this invention.

Soy isoflavones is a general term for flavonoid compounds with an isoflavone skeleton that are found primarily in soybean germ. Soy isoflavones are classified into four types: glycosides (glycosides; structures covalently bonded to sugars), aglycones (non-glycosides; structures in which the sugar moiety of glycosides has been removed), acetylated glycosides, and malonylated glycosides. Each type contains three known compounds, for a total of 12 known soy isoflavones. Of these, the three glycosides are genistin, daidzin, and glycitin, while their aglycone forms (those in which the sugar moiety has been removed) are genistein, daidzein, and glycitein, respectively. The composition and content of each compound vary depending on the type of soybean used, as well as the extraction, purification, and processing methods. Furthermore, as a means of separating specific compounds in soy isoflavones, for example, Patent Document 4 discloses a method for separating highly purified genistein from an isoflavone mixture using a solvent.

Soy isoflavones have a similar chemical structure to the female hormone estrogen and are also known as phytoestrogens. Furthermore, soy isoflavones in the aglycone form have estrogen-like effects and are believed to be effective in preventing heart disease, menopausal symptoms, osteoporosis, breast cancer, and other conditions.

Patent Document 5 discloses a method for inducing feminization in eels by feeding them soy isoflavones, etc. In addition, Non-Patent Document 3 describes that when carp were fed 0, 25, 50, 100, 500, and 1000 mg of genistein per kg of feed, growth was significantly improved at 100 mg and 500 mg, and improvements in body composition and lipid metabolism and enhanced immunity were also observed, and Non-Patent Document 4 describes that when golden pompano were fed 0, 10, 20, 40, 60, and 80 mg of soy isoflavones per kg of feed, growth was significantly improved at 40 mg, and enhanced antioxidant capacity and immunity were also observed. Patent document 5 describes that when swamp eels were fed 40% soy isoflavones at 2.5g/kg feed, they showed a decrease in growth rate and an increase in blood alkaline phosphatase (liver abnormalities, etc.), and non-patent document 6 describes that when rainbow trout were fed genistein at 0.3% of the dry matter feed, feed intake decreased but protein utilization improved, resulting in a growth rate at the same level as the control group, but overall it was determined that adding genistein at 0.3% did not have any beneficial effect on the growth of rainbow trout.
Japanese Patent Application Laid-Open No. 2006-254880 Japanese Patent Application Laid-Open No. 2000-167950 Japanese Patent Publication No. 2023-166028 Japanese Patent Application Publication No. 7-173148 Patent No. 6970992 “Mud crab aquaculture in Australia and Southeast Asia” Proceedings of the ACIAR Crab Aquaculture Scoping Study and Workshop 28-29 April 2003, Joondooburri Conference Centre, Bribie Island, edited by Geoff Allan and Don Fielder, January 2004 Emilia T. Quinitio, Fe Dolores P. Estepa “Survival and growth of Mud crab, Scylla serrata, juveniles subjected to removal or trimming of chelipeds” Aquaculture Volume 318 (2011) 229-234 Liping Yang, et al “Evaluation of dietary genistein on the antioxidant capacity, non-specific immune status, and fatty acid composition of common carp (Cyprinus carpio .L)” Aquaculture Volume 550, 15 March 2022, 737822. Chuanpeng Zhou, et al “The Effects of dietary soybean isoflavones on growth, innate immune responses, hepatic antioxidant abilities and disease resistance of juvenile golden pompano Trachinotus ovatus” Fish & Shellfish Immunology Volume 43, Issue 1, March 2015, Pages 158-166. Yajun Hu, et al “Effects of dietary soy isoflavone and soy saponin on growth performance, intestinal structure, intestinal immunity and gut microbiota community on rice field eel (Monopterus albus)” Aquaculture Volume 537, 15 May 2021, 736506. C. Torno, et al “Effects of resveratrol and genistein on growth, nutrient utilization and fatty acid composition of rainbow trout” Animal Volume 13, Issue 5, 2019, Pages 933-940

In the farming of edible shrimp, if juvenile shrimp are released into the sea at high densities and fed large amounts of food, they can easily cannibalize, deteriorate water quality, and become susceptible to the outbreak and spread of disease. As a result, many of the juvenile shrimp die before they have fully grown after release. This poses the issue of a low percentage of shrimp that grow to a shipping level compared to the number introduced into farming. As mentioned above, edible crabs are prone to cannibalism, making even high-density farming difficult.

