Seed production method of new purple golden crassostrea gigas strain with high meat percentage

Abstract

The invention provides a seed production method of a new purple golden crassostrea gigas strain with a high meat yield, and belongs to the technical field of aquaculture. The method comprises the following steps: firstly, preliminarily screening out a class group with two shells which are purple golden and purple mainly, 1-3 golden shells and high meat yield as a core group; the method comprises the following steps: selecting crassostrea gigas individuals with alternately purple and golden shells and high meat percentage as an optimal population by adopting a head cutting selection method, taking the optimal population as a breeding population, and carrying out filial generation breeding according to a conventional shellfish breeding method to obtain a new purple and golden shell strain F1 with high meat percentage; further purifying the purple golden shell character in a family breeding mode to form a second-generation breeding family F2; and then a plurality of generations of continuous purification are carried out to obtain the new crassostrea gigas strain with purple gold color, high meat yield and stable ovum shape. The survival rate, the growth speed and the fatness degree of the new purple golden crassostrea gigas strain with the high meat percentage are greatly improved.

Description

Technical Field

[0001] This invention relates to an oyster breeding method, specifically a method for cultivating a new purple-gold oyster variety with a high meat yield, belonging to the field of aquaculture. Background Technology

[0002] Oysters are an important marine biological resource, prized for their delicious flavor and rich nutritional value, earning them the nickname "milk of the sea." Widely distributed, fast-growing, and highly productive, oysters possess significant economic value and are the world's most widely farmed and highest-yielding economic shellfish. As one of my country's four major farmed shellfish, oysters hold a vital position in the country's marine aquaculture industry.

[0003] However, since the artificial breeding of Pacific oysters began, systematic and effective breeding work has been lacking. The parent stock used for breeding has always been derived from wild-type populations that have never undergone genetic improvement. In particular, most hatcheries have not selected the genetic background and quality of their breeding parents, and rarely use male parents, often leading to reduced genetic diversity and germplasm degradation. Aquaculture units and consumers urgently need the development of new oyster varieties that are fast-growing, plump, have high survival rates, and are of good quality to meet the needs of the market and aquaculture units.

[0004] Purple and gold oysters, known as "purple-gold oysters," are considered high-end oysters in both domestic and international markets, often referred to as the "aristocrats" of the oyster world. They are characterized by rapid growth, high survival rates, and excellent plumpness, making them highly sought after by consumers and thus commanding high prices. Developing new varieties of long oysters with purple-gold shells and high meat yields can improve both the edible value and aesthetics of oysters, thereby increasing their added value. This is a pressing need in the industry. Summary of the Invention

[0005] To address the problem of a lack of new oyster varieties, the purpose of this invention is to provide a breeding method for a new purple-gold oyster strain with high meat yield, so as to obtain a new strain with alternating purple and gold shells, high plumpness and oval shape, and stable inheritance, so as to meet the market demand for high-quality and diversified oyster products.

[0006] This invention employs selective breeding and hybridization breeding methods, targeting the purplish-gold color and plumpness of oyster shells, to develop a new strain of Pacific oyster with a purplish-gold color, high meat yield, and oval shell shape. The resulting strain not only grows rapidly but also possesses a vibrant purplish-gold color, high meat yield, and an oval shell shape. This strain is highly suitable for monoculture oyster farming and raw oyster production, thereby increasing the yield, commercial value, and economic benefits of Pacific oyster farming.

[0007] To achieve the above objectives, the specific technical solution adopted by the present invention is as follows: A method for breeding a new purple-gold oyster strain with high meat yield includes the following steps: a. Initial screening: In the wild purple oyster population, purplish-gold oysters with two shells that are alternating between purple and gold, with 1-3 gold stripes, and a meat yield of more than 20%, and with an oval shell shape, were initially screened as the core group. b. Secondary selection: Using the core population of purple and gold oysters with 1-3 gold stripes and high meat yield selected in step a as the basic population, the truncated selection method is used to select 10% of the purple and gold oysters with a meat yield of more than 20% and oval shell shape as the preferred population. c. Self-breeding of superior populations: Using the population selected in step b as the breeding population, offspring are bred according to conventional shellfish seedling cultivation methods to obtain a new strain F1 of purple-gold oval long oysters with high meat yield; d. Second-generation selection: Through family selection, select families with obvious purple-gold shell traits and no other color separation from the established first-generation selection families, and discard other families with indistinct purple-gold shell traits; from the selected families, select oysters with purple-gold shells on both sides, meat yield higher than 20%, and oval shell shape, and perform one-to-one insemination and mating, mark them separately, and carry out strict isolation measures for larval culture, place them in the same sea area for intermediate cultivation and growth, and further purify the purple-gold high meat yield oval oval oyster traits to form the second-generation selection family F2; e. Targeted purification: Using the F2 purplish-gold oval-shaped new oyster strain with high meat yield from step d as the parent, steps b, d, and e were repeated several times. Through several generations of continuous purification and heritability assessment techniques, a new oyster strain with stable traits, oval-shaped purplish-gold shells, and a meat yield of over 20% was obtained.

