A method for breeding color snakehead

Abstract

The application discloses a cultivation method of colorful snakehead. The method comprises the following steps: taking common white snakehead and golden snakehead in the Sichuan-Chongqing region as original parents, completing positive and reverse cross, self-population cross, backcross to establish paternal and maternal lines, and then mating to obtain G0 generation; taking white ground color and colorful patches as phenotypic markers, and combining growth, low-temperature tolerance and disease resistance to continuously select and breed 6-8 generations; and finally obtaining a new strain of colorful snakehead with diverse body color and stable heredity. The body weight of the new strain of colorful snakehead at 180 days old is increased by more than 20% compared with that of white snakehead, the low-temperature survival rate is increased by more than 24%, the disease resistance is significantly enhanced, and the new strain is suitable for large-scale breeding and ornamental fish market.

Description

Technical Field

[0001] This invention relates to the field of aquatic animal genetic breeding technology, specifically to a method for breeding the colored snakehead. Background Technology

[0002] Snakehead fish is an important freshwater economic fish in my country, but traditional aquaculture populations suffer from problems such as uniform body color, significant differences in growth rate, poor tolerance to low temperatures, and frequent disease outbreaks. Among existing technologies, researchers such as Zhu Xinping from the Pearl River Fisheries Research Institute of the Chinese Academy of Fishery Sciences have disclosed a method for "hybrid breeding of white snakehead and spotted snakehead," which aims only to improve growth rate and does not address the improvement of body color or the integration of cold resistance and disease resistance. Mao Leigang et al. from Shanghai Ocean University have disclosed "golden snakehead breeding technology," but this only purifies a single golden strain and fails to solve the problems of trait segregation and poor genetic stability.

[0003] Therefore, there is an urgent need for a new breeding technology for snakehead fish that can simultaneously fix fast growth, low temperature resistance, strong disease resistance, good meat quality, and diverse body colors. Summary of the Invention

[0004] The purpose of this invention is to provide a method for breeding colored snakehead fish, which can obtain new colored snakehead fish strains with diverse body colors, consistent genetics, and excellent production performance within 6-8 generations.

[0005] To achieve the above objectives, the technical solution adopted by the present invention includes: A method for cultivating the colored snakehead fish includes the following steps: (1) Common white snakehead and golden snakehead were selected as the original parents; (2) Cross the white snakehead and the golden snakehead in opposite directions to obtain the F1 generation; (3) The F1 generation is obtained by reciprocal crosses between male and female individuals within the population; (4) Backcross the F2 generation with white snakehead to establish the paternal and maternal lines of colored snakehead; (5) Cross the male line of the colored snakehead with the female line of the colored snakehead to obtain the G0 generation of colored snakehead; (6) Conduct continuous 6-8 generations of in-situ breeding of the G0 generation of colored snakehead; (7) When the number of new strains is ≥50,000 and the body color consistency rate is ≥95% for three consecutive generations, large-scale propagation and promotion shall be carried out.

[0006] Furthermore, the common white snakehead is 2 years old, weighs ≥800 g, and has a pure white body without any other colors; the golden snakehead is 2 years old, weighs ≥700 g, and has a golden yellow body without any black spots.

[0007] Furthermore, in step (6), during the succession breeding, a colored snakehead with white as the base color and obvious colored patches is selected, and its growth performance, disease resistance performance, and low temperature resistance performance are combined. The colored patches have four main color systems: pure white, golden white, orange white, and black and white.

[0008] Furthermore, the growth performance is a body weight of ≥450 g at 180 days of age.

[0009] Furthermore, the disease resistance is described as having a survival rate of >80% against Aeromonas hydrophila.

[0010] Furthermore, the low-temperature resistance performance is a survival rate of ≥90% after 30 days at 4-6 ℃.

[0011] The beneficial effects of this invention are as follows: (1) Diverse body color: The new strain has white as the base color and has four main color systems: pure white, golden white, orange white, black and white. The shape and arrangement of the patches are stable, and it has both ornamental and economic value. (2) Overall performance: The new strain has a 20.1% higher body weight at 180 days of age than the white snakehead, a more than 24% higher low-temperature survival rate, and a 41.2% higher survival rate against Aeromonas hydrophila. (3) Genetic stability: After 8 generations of selection, the genetic consistency rate of body color of the new strain is ≥96%, and the coefficient of variation (CV) of the main economic traits is ≤8%; (4) Promotion benefits: The annual production of fry per parent fish is ≥6000, which is suitable for large-scale propagation.

