Method for producing crustaceans, method for improving survival rate of crustaceans, crustacean feed, and agent for improving survival of crustaceans

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

[0001] 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.

[0002] Crustaceans are a taxonomic group of arthropods that includes shrimp, crabs, mysids, and daphnia. Their entire bodies are covered by a hard shell, and most live in water and breathe through gills.

[0003] 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 Spinylocarpus 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. Commonly edible species include snow crab, spider crab, red snow crab, red snow crab, hairy crab, chestnut crab, mitten crab, blue crab, king crab, and red king crab. Other crustaceans are also used for food and are cultivated artificially.

[0004] 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 in the Penaeidae and Primarinidae families lay and release eggs, which hatch as nauplii larvae and then undergo repeated molting to metamorphose into zoea larvae. Other shrimp species hatch as zoea larvae. The zoea 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. Note that shrimp in the Palaemonidae family undergo protoandrogenous sex change, so all large individuals are female. The development of crabs also varies depending on the species, but is generally similar: fertilized eggs hatch and become larvae that float in the sea while repeatedly molting and metamorphosing, then metamorphose into zoea larvae, which go through the megalopa stage and drift to a place suitable for habitation, where they become juvenile crabs and begin a benthic lifestyle.

[0005] Traditionally, edible shrimp have been caught by fishing in accordance with their habitats, but while consumption is increasing year by year, catches are on the 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 on the decline due to increased consumption and overfishing.

[0006] 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 cultivate 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 the method has rarely been commercialized.

[0007] There are various known methods for cultivating and raising shrimp, but the most common method used for cultivating kuruma shrimp is intensive farming, in which artificially produced juvenile shrimp are released into the sea at high densities and raised on large amounts of feed. Patent Document 2 also describes a shrimp farming system, and Patent Document 3 describes a method for cultivating aquacultured shrimp by feeding them a carotenoid-containing feed.

[0008] Here, soy isoflavones will be explained as a matter relating to the present invention.

[0009] Soy isoflavones are a general term for flavonoid compounds with an isoflavone skeleton, found primarily in soybean germ. Soy isoflavones are classified into four types: glycosides (glycosides; covalently bonded to sugars), aglycones (non-glycosides; structures in which the sugar moiety has been removed), acetylated glycosides, and malonylated glycosides. Each type contains three known compounds, for a total of 12 known soy isoflavones. The three glycosides are genistin, daidzin, and glycitin, while their aglycone forms (with the sugar moiety removed) are genistein, daidzein, and glycitein, respectively. The composition and content of each compound vary depending on the type of soybean used and the extraction, purification, and processing methods. Furthermore, as a means for separating specific compounds in soy isoflavones, for example, Patent Document 4 discloses a means for separating highly purified genistein from an isoflavone mixture using a solvent.

[0010] Soy isoflavones have a similar chemical structure to the female hormone estrogen and are also known as phytoestrogens. The aglycone form of soy isoflavones has estrogen-like effects and is believed to be effective in preventing heart disease, menopausal symptoms, osteoporosis, breast cancer, and other conditions.

[0011] 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. JP 2006-254880 JP 2000-167950 JP 2023-166028 JP 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 2004Emilia 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) 229-234Liping 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.

[0012] In shrimp farming, if juvenile shrimp are released at high densities and fed large amounts of food, they cannibalize, the water quality deteriorates, and diseases become more likely to occur and spread, resulting in many of the juvenile shrimp dying before they can fully develop after release. This creates the problem of a low percentage of shrimp that grow to marketable levels compared to the number of shrimp introduced into farming. As mentioned above, even high-density farming of edible crabs is difficult due to their tendency to cannibalize.

[0013] Therefore, an object of the present invention is to improve production efficiency in the breeding and cultivation of crustaceans such as shrimp and crabs.

[0014] As a result of extensive research, the present inventors have newly discovered that by feeding crustaceans crustacean feed containing soy isoflavones, it is possible to keep the number of deaths low and significantly improve survival rates, even when reared at high densities.

[0015] Therefore, the present invention provides a method for improving the survival rate of crustaceans, which includes a step of feeding crustaceans feed containing soybean isoflavones, and a method for producing crustaceans, which includes a similar step.