The present invention aims to improve production efficiency in the breeding and farming of crustaceans such as shrimp and crabs.

After extensive research, the inventors have newly discovered that by feeding crustaceans crustacean feed containing soy isoflavones, it is possible to keep mortality low and significantly improve survival rates, even when reared at high densities.

The present invention therefore provides a method for improving the survival rate of crustaceans, which includes the step of feeding crustaceans feed containing soy isoflavones, as well as a method for producing crustaceans, which includes a similar step.

When raising and culturing crustaceans, feeding them feed containing soy isoflavones can maintain a high survival rate during the rearing period. This means that the mortality rate of crustaceans introduced into rearing and culturing can be reduced and the number of crustaceans that grow to shipping level can be increased, thereby improving production efficiency in rearing and culturing crustaceans.

The mechanism by which the survival rate of crustaceans can be improved by feeding them crustacean feed containing soy isoflavones is hypothesized to be as follows: First, when crustaceans ingest soy isoflavones, feminization is induced. Although feminization of crustaceans temporarily suppresses their growth rate slightly compared to males, it reduces variation in growth rate and makes each individual relatively uniform in size. This prevents fast-growing individuals (large individuals) from monopolizing food and from attacking and excluding slow-growing individuals (small individuals), reducing the number of deaths and improving survival rates.

In addition, because the present invention can maintain the number of surviving crustaceans, it has the advantage of being able to prevent deterioration of water quality due to leftover feed during breeding and aquaculture, and also of being able to prevent the occurrence and spread of disease that results from this. Similarly, because it can reduce the number of dead crustaceans, it has the advantage of being able to prevent deterioration of water quality due to decay from dead individuals, and the occurrence and spread of disease.

In addition, from the perspective of the entire breeding and cultivation period, this invention has the following advantages: (1) the ingestion of soy isoflavones feminizes crustaceans, increasing their resistance to disease and stress and enabling them to grow better; and (2) the feminization process also allows them to grow into larger individuals, or to reach a specified size, such as shipping level, in a shorter period of time.

This invention can improve production efficiency in the breeding and farming of crustaceans such as shrimp and crabs.

<About the Crustacean Feed of the Present Invention>
The present invention broadly encompasses crustacean feed containing 0.01% by weight or more of soybean isoflavones, crustacean feed containing 0.01% by weight or more of soybean isoflavone aglycones, crustacean feed containing 0.002% by weight or more of genistein, and crustacean feed containing 0.002% by weight or more of daidzein.

By adding soy isoflavones (or soy isoflavone aglycones, or one or more specific compounds thereof, such as genistein or daidzein) to crustacean feed and feeding the feed to crustaceans for a certain period of time, it is possible to improve the survival rate of crustaceans and increase production efficiency in the raising and farming of crustaceans.

In the present invention, the feed should preferably contain 0.01% by weight or more of soy isoflavones, more preferably 0.1% by weight or more, and most preferably 1.0% by weight or more. There are no particular upper limits on the soy isoflavone content, but from the standpoint of feed efficiency, 40% by weight or less is preferred, 30% by weight or less is more preferred, and 20% by weight or less is most preferred.

A wide variety of known soy isoflavones can be used, and there are no particular limitations. For example, ready-made soy isoflavones may be used, or soy isoflavones prepared by extracting, purifying, and processing raw materials such as soybeans using known methods may be used. The means for incorporating soy isoflavones into feed is also wide-ranging, and there are no particular limitations. For example, they may be mixed into compound feed, or they may be spread (externally distributed) in compound feed. In addition, the soy isoflavones (or soy isoflavone aglycones) of the present invention broadly encompass pharmacologically acceptable salts or mixtures containing at least one or more of these, compounds with similar chemical structures or mixtures containing at least one or more of these, and soy isoflavone derivatives or mixtures containing at least one or more of these, as long as they retain the effect of inducing feminization or improving survival rates in crustaceans.