[0008] Furthermore, in steps c, d, and e above, progeny rearing is carried out according to conventional oyster seedling rearing methods. During the larval rearing process, the larval rearing density, feeding amount, water exchange rate, and rearing conditions of each group of selected breeding lines are kept the same. The seedling containers and equipment of each group of selected breeding lines are used separately to avoid mixing.

[0009] Furthermore, in steps c, d, and e above, the specific method for raising offspring according to conventional artificial oyster rearing methods is as follows: the density of type D larvae is 5-6 cells / ml, gradually decreasing as the larvae grow, until the density of creeping larvae drops to 2-3 cells / ml; water is changed twice daily, with 30%-50% replaced each time, increasing to 100%-120% after the larvae attach; type D larvae are then fed golden algae, with the daily feeding amount gradually increasing from 10,000-20,000 cells / ml initially to 30,000 cells / ml in the middle stage. Initially, feed 40,000 cells / ml, increasing to 50,000-60,000 cells / ml later. During the later stages of larval development up to the apex of the shell, add *Platycladus orientalis*, with a daily feeding rate of 10,000-20,000 cells / ml. Chlorella can be fed appropriately during larval rearing. The water temperature during larval rearing should be 23-26℃. It takes 18-22 days to develop from D-type larvae to creeping larvae. When the larvae grow to a shell length of 330-360 μm and 60-80% show eye spots, begin collecting seedlings using a substrate. Use *Pterygosperma* shells as the substrate, at a rate of 5000 pieces / m². 3 On average, 15-20 oysters are collected from each area to meet the requirements for oyster collection. When the oyster seedlings grow to a shell length of about 1-2 mm, each selected breeding line is marked and transferred to the sea area for cultivation. During the larval cultivation process, the larval cultivation density, feeding amount and water exchange rate of each selected breeding line are kept the same, and the cultivation conditions are the same. The seedling containers and equipment of each selected breeding line are used separately to avoid mixing.

[0010] In step e above, the heritability assessment technique involves establishing full-sib and half-sib families using nested design, and then using variance and covariance analysis of two-factor system groupings to evaluate and estimate the heritability and genetic correlation of growth traits such as shell height, shell length, shell width, total weight, shell weight, meat weight, and meat yield of the purple-gold oyster. This provides a theoretical basis for establishing a new purple-gold oval-shaped oyster strain with high meat yield.

[0011] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: This invention develops a new purple-gold oyster variety with fast growth, beautiful shell shape, and easy fattening, meeting urgent industry demand and solving the problem of the lack of high-end oyster varieties. Based on the stable heritability of shell color in the Pacific oyster, this invention utilizes its shell color inheritance mechanism. Through initial screening, secondary selection, self-breeding of superior populations, and targeted purification, it achieves synergistic selection of quantitative and economic traits. Through heritability assessment and other techniques, it obtains a new purple-gold oval-shaped Pacific oyster strain with high meat yield, stable genetic traits, and significantly improved meat yield.

[0012] This invention cultivates a new oval-shaped, purple-gold oyster strain with a high meat yield. Under the same culture conditions, at 10 months of age, the average shell height is 12% higher, the weight is 15% higher, and the meat yield is 20% higher than that of oysters cultured from ordinary commercial seedlings. Both shells are purple-gold. This invention provides a method for breeding a new oyster strain with stable genetic traits and high economic value, injecting a new high-end oyster culture into current oyster farming. Detailed Implementation

[0013] The present invention will be further explained and illustrated below through specific embodiments.

[0014] Example 1: 10,000 wild oysters imported from South Korea were selected.

