A breeding method for high temperature resistant largemouth bass

Abstract

The invention provides a breeding method for high-temperature resistant largemouth black bass, comprising large-group breeding, gene sequencing, F1 generation breeding and breeding grouping and gene homozygosity determination, F1 population establishment, F2 generation breeding and group breeding, F3 generation breeding and high-temperature resistance verification; three generations are cultivated by a breeding method combining group breeding and gene breeding, largemouth black bass with fast growth rate and high-temperature resistance are bred, the temperature range suitable for the growth of largemouth black bass is expanded, and the yield of largemouth black bass is increased.

Description

Technical Field

[0001] The invention relates to a method for breeding improved varieties of aquaculture species, in particular to a method for breeding high-temperature resistant largemouth black bass. Background Art

[0002] Largemouth bass, commonly known as California bass, is native to freshwater waters of North America. It was introduced to my country in the early 1980s. As of 2021, my country's California bass farming output has reached more than 500,000 tons, mainly farmed in Guangdong, Jiangsu, Zhejiang, Shanghai and other places, of which Guangdong's farming output accounts for more than 60% of the national output. Largemouth bass is a wide-temperature carnivorous freshwater precious fish with the characteristics of fast growth and high nutritional value. The survival temperature is 1℃-36℃, and the most suitable temperature for growth is 20-30℃. When the temperature reaches above 30℃, the largemouth bass's foraging situation will gradually decrease with the increase in temperature, and diseases are prone to break out.

[0003] The temperature in Guangdong in spring, autumn and winter is about 12℃~30℃, which is suitable for the growth of largemouth bass. Generally, the fry are released in March and caught in October. They can reach sexual maturity in one year. However, in July-September in Guangdong, the temperature can reach up to 37℃, and the surface temperature of the water can reach 36℃. Largemouth bass live 1.5 meters underwater, and the temperature of their living layer can reach 32℃, which has exceeded the maximum temperature suitable for the growth of largemouth bass. Therefore, largemouth bass grow slowly and are prone to disease and death under high temperatures in summer, which seriously affects the production of largemouth bass. Therefore, it is urgent to genetically improve the temperature resistance of largemouth bass and select new high-temperature resistant varieties with excellent growth performance.

[0004] Commonly used breeding methods include group breeding, family breeding and gene breeding. Group breeding has the advantages of being able to intuitively breed individuals with excellent traits and the selected individuals can match the actual production, but this method has a large population and a large workload, and the bred individuals are not genetically homozygous, so it takes 3-5 generations of breeding, and the bred offspring may be heterozygous; family breeding has the advantage of high genetic homozygosity, but because family breeding is carried out in small ponds, the individuals bred with excellent traits are prone to lack of excellent traits during large-scale production and breeding; gene breeding has the advantages of fast breeding and directional change of biological traits, but the genotype and phenotype of individuals bred by gene breeding are difficult to match. Summary of the invention

[0005] The present invention provides a breeding method for high-temperature resistant largemouth black bass. The breeding method combining group breeding and gene breeding is used to breed three generations, and largemouth black bass with fast growth rate and high-temperature resistance are bred, thereby expanding the temperature range suitable for the growth of largemouth black bass, increasing the output of largemouth black bass, and further improving the economic benefits of largemouth black bass breeding.

[0006] A method for breeding high temperature resistant largemouth bass, the specific operation is as follows:

[0007] S01. Selection and breeding of large groups of broodstock

[0008] In March, 50 ponds of 6 mu were prepared, and 20,000 largemouth black bass fry were placed in each pond. The largemouth black bass breeding ponds were kept until July, when the temperature in Guangdong was above 30℃. The largemouth black bass breeding ponds were observed twice a day in the morning and evening, and the air temperature, water surface temperature, water depth of 0.5 meters, 1 meter and 1.5 meters and the feeding status of the largemouth black bass in each breeding pond were recorded. The observations and records were made for 3 months. When the breeding ponds were kept until November, the weight of the adult largemouth black bass in the breeding ponds was counted, the average weight was calculated, and the individuals with fast growth rate and weight more than 1.8 times the average weight were selected as candidate broodstock.

[0009] S02. Conduct preliminary gene sequencing

[0010] The broodstock selected in step S01 and conventional largemouth bass were subjected to preliminary gene sequencing, and the gene differences were compared and analyzed to discover and determine the main effect genes of high temperature resistance.

[0011] S03, Yes Grouping by generation

[0012] The broodstock selected by S02 were bred in the usual way. Generation, 50 6-acre ponds, each with 20,000 largemouth bass Repeat the above step S01 for fry. In November, the weight of adult largemouth bass in the breeding pond is counted and the average weight is calculated. The weight of adult largemouth bass in the breeding pond is compared with the measured average weight and divided into 6 groups according to different proportions, which are 1.5 times Adult fish, 1.3 times Adult fish, 1.2 times Adult fish, 1x Adult fish, 0.8 times Adult fish, 0.7 times Adult fish.