[0012] (5) The new strain combines the superior traits of "good meat quality and low temperature resistance" of white snakehead with "fast growth and strong disease resistance" of golden snakehead, and inhibits trait segregation during hybridization and backcrossing, so as to achieve rapid fixation of quality traits such as body color. Attached Figure Description

[0013] Figure 1 This is a technical roadmap for breeding colored snakehead fish.

[0014] Figure 2 Photographs of the parent's body color phenotype. Detailed Implementation

[0015] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0016] Unless otherwise specified, the methods involved in the following embodiments are all conventional techniques in the art.

[0017] Example 1 Time: May-June 2016; Location: Aquaculture Base of Neijiang Academy of Agricultural Sciences, Sichuan Province.

[0018] White snakehead parent stock: sourced from natural water systems in the Sichuan-Chongqing region, 2-year-old, weight ≥800 g, pure white body surface without any other colors; Golden snakehead parent stock: artificially bred and purified for more than 5 generations, 2-year-old, weight ≥700 g, golden yellow body surface without any black spots; see parent stock color phenotypes for details. Figure 2 .

[0019] Parent breeding: Feed high-protein (≥42%) compound feed containing 3% spirulina powder and 0.5% VC for 30 days before overwintering to strengthen their physique; control the overwintering water temperature at 10-12 ℃ and dissolved oxygen ≥6 mg / L.

[0020] 1. Selection and cultivation of parent plants Sixty female white snakehead (average weight 832 g) and sixty male golden snakehead (average weight 748 g) were selected for artificial spawning induction at a water temperature of 26℃. The effect lasted for about 30 hours, with an average egg production of 10,500 eggs, a fertilization rate of 67%, a hatching rate of 74%, and a yield of 312,000 F1 larvae.

[0021] 2. Hybridization and Recurrent Breeding Process 2.1 Preparation of F1 generation: ① Orthogonal: White snakehead female × Golden snakehead male; ② Reciprocal cross: Golden snakehead female × White snakehead male; Each group lays ≥12,000 eggs, with a hatching rate ≥80%, resulting in a Platinum Hybrid F1 generation mixed population.

[0022] 2.2 Preparation of F2 generation: Select 50 female and 50 male individuals from the F1 generation of platinum hybrids and perform reciprocal crosses within the population to obtain the F2 generation of platinum hybrids.

[0023] 2.3 Backcrossing to create paternal and maternal lineages: ① Paternal line: Backcrossing of Platinum hybrid F2 generation ♂ × White snakehead ♀ yields colored snakehead paternal line ♂; ② Maternal line: Backcrossing of Platinum hybrid F2 generation ♀ with White Snakehead ♂ yields Colored Snakehead female maternal line; 1000 tails were retained from each group for breeding, and the group with superior growth (daily weight gain ≥2.5 g / d) was selected.

[0024] 2.4 Crossbreeding with breeding systems: By combining a male (male) and a female (female) of the colored snakehead, you can obtain the target colored snakehead G0 generation.

[0025] 3. Target trait fixation and subgeneration selection 3.1 Body color selection: Each generation was selected based on the criteria of "white as the base color, with obvious colored stripes or round spots, and clear and unconnected patch boundaries", with a retention rate of ≤10%.

[0026] 3.2 Production performance threshold: ① Each female fish lays ≥12,000 eggs per year; ② Each female fish can produce ≥6000 healthy live fry per year; ③ Overwintering survival rate ≥90% (water temperature 4-6 ℃, 30 days); ④ 180-day-old animals with a body weight ≥450 g and a feed conversion ratio ≤1.1.

[0027] 3.3 Subgeneration breeding: Subgeneration within the population for 6-8 consecutive generations, estimating heritability h in each generation. 2 ≥0.35, to ensure stable body color and major economic traits.

[0028] 4. Propagation and Promotion: After selective breeding, the new snakehead strain has an average yield of 11,700 fry per parent fish, with a total yield of 144,000 fry. Except for those selected for further breeding as parent fish, the others are promoted as commercial fish for consumption and ornamental purposes in Sichuan, Chongqing, Jiangsu, Shandong and other places.

[0029] The obtained colored snakehead was compared with white and golden snakehead. The new snakehead strain (strain) was significantly superior to the parent strain in terms of effect time, number of eggs laid per clutch, fertilization rate, and number of fry surviving in the clutch, and the performance was extremely significant. P <0.01%, and the hatching rate was also better than that of the parents, showing significant performance. P <0.05). See Tables 1-4 for specific results.

