Cultivation method of new variety of high-temperature-resistant fast-growing penaeus monodon

Abstract

The invention relates to a method for cultivating a new variety of high-temperature-resistant fast-growing penaeus monodon, which belongs to the field of aquatic breeding and comprises the following steps of: performing extreme high-temperature acute stress for 4-7 days at a juvenile penaeus monodon stage of a batch constructed family and performing high-temperature long-term cultivation stress for 45-60 days at a juvenile penaeus monodon stage; performing weighted comprehensive evaluation on growth and survival rates of different families under a high-temperature condition by combining growth parameters including average survival time of individuals of the extreme high-temperature acute stress families and average survival rates and average weights of the high-temperature long-term bred families; and screening out family individuals which grow quickly and have strong high-temperature tolerance, carrying out breed conservation and cultivation to obtain parent parents, and carrying out passage and generation breeding to obtain the new high-temperature-resistant fast-growing penaeus monodon variety.

Description

Technical Field

[0001] The invention relates to the technical field of breeding new aquatic species, and in particular to a method for breeding a new high-temperature-resistant and fast-growing Penaeus monodon species. Background Art

[0002] Giant tiger shrimp grow rapidly, are large, and have thick shells. They are highly durable when exposed to air after leaving the water and can be sold alive. As poikilotherms, their ability to adapt to environmental changes (especially water temperature) directly impacts their growth, survival, and reproduction. Studies have shown that the optimal growth temperature for giant tiger shrimp is 28-32°C. Water temperatures that are too low or too high significantly impact their feeding, metabolism, and immune function. When water temperatures drop below 20°C or rise above 35°C, their growth rate and survival rate decrease significantly. Furthermore, high temperature stress can increase oxidative stress responses in aquatic animals and reduce their immune system, leading to growth retardation, developmental abnormalities, and even death.

[0003] The trend of global warming is becoming increasingly pronounced. Prolonged periods of high summer temperatures can lead to deteriorating water quality, often leading to disease outbreaks in shrimp farming, reduced production, or even total crop failure, posing a challenge to the sustainable development of shrimp farming. Therefore, conducting research on the heat tolerance of Penaeus monodon and breeding strains adapted to summer high temperatures through genetic improvement is crucial to enriching my country's shrimp farming varieties and implementing rotational culture methods for different varieties, thereby helping farmers avoid losses, promoting the sustainable development of shrimp farming, and enhancing the profitability and competitiveness of the industry. Summary of the Invention

[0004] The invention overcomes the shortcomings of the prior art and provides a method for cultivating a new high-temperature-resistant and fast-growing Penaeus monodon species.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for breeding a new strain of high-temperature-resistant and fast-growing Penaeus monodon prawns, comprising the following steps: subjecting batch-constructed families to acute extreme high-temperature stress for 4-7 days at the juvenile stage and to long-term high-temperature culture stress for 45-60 days at the juvenile stage; combining the average survival time of individuals in the families subjected to acute extreme high-temperature stress with the average survival rate and average body weight of each family subjected to long-term high-temperature culture; conducting a weighted comprehensive evaluation of the growth and survival rates of different families under high-temperature conditions; screening out individuals from families with fast growth and strong high-temperature tolerance for seed conservation and breeding to become parents; and conducting selective breeding through generations and cumulative generations to obtain a new strain of high-temperature-resistant and fast-growing Penaeus monodon prawns.

[0007] Furthermore, the extreme high temperature acute stress temperature is 36-40°C, the temperature of the aquaculture water body increases by 2°C every 24 hours from 30-32°C, and after the temperature reaches 36-40°C, the constant water temperature aquaculture is completed after 4-7 days.

[0008] Furthermore, the high temperature long-term culture stress temperature is 33-35°C.

[0009] Furthermore, the weighted comprehensive evaluation is as follows: growth traits are weighted 70%, and high temperature resistance traits are weighted 30%.

[0010] Furthermore, the temperature tolerance tests of each family were conducted in the same water environment. The tests at different stages could be conducted in different water bodies, but the test environment should be kept consistent at the same stage. In the first stage, the shrimps (P15-P25) were cultured in different small cages or small containers in the same water body.

