Eel feed utilizing microalgae of the genus Schizochytrium and method for producing the same

Abstract

This invention relates to an eel feed composition containing biomass derived from microalgae of the genus Schizochytrium, and a method for cultivating eels using the same. When eels are fed the eel feed composition containing biomass derived from microalgae of the genus Schizochytrium of this invention, the growth of the eels is promoted, and therefore it can be usefully utilized as an eel feed composition or feed additive.

Description

Technical Field

[0001] Mutual citation with related applications This disclosure claims the benefit of priority based on Korean Patent Application No. 10-2023-0086717 filed on July 4, 2023, and all the contents disclosed in the documents of the Korean Patent Application are included as part of this disclosure.

[0002] Throughout this disclosure, numerous papers and patent documents are referenced and their citations are indicated. The disclosed contents of the cited papers and patent documents are incorporated herein by reference in their entirety to better explain the level of the technical field to which the present invention pertains and the content of the present invention.

[0003] This application relates to a feed composition for eels utilizing microalgae of the genus Schizochytrium and a method for producing the same.

Background Art

[0004] Due to the global population increase and the stagnation and continuous decline of cereal and fishery production, concerns about future food security continue, and many scientists estimate that the aquaculture industry has the only potential to solve such food problems. The world aquaculture fish production started at 2.4 million tons half a century ago and reached 87.5 million tons in 2020, with farmed fish accounting for 49% of the total aquatic product production. Among these farmed fish, the feed intake of marine fish and crustaceans has been growing rapidly (FAO 2022), and such an increasing trend is expected to continue. Currently, the field of fish feed nutrients is one of the important keys to the success of the aquaculture industry. It is a well-known fact that if important fish species that can be preferentially cultured in the aquaculture industry are selected and seedling production technology is developed, feeding management with high-quality feed must be promoted. Especially considering that the feed cost accounts for 30 - 60% of the unit aquaculture production cost depending on the fish species, the importance of feed nutrition can be understood.

[0005] Feed utilization rates differ depending on the protein source. Fishmeal, made by drying and powdering the fish meal and fish fragments remaining after extracting fish oil from fish, has long been used as the main protein source in aquaculture feed due to its high protein content, excellent amino acid composition, and high palatability. However, recently, its production has declined sharply, leading to unstable supply and soaring prices, which now account for the largest portion of feed source purchase costs. The catch volume of various small fish that produce fishmeal has decreased rapidly due to overfishing and marine environmental problems, and it is predicted that production will continue to decline until 2030. For these reasons, much research is being conducted to find inexpensive and high-quality alternative protein sources that can replace fishmeal in compound feed for aquaculture. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Korean Published Patent Publication No. 10-2011-0026232 [Overview of the project] [Problems that the invention aims to solve]

[0007] The inventors diligently researched and worked to develop fish farming feed utilizing microalgae. As a result, they completed the present invention by demonstrating that a feed composition containing biomass derived from the genus Schizochytrium sp. microalgae promotes eel growth.

[0008] Therefore, the object of this application is to provide an eel feed composition containing biomass derived from microalgae of the genus Schizochytrium sp.

[0009] Another object of this application is to provide a method for farming eels and / or a method for promoting eel growth, which includes the step of feeding eels with an eel feed composition containing the aforementioned Schizochytrium microalgae-derived biomass. [Means for solving the problem]

[0010] According to one aspect of this application, the application provides an eel feed composition comprising biomass derived from microalgae of the genus Schizochytrium sp.; and / or the use of the said microalgae-derived biomass and / or the said eel feed composition for promoting eel growth.

[0011] Microalgae of the genus Schizochytrium sp. In this specification, the term "microalgae" refers to organisms of the plant species that are not easily visible to the naked eye but can be seen with a microscope, and that float freely in water; they are also called phytoplankton. Microalgae encompass a diverse range of species, including strains that are incapable of photosynthesis and grow solely on heterotrophic means. In this specification, the term "microalgae" may be used interchangeably with "strain."

[0012] In this specification, the term "Schizochytrium sp." refers to one of the genus names belonging to the family Thraustochytriaceae in the order Thraustochytriales, and can be used interchangeably with the term "genus Schizochytrium."

[0013] In this specification, the microalgae of the genus Schizochytrium is a microorganism belonging to the family Thraustochytriaceae, and may be one or more species selected from the group consisting of Schizochytrium aggregatum, Schizochytrium limacinum, and Schizochytrium minutum.

[0014] For example, the aforementioned microalga of the genus Schizochytrium may be Schizochytrium limacinaum.

[0015] For example, the aforementioned microalga of the genus Schizochytrium may be Schizochytrium agregatum.

[0016] For example, the aforementioned microalga of the genus Schizochytrium may be Schizochytrium minutum.

[0017] In one embodiment of the present invention, the aforementioned Schizochytrium strain may be, but is not limited to, the CD03-7004 strain (deposit number KCTC15006BP).

[0018] The inventors irradiated wild-type Schizochytrium strain CD01-5000 (deposit number KCTC 14344BP) with gamma rays to induce mutations, selected a strain capable of producing antioxidant pigments from among the mutant strains, named it Schizochytrium sp. CD03-7004, and deposited it with the Korean Collection for Type Cultures (KCTC), an international depositary organization under the Budapest Convention, on June 20, 2022, receiving accession number KCTC15006BP.

[0019] Biomass derived from microalgae of the genus Schizochytrium sp. In this specification, the term “biomass” refers to living organisms such as plants, animals, and microorganisms that can be used as chemical energy, i.e., energy sources of bioenergy, and may also refer to the weight or energy amount of specific living organisms present in a unit of time and space ecologically. Furthermore, the biomass includes, but is not limited to, compounds secreted by cells, and may include not only extracellular material but also cellular and / or intracellular contents.

[0020] In this specification, the microalgae-derived biomass can include the microalgae themselves, their cultures, their fermented products, their dried products, their crushed products, or products produced by culturing or fermenting the microalgae, or can include a concentrate or dried product of the biomass, but is not limited thereto. In one embodiment, the microalgae-derived biomass may include one or more selected from the group consisting of microalgae, cultures of the microalgae, dried products of the cultures, and crushed products of the dried products. Drying can be performed by, but is not limited to, spray drying, hot air drying, freeze drying, natural drying, and vacuum drying.

[0021] The "culture" of the microalgae refers to a product produced by culturing the microalgae, and specifically may be a culture solution containing microalgae or a culture filtrate from which microalgae have been removed from the culture solution, but is not necessarily limited thereto. The "dried product" of the microalgae culture is one from which moisture has been removed from the microalgae culture, and may be, for example, the dried cell form of the microalgae, but is not necessarily limited thereto. Further, the "crushed product" of the dried product is a general term for the result of crushing the dried product from which moisture has been removed from the microalgae culture, and may be, for example, dried cell powder, but is not necessarily limited thereto. The culture of the microalgae can be produced by inoculating the microalgae into a microalgae culture medium and using a culture method known in the art, and the dried product of the culture and its crushed product can also be produced by a method for treating or drying microalgae or a culture solution known in the art.