From another perspective, the feed should preferably contain soy isoflavone aglycones at 0.01% by weight or more, more preferably 0.1% by weight or more, and most preferably 1.0% by weight or more. There are no particular upper limits on the soy isoflavone content, but from the standpoint of feed efficiency, 40% by weight or less is preferred, 30% by weight or less is more preferred, and 20% by weight or less is most preferred. Note that "soy isoflavone aglycones" refers to the non-sugar portion of soy isoflavones (the same applies hereinafter), and the content weight can be obtained, for example, by converting the weight of added soy isoflavones into the ratio of the molecular weights of the glycosides and aglycones, or by analysis using known test methods. The means for incorporating soy isoflavone aglycones into feed are the same as those described above.

From another perspective, the feed should preferably contain 0.002% by weight or more of genistein, more preferably 0.02% by weight or more, and most preferably 0.4% by weight or more. There are no particular restrictions on the upper limit of the genistein content, but from the perspective of feed efficiency, it is preferably 16% by weight or less, more preferably 12% by weight or less, and most preferably 8.0% by weight or less. Alternatively, the feed should preferably contain 0.002% by weight or more, more preferably 0.02% by weight or more, and most preferably 0.4% by weight or more. There are no particular restrictions on the upper limit of the genistein content, but from the perspective of feed efficiency, it is preferably 16% by weight or less, more preferably 12% by weight or less, and most preferably 8.0% by weight or less.

There are no particular limitations on the means by which genistein or daidzein can be incorporated into feed. For example, genistein or daidzein can be incorporated into feed by adding soy isoflavones containing genistein or daidzein to the feed, genistein or daidzein can be added directly to the feed, or soy isoflavones, genistein, or daidzein can be incorporated into the feed in advance during the feed production stage.

Genistein and daidzein can be a wide variety of known genistein and daidzein and are not particularly limited. For example, ready-made products may be used, or soy isoflavones containing genistein or daidzein may be used as is, or those isolated or highly purified by extraction, purification, or processing from soy isoflavones using known methods may be used, or those obtained by separation, extraction, fermentation, or the like using known methods from beans or processed beans, or those synthesized using known methods. For example, soy isoflavones containing 10% or more genistein by weight, or soy isoflavones containing 10% or more daidzein by weight, have the advantage of being relatively easy to obtain, manufacture, and prepare, and can effectively improve the survival rate of shrimp.

In addition, the genistein or daidzein of the present invention broadly encompasses its pharmacologically acceptable salts and derivatives of genistein or daidzein, as long as they retain their feminization-inducing or survival rate-improving effects on crustaceans.

The crustacean feed of the present invention is not limited to any particular formulation or ingredient composition, as long as it contains at least soy isoflavones (or soy isoflavone aglycones, or one or more specific compounds thereof, such as genistein or daidzein).

For example, the composition and ingredients of the feed other than soy isoflavones (or soy isoflavone aglycones, or one or more specific compounds thereof) may be the same as those of commonly used compound feed. Compound feed is a mixture of nutrients for growth in appropriate proportions, and may contain, for example, fish meal, soybean meal, corn, wheat flour, rice bran, wheat germ, fish oil, amino acids, carotenoids, vitamins, minerals, etc.

<About the Crustacean survival rate improver according to the present invention>
The present invention broadly encompasses (1) a crustacean survival rate enhancer containing soy isoflavone as an active ingredient, which is administered to crustaceans at a daily intake of 5 mg/kg (crustacean body weight) or more, (2) a shrimp survival rate enhancer containing soy isoflavone aglycone as an active ingredient, which is administered to crustaceans at a daily intake of 5 mg/kg (crustacean body weight) or more, (3) a crustacean survival rate enhancer containing genistein as an active ingredient, which is administered to crustaceans at a daily intake of 0.625 mg/kg (crustacean body weight) or more, and (4) a crustacean survival rate enhancer containing daidzein as an active ingredient, which is administered to crustaceans at a daily intake of 0.625 mg/kg (crustacean body weight) or more.

The crustacean survival rate enhancer of the present invention contains soy isoflavones (or soy isoflavone aglycones, or one or more specific compounds thereof, such as genistein or daidzein) as an active ingredient. By feeding soy isoflavones to crustaceans, the survival rate of crustaceans can be improved in breeding and aquaculture facilities.

For example, the amount of compound feed given may be 5-10% of body weight, and soy isoflavones may be ingested at a level of preferably 5 mg/kg (crustacean body weight) or more per day, more preferably 50 mg/kg or more, and most preferably 1.0 g/kg or more. Furthermore, from the standpoint of feed efficiency, the amount of soy isoflavone intake is preferably 40 g/kg (crustacean body weight) or less per day, more preferably 30 g/kg or less, and most preferably 20 g/kg or less.