[0016] When raising and culturing crustaceans, feeding them feed containing soy isoflavones can maintain a high survival rate during the rearing period. In other words, it is possible to reduce the number of deaths of crustaceans introduced into rearing and culturing and increase the number of crustaceans that grow to shipping level, thereby improving production efficiency in rearing and culturing crustaceans.

[0017] The mechanism by which the survival rate of crustaceans can be improved by feeding them crustacean feed containing soy isoflavones is presumed to be as follows: First, feminization is induced when crustaceans ingest soy isoflavones. 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 eliminating slow-growing individuals (small individuals), reducing the number of dead fish and improving survival rates.

[0018] In addition, the present invention has the advantage that, since the number of surviving crustaceans can be maintained, deterioration of water quality due to leftover feed can be suppressed during breeding and aquaculture, and the resulting outbreak and spread of diseases can also be suppressed. Similarly, since the number of dead crustaceans can be reduced, there is also the advantage that deterioration of water quality due to decay of dead individuals and the outbreak and spread of diseases can be suppressed.

[0019] In addition, from the perspective of the entire rearing and cultivation period, the present 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 also allows them to grow into larger individuals or to reach a specified size, such as shipping level, in a shorter period of time.

[0020] According to the present invention, production efficiency in the breeding and cultivation of crustaceans such as shrimps and crabs can be improved.

[0021] <Regarding 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.

[0022] 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 the crustaceans and increase the production efficiency in the breeding and cultivation of crustaceans.

[0023] In the present invention, the soy isoflavone content in the feed is preferably 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 restrictions on the upper limit of the soy isoflavone content, but from the viewpoint 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.

[0024] Soy isoflavones can be widely used and are not particularly limited. For example, ready-made soy isoflavones can be used, or soy isoflavones prepared by extracting, purifying, and processing soybeans or other raw materials using known methods can be used. The means for incorporating soy isoflavones into feed can also be widely used and are not particularly limited. For example, they can be mixed into compound feed, or they can 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 salts, compounds with similar chemical structures or mixtures containing at least one or more of these salts, and soy isoflavone derivatives or mixtures containing at least one or more of these salts, as long as they retain the feminization-inducing or survival rate-improving effect on crustaceans.

[0025] From another perspective, soy isoflavone aglycones should preferably be contained in the feed 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 limitations on the upper limit of the soy isoflavone content, but from the viewpoint 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 below). The content weight can be obtained, for example, by converting the weight of added soy isoflavones into the ratio of the molecular weights of glycosides and aglycones, or by analysis using known test methods. The means for incorporating soy isoflavone aglycones into the feed are the same as those described above.

[0026] From another perspective, the feed may contain genistein at a concentration of preferably 0.002% by weight or more, more preferably 0.02% by weight or more, and most preferably 0.4% by weight or more. The upper limit of the genistein content is not particularly limited, but from the viewpoint 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 may contain daidzein at a concentration of preferably 0.002% by weight or more, more preferably 0.02% by weight or more, and most preferably 0.4% by weight or more. The upper limit of the genistein content is not particularly limited, but from the viewpoint 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.

[0027] The means for incorporating genistein or daidzein into the feed is not particularly limited. For example, genistein or daidzein may be incorporated into the feed by adding soybean isoflavones containing genistein or daidzein to the feed, genistein or daidzein may be added directly to the feed, or soybean isoflavones, genistein, or daidzein may be incorporated into the feed in advance during the production stage of the feed.

[0028] Genistein and daidzein can be widely used from known sources and are not particularly limited. For example, ready-made products may be used, or soy isoflavones containing genistein or daidzein may be used as they are, 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 from beans or processed products thereof using known methods may be used, or those synthesized using known methods. For example, soy isoflavones containing 10% by weight or more of genistein or soy isoflavones containing 10% by weight or more of daidzein have the advantage of being relatively easy to obtain, produce, and prepare, and can effectively improve the survival rate of shrimp.