[0022] In one embodiment, the aforementioned microalgae-derived biomass can contain 40% to 95% by weight of protein (crude protein), more specifically 40% to 95% by weight, 40% to 90% by weight, 40% to 85% by weight, 40% to 82.5% by weight, 40% to 81.5% by weight, 40% to 80.5% by weight, 50% to 95% by weight, 50% to 90% by weight, 50% to 85% by weight, and 50% to 82% by weight. .5wt%, 50wt%~81.5wt%, 50wt%~80.5wt%, 60wt%~95wt%, 60wt%~90wt%, 60wt%~85wt%, 60wt%~82. 5wt%, 60wt%~81.5wt%, 60wt%~80.5wt%, 70wt%~95wt%, 70wt%~90wt%, 70wt%~85wt%, 70wt%~82.5 Weight%, 70% to 81.5% by weight, 70% to 80.5% by weight, 75% to 95% by weight, 75% to 90% by weight, 75% to 85% by weight, 75% to 82.5% by weight Amount%, 75% to 81.5% by weight, 75% to 80.5% by weight, 77.5% to 95% by weight, 77.5% to 90% by weight, 77.5% to 85% by weight, 77.5% by weight It may include, but is not limited to, percentages of 82.5% by weight, 77.5% by weight to 81.5% by weight, 77.5% by weight to 80.5% by weight, 79.5% by weight to 95% by weight, 79.5% by weight to 90% by weight, 79.5% by weight to 85% by weight, 79.5% by weight to 82.5% by weight, 79.5% by weight to 81.5% by weight, or 79.5% by weight to 80.5% by weight.

[0023] In one embodiment, the aforementioned biomass derived from microalgae can contain 3 wt% to 30 wt% of fat (crude lipids), more specifically, it can contain 3 wt% to 30 wt%, 3 wt% to 20 wt%, 3 wt% to 15 wt%, 3 wt% to 13 wt%, 3 wt% to 12 wt%, 6 wt% to 30 wt%, 6 wt% to 20 wt%, 6 wt% to 15 wt%, 6 wt% to 16 wt%, 6 wt% to 12 wt%, 9 wt% to 30 wt%, 9 wt% to 20 wt%, 9 wt% to 15 wt%, 9 wt% to 16 wt%, 9 wt% to 12 wt%, 10 wt% to 30 wt%, 10 wt% to 20 wt%, 10 wt% to 15 wt%, 10 wt% to 16 wt%, 10 wt% to 12 wt%, 11 wt% to 30 wt%, 11 wt% to 20 wt%, 11 wt% to 15 wt%, 11 wt% to 16 wt%, or 11 wt% to 12 wt%, but is not limited thereto.

[0024] In one embodiment, the aforementioned biomass derived from microalgae can contain 0.05 wt% to 5 wt% of moisture, more specifically, it can contain 0.05 wt% to 5 wt%, 0.05 wt% to 3 wt%, 0.05 wt% to 1.75 wt%, 0.05 wt% to 1.5 wt%, 0.05 wt% to 1 wt%, 0.05 wt% to 0.7 wt%, 0.1 wt% to 5 wt%, 0.1 wt% to 3 wt%, 0.1 wt% to 1.75 wt%, 0.1 wt% to 1.5 wt%, 0.1 wt% to 1 wt%, 0.1 wt% to 0.7 wt%, 0.5 wt% to 5 wt%, 0.5 wt% to 3 wt%, 0.5 wt% to 1.75 wt%, 0.5 wt% to 1.5 wt%, 0.5 wt% to 1 wt%, 0.5 wt% to 0.7 wt%, 0.6 wt% to 5 wt%, 0.6 wt% to 3 wt%, 0.6 wt% to 1.75 wt%, 0.6 wt% to 1.5 wt%, 0.6 wt% to 1 wt%, 0.6 wt% to 0.7 wt%, but is not limited thereto.

[0025] In this specification, ash content may mean the ash produced by burning a sample or the total amount of inorganic substances contained in the sample. Ash content may be used interchangeably with terms such as minerals, inorganic substances, inorganic salts, and mineral substances, and may include one or more inorganic elements selected from the group consisting of calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium, iron, copper, manganese, iodine, cobalt, zinc, molybdenum, selenium, chromium, fluorocarbon, boron, arsenic, tin, silicon, vanadium, and nickel.

[0026] In one embodiment, the aforementioned microalgae-derived biomass may contain ash in an amount of 2.5% to 20% by weight, more specifically, 2.5% to 20% by weight, 2.5% to 15% by weight, 2.5% to 13.5% by weight, 2.5% to 12.5% ​​by weight, 2.5% to 10% by weight, 2.5% to 8% by weight, 2.5% to 7.5% by weight, 5% to 20% by weight, 5% to It may, but is not limited to, contain 15% by weight, 5% to 13.5% by weight, 5% to 12.5% ​​by weight, 5% to 10% by weight, 5% to 8% by weight, 5% to 7.5% by weight, 7% to 20% by weight, 7% to 15% by weight, 7% to 13.5% by weight, 7% to 12.5% ​​by weight, 7% to 10% by weight, 7% to 8% by weight, or 7% to 7.5% by weight.

[0027] In one embodiment, the aforementioned microalgae-derived biomass may contain 30 to 70 parts by weight of glutamic acid based on 100 parts by weight of total amino acids, more specifically, 30 to 70 parts by weight, 30 to 60 parts by weight, 30 to 57 parts by weight, 30 to 54 parts by weight, 45 to 70 parts by weight, 45 to 60 parts by weight, 45 to 57 parts by weight, 45 to 54 parts by weight, 50 to 70 parts by weight, 50 to 60 parts by weight, 50 to 57 parts by weight, 50 to 54 parts by weight, 53 to 70 parts by weight, 53 to 60 parts by weight, 53 to 57 parts by weight, or 53 to 54 parts by weight, but is not limited thereto.

[0028] In one embodiment, the aforementioned microalgae-derived biomass may contain arginine in amounts of 7 to 25 parts by weight, based on 100 parts by weight of total amino acids. More specifically, it may contain arginine in amounts of 7 to 25 parts by weight, 7 to 20 parts by weight, 7 to 15 parts by weight, 7 to 13 parts by weight, 10 to 25 parts by weight, 10 to 20 parts by weight, 10 to 15 parts by weight, 10 to 13 parts by weight, 12 to 25 parts by weight, 12 to 20 parts by weight, 12 to 15 parts by weight, or 12 to 13 parts by weight, but is not limited thereto.

[0029] In one embodiment, the aforementioned microalgae-derived biomass may contain 20 to 50 parts by weight of palmitic acid based on 100 parts by weight of total fatty acids, more specifically, 20 to 50 parts by weight, 20 to 40 parts by weight, 20 to 37 parts by weight, 30 to 50 parts by weight, 30 to 40 parts by weight, 30 to 37 parts by weight, 36 to 50 parts by weight, 36 to 40 parts by weight, or 36 to 37 parts by weight, but is not limited thereto.

[0030] In this specification, the term “palmitic acid” refers to CH3(CH2) 14 It is one of the saturated fatty acids with the chemical formula COOH, also known as hexadecanoic acid, and can be abbreviated as C16:0.

[0031] In one embodiment, the aforementioned microalgae-derived biomass may contain 30 to 60 parts by weight of docosahexaenoic acid ((4Z,7Z,10Z,13Z,16Z,19Z)-Docosa-4,7,10,13,16,19-hexaenoic acid, DHA) based on 100 parts by weight of total fatty acids. More specifically, it may contain 30 to 60 parts by weight, 30 to 50 parts by weight, 30 to 46 parts by weight, 40 to 60 parts by weight, 40 to 50 parts by weight, 40 to 46 parts by weight, 45 to 60 parts by weight, 45 to 50 parts by weight, or 45 to 46 parts by weight, but is not limited to these amounts.

[0032] In this specification, the term “docosahexaenoic acid ((4Z,7Z,10Z,13Z,16Z,19Z)-Docosa-4,7,10,13,16,19-hexaenoic acid, DHA)” is C 22 H 32 Docosahexaenoic acid (Docosahexaenoic acid) is one of the polyunsaturated fatty acids with the chemical formula O2. Along with alpha-linolenic acid (ALA) and eicosapentaenoic acid (EPA), it is classified as an omega-3 fatty acid. Its common name is cervonic acid, and it can also be abbreviated as C22:6n3. Docosahexaenoic acid cannot be produced in fish and must be obtained through their diet. It is known as an essential fatty acid that plays a crucial role in the metabolism and cellular function of fish.