[0011] The beneficial effects of the present invention compared with the prior art are as follows: the present invention subjects Penaeus monodon to different temperature stresses at two growth stages and, based on the growth conditions, rapidly screens out new varieties of Penaeus monodon that are heat-resistant and fast-growing. DETAILED DESCRIPTION

[0012] The technical solution of the present invention is further explained below through examples, but the protection scope of the present invention is not limited in any form by the examples.

[0013] Example 1

[0014] In a preferred embodiment of the present invention, the method for cultivating a new high-temperature resistant and fast-growing Penaeus monodon strain is carried out according to the following steps:

[0015] (1) Family scale construction and initial screening: Construct at least 20 families of Penaeus monodon with an age difference of ≤3 days, and cultivate each family to P15;

[0016] (2) 100-200 P15 shrimp larvae were randomly selected from each family. The temperature of the culture water was raised from 30-32°C by 2°C every 24 hours to 38±0.5°C for acute extreme high temperature stress. The water temperature was then kept constant for 7 days, and the survival time of each individual of each family was recorded. The temperature tolerance test of each family was carried out in the same water environment. In this example, the culture was carried out in different small cages in the same water body to ensure the same culture environment.

[0017] Under 38℃ high temperature stress, the cumulative survival rate and survival time of each family of Penaeus monodon are shown in Table 1. When the high temperature stress was 38℃ for 25h, no shrimp died in each family; after 50h, no shrimp died in families F0458, M0064, T0001 and S0001; after 100h, all shrimp in family M0003 died, and nearly half of the shrimp in families F0416, M0019, M0060 and M0064 died, with survival rates of 48%, 48%, 50% and 52% respectively, while F0415, F0432, F0458, M0008, The survival rates of F0442, M0007, M0095, S2028, S0001 and T0001 were between 55% and 90%, while the survival rates of other families were lower than 50%; at 125h, all shrimps from seven families, F0415, F0430, F0451, M0003, M0019, M0064 and M0080, died, while T0001 and S0001 still had survival rates of 70% and 64% respectively; at 150h, all shrimps died.

[0018] Survival times ranged from 48 to 150 hours across families. One-way analysis of variance (ANOVA) revealed highly significant differences in survival time between families (P < 0.0001). The standard deviations of survival time varied significantly among families, with the M0003 family having the smallest standard deviation (11.24) and the M0008 family having the largest (30.91). Furthermore, the coefficient of variation for survival time was highest in families M0060 and F0441 (33%), while the lowest was in family M0064 (14%).

[0019] Table 1 Cumulative survival rate and average survival time of each family of Penaeus monodon

[0020]

[0021]

[0022] Table 2 shows the results of a one-way ANOVA of the survival time of individuals from different families of Penaeus monodon at 38°C. This analysis revealed significant differences in survival time between families, with the F-test reaching an extremely significant level (P<0.0001). Further analysis of the results of the multiple comparison test revealed that the differences in survival time between experimental families were extremely statistically significant (P<0.0001), further confirming the significant differences in heat tolerance between families.

[0023] Table 2 Variance analysis of survival time of each family of Penaeus monodon at high temperature of 38℃

[0024]

[0025] (3) 1000-1200 P15 shrimp were randomly selected from each family and cultured for 30-45 days until P45-P60;

[0026] (4) Randomly select 300-400 uniform P60 juvenile shrimp from each family and perform fluorescent labeling;

[0027] (5) 30-50 fluorescently labeled individuals were randomly selected from each family and placed in six 20-square-meter cement pools for long-term culture experiments, including three normal temperature groups and three high-temperature long-term culture groups, with the water temperature at 34±0.5℃;

[0028] (6) After 56-60 days of breeding, the marking color and position of each surviving individual were collected, as well as the family to which they belonged. The data on traits such as carapace length, body length, and weight were shown in Tables 3 and 4. The growth, survival rate, and other important traits of each family were statistically analyzed based on the test data.