[0029] In addition, the genistein or daidzein of the present invention broadly includes pharmacologically acceptable salts thereof and derivatives of genistein or daidzein, as long as they retain the effect of inducing feminization or improving survival rate in crustaceans.

[0030] The crustacean feed of the present invention is not limited narrowly by other blends or ingredient compositions, 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).

[0031] For example, the blending and composition of ingredients other than soy isoflavones (or soy isoflavone aglycones, or one or more specific compounds thereof) in the feed may be the same as that of a commonly used formulated feed. The formulated 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.

[0032] <Regarding the Crustacean Survival Rate Improver of the Present Invention> The present invention broadly encompasses (1) a crustacean survival rate improver containing soy isoflavone as an active ingredient, which is ingested by crustaceans at 5 mg / kg (crustacean body weight) or more per day; (2) a shrimp survival rate improver containing soy isoflavone aglycone as an active ingredient, which is ingested by crustaceans at 5 mg / kg (crustacean body weight) or more per day; (3) a crustacean survival rate improver containing genistein as an active ingredient, which is ingested by crustaceans at 0.625 mg / kg (crustacean body weight) or more per day; and (4) a crustacean survival rate improver containing daidzein as an active ingredient, which is ingested by crustaceans at 0.625 mg / kg (crustacean body weight) or more per day.

[0033] The crustacean survival rate enhancer according to the present invention contains soybean isoflavones (or soybean isoflavone aglycones, or one or more specific compounds thereof, such as genistein or daidzein) as an active ingredient. By feeding soybean isoflavones to crustaceans, the survival rate of crustaceans can be improved at breeding and aquaculture sites.

[0034] For example, the amount of compound feed fed 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, more preferably 50 mg / kg or more, and most preferably 1.0 g / kg or more per day. 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.

[0035] From another perspective, the amount of compound feed fed may be set at 5-10% of body weight, and soy isoflavone aglycones may be ingested at preferably 5 mg / kg (crustacean body weight) or more per day, more preferably 50 mg / kg or more, and most preferably 500 mg / kg or more. 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.

[0036] From another perspective, the amount of compound feed fed may be 5-10% of body weight, and genistein intake may be preferably 0.625 mg / kg (crustacean body weight) or more, more preferably 6.25 mg / kg or more, and most preferably 62.5 mg / kg or more per day. From the standpoint of feed efficiency, the genistein intake is preferably 16 g / kg (crustacean body weight) or less per day, more preferably 12 g / kg or less, and most preferably 8.0 g / kg or less. Alternatively, daidzein may be preferably 0.625 mg / kg (crustacean body weight) or more, more preferably 6.25 mg / kg or more, and most preferably 62.5 mg / kg or more per day. From the standpoint of feed efficiency, the genistein intake is preferably 16 g / kg (crustacean body weight) or less per day, more preferably 12 g / kg or less, and most preferably 8.0 g / kg or less.

[0037] The shrimp survival rate improver according to the present invention may contain, as appropriate, excipients, lubricants, binders, disintegrants, solvents, solubilizers, suspending agents, buffers, isotonicity agents, preservatives, antibacterial agents, antioxidants, pH adjusters, dispersants, colorants, antifoaming agents, and the like, depending on the purpose, application, dosage form, and the like.

[0038] Suitable examples of excipients that can be used include lactose, sucrose, D-mannitol, starch, crystalline cellulose, and light anhydrous silicic acid.

[0039] Suitable examples of lubricants that can be used include magnesium stearate, calcium stearate, talc, and colloidal silica.

[0040] Suitable examples of binders that can be used include crystalline cellulose, sucrose, D-mannitol, dextrin, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and polyvinylpyrrolidone.

[0041] Suitable examples of disintegrants that can be used include starch, carboxymethylcellulose, carboxymethylcellulose calcium, croscarmellose sodium, and carboxymethylstarch sodium.

[0042] Suitable examples of the solvent include water for injection, alcohol, propylene glycol, macrogol, sesame oil, and corn oil.

[0043] Suitable examples of the solubilizing agent include polyethylene glycol, propylene glycol, D-mannitol, benzyl benzoate, ethanol, trisaminomethane, cholesterol, triethanolamine, sodium carbonate, and sodium citrate.