[0033] Feed composition In this specification, the term “feed composition” may mean a substance that is nutritious to animals (including unicellular or multicellular heterotrophic organisms such as zooplankton, livestock, and fish) or necessary for maintaining their health or growth. The feed composition may be a single-ingredient feed, a compound feed, or a supplementary feed. The single-ingredient feed may mean a plant, animal, or mineral substance that is used directly as feed or as an ingredient in a compound feed. The supplementary feed may mean a substance added to feed to prevent deterioration of feed quality or to enhance the effectiveness of feed. The compound feed may be a mixture or processed product of single-ingredient feeds, supplementary feeds, etc., in appropriate proportions.

[0034] The feed composition may mean a substance that supplies organic or inorganic nutrients necessary for sustaining the life of an animal or for producing meat, milk, etc. The feed composition may additionally contain nutrients necessary for sustaining the life of an animal or for producing meat, milk, etc. The feed composition can be manufactured as a variety of feed forms known in the industry, and may specifically include concentrated feed, roughage and / or specialty feed. Alternatively, the feed composition can be manufactured in the form of compound feed (extruded pellet, EP feed, dry feed) or raw feed (moist pellet, MP feed, wet feed), paste feed, etc.

[0035] In this specification, feed additives may include substances added to feed for a variety of purposes, such as supplementing nutrients and preventing weight loss, improving the digestibility of fiber in the feed, improving milk quality, preventing reproductive disorders and improving conception rates, and preventing summer heat stress. The feed additives may mean supplemental feeds under the Feed Management Act, and may additionally include mineral preparations such as sodium bicarbonate, bentonite, magnesium oxide, and complex minerals; mineral preparations such as trace minerals such as zinc, copper, cobalt, and selenium; vitamin preparations such as carotene, vitamin E, vitamins A, D, and E, nicotinic acid, and vitamin B complexes; protective amino acid preparations such as methionine and lysine; protective fatty acid preparations such as calcium fatty acid salts; probiotics (lactic acid bacteria), probiotics such as yeast cultures and mold fermentations, and yeast preparations.

[0036] In this specification, the term “feed composition” can be interpreted to encompass the meaning of “feed additives.”

[0037] The feed composition may further include grains, such as ground or crushed wheat, oats, barley, corn, and rice; plant protein feeds, such as feeds mainly composed of beans and sunflowers; animal protein feeds, such as fish meal, blood meal, meat meal, and / or bone meal; sugars and dairy products, such as dried components consisting of various milk powders and whey powders, and may also further include nutritional supplements, digestive and absorption enhancers, growth promoters, and so on.

[0038] The feed composition may be administered to animals alone or in combination with other feed additives in an edible carrier. The feed composition can also be readily administered to animals as a top dressing, mixed directly into the feed, or in an oral dosage form separate from the feed. When the composition is administered separately from the feed, it can be prepared in an immediate-release or sustained-release dosage form in combination with an edible carrier acceptable in the feed field, as is well known in the art. The edible carrier may be solid or liquid, such as corn starch, lactose, sucrose, bean flakes, peanut oil, olive oil, sesame oil, and propylene glycol. When a solid carrier is used, the feed composition may be in the form of tablets, capsules, powders, lozenges, sugar-containing tablets, or an undispersed top dressing. When a liquid carrier is used, the feed composition may be in the form of gelatin soft capsules, or a syrup, suspension, emulsion, or solution.

[0039] The feed composition may include, for example, preservatives, stabilizers, wetting agents or emulsifiers, cryoprotectants, or excipients. The cryoprotectant may be one or more selected from the group consisting of glycerol, trehalose, maltodextrin, skim milk powder, and starch. The preservative, stabilizer, or excipient may be included in the composition in an effective amount sufficient to reduce the deterioration of microalgae contained in the feed composition. Furthermore, the cryoprotectant may be included in the composition in an effective amount sufficient to reduce the deterioration of microalgae contained in the composition when the composition is in a dry state.

[0040] The feed composition can be used by immersion, spraying, or mixing and adding it to animal feed.

[0041] The feed composition can be applied to the diets of a wide range of animals, including but not limited to mammals, birds, fish, crustaceans, cephalopods, reptiles, and amphibians. For example, the mammals may include pigs, cattle, sheep, goats, laboratory rodents, or pets; the birds may include poultry, and the poultry may include but not limited to chickens, turkeys, ducks, geese, pheasants, or quail; the crustaceans may include but not limited to shrimp, barnacles, etc. The feed composition can also be applied to the diets of zooplankton, such as rotifers, artemia, and daphnia pulex. The fish may include freshwater fish, saltwater fish, commercially farmed fish and their juveniles, and ornamental fish.

[0042] Eel feed composition One example of this application is the provision of an eel feed composition containing biomass derived from the aforementioned microalgae of the genus Schizochytrium sp.

[0043] The aforementioned Schizochytrium sp. microalgae, the biomass derived from the microalgae, and the feed composition are as described above.

[0044] In this specification, the term “eel” means fish belonging to the genus Anguilla of the family Anguillidae, and can be used interchangeably with “freshwater eel” or “Japanese eel.” In one embodiment, the eel may be one or more species selected from the group consisting of Japanese eel (Anguilla japonica), giant eel (Anguilla marmorata), European eel (Anguilla anguilla), American eel (Anguilla rostrata), and bicolor eel (Anguilla bicolor), and more specifically, Japanese eel (Anguilla japonica), but is not limited thereto.

[0045] As demonstrated in the examples described below, the aforementioned feed composition containing microalgae biomass can promote eel growth.

