CATDOLL : CATDOLL: Fish breeding programmes? What is selective breeding? What are the main types of variation used in selective breeding?

1. Fish breeding program?

Water insemination

Use a large shallow white basin, fill it with clean, air-dried tap water to a depth of 1/2, and put an appropriate amount of duckweed or foxtail algae bundles, let them float in the water as a fish nest. Then, goldfish breeders can hold the determined standard parent fish in the water with their left and right hands, let their cloaca face each other, and gently squeeze the abdomen of the male parent fish with the thumb to squeeze out the milky white semen. At the same time, the thumb of the other hand also gently squeezes the abdomen of the female parent fish to squeeze out the mature eggs. The sperm and eggs complete the fertilization process in the water, and the fertilized eggs will immediately adhere to the water plants. In order to ensure the normal hatching of the fertilized eggs, goldfish breeders should immediately move the water plants attached to the fish eggs to another water body with better conditions to hatch the seedlings.

The cloaca of the broodstock are facing each other, and the thumb gently squeezes the abdomen of the broodstock to squeeze out the semen and eggs at the same time.

Both hands gently shake in the water, allowing the eggs to fall evenly into the fish nest with the water.

2. What is selective breeding? What are the main variations used in selective breeding?

During the planting process, plants will produce many trait variations. The process of artificially selecting and breeding these natural variations or artificial pollination variations to cultivate new strains is called selective breeding. This is one of the important means in conventional plant breeding.

Since it is a natural variation, it means that gene mutation, gene recombination and chromosome variation can be utilized.

3. What are the differences between hybrid breeding and selective breeding?

1. There is a difference between hybrid breeding and selective breeding. 2. Hybrid breeding refers to the mating of two parents with different genotypes to produce offspring with better traits through the combination of genes. Selective breeding is based on selective breeding. Some individuals are selected for breeding according to certain traits of the variety to obtain offspring with better traits. 3. Both hybrid breeding and selective breeding have a wide range of application scenarios in practical applications. Choosing appropriate breeding methods according to different purposes and breeding objects can effectively improve the yield and quality of crops and livestock. At the same time, in hybrid breeding, factors such as the adaptability and genetic background of the parents are usually considered, while in selective breeding, attention should be paid to the stability and plasticity of the breeding characteristics so that they can better adapt to various environmental conditions.

4. What are the factors that affect the effectiveness of selective breeding?

The factors that affect the effectiveness of selective breeding are as follows:

(1) Environmental impact

The purpose of selection is to obtain the genotype required for production in a relatively short period of time. Generally, genotype is known through phenotype, but because the heritability of many quantitative traits is not strong enough, they are easily affected by the environment, so the phenotype of an individual cannot represent the genotype well.

The selection conditions and surrounding environment should be fully considered when carrying out breeding.

(2) Genes that control traits and their heritability

Generally speaking, quality traits are controlled by one or two pairs of alleles and are dominant or recessive, making them easy to observe and distinguish; while quantitative traits are controlled by multiple pairs of genes and are more difficult to select.

The size of heritability is also an important factor affecting selection. Heritability refers to the relative ability of a trait to be passed from parents to offspring. Generally, traits with high heritability are easy to select, while traits with low heritability are more difficult to select.

(3) Selecting strong individuals as parents often affects the selection effect

Because the strong traits of animals are often related to heterozygosity, selecting strong animals for breeding and passing on will unconsciously make the heterozygous type dominant and inhibit the development of the homozygous type.

In short, there are many factors that affect the effect of selection, including whether the selection target can remain unchanged for a long time, whether the basis for selection is correct and reliable, whether the genes, heritability and genetic correlation of the selected traits are clearly studied, etc.

5. What is the significance of triploid breeding in fish?

The sterility of triploids makes the artificial induction of triploid fish one of the research areas of concern in the aquaculture industry. In recent years, some research results have begun to be applied in aquaculture production. This article briefly introduces the significance, principle, method, research status and prospects of fish triploid induction.

6. What is the overview of fish breeding technology research in my country?

my country has made remarkable progress and achievements in the research of fish breeding technology, especially the development in the fields of genetic breeding and molecular biology in recent years, which has greatly promoted the progress in this field. At present, the main research directions of fish breeding technology in my country include the following aspects:

1. Breeding of superior species: Breed fish species with excellent traits such as disease resistance, high yield and high quality through genetic improvement and artificial selection.