[0013] S04. Conduct genetic verification

[0014] 1.5 times the selected Adult fish, 1.3 times Adult fish, 1.2 times Adult fish, 1x Adult fish, 0.8 times Adult fish and 0.7 times 6 groups of adult fish Gene sequencing was performed on adult fish separately, and the gene sequencing was compared and analyzed to determine the gene homozygosity in each group of the main effect gene of high temperature resistance.

[0015] S05. Establish high temperature resistance Broodstock

[0016] Select homozygous high temperature resistance main effect gene with a content of more than 1.5 times that of 3 groups Adult fish as Broodstock reserve.

[0017] S06. Carry out second generation population breeding. The specific operations are as follows:

[0018] Set the S05 selected The broodstock reproduced in the usual way Generation, 50 6-acre ponds, each with 20,000 largemouth bass Repeat the above step S01 method for fry. In November, measure Substitute body weight, verify The growth rate of largemouth bass was verified The high temperature resistance of the adult fish is selected to grow fast and weigh the largest Alternative broodstock.

[0019] S07. Breeding of heat-resistant largemouth bass The high temperature resistance capability is verified. The specific operations are as follows:

[0020] reserve The broodstock breeds the fry and raises them into adult fish in the conventional way. Generation, 50 6-acre ponds, each with 20,000 largemouth bass Repeat the above step S01 method for fry. In November, measure Adult fish weight, preliminary verification The homozygosity of the main effect gene for high temperature resistance and the growth rate of adult fish were measured, and the largest weight was selected. The adult fish were sequenced and the homozygosity of the main effect gene of high temperature resistance was verified again.

[0021] Further, the preliminary verification of step S07 The homozygosity of the main effect gene of high temperature resistance in adult largemouth bass is as follows: 80% The weight of the adult largemouth bass is greater than the weight of the parent fish selected in step S01 above, and 20% of the The weight of the adult largemouth bass is greater than 1.5 times the weight selected in step S03 above. Adult fish. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with specific embodiments.

[0023] The present invention provides a method for breeding a heat-resistant largemouth seabass, characterized in that the method comprises the following steps:

[0024] S01. Selection and breeding of large groups of broodstock

[0025] In March, 50 ponds of 6 mu were prepared, and 20,000 largemouth black bass fry were placed in each pond. They were raised until July, when the temperature in Guangdong was above 30℃. The largemouth black bass breeding ponds were observed twice a day in the morning and evening, and the air temperature, water surface temperature, temperature at 0.5 m, 1 m and 1.5 m depths, and the feeding conditions of the largemouth bass in each breeding pond were recorded. The observations and records were made for 3 months. When the largemouth black bass were raised to November, the weight of the adult largemouth black bass in the breeding ponds was counted, and the average weight was calculated to be 430g. The adult largemouth black bass with fast growth rate and weight greater than 780g were selected as candidate broodstock.

[0026] S02. Conduct preliminary gene sequencing

[0027] The broodstock selected in step S01 and conventional largemouth bass were subjected to preliminary gene sequencing, and the gene differences were compared and analyzed to discover and determine the main effect genes of high temperature resistance.

[0028] S03, conduct 1st generation population breeding

[0029] The broodstock selected by S02 were bred in the usual way. Generation, 50 6-acre ponds, each with 20,000 largemouth bass Repeat the above step S01 method for fry. In November, the weight of adult largemouth bass in the breeding pond is counted. There are largemouth bass of 400g to 900g in the breeding pond. The average weight is 600g. The weight of adult largemouth bass in the breeding pond is compared with the measured average weight, and divided into 6 groups according to different proportions, which are 1.5 times Adult fish, 1.3 times Adult fish, 1.2 times Adult fish, 1x Adult fish, 0.8 times Adult fish, 0.7 times There are 6 groups of different sizes of adult fish Adult fish, i.e. fish weighing 900g, 800g, 700g, 600g, 500g and 400g Substitute fish.

[0030] S04. Conduct genetic verification

[0031] The selected 900g, 800g, 700g, 600g, 500g and 400g are divided into 6 groups Gene sequencing was performed on adult fish separately, and the gene sequencing was compared and analyzed to determine the gene homozygosity in each group of the main effect gene of high temperature resistance.

[0032] S05. Establish high temperature resistance Broodstock population, the specific operations are as follows:

[0033] Select the largemouth bass with more than 3 groups of homozygous high temperature resistance main effect genes as 900g Broodstock reserve.

[0034] S06. Carry out second generation population breeding. The specific operations are as follows:

[0035] The 900g selected by S05 The broodstock reproduced in the usual way Generation, 50 6-acre ponds, each with 20,000 largemouth bass Repeat the above step S01 method for fry. In November, measure Substitute body weight, measured The weight of the adult fish is 730g-900g, verified The growth rate of largemouth bass was verified The high temperature resistance of the adult fish is selected, and the ones with fast growth rate and weight of 900g are selected. Alternative broodstock.