[0046] In one embodiment, the eel feed composition of this application can contain the aforementioned microalgae-derived biomass in an amount of 2.25% to 45% by weight, more specifically, 2.25% to 45% by weight, 2.25% to 30% by weight, 2.25% to 25% by weight, 2.25% to 22.5% by weight, 2.25% to 20% by weight, 2.25% to 17.5% by weight, 2.25% to 15% by weight, 2.25% to 13.3% by weight, 2.25% to 12% by weight, 2.25% to 10% by weight, 2.25% to 8% by weight, 2.25% to 7.5% by weight, and 2.25% to 8% by weight. 7% by weight, 2.25% to 6.6% by weight, 2.25% to 6.5% by weight, 2.25% to 6% by weight, 2.25% to 5% by weight, 2.25% to 4% by weight, 2.25% to 3.3% by weight, 3% to 45% by weight, 3% to 30% by weight, 3% to 25% by weight, 3 wt%~22.5wt%, 3wt%~20wt%, 3wt%~17.5wt%, 3wt%~15wt%, 3wt%~13.3wt%, 3wt%~12wt%, 3wt%~10wt%, 3wt%~8wt%, 3wt%~7.5wt%, 3wt%~7wt%, 3wt%~6.6wt %, 3% to 6.5%, 3% to 6%, 3% to 5%, 3% to 4%, 3% to 3.3%, 4% to 45%, 4% to 30%, 4% to 25%, 4% to 22.5%, 4% to 20%, 4% to 17.5% Amount%, 4% to 15% by weight, 4% to 13.3% by weight, 4% to 12% by weight, 4% to 10% by weight, 4% to 8% by weight, 4% to 7.5% by weight, 4% to 7% by weight, 4% to 6.6% by weight, 4% to 6.5% by weight, 4% to 6% by weight, 4% to 5% by weight , 5% to 45% by weight, 5% to 30% by weight, 5% to 25% by weight, 5% to 22.5% by weight, 5% to 20% by weight, 5% to 17.5% by weight, 5% to 15% by weight, 5% to 13.3% by weight, 5% to 12% by weight, 5% to 10% by weight, 5% to 8% by weight Amount%, 5% to 7.5%, 5% to 7%, 5% to 6.6%, 5% to 6.5%, 5% to 6%, 6% to 45%, 6% to 30%, 6% to 25%, 6% to 22.5%, 6% to 20%, 6% to 17.5% by weight, 6% to 15% by weight, 6% to 13.3% by weight, 6% to 12% by weight, 6% to 10% by weight, 6% to 8% by weight, 6% to 7.5% by weight, 6% to 7% by weight, 6% to 6.6% by weight, 6% to 6.5% by weight, 6.5% to 45% by weight, 6.5% to 30% by weight, 6.5% to 25% by weight, 6.5% to 22.5% by weight, 6.5% to 20% by weight, 6.5% to 17.5% by weight, 6.5% to 15% by weight, 6.5% to 13.3% by weight, 6.5% to 12% by weight, 6.5% to 10% by weight 6.5%~8% by weight, 6.5%~7.5% by weight, 6.5%~7% by weight, 6.5%~6.6% by weight, 6.6%~45% by weight, 6.6%~30% by weight, 6.6%~25% by weight, 6.6%~22.5% by weight, 6.6%~20% by weight, 6.6%~17.5% by weight, 6.6%~15% by weight, 6.6%~13.3% by weight, 6.6%~12% by weight, 6.6%~10% by weight, 6.6%~8% by weight, 6.6%~7.5% by weight, 6.6%~7% by weight, 7%~45% by weight, 7% by weight ~30 wt%, 7 wt%~25 wt%, 7 wt%~22.5 wt%, 7 wt%~20 wt%, 7 wt%~17.5 wt%, 7 wt%~15 wt%, 7 wt%~13.3 wt%, 7 wt%~12 wt%, 7 wt%~10 wt%, 7 wt%~8 wt%, 7 wt%~7.5 wt%, 7.5 wt%~45 wt%, 7.5 wt%~30 wt%, 7.5 wt%~25 wt%, 7.5 wt%~22.5 wt%, 7.5 wt%~20 wt%, 7.5 wt%~17.5 wt%, 7.5 wt%~15 wt%, 7.5 wt%~13.3 wt%, 7.5 wt%~12 % by weight, 7.5%~10% by weight, 7.5%~8% by weight, 8%~45% by weight, 8%~30% by weight, 8%~25% by weight, 8%~22.5% by weight, 8%~20% by weight, 8%~17.5% by weight, 8%~15% by weight, 8%~13.3% by weight, 8%~12% by weight, 8%~10% by weight, 10%~45% by weight, 10%~30% by weight, 10%~25% by weight, 10%~22.5% by weight, 10%~20% by weight, 10%~17.5% by weight, 10%~15% by weight, 10%~13% by weight.3wt%, 10wt%~12wt%, 12wt%~45wt%, 12wt%~30wt%, 12wt%~25wt%, 12wt%~22.5wt%, 12wt%~20wt%, 12wt%~17.5wt%, 12wt%~15wt%, 12wt%~ 13.3% by weight, 13.3% to 45% by weight, 13.3% to 30% by weight, 13.3% to 25% by weight, 13.3% to 22.5% by weight, 13.3% to 20% by weight, 13.3% to 17.5% by weight, 13.3% to 15% by weight, 15 It may include, but is not limited to, values ​​of % to 45% by weight, 15% to 30% by weight, 15% to 25% by weight, 15% to 22.5% by weight, 15% to 20% by weight, 15% to 17.5% by weight, 17.5% to 45% by weight, 17.5% to 30% by weight, 17.5% to 25% by weight, 17.5% to 22.5% by weight, 17.5% to 20% by weight, 20% to 45% by weight, 20% to 30% by weight, 20% to 25% by weight, or 20% to 22.5% by weight.

[0047] In one embodiment, the eel feed composition may contain 21 to 30 parts by weight of palmitic acid based on 100 parts by weight of total fatty acids, more specifically, 21 to 30 parts by weight, 21 to 25 parts by weight, 21 to 23.75 parts by weight, 21 to 22.5 parts by weight, 21 to 21.25 parts by weight, 21.25 to 30 parts by weight, 21.25 to 25 parts by weight, 21.25 to 23.75 parts by weight, 21.25 to 22.5 parts by weight, 22.5 to 30 parts by weight, 22.5 to 25 parts by weight, 22.5 to 23.75 parts by weight, 23.75 to 30 parts by weight, 23.75 to 25 parts by weight, and 25 to 30 parts by weight.

[0048] In one embodiment, the content of palmitic acid in the eel feed composition may increase as the content of microalgae-derived biomass in the eel feed composition increases.

[0049] In one embodiment, the eel feed composition is based on 100 parts by weight of total fatty acids, and contains docosahexaenoic acid ((4Z,7Z,10Z,13Z,16Z,19Z)-Docosa-4,7,10,13,16,19-hexaenoic acid The product may contain 15 to 27 parts by weight of acid (DHA), more specifically, 15 to 27 parts by weight, 15 to 23 parts by weight, 15 to 20.25 parts by weight, 15 to 18 parts by weight, 15 to 16.25 parts by weight, 16.25 to 27 parts by weight, 16.25 to 23 parts by weight, 16.25 to 20.25 parts by weight, 16.25 to 18 parts by weight, 18 to 27 parts by weight, 18 to 23 parts by weight, 18 to 20.25 parts by weight, 20.25 to 27 parts by weight, 20.25 to 23 parts by weight, or 23 to 27 parts by weight, but is not limited to these amounts.

[0050] In one embodiment, the content of docosahexaenoic acid in the eel feed composition may increase as the content of microalgae-derived biomass in the eel feed composition increases.

[0051] An example of an eel feed composition according to this application may further contain protein, carbohydrates, fat, etc. Yeast, starch, cellulose, vitamins. In one embodiment, the eel feed composition of this application may additionally contain fish meal.

[0052] In one embodiment, the eel feed composition of this application may additionally contain one or more selected from the group consisting of yeast (e.g., live bacteria such as yeast cultures and mold fermentations, yeast preparations), vitamins (e.g., vitamin preparations such as carotene, vitamin E, vitamins A, D, E, nicotinic acid, and vitamin B complex), minerals (e.g., mineral preparations such as sodium bicarbonate, bentonite, magnesium oxide, and complex minerals, and mineral preparations such as trace minerals such as zinc, copper, cobalt, and selenium), and starch.

[0053] In one embodiment, the eel feed composition may promote the growth of eels. Promoting the growth of eels may increase the weight gain rate (WGR), feed efficiency (FE), and / or the specific growth rate (SGR) of eels. For example, when eels are fed the eel feed composition, the weight gain rate (WGR), feed efficiency (FE), and / or the specific growth rate (SGR) of eels may increase compared to when they are fed a feed composition that does not contain microalgae-derived biomass.

[0054] As demonstrated in the examples described below, when eels ingested the eel feed composition containing the microalgae-derived biomass, the weight gain rate (WGR), feed efficiency (FE), and / or specific growth rate (SGR) increased, confirming that the eel feed composition of this application has the effect of promoting eel growth.

[0055] The aforementioned feed composition of this application promotes the growth of eels and can be usefully used as a feed composition for eels.

[0056] Eel farming methods In another aspect of this application, the application provides a method for farming eels, comprising the step of feeding eels with an eel feed composition containing the aforementioned biomass derived from microalgae of the genus Schizochytrium.

[0057] In the above method, the step of preparing an eel feed composition containing the aforementioned Schizochytrium microalgae-derived biomass may be additionally included before the feeding step.

[0058] In the above method, the feeding step can be carried out by any method of providing feed to eels, and may include, but is not limited to, the step of supplying or adding the eel feed composition containing the aforementioned Schizochytrium microalgae-derived biomass to the eels (which can be interpreted as including the aquatic environment in which the eels are contained).