[0029] Table 3 Growth status and comprehensive scores of each family in the normal temperature group of the long-term breeding experiment

[0030]

[0031] Table 4 Growth status and comprehensive scores of each family in the high temperature group of the long-term breeding experiment

[0032] (7) Genetic parameter evaluation: The mixed linear model was used to calculate the extreme high temperature acute stress experiment (38 ± 0.5 ° C). The weighted comprehensive evaluation method is as follows: y = u + a + e, where y represents the survival time of the individual in the temperature stress experiment; u is the overall mean: the average value of all families on this indicator. For example, if the average survival rate of all families is 60%, then μ = 60; a is the additive genetic effect; e is the random residual effect;

[0033] Phenotypic variation is decomposed into two parts: heritable additive effects and non-heritable environmental errors. The heritability (h2) parameter expresses the contribution of the additive genetic effect to the overall variation. Its mathematical expression is:

[0034] h 2 =σ a 2 / (σ a 2 +σ e 2 )

[0035] Where, σ a 2 represents the component of variation caused by the additive effect of genes, σ e 2Reflects the variation component caused by environmental factors and other non-genetic factors. Using the standard normal distribution Z test method, the calculated statistic is:

[0036]

[0037] Where: h 2 represents the estimated heritability, The Z value indicates the corresponding standard error. Z (normalized value): This value represents the relative performance of a family on a specific indicator (such as survival rate or body weight). The higher the Z value, the better the family performs on that indicator (relative to the average level of other families). When Z ≥ 1.96, the correlation between heritability and phenotype is significant (P < 0.05); when Z ≥ 2.58, it is extremely significant (P < 0.01).

[0038] Heritability of high temperature tolerance traits in Penaeus monodon 2 =0.20;

[0039] The heritability of long-term culture stress tolerance to high temperature of 34±0.5℃ was calculated by mixed linear model. 2 The heritability of growth traits is 0.27. 2 The heritability of growth traits at room temperature is 0.34. 2 is 0.25;

[0040] (8) Based on a weighting of 70% for growth traits and 30% for high temperature resistance traits, the top 30% of the comprehensive breeding values were selected for accumulative breeding and testing to obtain a new high temperature resistant and fast growing line of Penaeus monodon.

[0041] The weights of survival rate, growth status and temperature of each family in the high-temperature breeding experiment were assigned by hierarchical analysis method to obtain a comprehensive score, and families with better comprehensive traits were selected for breeding.

[0042] Construct a judgment matrix: Compare the criteria at each level pairwise to assess their importance relative to the goals at the previous level. A 1-9 scale is often used to indicate the strength of the comparison results:

[0043] 1: Both elements are equally important;

[0044] 3: One element is slightly more important than the other;

[0045] 5: One element is more important than another;

[0046] 7: One element is clearly more important than another;

[0047] 9: One element is extremely more important than another;

[0048] 2, 4, 6, 8: intermediate situations.

[0049] The high temperature resistance trait is assumed to be slightly more important than the growth trait. According to the 1-9 scale, the weight of survival rate (high temperature resistance) is 0.3 and the weight of body weight is 0.7.

[0050] The normalization formula (Z-score) is: Z = (X - μ) / σ; where X is the actual measured value of a particular criterion for a family (e.g., 50% survival rate or 10g body weight), and μ is the population mean: the average value of that criterion across all families. For example, if the average survival rate across all families is 60%, then μ = 60. σ (standard deviation) is the standard deviation of all families for that criterion, reflecting the degree of data dispersion. A larger σ indicates greater inter-family variability.

[0051] For each sample, the normalized weight and survival rate data were weighted and summed according to the weights, and the formula was as follows: comprehensive score = w1×Z 存活 +w2×Z 重量 , where w1 and w2 are weight values determined according to the analytic hierarchy process (AHP). In high temperature tolerance breeding, w1 = 0.3, w2 = 0.7;

[0052] a. Survival rate standard:

[0053] Normal temperature group: Families with a survival rate of more than 70% are preferred to ensure good survival ability in a standard environment.

[0054] High temperature group: Since the survival rate is generally low under high temperature conditions, families with a survival rate of more than 30% are preferred, but the criteria will be relaxed appropriately based on the comprehensive score and weight.

[0055] b. Weight standard:

[0056] Normal temperature group: Families with final body weight reaching or exceeding 11g are given priority, showing good growth traits.

[0057] High temperature group: Because high temperatures affect growth, families with body weights of 7g or more were given priority, indicating that they still have a certain growth ability in a high temperature environment.

[0058] c. Comprehensive score reference:

[0059] The comprehensive scores were calculated using the analytic hierarchy process (AHP), as shown in Tables 5 and 6, with a weight of 0.3 for survival and 0.7 for weight. Families with a comprehensive score of 0.4 or above were selected, indicating excellent overall growth and heat tolerance.