[0036] S07. Breeding of heat-resistant largemouth bass The high temperature resistance capability is verified. The specific operations are as follows:

[0037] reserve The broodstock breeds the fry and raises them into adult fish in the conventional way. Generation, 50 6-acre ponds, each with 20,000 largemouth bass Repeat the above step S01 for the fry, measure and count The weight of the adult fish was 750g-950g, and 84.8% was obtained. The weight of the adult fish is more than 780g, 21.1% The weight of the adult fish is more than 900g. The adult fish were sequenced and the homozygosity of the main effect gene of high temperature resistance was verified again.

[0038] The largemouth black bass bred by the technical solution provided by the present invention is conventionally cultivated until July. When the water depth is 1.5 meters and the temperature is 32°C, the largemouth black bass can forage normally. By the end of September, the normal size of the largemouth black bass can reach 800g-950g, while the normal size of the largemouth black bass before breeding is about 420g; the output of a 6-mu pond after breeding can reach more than 11 tons, while the output of a 6-mu pond before breeding is about 8 tons.

Claims

1. A method for selecting high temperature resistant largemouth bass, the specific operation is as follows: S01. Selection and breeding of large groups of broodstock In March, 50 ponds of 6 mu were prepared, and 20,000 largemouth bass fry were placed in each pond. The largemouth bass breeding ponds were kept until July, when the temperature in Guangdong was higher than 30℃. The largemouth bass breeding ponds were observed twice a day in the morning and evening, and the air temperature, water surface temperature, water depth of 0.5 meters, 1 meter and 1.5 meters, and the feeding status of the largemouth bass in each breeding pond were recorded. The observations and records were made for 3 months. When the breeding ponds were kept until November, the weight of the adult largemouth bass in the breeding ponds was counted, the average weight was calculated, and the individuals with fast growth rate and weight more than 1.8 times the average weight were selected as broodstock candidates; S02. Conduct preliminary gene sequencing The broodstock selected in step S01 and the conventional largemouth bass were subjected to preliminary gene sequencing, and the gene differences were compared and analyzed to discover and determine the main effect genes of high temperature resistance; S03. Grouping the F1 generation population The parent fish selected in step S02 are bred to F1 generation according to a conventional method, and 20,000 F1 generation fry of largemouth bass are placed in each of 50 ponds of 6 mu, and the above step S01 is repeated. By November, the weight of adult largemouth bass in the breeding ponds is counted to calculate the average weight, and the weight of adult largemouth bass in the breeding ponds is compared with the measured average weight, and the groups are divided into 6 groups according to different proportions, namely 1.5 times F1 generation adult fish, 1.3 times F1 generation adult fish, 1.2 times F1 generation adult fish, 1 times F1 generation adult fish, 0.8 times F1 generation adult fish, and 0.7 times F1 generation adult fish; S04. Conduct genetic verification The 1.5-fold F1-generation adult fish, 1.3-fold F1-generation adult fish, 1.2-fold F1-generation adult fish, 1-fold F1-generation adult fish, 0.8-fold F1-generation adult fish, and 0.7-fold F1-generation adult fish selected in step S03 are subjected to gene sequencing respectively, and the gene sequencing is compared and analyzed to determine the gene homozygosity in each group of the main effect gene of high temperature resistance; S05. Establishing a high temperature resistant F1 generation broodstock population Select F1 generation adult fish with more than 3 groups of homozygous high temperature resistance main effect genes and 1.5 times the amount as F1 generation parent fish reserves; S06. Conduct F2 generation population breeding The F1 generation broodstock selected in step S05 are bred into F2 generation offspring according to conventional methods, and 20,000 F2 generation fry of largemouth bass are placed in each of the 50 ponds of 6 mu, and the above step S01 is repeated. In November, the weight of the F2 generation is measured to verify the growth rate of the F2 generation largemouth bass, thereby verifying the high temperature resistance of the F2 generation adult fish, and the F2 generation broodstock with fast growth rate and the largest weight are selected as candidates; S07. Propagate the heat-resistant large-mouthed black scale F3 generation and verify its heat-resistant ability. The specific operation is as follows: The F2 generation broodstock selected in step S06 are bred and raised into F3 generation adult fish by conventional methods. 20,000 large-mouthed black-scaled F2 generation fry are placed in each of the 50 ponds of 6 mu, and the above step S01 is repeated. In November, the weight of the F3 generation adult fish is measured, and the homozygosity of the main effect gene for high temperature resistance and the growth rate of the F3 generation adult fish are preliminarily verified. The F3 generation adult fish with the largest weight are selected, and their genes are sequenced to verify the homozygosity of the main effect gene for high temperature resistance again.

2. The method for breeding a heat-resistant largemouth bass according to claim 1, characterized in that: The specific operation of the preliminary verification of the homozygosity of the main effect gene of high temperature resistance in F3 generation adult fish described in step S07 is as follows: the weight of 80% of the F3 generation largemouth black bass adult fish is greater than the weight of the parent fish selected in the above step S01, and the weight of 20% of the F3 generation largemouth black bass adult fish is greater than 1.3 times the weight of the F1 adult fish selected in the above step S03.