[0059] In the above method, the amount of eel feed composition containing the biomass derived from the genus Schizochytrium can be appropriately determined depending on the type, size, condition, and purpose of feeding the eels. For example, the amount of eel feed composition containing the biomass derived from the genus Schizochytrium can be fed based on the eel's body weight, specifically 1%(w / w) to 15%(w / w), more specifically 1%(w / w) to 15%(w / w), 1%(w / w) to 10%(w / w), 1%(w / w) to 8%(w / w), 1%(w / w) to 7%(w / w), and 2%(w / w). )~15%(w / w), 2%(w / w)~10%(w / w), 2%(w / w)~8%(w / w), 2%(w / w)~7%(w / w), 3%(w / w)~15%(w / w), 3%(w / w)~10%(w / w), 3%(w / w)~8%(w / w), or 3%(w / w)~7%(w / w), but are not limited to these.

[0060] The biomass derived from the microalgae of the genus Schizochytrium, the eel feed composition, and the growth promotion of eels are as described above.

[0061] In another aspect of this application, the application provides a method for promoting eel growth, comprising the step of feeding eels with an eel feed composition containing the aforementioned Schizochytrium microalgae-derived biomass.

[0062] In another aspect of this application, this application provides eel feed compositions containing the aforementioned Schizochytrium microalgae-derived biomass and / or Schizochytrium microalgae-derived biomass for eel growth promotion.

[0063] The biomass derived from the microalgae of the genus Schizochytrium, the eel feed composition, and the growth promotion of eels are as described above. [Effects of the Invention]

[0064] This invention relates to an eel feed composition containing biomass derived from microalgae of the genus Schizochytrium sp., and a method for cultivating eels using the same. When eels are fed the eel feed composition containing biomass derived from microalgae of the genus Schizochytrium sp. of this invention, their growth is promoted, and therefore it can be usefully utilized as an eel feed composition or feed additive. [Brief explanation of the drawing]

[0065] [Figure 1] This figure shows the color difference between the pure isolation and culture results of the Schizochytrium sp. CD03-7004 mutant strain and the wild-type Schizochytrium sp. strain CD01-5000. [Figure 2] This figure shows the size of the amplified DNA fragments from the wild-type CD01-5000 strain and the mutant CD03-7004 strain after performing PCR using a primer set that amplifies a DNA fragment containing a 15bp base sequence added in the mutant CD03-7004 strain compared to the wild-type CD01-5000 strain. [Modes for carrying out the invention]

[0066] The present application will be described in more detail below through the examples. These examples are merely for the purpose of illustrating the present application in more detail, and it will be obvious to those with ordinary skill in the art that the scope of the present application is not limited by these examples, as is evident from the gist of the application. [Examples]

[0067] (Throughout this specification, unless otherwise specified, “%” used to indicate the concentration of a particular substance means (weight / weight)% for solid / solid, (weight / volume)% for solid / liquid, and (volume / volume)% for liquid / liquid.)

[0068] Example 1: Research materials and methods 1-1. Test fish and breeding management The tanks used were 1-ton square tanks (working volume 60L), with each set consisting of three rearing tanks and two filtration tanks. The test method involved transplanting 25 freshwater eels (Anguilla japonica) (approximately 20g size), currently being reared and managed at Cofex Central Research Institute, to each test tank. After a one-week acclimatization period, the eels were fed a specially manufactured test feed at 3-7% of their body weight (w / w) twice daily (07:30 and 14:30) for eight weeks. 20-30 minutes after feed supply, any remaining feed was collected, freeze-dried, weighed, and excluded from the feed supply each time. Each test tank was maintained at a temperature of 29°C, a DO of 6.5, and a pH of 5.8±0.5. NH3 and NO2 were measured by chemical analysis after taking water samples once daily from the filtration tanks of each test tank.

[0069] After the rearing experiment was completed, the weight of every eel in all tanks was measured, and based on this, the growth performance was evaluated as follows. Initial Weight (IW) (g), Initial Weight (g / fish) Final Weight (FW) (g), Final Weight (g / fish) Weight gain (WG) (g), Weight Gain=final weight-initial weight Total Dry Feed Intake (DFI) (g) Feed Efficiency (FE) (%), Feed Efficiency = (wet weight gain / dry feed intake) × 100 Weight gain rate (WGR) (%), Weight Gain Rate=(final weight-initial weight)×100 / initial weight Specific Growth Rate (SGR) (%) = (log final weight - log initial weight) / day × 100 Survival rate (SR) (%), Survival Rate=(No. of fish at end of experiment / No. of fish at start of experiment)×100

[0070] 1-2. Preparation of a new Schizochytrium sp. CD03-7004 mutant strain 1-2-1. Development of novel Schizochytrium sp. CD03-7004 mutant strains through gamma-ray irradiation. Pure, isolated wild-type Schizochytrium sp. CD01-5000 strain (deposit number KCTC14344BP) was cultured for approximately 24 hours or more in modified-GYEP medium containing 30 g / L glucose (10 g / L glucose, 1 g / L yeast extract, 1 g / L peptone, 2 g / L MgSO4·7H2O, 5.0 mg / L H3BO, 3.0 mg / L MnCl, 0.2 mg / L CuSO4, 0.05 mg / L NaMo4·2H2O, 0.05 mg / L CoSO4, 0.7 mg / L ZnSO4·7H2O) to reach the early exponential phase. The culture sample was then centrifuged to harvest the cells. The harvested cells had approximately 10 cells. 9 The cells were suspended in a 0.1M Phosphate Buffer Solution containing 1.0% NaCl to a concentration of cells / mL and used for gamma irradiation.

[0071] The gamma-ray irradiation experiment was conducted at the Korea Atomic Energy Research Institute's Advanced Radiation Research Institute, where gamma rays were irradiated at doses of 2000-5000 GY. After the microalgae culture samples irradiated with gamma rays underwent an O / N recovery process in a dark room, they were spread on GYEP medium containing 20 g / L of agar and cultured at 30°C for approximately 5 days. The number of growing colonies was then counted to measure the mortality rate for each gamma dose.

[0072] [Formula 1] Mortality rate (%) = [{(Number of colonies in untreated area) - (Number of colonies in treated area)} / (Number of colonies in untreated area)] × 100

[0073] [Table 1]

[0074] As a result, as shown in Table 1, an appropriate dose was identified in which the CFU values ​​of the number of growing colonies and viable bacteria decreased by 95% or more depending on the gamma ray irradiation dose. Specifically, gamma ray irradiation doses of 2.0, 3.0, 4.0, 4.5, and 5.0 kGY resulted in 0%, 90.8%, 98.2%, 100%, and 100% death, respectively. Under gamma ray irradiation conditions of 4.5 GY or higher, all organisms died, making it impossible to secure microalgae colonies, so the gamma ray irradiation condition of 4.0 kGY, which showed a death rate of 98.2%, was selected.

[0075] A novel microalgae strain CD01-5000 was irradiated with gamma rays at a dose of 4.0 kGY using a similar method, and then cultured in GYEP medium. During cultivation, viable colonies were selected and subcultured under the same medium and culture environmental conditions. Colonies that showed a reddish morphology between subcultures were selected and isolated as single cell lines for pure culture, and the results of photographing these cells are shown in Figure 1. The aforementioned Schizochytrium strain was named Schizochytrium sp. CD03-7004 and deposited with the Korean Collection for Type Cultures (KCTC) of the Korea Institute of Biotechnology on June 20, 2022, receiving accession number KCTC15006BP.

[0076] 1-2-2. Derivation of a marker to distinguish between the CD03-7004 mutant strain and the wild-type CD01-5000 strain. We compared the whole genome sequences of wild-type Schizochytrium sp. CD01-5000 strains and mutant Schizochytrium sp. CD03-7004 strains to identify the mutated sequences in CD03-7004 and constructed PCR markers.