From another perspective, the amount of compound feed provided may be 5-10% of body weight, and soy isoflavone aglycones may be ingested at a daily dose of preferably 5 mg/kg (crustacean body weight) or more, more preferably 50 mg/kg or more, and most preferably 500 mg/kg or more. Furthermore, from the standpoint of feed efficiency, the daily intake of soy isoflavones is preferably 40 g/kg (crustacean body weight) or less, more preferably 30 g/kg or less, and most preferably 20 g/kg or less.

From another perspective, the amount of compound feed fed may be 5-10% of body weight, and genistein intake may be preferably at least 0.625 mg/kg (crustacean body weight) per day, more preferably at least 6.25 mg/kg, and most preferably at least 62.5 mg/kg. From the standpoint of feed efficiency and other factors, the genistein intake is preferably at most 16 g/kg (crustacean body weight) per day, more preferably at most 12 g/kg, and most preferably at most 8.0 g/kg. Alternatively, daidzein may be preferably at least 0.625 mg/kg (crustacean body weight) per day, more preferably at least 6.25 mg/kg, and most preferably at least 62.5 mg/kg. From the standpoint of feed efficiency and other factors, the genistein intake is preferably at most 16 g/kg (crustacean body weight) per day, more preferably at most 12 g/kg, and most preferably at most 8.0 g/kg.

The shrimp survival rate improver of the present invention may contain excipients, lubricants, binders, disintegrants, solvents, solubilizers, suspending agents, buffers, isotonicity agents, preservatives, antibacterial agents, antioxidants, pH adjusters, dispersants, colorants, antifoaming agents, etc., as appropriate, depending on the purpose, application, dosage form, etc.

Suitable examples of excipients include lactose, sucrose, D-mannitol, starch, crystalline cellulose, and light anhydrous silicic acid.

Suitable examples of lubricants include magnesium stearate, calcium stearate, talc, and colloidal silica.

Suitable examples of binders include crystalline cellulose, sucrose, D-mannitol, dextrin, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and polyvinylpyrrolidone.

Suitable examples of disintegrants include starch, carboxymethylcellulose, carboxymethylcellulose calcium, croscarmellose sodium, and carboxymethylstarch sodium.

Suitable examples of solvents include water for injection, alcohol, propylene glycol, macrogol, sesame oil, and corn oil.

Suitable examples of solubilizing agents include polyethylene glycol, propylene glycol, D-mannitol, benzyl benzoate, ethanol, trisaminomethane, cholesterol, triethanolamine, sodium carbonate, and sodium citrate.

Suitable examples of suspending agents include surfactants (stearyl triethanolamine, sodium lauryl sulfate, lauryl aminopropionic acid, lecithin, benzalkonium chloride, benzethonium chloride, glycerin monostearate, etc.), hydrophilic polymers (polyvinyl alcohol, polyvinylpyrrolidone, sodium carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, etc.), etc.

Suitable examples of buffering agents include buffer solutions such as phosphate, acetate, carbonate, citrate, tartrate, trishydroxymethylaminomethane, and HEPES.

Suitable examples of isotonic agents include sodium chloride, glycerin, and D-mannitol.

Suitable examples of agents for preservative purposes include thimerosal, parahydroxybenzoic acid esters, phenoxyethanol, chlorobutanol, benzyl alcohol, phenethyl alcohol, dehydroacetic acid, sorbic acid, and various other preservatives, antibiotics, and synthetic antibacterial agents.

Suitable examples of antioxidants include sulfites and ascorbic acid.

Suitable examples of pH adjusters include acids such as hydrochloric acid, carbonic acid, acetic acid, citric acid, phosphoric acid, boric acid, and sulfuric acid; alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, calcium hydroxide, and magnesium hydroxide; alkali metal carbonates or bicarbonates such as sodium carbonate; alkali metal acetates such as sodium acetate; alkali metal citrates such as sodium citrate; bases such as trometamol; monoethanolamine; and diisopropanolamine.

Suitable examples of dispersing agents include sodium carboxymethylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone, polysorbate 80, etc.