[0015] A method for breeding a new purple-gold oyster strain with high meat yield includes the following steps: a. Initial screening: From the wild purple oyster population introduced from South Korea, purplish-gold oysters with alternating purple and gold shells, 1-3 gold stripes, and a meat yield of more than 20% were initially screened out, and the oval-shaped shell group was selected as the core group. b. Secondary selection: Using the core population of purple and gold oysters with 1-3 gold stripes and high meat yield selected in step a as the basic population, the truncated selection method is used to select 10% of the purple and gold oysters with a meat yield of more than 20% and oval shell shape as the preferred population. c. Self-breeding of superior populations: Using the population selected in step b as the breeding population, offspring are bred according to conventional shellfish seedling cultivation methods to obtain a new strain F1 of purple-gold, high meat yield, oval-shaped long oysters; d. Second-generation selection: Through family selection, select families with obvious purple-gold shell characteristics and no other color separation from the established first-generation selection families, and discard other families with indistinct purple-gold shell characteristics; from the selected families, select oysters with purple-gold shells on both sides, meat yield higher than 20%, and oval shell shape for one-to-one insemination and mating, mark them separately, and carry out strict isolation measures for larval culture, place them in the same sea area for intermediate cultivation and growth, and further purify the purple-gold, high meat yield, and oval oval oyster characteristics to form the second-generation selection family F2; e. Targeted Purification: Using the F2 strain of the purple-gold oval-shaped oyster with high meat yield from step d as the parent, steps b, d, and e were repeated several times. Through several generations of continuous purification and heritability assessment techniques, a new stable oval-shaped purple-gold oyster strain with a meat yield exceeding 20% ​​was obtained. The heritability assessment techniques involved establishing full-sib and half-sib families using nested design. Two-factor systematic grouping variance and covariance analysis were used to evaluate and estimate the heritability and genetic correlation of growth traits such as shell height, shell length, shell width, total weight, shell weight, meat weight, and meat yield parameters of the purple-gold oyster, providing a theoretical basis for establishing the new purple-gold oval-shaped oyster strain with high meat yield.

[0016] f. In steps c, d, and e above, the specific method for raising offspring according to the conventional artificial oyster seedling cultivation method is as follows: The density of type D larvae is 5-6 cells / ml, and the density is gradually reduced as the larvae grow, until the density of creeping larvae drops to 2-3 cells / ml; the water is changed twice a day, with 30%-50% of the water changed each time, increasing to 100%-120% after the larvae attach; type D larvae are fed with golden algae, and the daily feeding amount is gradually increased from 10,000-20,000 cells / ml in the early stage to 30,000-40,000 cells / ml in the middle stage. Initially, feed 50,000-60,000 cells / ml, increasing to 50,000-60,000 cells / ml in later stages. During the later stages of larval development (towards the apex of the shell), supplement with *Platycladus orientalis*, with a daily feeding rate of 10,000-20,000 cells / ml. Chlorella can be fed appropriately during larval rearing. The water temperature during larval rearing should be 23-26℃. It takes 18-22 days to develop from D-type larvae to creeping larvae. When the larvae reach a shell length of 330-360 μm and 60-80% show eye spots, begin collecting larvae using a substrate. Use *Pterygosperma* shells as the substrate, at a rate of 5000 shells / m². 3 On average, 15-20 oysters are collected from each area to meet the requirements for oyster collection. When the oyster seedlings grow to a shell length of about 1-2 mm, each selected breeding line is marked and transferred to the sea area for cultivation. During the larval cultivation process, the larval cultivation density, feeding amount and water exchange rate of each selected breeding line are kept the same, and the cultivation conditions are the same. The seedling containers and equipment of each selected breeding line are used separately to avoid mixing.

[0017] Example 2: The new purple-gold oyster strain with high meat yield obtained in Example 1 was cultured normally. After 10 months of age, some strains were tested for various indicators and compared with ordinary oyster strains at 10 months of age, while others were bred normally.

[0018] 1. Shell height: 50 new purple-gold oyster strains with high meat yield obtained from Example 1, which were 10 months old, were randomly selected, and 50 ordinary oyster strains of 10 months old were randomly selected. The measurements were recorded. The results showed that the shell height of the purple-gold oyster strain with high meat yield obtained from Example 1 was on average 12.6% higher than that of ordinary oysters.

[0019] 2. Weight: As above, the overall weight was measured. The results showed that the shell height of the new oyster strain with high meat yield and purple-gold shell in Example 1 was on average 16.8% higher than that of ordinary oysters.

[0020] 3. Meat yield: As above, the focus was on removing the soft parts of the oyster. The results showed that the meat yield of the new purple-gold shell long oyster strain in Example 1 was on average 22.1% higher than that of the ordinary long oyster.

