Study On The Method Of Selection And Breeding Of Hybrid Swine

Synthetic line of hybrid swine is the direction of swine breeding in developed countries and the main pattern of producing market swine in the world in future. It is commercial behavior to breed the famous hybrid swine in the world, the selection method of hybrid swine is their commercial secret. In our country it is rarely to systemically study the method. In this article, the author analyses systemically the theory and the selection method of hybrid swine, by looking up the relevant information that report the breeding of the famous hybrid swine and binding the breeding practices of "Huate special strains". The results shows:Hybrid swine is the market swine that is produced by crossing between hybrid male and female or between pure sire line and hybrid female, which is produced by crossing between special strains. It is based on comprehensively genetic resources, the market requirement determined the breeding target. The selection method of hybrid swine is directed by quantitative genetics and the combination breeding theory , according to the genetic law of traits, using the trait separated within breed or cross between straits to establish nucleus population to breed special strains directly, every special line is a homogenote. The best cross pattern is determined by the results of combining ability test and estimation of the economic benefits.The breeding program describe all works of the breeding of hybrid swine, including genetic resources .breeding , reproducing and finishing, the classic breeding system only includes G.G. parent nucleus within breeding section, producing parent section and finishing section. The genetic resource is the base of the breeding of hybrid swine, breeding section is the core, in which completes the breeding of special strains, combining ability testing .determines the best cross system and establish the nucleus population of special strains. Within the third section, the main task is to produce the hybrid male and hybridABSTRACTfemale and commercial piglet according to the crossing system. Market pigs are finished in the last section.The breeding method of hybrid swine embodies mainly breeding of special lines and combining ability testing. Special strains are divided into dam lines and sire lines according to the difference that take on task in crossing system. Carcass traits and growing traits which have high & medial heritability are selected in sire lines, reproductive performance are selected in dam lines mainly. The hybrid female is produced by which the maternal sire line cross the maternal dam lines. The prolificacy is selected only that use family selection according to litter size and litter weight at birth, living litter size and litter weight at weaning in the maternal dam lines. Growing traits and reproduction performance are selected at time in the maternal sire lines, but the main trait selected is the growth traits according to backfat thickness and daily gain, the selection of the reproduction performance is subordinate according to litter size at birth and percentage pigs weaned, so the selection of maternal sire lines used individual selection within family. For the difference of crossing system , the paternal boars are pureline & hybrid male, they have the same selection aim, and use individual selection according to backfat and daily gain. If the paternal male is produced by crossing between paternal sire lines and dam lines, the prolificacy must be thought in paternal dam lines.According to breeding system theory , establishing the breeding system of 'Huate swine special lines' according to the requirement of the smallest population scale of the breeding special lines, 800,000 hybrid swine could be produced per year. There need 5250 G.G. parent sows and 97,000 parent sows if the breeding system is established according to producing 7,000,000 finishing pigs per year in Gansu province.