Suitable examples of colorants include caramel color, gardenia color, anthocyanin color, annatto color, paprika color, safflower color, red koji color, carotene color, carotenoid color, flavonoid color, cochineal color, amaranth (Red No. 2), erythrosine (Red No. 3), Allura Red AC (Red No. 40), New Coccine (Red No. 102), Phloxine (Red No. 104), Rose Bengal (Red No. 105), Acid Red (Red No. 106), tartrazine (Yellow No. 4), Sunset Yellow FCF (Yellow No. 5), Fast Green FCF (Green No. 3), Brilliant Blue FCF (Blue No. 1), indigo carmine (Blue No. 2), copper chlorophyll, and sodium copper chlorophyllin.

Suitable examples of anti-foaming agents include dimethicone, simethicone, silicone emulsion, sorbitan sesquioleate, and nonionic substances.

In addition to the above, this product may contain auxiliary ingredients, such as light-absorbing pigments (riboflavin, adenine, adenosine, etc.) that aid in preservation and efficacy, chelating agents and reducing agents (vitamin C, citric acid, etc.) for stabilization, carbohydrates (sorbitol, lactose, mannitol, starch, sucrose, glucose, dextran, etc.), casein digests, various vitamins, lactic acid bacteria, butyric acid bacteria, digestive enzymes, dried vegetables, etc. as appropriate.

<Method for improving the survival rate of crustaceans according to the present invention>
The present invention encompasses all methods for improving the survival rate of crustaceans, which include a step of feeding the above-mentioned feed to crustaceans, such as (1) a method for improving the survival rate of crustaceans, which includes a step of feeding crustaceans with feed containing 0.01% by weight or more of soy isoflavones, (2) a method for improving the survival rate of crustaceans, which includes a step of feeding crustaceans with feed containing 0.01% by weight or more of soy isoflavone aglycones, (3) a method for improving the survival rate of crustaceans, which includes a step of feeding crustaceans with feed containing 0.002% by weight or more of genistein, and (4) a method for improving the survival rate of crustaceans, which includes a step of feeding crustaceans with feed containing 0.002% by weight or more of daidzein. In addition, from the viewpoint of intake amount, for example, (5) a method for improving the survival rate of crustaceans, which comprises a step of having crustaceans ingest 5 mg/kg (of crustacean body weight) or more of soy isoflavones, (6) a method for improving the survival rate of crustaceans, which comprises a step of having crustaceans ingest 5 mg/kg (of crustacean body weight) or more of soy isoflavone aglycones, (7) a method for improving the survival rate of crustaceans, which comprises a step of having crustaceans ingest 0.625 mg/kg (of crustacean body weight) or more of genistein, and (8) a method for improving the survival rate of crustaceans, which comprises a step of having crustaceans ingest 0.625 mg/kg (of crustacean body weight) or more of daidzein, etc. are all included.

For example, by feeding crustaceans crustacean feed containing the above-mentioned proportions of soy isoflavones (or soy isoflavone aglycones, or one or more specific compounds thereof, such as genistein or daidzein), or from another perspective, by feeding crustaceans soy isoflavones (or soy isoflavone aglycones, or one or more specific compounds thereof, such as genistein or daidzein) within a specified intake range, the survival rate of crustaceans can be improved.

In terms of the content in the feed, shrimp may be fed feed containing, for example, 0.01 to 40% by weight, more preferably 0.1 to 20% by weight, and most preferably 1.0 to 20% by weight of soy isoflavones. In terms of intake amount, for example, crustaceans may be fed soy isoflavones at a rate of 5 mg/kg to 40 g/kg (crustacean body weight) per day, more preferably 50 mg/kg to 30 g/kg, and most preferably 1.0 g/kg to 20 g/kg.

From another perspective, in terms of the content in the feed, for example, crustacean feed containing soy isoflavone aglycones at 0.01 to 40% by weight, more preferably 0.1 to 20% by weight, and most preferably 1.0 to 20% by weight may be fed. In terms of intake amount, for example, crustaceans may be fed soy isoflavone aglycones at 5 mg/kg to 40 g/kg (shrimp body weight) per day, more preferably 50 mg/kg to 30 g/kg, and most preferably 1.0 g/kg to 20 g/kg.