[0044] Suitable examples of suspending agents that can be used include surfactants (stearyltriethanolamine, sodium lauryl sulfate, laurylaminopropionic acid, lecithin, benzalkonium chloride, benzethonium chloride, glycerin monostearate, etc.), hydrophilic polymers (polyvinyl alcohol, polyvinylpyrrolidone, sodium carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, etc.), and the like.

[0045] Suitable examples of the buffering agent include buffer solutions such as phosphate, acetate, carbonate, citrate, tartrate, trishydroxymethylaminomethane, and HEPES.

[0046] Suitable examples of the isotonic agent include sodium chloride, glycerin, and D-mannitol.

[0047] 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.

[0048] Suitable examples of antioxidants that can be used include sulfites and ascorbic acid.

[0049] Suitable examples of pH adjusters that can be used 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 hydrogen carbonates 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.

[0050] Suitable examples of dispersants that can be used include sodium carboxymethylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone, polysorbate 80, and the like.

[0051] Suitable examples of colorants include caramel color, gardenia color, anthocyanin color, annatto color, paprika color, safflower color, monascus 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.

[0052] Suitable examples of the antifoaming agent include dimethicone, simethicone, silicone emulsion, sorbitan sesquioleate, and nonionic substances.

[0053] In addition to the above, this preparation 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.

[0054] <Method for improving survival rate of crustaceans according to the present invention> The present invention encompasses all of the methods for improving survival rate of crustaceans, which comprise the step of feeding crustaceans with the feed described above, such as (1) a method for improving survival rate of crustaceans, which comprises the step of feeding crustaceans with feed containing 0.01% by weight or more of soy isoflavones, (2) a method for improving survival rate of crustaceans, which comprises the step of feeding crustaceans with feed containing 0.01% by weight or more of soy isoflavone aglycones, (3) a method for improving survival rate of crustaceans, which comprises the step of feeding crustaceans with feed containing 0.002% by weight or more of genistein, and (4) a method for improving survival rate of crustaceans, which comprises the 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.

[0055] 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 predetermined intake range, the survival rate of crustaceans can be improved.

[0056] In terms of the content in the feed, for example, shrimp feed containing 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 may be fed. In terms of intake amount, for example, crustaceans may be fed 5 mg / kg to 40 g / kg (crustacean body weight), more preferably 50 mg / kg to 30 g / kg, and most preferably 1.0 g / kg to 20 g / kg of soy isoflavones per day.

[0057] From another perspective, in terms of the content in the feed, for example, crustacean feed containing soybean isoflavone aglycones at 0.01 to 40 wt%, more preferably 0.1 to 20 wt%, and most preferably 1.0 to 20 wt% may be ingested. In terms of the intake amount, for example, crustaceans may be ingested with 5 mg / kg to 40 g / kg (shrimp body weight), more preferably 50 mg / kg to 30 g / kg, and most preferably 1.0 g / kg to 20 g / kg of soybean isoflavone aglycones per day.

[0058] From another perspective, in terms of the content in the feed, for example, 0.002 to 16 wt % of genistein may be ingested by feeding Crustaceans a genistein feed containing, for example, 0.002 to 16 wt %, more preferably 0.02 to 12 wt %, and most preferably 0.4 to 8.0 wt %. In terms of the intake amount, for example, 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 may be ingested by feeding Crustaceans a genistein feed containing, for example, 0.002 to 16 wt %, more preferably 0.02 to 12 wt %, and most preferably 0.4 to 8.0 wt % of daidzein. In terms of intake amount, for example, crustaceans may be allowed to ingest daidzein at a dose of 0.625 mg / kg to 16 g / kg (shrimp body weight) per day, more preferably 6.25 mg / kg to 12 g / kg, and most preferably 62.5 mg / kg to 8.0 g / kg.

[0059] There are no particular limitations on the means by which soybean isoflavones etc. are ingested. For example, the crustacean may be fed a feed containing soybean isoflavones etc., or the crustacean may be ingested with soybean isoflavones etc. separately from the feed, or a preparation of soybean isoflavones etc. may be directly ingested by the crustacean.