[0060] Example 2

[0061] The F2 generation family selected in Example 1 was subjected to a high temperature resistant culture experiment in an indoor cement pool. Healthy, fast-growing, high temperature resistant Penaeus monodon fry of about 4-5 cm in length were selected. Common Penaeus monodon fry of the same size were selected as controls. Each experimental group had 30 fry, and each group had 3 parallel groups. The culture environment was the same. During the culture process, a high temperature stress experiment was performed. The F2 generation family had mixed growth characteristics in a cement pool for 2 months in the workshop: the average body weight of the F2 generation family in the normal temperature group (30°C) was 9.25-16.63g, with an average body weight of 11.93±1.74g, while the average body weight of the control group was 10.59±3.87g, and the growth rate was 12.65% higher than that of the control group; the average body weight of the F2 generation family in the high temperature group (34°C) was 5.58-9.43g, with an average body weight of 7.19±1.06g, while the average body weight of the control group was 5.96±2.27g, and the growth rate was 20.64% higher.

[0062] Example 3

[0063] The F2 generation families bred in Example 1 were subjected to a summer high-temperature resistant culture experiment in outdoor high-position ponds in Shenzhen. 5,000 healthy, high-temperature resistant and fast-growing F2 generation juveniles of Penaeus monodon with a body length of about 4-5 cm were selected for fluorescent labeling. At the same time, 15,000 common Penaeus monodon juveniles of the same size were selected as controls. The pond stocking density was 20,000 per mu and mixed in the same pond for growth test. Two parallel groups were set up and cultured for 130 days: the average weight of the shrimp of each family in pond No. 13 ranged from 21.43 to 44.8 g, with an average weight of 34.15±5.56 g, while the average weight of the wild population control group ranged from 29.15±5.56 g. The growth rate of the F2 generation was increased by an average of 15.68% compared with the control group. The average weight of the shrimp of the family in pond No. 14 ranged from 35.56±7.94 g, while the average weight of the control group ranged from 30.84±7.84 g. The growth rate of the F2 generation was increased by an average of 15.31%.

[0064] Example 4

[0065] The F2 generation family bred in Example 1 was subjected to a high temperature resistant productivity test aquaculture experiment (9 ponds covering an area of 20 mu). Healthy, high temperature resistant and fast-growing F2 generation shrimp fry of Penaeus monodon with a body length of about 1.5 cm were selected, and common Penaeus monodon of the same size were selected as a control. On August 3, 930,000 F2 generation fry and 450,000 wild control fry were stocked at a stocking density of 100,000 to 120,000 tails per mu. The culture was carried out for 102 days. The average body length of the F2 generation was 12.52 ± 1.03 cm, the average body weight was 27.78 ± 7.13 g, and the average per mu yield was 2000 to 2125 kg. The average body length of the control group was 12.0 ± 1.11 cm, the average body weight was 25.01 ± 7.12 g, and the average per mu yield was 1650 to 1750 kg. The average body weight growth rate increased by 11.08%, the culture survival rate increased by 6%, and the yield increased by 21%.

Claims

1. A method for cultivating a new strain of high-temperature resistant and fast-growing Penaeus monodon, characterized in that: By subjecting the juvenile shrimp stage of batch-constructed families to extreme high temperature acute stress for 4-7 days and the juvenile shrimp stage to high temperature long-term cultivation stress for 45-60 days, and combining the average survival time of individuals in the families subjected to extreme high temperature acute stress and the average survival rate and average weight of each family subjected to high temperature long-term cultivation, a weighted comprehensive evaluation was conducted on the growth and survival rates of different families under high temperature conditions, and individuals from families with fast growth and strong tolerance to high temperature were screened out for seed preservation and cultivation into parents, and then carried out multi-generational selection and breeding to obtain a new variety of high-temperature resistant and fast-growing giant tiger shrimp.

2. The method according to claim 1, characterized in that The extreme high temperature acute stress temperature is 36-40°C, and the temperature of the aquaculture water body is increased by 2°C every 24 hours from 30-32°C. After the temperature is increased to 36-40°C, the aquaculture is carried out at a constant water temperature for 4-7 days.

3. The method according to claim 1, characterized in that The high temperature long-term culture stress temperature is 33-35°C.

4. The method according to claim 1, wherein The weighted comprehensive evaluation is as follows: growth traits are weighted 70% and high temperature resistance traits are weighted 30%.

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