From another perspective, in terms of the content in the feed, for example, crustacean feed containing 0.002 to 16% by weight, more preferably 0.02 to 12% by weight, and most preferably 0.4 to 8.0% by weight of genistein may be administered. In terms of the intake amount, for example, crustaceans may be administered 0.625 mg/kg to 16 g/kg (shrimp body weight), more preferably 6.25 mg/kg to 12 g/kg, and most preferably 62.5 mg/kg to 8.0 g/kg of genistein per day. Alternatively, for example, crustacean feed containing 0.002 to 16% by weight, more preferably 0.02 to 12% by weight, and most preferably 0.4 to 8.0% by weight of daidzein may be administered. In terms of intake amount, for example, crustaceans may be fed daidzein at a daily intake of 0.625 mg/kg to 16 g/kg (shrimp body weight), more preferably 6.25 mg/kg to 12 g/kg, and most preferably 62.5 mg/kg to 8.0 g/kg.

There are no particular limitations on the means by which soy isoflavones and the like are ingested. For example, this can be done by feeding the crustaceans feed containing soy isoflavones and the like, or the crustaceans can be ingested with soy isoflavones and the like separately from feed, or a preparation containing soy isoflavones and the like can be directly ingested by the crustaceans.

The period for the intake of soy isoflavones, etc., is not particularly limited; for example, they may be given soy isoflavones, etc. continuously during the period when they are juvenile shrimp or crabs, or this can be adjusted as appropriate based on their growth rate. For example, after they hatch and metamorphose into larvae, they may be given soy isoflavones, etc., 3 to 7 days a week for 1 to 3 months. Furthermore, for example, the amount to be consumed per day may be given all at once, or divided into 2 to 3 doses.

In addition to the survival rate and degree of weight variation in the bred and cultivated population, the proportion of females in the bred and shipped population can also be used as an indicator of whether the present invention has been applied. As mentioned above, when crustaceans are fed soy isoflavones, etc., they are feminized, so if the proportion of male individuals is significantly lower than female individuals, such an event is outside the scope of known technology and would not occur unless the present invention is used, so the fact that such an event actually occurs supports the use of the present invention.

<About the Crustacean Production Method (or Crustacean Rearing Method or Crustacean Farming Method) of the Present Invention>
The present invention encompasses all methods for producing crustaceans, including a step of feeding crustaceans the above-mentioned feed, such as (1) a method for producing crustaceans, including a step of feeding crustaceans with feed containing 0.01% by weight or more soybean isoflavones, (2) a method for producing crustaceans, including a step of feeding crustaceans with feed containing 0.01% by weight or more soybean isoflavone aglycones, (3) a method for producing crustaceans, including a step of feeding crustaceans with feed containing 0.002% by weight or more genistein, and (4) a method for producing crustaceans, including a step of feeding crustaceans with feed containing 0.002% by weight or more daidzein. In addition, from the viewpoint of intake amount, for example, (5) a method for producing crustaceans including a step of having crustaceans ingest 5 mg/kg (of crustacean body weight) or more of soy isoflavones, (6) a method for producing crustaceans including a step of having crustaceans ingest 5 mg/kg (of crustacean body weight) or more of soy isoflavone aglycones, (7) a method for producing crustaceans including a step of having crustaceans ingest 0.625 mg/kg (of crustacean body weight) or more of genistein, and (8) a method for producing crustaceans including a step of having crustaceans ingest 0.625 mg/kg (of crustacean body weight) or more of genistein are all included.

As mentioned above, for example, by feeding crustaceans feed containing the above-mentioned proportions of soy isoflavones (or soy isoflavone aglycones, or one or more specific compounds thereof, such as genistein or daidzein), or from another perspective, by feeding them soy isoflavones (or soy isoflavone aglycones, or one or more specific compounds thereof, such as genistein or daidzein) within a specified intake range, it is possible to improve the survival rate of crustaceans and increase production efficiency in the raising and farming of crustaceans.

The content or intake amount of soy isoflavones (or soy isoflavone aglycones, or one or more specific compounds therein, such as genistein or daidzein), as well as the means, duration, frequency, and timing of intake, are the same as above.