2. Genetic breeding: Using genetic principles and techniques to conduct genomics, develop genetic markers, construct genetic maps and other research to promote the progress of fish breeding.

3. Reproduction technology: including artificial insemination, controlled reproduction, genetic modification and other technologies, which solve problems such as limited breeding season and improve the reproduction efficiency of fish.

4. Farming management technology: including vertical technologies such as water quality management, feed nutrition, and disease prevention to ensure the healthy growth of fish during the farming process.

Overall, my country's fish breeding technology research has continuously made new progress and achievements, providing strong support for the development of my country's aquaculture industry.

7. What fish can be caught with garlic?

Garlic can be used to catch crucian carp and silver carp. Other fish are not easily attracted by the smell of garlic or do not like to eat flour bait. However, it is possible that other species of fish may occasionally take the bait.

Whether it is fishing competition or ordinary fishing, bait is always a very important part. In this technical field, it can be divided into two aspects: the selection of bait and the use of bait. Here we are talking about the latter. After you have determined the bait items to be used (it may be a single type or a mixture of multiple baits and additives), the use of bait can be considered from the beginning of mixing the bait.

8. What fish can be caught in Dongjiang River?

Dongjiang Lake is located in Zixing City, Chenzhou City, Hunan Province, with a total area of ​​160 square kilometers, an average water depth of 51 meters, a maximum depth of 157 meters, and a water storage capacity of 8.12 billion cubic meters. Dongjiang Lake is not only rich in tourism resources, but also rated as a 5A scenic spot by the state.

Dongjiang Lake is very rich in fish resources, including rainbow trout, Dongjiang Lake sturgeon, mandarin fish, red carp, triangular bream, tilapia, American spotted catfish, Xiangyun crucian carp, whitebait, sea bass and the four major carps, all of which can be caught in Dongjiang River.

9. What are the steps for systematic breeding and mixed selection breeding of sexually propagated plants and how to improve the efficiency of selective breeding?

The basic selection methods for selective breeding of sexually propagated horticultural plants include mass selection and single plant selection.

Mixed selection method: Select excellent individual plants that meet the breeding goals from an original mixed population, mix them for seeds, sow them in the same nursery the next year, plant them adjacent to standard varieties and original population plots, and compare and identify them. Mixed selection of the original population is only performed once, and when the selection is effective, it is propagated and promoted, which is called a single mixed selection method. Multiple mixed selections are performed on the original population and then propagated and promoted, which is called multiple mixed selections.

Advantages of hybrid selection method:

It is simple and easy, saving time and effort. It does not require a lot of land, labor and special experimental nurseries to quickly separate excellent types from mixed groups, and can obtain more breeding materials in a short time, which is convenient for early promotion. It can also purify good varieties of seriously mixed farm varieties. During mixed selection, different individual plants can be freely pollinated, which can maintain rich genetic characteristics, so it will not cause vitality decline.

Disadvantages of hybrid selection method:

Mixed breeding cannot identify the advantages and disadvantages of each individual genotype, which means that individual plants with outstanding traits due to superior environmental conditions are selected, but their genotypes are not excellent, thus reducing the selection effect.

Single plant selection method: select excellent single plants from the original population, number them, keep them as seeds, plant them into a single plant plot the next year, and compare and identify them based on their performance. If single plant selection is only performed once, each plant line will be used as the selection unit in the future, which is called single plant selection.

Advantages of single plant selection method:

The genotype of the selected superior strain can be identified, errors caused by environmental variation can be eliminated, and selection efficiency can be improved.

Disadvantages of single plant selection method:

A. It is time-consuming and labor-intensive. Special nurseries need to be set up and cross-pollinating crops need to be isolated.

B. Repeated isolation pollination of cross-pollinated crops can easily lead to a decline in vitality.

C. The amount of seeds retained after one selection is limited, and it is difficult to quickly apply the superior lines to production after they are selected.

The main methods of accelerating seed selection: conducting production tests and multi-point tests in advance; using protected areas to carry out multi-generation breeding selection in one year; accelerating breeding by cultivating in other places; accelerating breeding and improving seed reproduction coefficient.

10. Parent selection for backcross breeding?

The effectiveness of backcross breeding depends to a large extent on whether the parent selection is appropriate.