[0030] Table 1. Comparison of spawn-inducing effects between new varieties (strains) of snakehead and white snakehead.

[0031] Note: The new snakehead varieties mentioned in the table are snakeheads that have undergone eight consecutive generations of subculture within a population; peer comparison. P <0.05 indicates a significant difference. P <0.01 indicates a highly significant difference. P >0.05 indicates that the difference is not significant, and the same applies below.

[0032] Table 2 Comparison of spawn-inducing effects between new varieties (strains) of snakehead and golden snakehead.

[0033] Table 3 Comparison of reproductive performance between new varieties (strains) of Snakehead fish and White Snakehead fish

[0034] Table 4 Comparison of reproductive performance between new varieties (strains) of snakehead and golden snakehead.

[0035] Example 2: Low Temperature Tolerance Test Three hundred 180-day-old colored snakehead G6 generation fish were selected, with 150 white snakehead fish and 150 golden snakehead fish as controls. The water temperature was set at 5±0.5℃, and a low-temperature tolerance test was conducted for 30 consecutive days. The results are shown in Tables 5 and 6. The survival rate of colored snakehead fish was 94.6%, that of white snakehead fish was 65.3%, and that of golden snakehead fish was 71.3%, with extremely significant differences (P<0.01).

[0036] Example 3: Virus Invitation Protection Rate Test Three hundred 180-day-old colored snakehead G6 generation individuals were collected, with 150 white snakehead individuals and 150 golden snakehead individuals serving as controls. Aeromonas hydrophila was activated (streaked onto agar solid medium), amplified (single colonies were picked and inoculated onto broth liquid medium, shaken and cultured to mid-logarithmic phase), and its concentration and dilution were determined (the optical density (OD) of the bacterial suspension at 600 nm was measured using a spectrophotometer; the OD value was converted to a specific bacterial concentration according to the standard curve; and the bacterial suspension was diluted with sterile physiological saline to achieve a concentration of 1 × 10⁻⁶). 7 The drug was administered via intraperitoneal injection (CFU / mL) at a dose of 0.2 ml / kg, and observed at 28℃ for 7 days. The results are shown in Tables 5 and 6. The relative survival rates of the colored snakehead were 82.5%, the white snakehead 41.3%, and the golden snakehead 54.7%.

[0037] Example 4: Proliferating Data In 2024, the core breeding farm preserved 2,500 fish fry, and the propagation farm produced 520,000 commercial fish fry, with an average yield of 9,280 fry per female, meeting the requirements for promotion.

[0038] Table 5 Comparison of growth performance between new varieties (strains) of snakehead and white snakehead.

[0039] Table 6 Comparison of growth performance between new varieties (strains) of snakehead and golden snakehead.

[0040] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for cultivating colored snakehead fish, characterized in that: Includes the following steps: (1) Common white snakehead and golden snakehead were selected as the original parents; (2) Cross the white snakehead and the golden snakehead in opposite directions to obtain the F1 generation; (3) The F1 generation is obtained by reciprocal crosses between male and female individuals within the population; (4) Backcross the F2 generation with white snakehead to establish the paternal and maternal lines of colored snakehead; (5) Cross the male line of the colored snakehead with the female line of the colored snakehead to obtain the G0 generation of colored snakehead; (6) Conduct continuous 6-8 generations of in-situ breeding of the G0 generation of colored snakehead; (7) When the number of new strains is ≥50,000 and the body color consistency rate is ≥95% for three consecutive generations, propagation and promotion shall be carried out; In step (6), during the selection of successor generations, select colored snakehead with white as the base color and obvious colored patches, and combine growth performance, disease resistance performance and low temperature resistance performance. The colored patches have four main color systems: pure white, golden white, orange white and black and white. The disease resistance is defined as a survival rate of >80% after challenge with Aeromonas hydrophila; the low temperature resistance is defined as a survival rate of ≥90% after 30 days at 4-6 ℃.

2. The cultivation method according to claim 1, characterized in that: The common white snakehead mentioned in step (1) is 2 years old, weighs ≥800 g, and has a pure white body without any other colors; the golden snakehead is 2 years old, weighs ≥700 g, and has a golden yellow body without any black spots.

3. The cultivation method according to claim 1, characterized in that: The growth performance is defined as a body weight ≥450g at 180 days of age.

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