The subject of this invention is not particularly limited as long as it is classified as a crustacean. In this invention, "crustacean" includes all arthropods that are covered entirely by a hard shell, live in water, and breathe through gills, such as shrimp, crabs, mysids, and daphnia. "Shrimp" includes all crustaceans in the order Decapoda (Decapoda) other than crabs and hermit crabs, such as "edible shrimp" that include shrimps of the families Penaeidae, Primarinidae, Palaemonidae, and Spinylocarpus. "Crabs" encompass all crustaceans belonging to the infraorder Brachyura (infraorder Crabs) of the order Decapoda, and all crustaceans belonging to the infraorder Anomura (infraorder Hermit Crabs). For example, "edible crabs" include snow crab, spider crab, red snow crab, hairy crab, chestnut crab, mitten crab, blue crab, swimming crab, blue crab, king crab, and red king crab. The term "juvenile shrimp" encompasses shrimp from the hatched larvae to the adult stage. For example, shrimp from the postlarvae stage to the adult stage at aquaculture sites may be referred to as "juvenile shrimp," but is not limited thereto. Size also varies depending on the species, but for example, in the case of shrimp of the Primate family, shrimp weighing 0.001g to 10g may be referred to as "baby shrimp" for convenience, but is not limited to this. Similarly, "baby crab" refers to crabs from the larvae after hatching to the stage before they become adults. For convenience, crabs weighing 0.001g to 10g may be referred to as "baby crab", but is not limited to this.

In Example 1, the survival rate of juvenile shrimp was examined when they were given soy isoflavones.

25 L of seawater (salinity 30-35 ppt) was placed in a glass aquarium, and 400 vannamei shrimp 12 days after postlarva metamorphosis (PL12) were introduced. Starting the day after introduction, they were fed a diet containing 10% of their body weight in soy isoflavones per day and reared in a static water environment for 38 days (50 days after postlarva metamorphosis). During the experiment, the water temperature was set at 28°C, and 40% of the water was replaced once daily. Next, 75 L of seawater (salinity 30-35 ppt) was placed in a larger aquarium, and a Tot Perfect Filter III-M (filtration device, Bio Lab Tot Co., Ltd.) was installed. The juvenile shrimp were then transferred to this tank and reared in a circulating water system at 28°C while being fed in the same way for another 12 days.

The soy isoflavone mixed feed was made by spreading (adding externally) 4% by weight of soy isoflavone powder onto regular shrimp feed. The soy isoflavones used contained 40.88% by weight of genistein and 40.94% by weight of daidzein, so the genistein and daidzein contents of the soy isoflavone-added feed were both approximately 1.6% by weight, when the weight of the feed before the addition of soy isoflavones was taken as 100%.

As a control, the same number of juvenile shrimp were fed regular formulated feed without added soy isoflavones and raised for the same period and under the same conditions.

As a result, 50 days after the start of feeding (62 days after postlarva metamorphosis), the number of surviving juvenile shrimp (control) raised on regular compound feed was 125, with a survival rate of 31.3%, while the number of surviving juvenile shrimp raised on mixed feed supplemented with soy isoflavones was 235, with a survival rate of 58.8%, a significant improvement in survival rate.

Furthermore, during the period when the shrimp were fed the compound feed supplemented with soy isoflavones, the amount of feed given per feeding was 10% by weight of the shrimp's body weight, and the amount of soy isoflavones added to the compound feed was 4% by weight. Based on this, the amount of soy isoflavones ingested per individual in this experiment was approximately 4g/kg of body weight, and the amount of genistein and daidzein ingested per individual per feeding was approximately 1.6g/kg of body weight.

In Example 2, we investigated the mechanism by which survival rates were significantly improved in Example 1.

As in Example 1, 25 L of seawater (salinity 30-35 ppt) was placed in each of two glass aquaria, and 400 vannamei shrimp on the 12th day after postlarva metamorphosis (PL12) were introduced into each tank. Starting the day after introduction, the shrimp were reared in a still water environment for 38 days (50 days after postlarva metamorphosis) while being fed a diet containing 10% of their body weight in soy isoflavones per day (regular compound feed was used in the control tank). Rearing conditions were the same as in Example 1.

38 days after the start of feeding (50 days after postlarva metamorphosis), 20 fish were randomly selected from each tank and individually weighed.

As a result, 38 days after the start of feeding (50 days after postlarva metamorphosis), the average weight of juvenile shrimp (control) raised on a regular compound feed was 0.069g with a standard deviation of 0.067g, while the average weight of juvenile shrimp raised on a mixed feed supplemented with soy isoflavones was 0.050g with a standard deviation of 0.033g.

