Study On The Genetic Structure And Seletion Method Of Multi-line Hybrid Breed System

Special line of hybrid swine is the direction of swine breeding in developed countries and the main measure of breeding of domestic swine. The research of Special line of our country is still in the stage of start and has a large gap contrast with the abroad ,especially in molecule research. The consciousness of utilization of total heterosis of multi-line hybrid breed system is not enough, The knowledge of heterosis mechanisms is scarce.The purpose of study is aimed at studying the genetic structure of Duroc × Landrace × Yorkshire of the three-breed cross breeding System and Seghers 5-line-crossbreed commercial hybrid line by using eight microsatellite DNA genetic markers and quantity genetics.It was systematically analyzed that the relationship between economic traits and DNA marker locus, in which some works were done to explore the genetic effect. The emphases are to reversely deduce the process of breeding and method through the characteristic bands of special line and provide the academic theory in order to establish Special line of hybrid swine of our country. Results as follow:1. Five herds of Duroc × Landrace × Yorkshire of three-breed cross breeding System and eight herds of Seghers 5-line-crossbreed commercial hybrid line were studied. The herd genetic structures, genetic diversity and the distance among herds were analyzed. Result show: The numbers of alleles in each pure breed herds were different from each other. There were great genotype frequency differences among pure breed herds. This indicated that pure breeds have different genetic background.2. The average locus heterozygosity and average polymorphism information content of pure breed herds were wide. The result above showed that the genetic diversity of DLY and Seghers herds at these locus was high, The average locus heterozygosity and average polymorphism information content of pure breed herd, grandparent herd, parent herd and commercial hybrid herd rose gradually with the decline of herd position in the hybrid system. The average locus heterozygosity is positive correlation with heterosis and can be used to predict the heterosis.3. Maternal line and paternal line have large genetic distance according to standardgenetic distance of Nei 's. Maternal line and paternal line with large genetic distance will...