[0060] The period for the intake of soy isoflavones and the like is not particularly limited, and can be adjusted as appropriate based on the growth rate, for example, by continuously ingesting soy isoflavones and the like during the period when the shrimp or crab are juveniles. For example, after hatching and metamorphosing into larvae, the shrimp or crabs may be ingested soy isoflavones and the like 3 to 7 days a week for 1 to 3 months. Furthermore, for example, the amount to be ingested daily can be given in one dose or in 2 to 3 divided doses.

[0061] In addition to the survival rate and degree of variation in weight in the reared and cultivated population, the proportion of females in the population that has been grown and shipped can also be used as indicators 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.

[0062] <Regarding the Crustacean Production Method (or Crustacean Rearing Method or Crustacean Farming Method) of the Present Invention> The present invention encompasses all of the following methods of producing crustaceans, which include a step of feeding crustaceans with the feed described above, such as (1) a crustacean production method including a step of feeding crustaceans with feed containing 0.01% or more by weight of soy isoflavones, (2) a crustacean production method including a step of feeding crustaceans with feed containing 0.01% or more by weight of soy isoflavone aglycones, (3) a crustacean production method including a step of feeding crustaceans with feed containing 0.002% or more by weight of genistein, and (4) a crustacean production method including a step of feeding crustaceans with feed containing 0.002% or more by weight of 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.

[0063] As described 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 predetermined intake range, the survival rate of Crustaceans can be improved, and production efficiency in the raising and farming of Crustaceans can be improved.

[0064] The content or intake amount of soy isoflavones (or soy isoflavone aglycones, or one or more specific compounds thereof, such as genistein or daidzein), as well as the means, duration, frequency, and timing of intake, are the same as those described above.

[0065] Additionally, the subject of the present invention is not particularly limited as long as it is classified as a crustacean. In the present invention, "crustaceans" includes all arthropods that are covered entirely by a hard shell, live in water, and breathe through gills, such as shrimps, crabs, mysids, and daphnia. "Shrimp" includes all crustaceans that belong to the order Decapoda (Decapoda) other than crabs and hermit crabs, and for example, "edible shrimp" includes shrimps that belong to 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. 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 before they become adults. For convenience, crabs weighing 0.001g to 10g may be referred to as "baby crab" for convenience, but is not limited to this.

[0066] In Example 1, the survival rate of shrimp when juvenile shrimp were fed soybean isoflavones was examined.

[0067] Four hundred vannamei shrimp (PL12) were introduced into a glass aquarium containing 25 L of seawater (salinity 30-35 ppt) and maintained at 12 days after postlarval metamorphosis (PL12). Starting the day after introduction, they were fed a diet containing 10% soy isoflavone per day, and maintained in a static water environment for 38 days (50 days after postlarval metamorphosis). The water temperature was maintained at 28°C, and 40% of the water was changed daily. Subsequently, 75 L of seawater (salinity 30-35 ppt) was added to a larger aquarium, and a Tot Perfect Filter III-M (Bio Lab Tot Co., Ltd.) was installed. The shrimp were then transferred to a larger aquarium and maintained in a recirculating water system at 28°C, with the same feeding regime, for another 12 days.

[0068] The soy isoflavone mixed feed was prepared 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 contents of both genistein and daidzein in the soy isoflavone-added feed were approximately 1.6% by weight, when the weight of the feed before the addition of soy isoflavones was taken as 100%.

[0069] As a control, the same number of juvenile shrimp were fed with a normal compound feed without soy isoflavones and reared for the same period under the same conditions.

[0070] As a result, 50 days after the start of feeding (62 days after postlarva metamorphosis), the number of surviving juvenile shrimp (control) raised on normal compound feed was 125, with a survival rate of 31.3%, whereas 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.

[0071] Furthermore, the amount of feed given per feeding during the period in which the shrimp were fed the compound feed supplemented with soy isoflavones 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 taken in per individual per feeding in this experiment was approximately 4g / kg body weight, and the amount of genistein and daidzein taken in per individual per feeding was both approximately 1.6g / kg body weight.