[0021] This invention leverages the stable heritability of shell color in the Pacific oyster (Crassostrea gigas) and its genetic mechanism. Through initial screening, secondary selection, self-breeding of superior populations, and targeted purification, it achieves synergistic selection of quantitative and economic traits. By employing techniques such as heritability assessment, a new oval-shaped, purplish-gold Pacific oyster strain with high meat yield can be obtained, providing a possibility for breeding new varieties. The purplish-gold, oval-shaped strain with high meat yield developed by this invention, under the same culture conditions, exhibits a 12.6% higher average shell height, a 16.8% higher body weight, and a 22.1% higher meat yield at 10 months of age compared to Pacific oysters cultured from ordinary commercial seedlings. This invention has the advantages of simple operation and ease of promotion.

[0022] The above embodiments are only for illustrating the technical concept and features of the present invention and should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for breeding a new purple-gold oyster strain with high meat yield, characterized in that, Includes the following steps: a. Initial screening: In the wild purple oyster population, purplish-gold oysters with two shells that are alternating between purple and gold, with 1-3 gold stripes, and a meat yield of more than 20%, and with an oval shell shape, were initially screened as the core group. b. Secondary selection: Using the core group selected in step a as the base group, the truncated selection method is used to select 10% of the long oysters with purple and gold shells, a meat yield of more than 20%, and an oval shell shape as the preferred group. c. Self-breeding of superior populations: Using the population selected in step b as the breeding population, offspring are bred according to conventional shellfish seedling cultivation methods to obtain a new strain F1 of purple-gold oval long oysters with high meat yield; d. Second-generation selection: Through family selection, select families with obvious purple-gold shell traits and no other color separation from the established first-generation selection families, and discard other families with indistinct purple-gold shell traits; from the selected families, select oysters with purple-gold shells on both sides, meat yield higher than 20%, and oval shell shape, and perform one-to-one insemination and mating, mark them separately, and carry out strict isolation measures for larval culture, place them in the same sea area for intermediate cultivation and growth, and further purify the purple-gold high meat yield oval oval oyster traits to form the second-generation selection family F2; e. Targeted purification: Using the F2 purplish-gold oval-shaped new oyster strain with high meat yield from step d as the parent, steps b, d, and e were repeated several times. Through several generations of continuous purification and heritability assessment techniques, a new oyster strain with stable traits, oval-shaped purplish-gold shells, and a meat yield of over 20% was obtained.

2. The seed production method as described in claim 1, characterized in that, In steps c, d, and e above, progeny rearing is carried out according to conventional oyster seedling rearing methods. During the larval rearing process, the larval rearing density, feeding amount, water exchange rate, and rearing conditions of each group of selected breeding lines are kept the same. The seedling containers and equipment of each group of selected breeding lines are used separately to avoid mixing.

3. The seed production method as described in claim 2, characterized in that, The specific method for raising offspring according to the conventional artificial oyster seedling cultivation method is as follows: the density of type D larvae is 5-6 larvae / ml, and the density is gradually reduced as the larvae grow, until the density of creeping larvae drops to 2-3 larvae / ml; the water is changed twice a day, with 30%-50% of the water being changed each time, and increased to 100%-120% after the larvae attach; type D larvae are fed with golden algae, and the daily feeding amount is gradually increased from 10,000-20,000 cells / ml in the early stage to 30,000-40,000 cells / ml in the middle stage. In the later stages, the cell / ml level should be 50,000-60,000 cells. During the later stages of larval development to the apex of the shell, add *Platycladus orientalis*, with a daily feeding rate of 10,000-20,000 cells / ml. Chlorella can be fed appropriately during larval rearing. The water temperature during larval rearing should be 23-26℃. It takes 18-22 days to develop from D-type larvae to creeping larvae. When the larvae grow to a shell length of 330-360 μm and 60-80% show eye spots, begin collecting seedlings using a substrate. Use *Pterygosperma* shells as the substrate, at a rate of 5000 pieces / m². 3 On average, 15-20 oysters are collected from each area to meet the requirements for oyster collection. When the oyster seedlings grow to a shell length of about 1-2 mm, each selected breeding line is marked and transferred to the sea area for cultivation. During the larval cultivation process, the larval cultivation density, feeding amount and water exchange rate of each selected breeding line are kept the same, and the cultivation conditions are the same. The seedling containers and equipment of each selected breeding line are used separately to avoid mixing.

4. The seed production method as described in claim 1, characterized in that, In step e above, the heritability assessment technique involves establishing full-sib and half-sib families using nested design, and then using variance and covariance analysis of two-factor system groupings to evaluate and estimate the heritability and genetic correlation of growth traits such as shell height, shell length, shell width, total weight, shell weight, meat weight, and meat yield of the purple-gold oyster. This provides a theoretical basis for establishing a new purple-gold oval-shaped oyster strain with high meat yield.