The genetic variation analysis of (1) population, as the basis of genetic diversity preservation, requires a comprehensive understanding of the genetic variation within and between existing livestock and poultry genetic resources. With the development of molecular genetics technology, the analysis of genetic variation has developed from phenotype and protein polymorphism to DNA molecular level. Using DNA polymorphism, we can analyze the genetic variation of populations more comprehensively and accurately, and also determine the genetic relationship between populations. (2) Cryopreservation At present, it is basically feasible to preserve the semen of most livestock and poultry for a long time by using ultra-low temperature freezing technology. It is best to combine frozen semen bank with live seed preservation to reduce the influence of natural selection, inbreeding and genetic drift, and is not limited by population size. However, an important defect of frozen semen is that a series of backcross must be carried out with frozen semen if you want to obtain purebred basically consistent with the existing genetic characteristics in the future.
In order to overcome the defects of frozen semen, it is best to combine frozen embryos for livestock and poultry translocation and preservation, and it can be obtained in time through suitable recipients when purebred is needed. (3) With the progress of various reproductive technologies, reproductive technologies are playing an increasingly important role in the preservation of genetic resources, such as superovulation and embryo transfer, embryo segmentation and embryo cloning. Superovulation and embryo transfer technology can give full play to the role of excellent female livestock, which is very valuable for livestock with low fertility, such as cattle, horses and sheep.
Embryo segmentation and cloning have been successful in many mammals, and somatic cell cloning has also been successfully reported. Normal embryos can obtain genetically identical embryos through mechanical division. (4) Gene Localization and DNA Library With the progress of molecular genetic technology, some efficient DNA molecular genetic markers have pushed the research of various livestock and poultry genetic maps into practical use. Through gene mapping, some genes with unique properties are located in a specific section of a chromosome, and the order of linear arrangement of genes on the chromosome and the distance between them are determined. More importantly, great progress has been made by mapping some quantitative trait genes closely related to the production performance of livestock and poultry, and some quantitative trait loci (QTL) which have great influence on quantitative traits have been located. (5) The disease diagnosis and control of the health status of breeding pigs is one of the important limiting factors for the international exchange and utilization of genetic resources. With the introduction of excellent breeding pigs, some infectious diseases may also be introduced, whose side effects may offset the potential benefits of the introduction and even have long-term adverse effects, while the quarantine procedures for germplasm import are very cumbersome and expensive. New technologies such as semen filtration and embryo washing have considerable application prospects for improving the health status of germplasm.