[0072] In Example 2, the mechanism by which the survival rate in Example 1 was significantly improved was investigated.

[0073] 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 aquaria. 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 of soy isoflavone per day (a regular formulated feed was used in the control aquaria). The rearing conditions were the same as in Example 1.

[0074] Thirty-eight days after the start of feeding (50 days after postlarva metamorphosis), 20 fish were randomly selected from each tank and weighed individually.

[0075] As a result, 38 days after the start of feeding (50 days after postlarva metamorphosis), the average weight of the juvenile shrimp (control) raised on a normal compound feed was 0.069g with a standard deviation of 0.067g, while the average weight of the juvenile shrimp raised on a mixed feed supplemented with soy isoflavones was 0.050g with a standard deviation of 0.033g.

[0076] Thus, when juvenile shrimp were raised on a mixed feed supplemented with soy isoflavones, the average weight was significantly lower than when they were raised on a regular formula feed, but the variation in weight was also greatly reduced, from 0.067g to 0.033g. These results indicate that when shrimp are raised on a formula feed supplemented with soy isoflavones, although the growth rate is temporarily suppressed slightly, the variation in growth rate is reduced and the size becomes relatively uniform.

[0077] Based on the results of this experiment, it is estimated that raising juvenile shrimp on a mixed feed 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.

[0078] In Example 3, following Example 2, the ratio of males to females in the case of raising fish fed soy isoflavone was investigated to investigate the mechanism by which the survival rate was significantly improved in Example 1.

[0079] 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 thereinto. From the day after introduction, the shrimp were reared in a still water environment while being fed a soybean isoflavone-mixed diet (a compound feed in which 4% by weight of soybean isoflavone powder had been spread (externally added)) 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 thereto and further reared in a circulating environment while being similarly fed.

[0080] On days 110 (PL110), 204 (PL204), and 207 (PL207) after postlarva metamorphosis, individuals that had grown to a size that allowed for sex identification were picked up and sexed. Sex identification 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.

[0081] As a result, the juvenile shrimp (control) raised on a normal compound feed were 55% male and 45% female (n=60), whereas the juvenile shrimp raised on a mixed feed supplemented with soy isoflavones were 42% male and 58% female (n=43).

[0082] 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 a balance of both males and females compared to when they were raised on a standard compound diet. Meanwhile, it is known that in crustaceans, there are differences between males and females in feeding behavior, with males being 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 vary more in size and growth rate than females.

[0083] Based on these results, one mechanism of action suggested is that when juvenile shrimp are raised on a mixed feed containing added soy isoflavones, the proportion of females increases, which in turn suppresses excessive competition for food and reduces the variation in size and growth rate among individuals. This suppresses food monopolization by fast-growing individuals (large individuals) and the attack and exclusion of slow-growing individuals (small individuals), thereby significantly improving the survival rate of juvenile shrimp.

[0084] 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, there is also the advantage that increasing the proportion of females can improve crustacean productivity.

Claims

1. A method for producing crustaceans, comprising the step of feeding crustaceans feed containing soy isoflavones.

2. A method for producing crustaceans, comprising the step of feeding crustaceans feed containing soy isoflavone aglycones.

3. The method for producing crustaceans according to claim 1, wherein soy isoflavones containing genistein or daidzein are contained.

4. The method for producing crustaceans according to claim 1, which comprises a step of feeding the crustaceans feed containing 0.01% by weight or more of soy isoflavones.

5. 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.

6. The method for producing crustaceans according to claim 1, wherein the crustaceans are shrimp of the Penaeidae family.

7. A method for improving the survival rate of crustaceans, comprising the step of feeding crustaceans feed containing soy isoflavones.

8. Crustacean feed containing 0.01% or more by weight of soy isoflavones.

9. A crustacean survival rate enhancer containing soy isoflavone as an active ingredient, which is to be ingested by crustaceans at a dose of 5 mg / kg (crustacean body weight) or more per day.

10. A crustacean survival rate enhancer containing genistein or daidzein as an active ingredient, which is to be ingested by crustaceans at a dose of 0.625 mg / kg (crustacean body weight) or more per day.