[0077] Specifically, when comparing the genome of the mutated CD03-7004 strain with that of the wild-type CD01-5000 strain, we confirmed that it had 15 additional base pairs (the bolded portion in sequence number 1 and sequence number 5 below).

[0078] [ka]

[0079] Primers A: 5'-TTTCAGACTGCTTTTTGCTTTTTG-3' (SEQ ID NO: 3) and B: 5'-CTCTCTTCGGATTGACTCTTTTCT-3' (SEQ ID NO: 4) were selected to amplify this region, and PCR amplification was performed using these primers. The PCR reaction was carried out using a reaction solution containing taq polymerase, followed by denaturation at 95°C for 5 minutes, denaturation at 95°C for 10 seconds, annealing at 50°C for 10 seconds, polymerization at 72°C for 15 seconds, and this was repeated 35 times, followed by polymerization at 72°C for 5 minutes. The reaction solution amplified throughout the PCR process was subjected to electrophoresis on a 1.7% agarose gel to confirm the size of the amplified DNA, which is shown in Figure 2.

[0080] As a result, as shown in Figure 2, the DNA fragments amplified in the mutant CD03-7004 strain were approximately 140 bp in size, which is different from the wild-type CD01-5000 strain, in which DNA fragments of approximately 120 bp were amplified.

[0081] Therefore, the above results show that primer A: 5'-TTTCAGACTGCTTTTTGCTTTTTG-3' (SEQ ID NO: 3) and primer B: 5'-CTCTCTTCGGATTGACTCTTTTCT-3' (SEQ ID NO: 4) can be used to select mutant CD03-7004 strains.

[0082] 1-2-3. Production of dried microalgae biomass powder (Schizochytrium sp. powder) The dried microalgae biomass powder used in the experiment was prepared using the Schizochytrium sp. CD03-7004 strain (KCTC15006BP) by the following method.

[0083] Prior to the main 30L scale culture, each bacterial strain was inoculated into GYEP medium containing 50ml of working volume and 30g / L of glucose in a 500ml flask, and incubated in a shaking incubator at 30°C and 180rpm for approximately 20 hours. The preliminary cultures were inoculated into a 30L fermenter containing medium under the same conditions and fermented in a total working volume of 20L. Glucose equivalent to 20% of the working volume was continuously added under conditions of 30°C, 500rpm, 0.5-1vvm, and pH 5-7 to utilize for cell culture, while the glucose concentration was maintained at a level of 20g / L. The culture was terminated when all the supplied glucose, which was the carbon source, was consumed. The culture medium was dried using a dryer to a moisture content of approximately 5-8%.

[0084] 1-3. Experimental Feed Production For the production of the test feeds, Cofex Feed Manufacturing fishmeal (Glumar Co., Chille) and Schizochytrium sp. powder produced in Example 1-2-3 (CJ Co., Korea) were used as protein sources, and yeast (Biolife Co., Brazil), vitamins (Seoul vet Pharm Co., Korea), minerals (Seoul vet Pharm Co., Korea), and starch (Asai Co., Thailand) were used. A control feed (CTL) with 100% fishmeal as the protein source and test feeds (alternative feeds) T1, T2, T3, T4, and T5 were produced in which 5%, 10%, 15%, 20%, and 30% of the fishmeal were replaced with Schizochytrium sp. powder, respectively. All protein sources were ground to approximately 100 mesh size using a grinder owned by Cofex Research Institute Co., Ltd. The composition of the control feed and test feeds is described below in Table 8.

[0085] 1-4. Biological (Liver Weight) Index Assessment After the experiment, 10 animals were randomly selected from each test group, and their hepatosomatic index (HSI) and intestinosomatic index (ISI) were measured. Body weight and the weight of the liver and intestines removed after dissection were measured using an electronic scale, and the hepatosomatic index [(liver weight / body weight) × 100] and intestinosomatic index [(liver weight / body weight) × 100] were calculated.

[0086] 1-5. Analysis of research materials and basic components of fish bodies The moisture, fat, protein, and ash content of the research materials and fish bodies were analyzed. For the research materials, fish meal (Glumar Co., Chile) and the aforementioned Schizochytrium sp. powder were used. For the fish bodies, five eels of similar weight were randomly selected from each test group, finely ground using a shredder, and then analyzed for moisture, fat, protein, and ash content. The analytical methods were carried out according to food safety standards, and crude fat analysis was performed by acid hydrolysis, taking into account the properties of the Schizochytrium sp. powder.

[0087] 1-6. Amino acid, fatty acid analysis, and Ca, P analysis The amino acid, fatty acid, and Ca and P content were evaluated for the research materials: fish meal, the aforementioned Schizochytrium sp. powder, and fish body. For fish body, the amino acid, fatty acid, and Ca and P content were evaluated using freeze-dried powder of ground meat from five fish randomly collected in each test plot. The analysis was performed at the Feed Testing and Certification Center of the Chungnam National University Agricultural Science Research Institute. https: / / agro.cnu.ac.kr / agro / index.do I requested it from them.

[0088] 1-6-1. Methods for analyzing amino acids For the analysis of constituent amino acid content, 18 components were analyzed using a ninhydrin post-column reaction method with ion exchange chromatography, a modified version of the AOAC method (2005). For the 16 constituent amino acids, 0.2 g of the sample was placed in a decomposition tube, 10 ml of 6N HCl was added, and nitrogen gas was injected. Hydrolysis was then carried out at 110°C for 24 hours. The filtrate was concentrated using a vacuum concentrator, then diluted to 50 ml with 0.2 M sodium citrate buffer, and filtered through a 0.20 μm cellulose acetate syringe filter. The filtrate was used as the analytical sample. For the sulfur-containing compounds methionine and cysteine, the performic acid oxidation method was used, and for tryptophan, the alkaline hydrolysis method was used. The analytical conditions are shown in Tables 2 and 3.

[0089] [Table 2]

[0090] [Table 3]

[0091] 1-6-2. Fatty acid composition analysis method The fatty acid composition was prepared by adding approximately 100 ml of a chloroform and methanol mixture (2:1) to approximately 10 g of pulverized sample according to the method of Folch et al. (1957), extracting at room temperature for 24 hours, and then concentrating under reduced pressure. The extract was then methyl esterified with a 14% BF3-MeOH (Sigma, St. Louis, Mo, USA) solution and analyzed by gas chromatograph (HP6890, Heslett Packard Ltd., USA). An HP-88 column (100 m × 0.25 mm id, film thickness 0.20 μm, Agilent, USA) was used, and the column oven temperature was maintained at 140°C for 5 minutes, then increased by 4°C per minute to 240°C for 20 minutes. The injection port temperature was set to 260°C, the detector FID temperature to 270°C, N2 was used as the transport gas at 1 ml / min, and the split ratio was adjusted to 1 / 50. Gas chromatography analysis was performed under the conditions shown in Table 4 below. The peaks of each fatty acid were identified by comparing them with the residence times of methyl esters of standard fatty acids. The fatty acid composition was determined by calculating the area of ​​each identified peak, and then showing the area ratio of each peak as a percentage.

[0092] [Table 4]

[0093] 1-6-3.Inorganic analysis method Inorganic content was determined by preparing a sample solution by dissolving the residue after ashing using the dry ashing method in a hydrochloric acid solution (1:1, v / v). Calcium (Ca) was measured using an atomic absorption spectrophotometer (GBC Scientific Equipment, SavantAA, Australia), and phosphorus (P) was measured at 470 nm using a spectrophotometer (UV-2450, Shimadzu Co., Japan) by the molybdenum blue colorimetric method. All reagents and distilled water used were those intended for inorganic analysis.