As such, when juvenile shrimp were raised on a mixed feed supplemented with soy isoflavones, their average weight was significantly lower than when they were raised on a regular compound feed, but the variation in weight was also significantly reduced, from 0.067g to 0.033g. These results indicate that when shrimp are raised on a compound feed supplemented with soy isoflavones, although their growth rate is temporarily suppressed slightly, the variation in growth rate is reduced and their size becomes relatively uniform.

Based on the results of this experiment, it is estimated that raising juvenile shrimp on a mixed diet supplemented with soy isoflavones can reduce variation in growth rates, thereby preventing fast-growing individuals (large individuals) from monopolizing food and attacking and excluding slow-growing individuals (small individuals), thereby significantly improving the survival rate of juvenile shrimp.

In Example 3, following on from Example 2, the ratio of males to females in fish raised with soy isoflavones was examined to investigate the mechanism by which survival rates were significantly improved in Example 1.

As in Example 1, 25 L of seawater (salinity 30-35 ppt) was placed in a glass aquarium, and vannamei shrimp on the 12th day after postlarva metamorphosis (PL12) were introduced. From the day after introduction, the shrimp were raised in still water while being fed a soy isoflavone-mixed diet (4% by weight of soy isoflavone powder spread (externally added) to a compound feed) at a rate of 10% of their body weight per day. Subsequently, 75 L of seawater (salinity 30-35 ppt) was placed in a larger aquarium, and the juvenile shrimp were transferred there and further raised in a circulating system while being fed the same amount of food.

On days 110 (PL110), 204 (PL204), and 207 (PL207) after postlarva metamorphosis, individuals that had grown to a size where they could be distinguished were picked up in order and sexed. Sexing was performed by visually inspecting the protrusion of the male's first swimming leg or by observing the genital pores of both sexes under a stereomicroscope. On day 207 (PL207) after postlarva metamorphosis, all individuals could be sexed.

The results showed that 55% of the juvenile shrimp (control) raised on a regular compound feed were male and 45% were female (n=60), while 42% of the juvenile shrimp raised on a mixed feed supplemented with soy isoflavones were male and 58% were female (n=43).

The results of this experiment showed that when juvenile shrimp were raised on a mixed diet supplemented with soy isoflavones, the proportion of females increased while maintaining the presence of both males and females compared to when they were raised on a regular compound feed. Meanwhile, in crustaceans, there are differences between males and females in feeding behavior, with males being known to be more competitive in obtaining food. This is consistent with the findings of the inventors from observations in various experiments, which show that males tend to have greater variation in size and growth rate compared to females.

Based on these results and others, one mechanism of action suggested is that when juvenile shrimp are raised on a mixed feed supplemented with soy isoflavones, the proportion of females increases, which in turn suppresses excessive competition for food and reduces variation in size and growth rate among individuals. This suppresses food monopolization by fast-growing individuals (large individuals) and attacks and exclusion of slow-growing individuals (small individuals), thereby significantly improving the survival rate of juvenile shrimp.

In addition, it is generally known that females of crustaceans are larger and grow faster than males, and these results suggest that in addition to the effect of improving survival rates mentioned above, an increase in the proportion of females also has the advantage of improving crustacean productivity.

Claims (10)

A method for producing crustaceans, comprising the step of feeding crustaceans feed containing soy isoflavones. A method for producing crustaceans, comprising the step of feeding crustaceans feed containing soy isoflavone aglycones. The method for producing crustaceans according to claim 1, wherein soy isoflavones containing genistein or daidzein are contained. The method for producing crustaceans according to claim 1, which includes a step of feeding the animals feed containing at least 0.01% by weight of soy isoflavones. The method for producing crustaceans according to claim 3, wherein the genistein or daidzein is contained in an amount of 0.002% by weight or more. The method for producing crustaceans according to claim 1, wherein the crustaceans are shrimp of the Penaeidae family. A method for improving the survival rate of crustaceans, comprising the step of feeding crustaceans feed containing soy isoflavones. Crustacean feed containing 0.01% or more by weight of soy isoflavones. A survival rate enhancer for crustaceans containing soy isoflavones as the active ingredient, which should be ingested at a dose of 5mg/kg (crustacean body weight) or more per day. A survival rate enhancer for crustaceans containing genistein or daidzein as the active ingredient, with a daily intake of 0.625 mg/kg (crustacean body weight) or more.