Study On Selection Of Large White New Line Of High NBA Base On Gene Pyramiding Strategy

To select new large white line with high NBA (number of piglets born alive) based on gene pyramiding strategy, genotypes of four candidate major genes, ESR, FSHβ, PRLR, RBP4 were tested in two Large White sow's populations, including 472 sows from Tianzhong company and 330 sows from Chia Tai company, were tested. Except for the genotypes of the RBP4 loci was homozygous with AA genotype, the ESR, FSHβand PRLR locus showed different polymorphism in the tested populations. The correlation between different genotypes and reproductive traits was also studied in this paper.The ESR, FSHβand PRLR locus showed different polymorphism in Tianzhong population and the frequencies of allele B were 0.507,0.553 and 0.718, respectively. Association of the polymorphism with reproductive traits showed that:no significantly associations of ESR allele with NBA were observed. The effect of FSHβloci was AB>AA>BB except for the first parities, the NBA of AB genotype population was significantly higher than BB genotype group. The largest effect in NBA was the PRLR loci and the NBA of AA was significant higher than others.Similarly, the ESR, FSHβand PRLR locus showed different polymorphism in the Chia Tai population and the frequencies of B allele were 0.502,0.688,0.538, respectively. Association of the polymorphism with NBA and TBA showed that:No significantly associations of ESR and PRLR alleles with NBA and TBA were observed. There were no significantly associations of FSHβon TBA. The results showed that the effect of A allele (Total Number of Piglet Born) was better than B allele on the NBA in Large White. The NBA of the sows of AA genotype population was higher than the sows of other genotypes. No regularity in three combin genotypes was found.According to the polymorphism and correlation analysis results of the four genes and information from reports,153 sows,25 boars with 9 different combinations of genotypes were selected to form the breeding F0 generation for higher reproductive performance line breeding. The marker gene pyramiding direction is BB-BB-AA (ESR genotype-FSHβgenotype-PRLR genotype). In breeding plan, the favorable genotypes will be pyramided in 3-5 generations. At the same time, a mating plan was constructed based on the result of genotypes test and reproductive performance recording.