[0094] 1-7.Blood chemical element analysis After the experiment, 10 animals were randomly selected from each test group. Plasma for blood analysis was collected from the tail vein using a disposable syringe into a heparin tube and obtained after centrifugation (2000 rpm, 15 min, 4°C). A blood analyzer (NX500i, FUJIFILM, JAPAN) was used to measure glutamate oxaloacetate transaminase (GOT), cholesterol (CHO), triglycerides (TG), alkalinity phosphatase (ALP), and total protein (TP).

[0095] 1-8.Non-specific immunoassay To measure lysozyme activity, after the experiment, 50 µl of serum isolated from the caudal veins of 10 eels from each test group and 1 ml of a solution containing Micrococcus lysodeikticus (0.2 mg / ml) suspended in 0.05 M sodium phosphate buffer (Sigma, USA, pH 6.2) were mixed in a 96-well plate. The reaction was measured at 20°C using a molecular device (USA) at 530 nm absorbance at 0.5 min and 5 min. Lysozyme activity units were defined as the amount of enzyme showing a decrease in absorbance of 0.001 per minute.

[0096] To measure neutrophil phagocyte activity, after the experiment, 50 μL each of serum isolated from the tail veins of 10 eels from each test group and NBT solution (Sigma, USA) were mixed in a 1:1 ratio. The mixture was then reacted at 25°C for 30 minutes. 50 μL of the reaction mixture was transferred to glass tubes, and 1 mL of dimethyl formamide (Sigma, USA) was added to reduce formazan production. The mixture was then centrifuged at 2,000 × g for 5 minutes, and the supernatant was collected. The reduction range of NBT was measured at 540 nm using a molecular device (USA). Dimethyl formamide (Sigma, USA) was used as the blank.

[0097] 1-9. Analysis of cholecystokinin and superoxide dismutase To analyze the activity of the digestive enzyme cholecystokinin and the antioxidant enzyme superoxide dismutase (SOD), blood samples were collected from 10 eels in each test group. Serum was separated by centrifugation at 2,000 × g for 10 minutes at 4°C, and then stored at -70°C. ELISA analysis using serum was performed using a kit capable of measuring cholecystokinin (CUSABIO, USA) and SOD (CUSABIO, USA) for fish, with 3 replicates using 50 μL of plasma per well according to the manufacturer's protocol. The activity level was measured using a molecular device (Molecular Device, USA) at 450 nm absorbance, and the results were calculated in ng / ml (SOD) or pg / mL (Cholecystokinin) based on the standard curve.

[0098] Example 2: Analysis of research materials (fish meal and powder of Schizochytrium microalgae) 2-1.Proximate components The general components of fishmeal powder and Schizochytrium sp. powder, which were used as protein sources in this study, were evaluated and are shown in Table 5 below.

[0099] [Table 5]

[0100] As shown in Table 5, we were able to confirm that Schizochytrium sp. powder has lower moisture and ash content compared to fish meal, and higher crude protein and crude fat content compared to fish meal.

[0101] 2-2. Amino acids The amino acid composition of the two proteins used in this study, fish meal and Schyzochytrium sp. powder, was evaluated and is shown in Table 6, expressed as g / 100g of total amino acids.

[0102] [Table 6]

[0103] As shown in Table 6, most amino acid content was high in fish meal, but glutamic acid content was about four times higher in Schyzochytrium sp. powder compared to fish meal, and the essential amino acid arginine was also higher in Schyzochytrium sp. powder than in fish meal.

[0104] 2-3.Fatty acids The fatty acid composition of the fats contained in the two types of protein powders used in this study was evaluated and is shown in Table 7, expressed as g / 100g of total fatty acids.

[0105] [Table 7] TIFF2026522699000010.tif122149

[0106] The content ratios of certain fatty acids differed significantly between the two protein source materials. The main fatty acids showing differences were myristic acid (C14:0, FP, 5.60; SP, 1.70), palmitic acid (C16:0, FP, 19.96; SP, 36.70), stearic acid (C18:0, FP, 6.68; SP, 1.51), palmitoleic acid (C16:1, FP, 5.99; SP, 0.11), oleic acid (C18:1n9, FP, 18.87; SP, 0.51), linoleic acid (C18:2n6, FP, 2.37; SP, 0.37), and linolenic acid. These included eicosadienoic acid (C18:3n3, FP, 0.64; SP, 0.25), eicosadienoic acid (C20:1n9, FP, 1.89; SP, 0.01), arachidonic acid (C20:4n6, FP, 2.84; SP, 0.12), EPA (eicosapentaenoic acid) (C16:0, FP, 9.63; SP, 0.72), nervonic acid (C24:1n9, FP, 3.25; SP, 0.40), and DHA (docosahexaenoic acid) (C22:6n3, FP, 15.09; SP, 45.12). While Schizochytrium sp. powder tended to have lower levels of many fatty acids than fish meal, the composition ratio of palmitic acid and DHA was significantly higher in Schizochytrium sp. powder compared to fish meal.

[0107] 2-4. Preparation of control feed and test feed A control feed (CTL) consisting of 100% fish meal as the protein source, and test feeds (alternative feeds) T1, T2, T3, T4, and T5, in which 5%, 10%, 15%, 20%, and 30% of the fish meal were replaced with Schizochytrium sp. powder, respectively, were prepared with the compositions shown in Table 8 below.

[0108] [Table 8]

[0109] 2-5. General components of test feed The basic components of the control feed (CTL) and test feeds (alternative feeds) T1-T5 used in this experiment were evaluated and are shown in Table 9.

[0110] [Table 9]

[0111] As shown in Table 9, there were no differences in moisture content, crude protein content, crude fat content, and ash content, and the crude carbohydrate content was evaluated identically. We were also able to confirm that there was almost no difference in calories between the feeds.

[0112] 2-6. Fatty Acid Analysis of Test Feeds The fatty acid composition ratios (profiles) of the control feed (CTL) and test feeds (alternative feeds) T1-T5 used in this experiment were evaluated and are shown in Table 10 as g / 100g of total fatty acids.

[0113] [Table 10] TIFF2026522699000014.tif192149

[0114] As shown in Table 10 above, in test feeds mixed with fish meal and Schizochytrium sp. powder in a fixed ratio, differences in fatty acid composition were observed in proportion to the mixing ratio. It was confirmed that the content of palmitic acid and DHA increased as the mixing ratio of Schizochytrium sp. powder increased.

[0115] Example 3: Growth Performance Evaluation Growth performance was evaluated in rearing eels (A. japonica, approximately 20g size) by feeding them control feed and test feeds T1-T5 twice a day for 8 weeks each, and the results are shown in Table 11 below.

[0116] [Table 11]

[0117] As shown in Table 11 above, the weight growth rate (WGR) is in the order of T2 (196.25±13.47) > control feed (188.59±4.84) ​​> T1 (182.87±4.77) > T3 (182.07±4.47) > T4 (176.52±8.32) > T5 (175.99±6.99), the feed efficiency (FE) is in the order of T2 (90.86±5.0) > control feed (87.09±2.16) > T1 (85.55±1.52) > T3 (84.53±1.89) > T4 (81.54±3.54) > T5 (81.45±2.97), and the normal daily growth rate (SGR) is also in the order of T2 (1.94±0.08) > control feed (1.89±0.03). n The order of growth rates was T1 (1.86±0.03), T3 (1.85±0.03), T4 (1.82±0.05), and T5 (1.81±0.05). It was confirmed that test feed T2 showed the best growth rate, feed efficiency, and daily growth rate. Survival rates (SR) did not show significant differences between the test intervals of 97.72% to 100%.

[0118] Thus, when fish meal was replaced with Schizochytrium sp. powder at the same mixing ratio as test feed T2, it was confirmed that eel growth was promoted and the composition could be useful as an eel feed composition.

