Selection And Its Use And Breeding

Selection And Its Use And Breeding
Selection And Its Use And Breeding

Video: Selection And Its Use And Breeding

Отличия серверных жестких дисков от десктопных
Video: Selective Breeding | Evolution | Biologyl | FuseSchool 2023, February

Selection, along with selection and proper rearing of young stock, is an essential element of breeding work. After the selection of the best animals for breeding purposes has been made on the basis of a comprehensive comprehensive assessment, the question arises of further work with the selected animals.

Zootechnical practice shows that arbitrary pairing of animals selected for a tribe does not always give the expected results. The value of the broodstock largely depends on the quality of the queens with which they mate. Their compatibility with different queens is not the same: with some queens, producers give valuable offspring, with others - mediocre and even bad. The problem of breeding selection appears, which, in contrast to selection, which decides the fate of each individual, determines the quality of future offspring.

English Setter, dog photo photo
English Setter, dog photo photo

English setter

Breeding is the most appropriate pairing of selected animals in order to obtain from them offspring with the desired qualities. In zootechnical practice, it is often necessary to leave not only excellent, but also mediocre animals for further breeding, and the task of breeders is to use them correctly in breeding work, take the best from them and get rid of shortcomings. And this is achieved by a reasonable selection of appropriate partners for such animals.

In breeding work, a distinction is made between the selection of males to queens and queens to males. For the improvement of broodstock, they select producers who are superior in value to queens. When working with lines, in particular with line successors, queens are usually matched to the producer, with the aim of not only preserving the valuable qualities of the producer, but also enriching them. Selection is closely related to selection. On the one hand, he completes the selection, and on the other, he completes it, since after obtaining the offspring and correctly rearing it, selection is again made on the basis of a comprehensive assessment.

Известно, что Ч. Дарвин мало касался проблем подбора, хотя и считал, что подбор имеет решающее значение в племенной работе. В научную разработку проблем племенного подбора большой вклад внесли такие известные русские ученые, как П. Н. Кулешов, Е. А. Богданов, М. Ф. Иванов, М. М. Щепкин, Д. А. Кисловский, Н. А. Кравченко и другие. Е. А. Богданов впервые подошел к вопросам подбора с генетических позиций, считая, что путем подбора удается все ценные гены, обусловливающие наибольшее развитие ценных признаков, собрать в одну цепочку, воедино и таким образом улучшить наследственность животных.

MM Shchepkin believed that it was necessary to carefully study and comprehensively know the hereditary qualities of animals, to find out how they are combined. All zootechnicians are well aware of the catch phrase from his book "From the observations and thoughts of a breeder": "Without knowledge of blood, there is no breeding business."

MF Ivanov, studying specific animals, always tried to determine what of them can be "squeezed out" on the way to the set goal, with which partners it is more expedient to use them in further work.

Selection was the basis of the art of cattle breeding, which, with the accumulation of scientific data, turned into the science of breeding farm animals.

Italian bracque, or Italian Pointing Dog, photo photograph of a dog
Italian bracque, or Italian Pointing Dog, photo photograph of a dog

Italian marriage

Despite the fact that selection plays a leading role in the improvement of animals, its theoretical foundations are poorly developed.

In general, the reasons for the different combinations of animals in the selection are well known. They are associated primarily with a complex genetic conditionality of most of the useful traits of animals. The value of any quantitative trait (namely, they are dealt with in the improvement of animals in most cases) depends on the entire set of genes in the body, the interaction of allelic and non-allelic genes with each other through the products of their synthesis and the influence of environmental conditions. Outstanding performance of an individual is determined by a favorable combination of genes and their interactions. These favorable combinations of genes, which give the greatest phenotypic manifestation of a trait, are difficult to preserve in offspring, since they are destroyed as a result of the formation of gametes during sexual reproduction.Accidental separation of chromosomes during gamete formation and accidental combination of chromosomes during fertilization lead to tremendous hereditary variability.

Even if the chromosome maps of mating animals were fully known (and this question is still very far from being solved in relation to domestic animals), due to a random combination of germ cells, it is impossible to predict the quality of the offspring obtained. To do this, you still need to master the management of the processes of separation of chromosomes and the combination of their favorable sets during fertilization. The problem is extremely difficult, and at present it is not even posed for practical solution.

In connection with the development of immunogenetics and the accumulation of information about specific gene sets in individual individuals, which can be considered as a sample for characterizing the genotype of an animal, attempts were made to trace the relationship between them and the productive and reproductive qualities of animals.

Data on the relationship between individual genes, as well as their complexes, on the one hand, and the productive qualities of animals, on the other, are extremely contradictory and have not yet found practical application. More encouraging are data on the immunogenetic similarity of offspring with their outstanding ancestors and materials on the relationship between the general homo- or heterozygosity of an organism with its productivity and reproductive function.

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