[0119] Example 4: Bioindex Assessment The liver weight index (HSI) and intestinal weight index (ISI), which are biological characteristics, are generally known to vary depending on the dietary nutritional status, habitat conditions, and stress levels of fish. The results of evaluating the liver weight index and intestinal weight index of eel groups fed with control feed and test feeds T1-T5 are shown in Table 12 below.

[0120] [Table 12]

[0121] As shown in Table 12, no significant differences were observed in the liver weight index and intestinal weight index between the control feed and the test feed (T1-T5) supplied to the eel groups. This confirmed that fish meal can be safely substituted with Schizochytrium sp. powder within the content ratio range of the test feed.

[0122] Example 5: Blood Chemical Element Analysis Chemical analysis of fish blood can diagnose a variety of diseases, as well as physiological changes such as organ damage and stress levels, and has long been used as an indicator for health checkups. Ten test fish each, fed 8 weeks of control feed and test feed, were randomly collected, and plasma levels of glutamate oxaloacetate transaminase (GOT), triglycerides (TG), cholesterol (CHO), alkalinity phosphatase (ALP), and total protein (TP) were measured and are shown in Table 13.

[0123] [Table 13]

[0124] As shown in Table 13, both the control feed group and the test feed (T1-T5) group showed similar values ​​for blood concentrations of GOT (also known as aspartate aminotransferase (AST)), cholesterol (CHO), alcohol phosphatase (ALP), a major liver enzyme, and total protein (TP). Blood triglycerides (TG) in the test feed T1-T5 groups tended to decrease as the fishmeal substitution ratio increased compared to the control feed group, but the difference was not statistically significant.

[0125] This confirmed that fish meal could be safely substituted with Schizochytrium sp. powder within the content ratio range of the test feed.

[0126] Example 6: Nonspecific immunoassay, cholecystokinin, and superoxide dismutase analysis Fish, being vertebrates, possess a defense system comprised of both nonspecific and specific immunity, and their immune activity is known to respond sensitively to changes in the feed environment and water quality. The effects on nonspecific immunity between eel groups supplied with control feed (CTL) and eel groups supplied with test feeds T1-T5 were evaluated by assessing the activity of lysozyme, a humoral immune factor, and the phagocytic activity of neutrophils, a cellular immune component (Table 14).

[0127] Simultaneously, digestive function was evaluated through assessment of gallbladder contraction and cholecystokinin, a pancreatic enzyme secretion-promoting hormone, and blood antioxidant activity was compared by evaluating superoxide dismutase (SOD) activity, a blood antioxidant enzyme (Table 14).

[0128] [Table 14]

[0129] As shown in Table 14, lysozyme activity, phagocytic activity, cholecystokinin activity, and superoxide dismutase activity were all at similar levels between the alternative feed and the test feed-fed eel groups, confirming that fish meal can be safely replaced with Schizochytrium sp. powder within the content ratio range of the test feed.

[0130] Example 7: Whole fish analysis 7-1.Basic ingredients After grinding and mixing all five fish, the moisture content was measured. For the dried ground powder, the basic components (crude protein, crude fat, ash) and Ca and P content were measured, and the results are shown in Table 15.

[0131] [Table 15]

[0132] As shown in Table 15, the total water content, crude protein, crude fat, ash, Ca, and P content were similar between the control feed (CTL) group and the test feed (T1-T5) group, confirming that fish meal can be safely substituted with Schizochytrium sp. powder within the content ratio range of the test feed.

[0133] 7-2. Constituent Amino Acids The results of evaluating the amino acid composition of eels supplied with control feed (CTL) and eels supplied with test feed (T1-T5) are shown in Table 16 below.

[0134] [Table 16] TIFF2026522699000021.tif132149

[0135] As shown in Table 16, the total amino acid composition of the eels was similar between the control feed (CTL) group and the test feed (T1-T5) group. Thus, although there was a significant difference in amino acid composition ratio between fish meal and Schizochytrium sp. powder, including essential amino acids (Table 6), as shown in Table 16, it was determined that there was almost no effect on the total protein composition of eels fed the test feed in which fish meal was replaced with Schizochytrium sp. powder. This confirmed that fish meal can be safely replaced with Schizochytrium sp. powder within the content ratio range of the test feed.

[0136] 7-3.Fatty acids The results of evaluating the fatty acid composition of eels supplied with control feed (CTL) and eels supplied with test feed (T1-T5) are shown in Table 17 below.

[0137] [Table 17] TIFF2026522699000023.tif192149

[0138] As shown in Table 17, it was confirmed that some highly unsaturated fatty acids, such as linoleic acid (CTL, 1.12 > T1, 1.16 > T2, 1.05 > T3, 0.91 > T4, 0.96 > T5, 0.92), EPA (CTL, 2.05 > T1, 2.01 > T2, 2.00 > T3, 1.82 > T4, 1.76 > T5, 1.55), DHA (CTL, 5.36 < T1, 5.75 < T2, 6.33 < T3, 6.82 < T4, 7.95 < T5, 8.27), etc., showed content differences proportional to the substitution ratio of Schizochytrium sp. powder. This is consistent with the fact that there were significant differences in the composition ratios of some fatty acids in the fatty acid composition ratios of the fish meal and Schizochytrium sp. powder used in the test evaluation (Table 7), and there were also differences due to the mixing ratio of Schizochytrium sp. powder in the control feed (CTL) and test feeds T1 - T5 (Table 10). Thus, it was confirmed that the fatty acid compositions of fish meal and Schizochytrium sp. powder showed significant differences, and the composition differences of some essential highly unsaturated fatty acids among them also affected the differences in the fatty acid compositions of fish bodies after feed supply.

Deposit Number

[0139] Name of the depository institution: Korea Research Institute of Bioscience and Biotechnology, Biological Resource Center (KCTC) Deposit Number: KCTC15006BP Date of deposit: 20220620

Claims

1. An eel feed composition containing 2.25% to 45% by weight of biomass derived from microalgae of the genus Schizochytrium sp.

2. The eel feed composition according to claim 1, wherein the microalgae-derived biomass comprises one or more selected from the group consisting of microalgae, cultures of the microalgae, dried products of the cultures, and crushed products of the dried products.

3. The eel feed composition according to claim 1, comprising 4% to 8% by weight of the microalgae-derived biomass.

4. The eel feed composition according to claim 1, wherein the microalgae-derived biomass contains 40% to 95% by weight of protein.

5. The eel feed composition according to claim 1, wherein the microalgae-derived biomass contains 3% to 30% by weight of fat.

6. The eel feed composition according to claim 1, wherein the microalga of the genus Schizochytrium is one or more selected from the group consisting of Schizochytrium aggregatum, Schizochytrium limacinum, and Schizochytrium minutum.

7. The eel feed composition according to claim 1, wherein the eel is one or more species selected from the group consisting of Japanese eel (Anguilla japonica), giant eel (Anguilla marmorata), European eel (Anguilla anguilla), American eel (Anguilla rostrata), and bicolor eel (Anguilla bicolor).

8. The eel feed composition according to claim 1, which promotes the growth of eels.

9. The eel feed composition according to claim 8, wherein promoting the growth of the eel means increasing the weight gain rate (WGR) of the eel.

10. The eel feed composition according to claim 8, wherein promoting the growth of the eel is to increase the feed efficiency (FE) of the eel.

11. The eel feed composition according to claim 8, wherein promoting the growth of the eel means increasing the daily growth rate (SGR, Specific Growth Rate) of the eel.

12. A method for farming eels, comprising the step of feeding eels with an eel feed composition according to any one of claims 1 to 11.

13. A method for promoting the growth of eels, comprising the step of feeding eels with an eel feed composition according to any one of claims 1 to 11.

14. An eel feed composition according to any one of claims 1 to 11 for the purpose of promoting eel growth.

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